Wednesday, November 18, 2009

Diamond Concrete Cutting, Drilling and anti Slip Floor grooving specialist Contractors

Diamond Concrete Cutting, Drilling and anti Slip Floor grooving specialist Contractors.

Services

Castle & Pryor supply leading edge diamond drilling and diamond cutting services to the construction industry and the demolition industry nationally. We provide innovative and cost-effective solutions on precision;

•Concrete cutting
•Concrete crushing
•Wall sawing
•Floor sawing
We also hire out specialist demolition and diamond cutting equipment. Our drilling services include diamond core drilling, percussion drilling and rock drilling.

Wall sawing (also called track sawing) and floor sawing provide efficient methods of precision concrete cutting and masonry cutting.

Hand concrete crushing provides almost silent controlled demolition reducing concrete to rubble without vibration or water. Our Brokk 3 phase electrical robotic demolition equipment allows us to extend many of the benefits of hand concrete crushing to a wider set of situations where conventional demolition machines cannot be used. We also provide other techniques such as wire sawing and concrete bursting to enable demolition and removal of large concrete structures.

Anti Slip Floor Grooving Services:

Castle and Pryor are able to undertake contracts installing Anti Slip Floor Grooving using the existing flooring, this approach is lower in cost and can be completed in a far shorter period of time then it would take to install a new floor.

What Surfaces would it work on?

•Wet and greasy floor areas in commercial kitchens such as Hospitals, Universities, Hotels and Restaurants
•Airports, Railway Stations, Shopping Malls, and Leisure Complexes
•Entryways and walkways via the stairs or down ramps
•All areas where the public walks and the problem exists
•Brick, concrete, ceramic, marble, terrazzo and similar surfaces
Previous contracts include

•RFU Twickenham
•Borehamwood Swimming pool
Companies and authorities use anti slip floor grooving to prevent aquaplaning on large areas where skidding or slipping is likely to happen. Using natural surface contours, water can be dispersed by using the shallow grooves as channels, moving the water away from a particular area.

PLANT HIRE SERVICES

We also hire out our specialist demolition and diamond cutting equipment - please ask for details …

Contact us to find our more about our leading range of concrete demolition, diamond cutting and diamond drilling services.

Specialists in diamond drilling and sawing, hire and sales. Working within the construction & civil engineering industries & aiding the controlled demolition industry with robotic demolition equipment & expertise.

A Quality Assured ISO 9001:2000 Company who are members of the Drilling and Sawing Association. All operatives are CSCS NVQ level 2 trained who are managed by internal D33 NVQ Assessors.

Our work is in the UK and overseas in a wide variety of materials and project situations - mainly with concrete and masonry but also with rock, percussion drilling for example.

Castle & Pryor Ltd has a wide range of concrete drilling and cutting products, for sale, hire or use.

Drilling & Cutting
•Diamond Drilling
•Rock Driling
•Floor Sawing
•Diamond Wire Sawing
Controlled Demolition
•Robotic Brokk Machines
•Hydraulic Concrete Demolition
Floor & Wall Preparation

•Floor Paning
•Wall Preparation
Anti Slip Solutions

•Anti Slip Grooving
•Anti Slip Step Treatment
Drilling and Cutting:Diamond Drilling Service,Concrete Drilling Offer,Rock Drilling Service,Floor Sawing,Wall Sawing,Diamond Wire Sawing.

Controlled Demolition: Brokk Robotic Machines, Hydraulic Concrete Demolition.

Floor and Wall Preparation: Floor Planning, Wall Preparation.

Anti Slip Solutions: Anti Slip Grooving,Anti Slip Step Treatment

Refractory Kiln Wrecking. Refractory kilns

Castle and Pryor Ltd
Elles House
4B Invincible Road
Farnborough
GU14 7QU (Road Map)
Hampshire

Tel: 01252 524080
Fax: 01252 524090

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Portable Toilets

At Portaloo, our all-steel, high-quality toilet and washroom facilities offer the same high standards you expect from permanent amenities. Our product range includes toilets, showers, changing rooms and toilet facilities designed especially for children.

Portable facilities - no compromise on quality

Because we believe plastic chemical loos do not meet the modern standards customers expect, we only offer all-steel portable washroom units. Our quality facilities are used all over the country by schools, councils, retailers and businesses for short and long-term use by staff, pupils and customers.

Quality comes as standard

•Outanding product quality - full flushing toilets, hot and cold running water and self-closing taps.
•All-steel construction - ensuring your facilities are robust and comfortable.
•Disabled persons and baby changing facilities.
•Complete solutions - including access ramps and steps.
A local service from the name you can trust

Portaloo is the name you can trust to supply the very best portable toilet and shower facilities. Unlike many competitors, Portaloo can offer you national coverage with our large number of Hire Centres which all offer the following service benefits:

•Promise to deliver on time and on budget.
•Free site visits to assess your needs.
•Quotes within 24 hours.
•Consumables refill service.
Click HERE to visit our website.

Portaloo Ltd
New Lane
Huntington
York
YO32 9PT (Road Map)
North Yorkshire

Tel: 0845 359 5960

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Retaining Structures

Retaining Structures

Enviromesh are the UK's leading name in gabion retaining walls with the company's personnel having over 40 years experience in design, sales, manufacture and on site support.

To support specifiers, three Technical Design Volumes and support documentation are available on the website for download. The company's products include:
•Welded mesh gabions and mattresses
•Gabion 39 system
•Gabion 27 system
•Gabion cladding
•Gabion trapezoidal units
•Woven wire mesh gabions
•Woven wire mesh gabion mattresses
•Woven wire mesh rock netting
•Assembly systems
•Clipping tools
•Helicals
•Bracing ties
•Lacing wire
The companies services include:
•FREE in house desk top design advisory service
•Site advice
•CPD approved presentation
•Technical design volumes and documentation
•Colour brochure
Enviromesh's products and services are available through a national network of 45 distribution points positioned throughout the UK and Ireland.

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Concrete - Drilling Equipment, Accessories

Concrete - Drilling Equipment, Accessories

Diamond Concrete Cutting, Drilling and anti Slip Floor grooving specialist Contractors.

Services

Castle & Pryor supply leading edge diamond drilling and diamond cutting services to the construction industry and the demolition industry nationally. We provide innovative and cost-effective solutions on precision;

•Concrete cutting
•Concrete crushing
•Wall sawing
•Floor sawing
We also hire out specialist demolition and diamond cutting equipment. Our drilling services include diamond core drilling, percussion drilling and rock drilling.

Wall sawing (also called track sawing) and floor sawing provide efficient methods of precision concrete cutting and masonry cutting.

Hand concrete crushing provides almost silent controlled demolition reducing concrete to rubble without vibration or water. Our Brokk 3 phase electrical robotic demolition equipment allows us to extend many of the benefits of hand concrete crushing to a wider set of situations where conventional demolition machines cannot be used. We also provide other techniques such as wire sawing and concrete bursting to enable demolition and removal of large concrete structures.

Anti Slip Floor Grooving Services:

Castle and Pryor are able to undertake contracts installing Anti Slip Floor Grooving using the existing flooring, this approach is lower in cost and can be completed in a far shorter period of time then it would take to install a new floor.

What Surfaces would it work on?

•Wet and greasy floor areas in commercial kitchens such as Hospitals, Universities, Hotels and Restaurants
•Airports, Railway Stations, Shopping Malls, and Leisure Complexes
•Entryways and walkways via the stairs or down ramps
•All areas where the public walks and the problem exists
•Brick, concrete, ceramic, marble, terrazzo and similar surfaces
Previous contracts include

•RFU Twickenham
•Borehamwood Swimming pool
Companies and authorities use anti slip floor grooving to prevent aquaplaning on large areas where skidding or slipping is likely to happen. Using natural surface contours, water can be dispersed by using the shallow grooves as channels, moving the water away from a particular area.

PLANT HIRE SERVICES

We also hire out our specialist demolition and diamond cutting equipment - please ask for details …

Contact us to find our more about our leading range of concrete demolition, diamond cutting and diamond drilling services.

Specialists in diamond drilling and sawing, hire and sales. Working within the construction & civil engineering industries & aiding the controlled demolition industry with robotic demolition equipment & expertise.

A Quality Assured ISO 9001:2000 Company who are members of the Drilling and Sawing Association. All operatives are CSCS NVQ level 2 trained who are managed by internal D33 NVQ Assessors.

Our work is in the UK and overseas in a wide variety of materials and project situations - mainly with concrete and masonry but also with rock, percussion drilling for example.

Castle & Pryor Ltd has a wide range of concrete drilling and cutting products, for sale, hire or use.

Drilling & Cutting
•Diamond Drilling
•Rock Driling
•Floor Sawing
•Diamond Wire Sawing
Controlled Demolition
•Robotic Brokk Machines
•Hydraulic Concrete Demolition
Floor & Wall Preparation

•Floor Paning
•Wall Preparation
Anti Slip Solutions

•Anti Slip Grooving
•Anti Slip Step Treatment
Drilling and Cutting:Diamond Drilling Service,Concrete Drilling Offer,Rock Drilling Service,Floor Sawing,Wall Sawing,Diamond Wire Sawing.

Controlled Demolition: Brokk Robotic Machines, Hydraulic Concrete Demolition.

Floor and Wall Preparation: Floor Planning, Wall Preparation.

Anti Slip Solutions: Anti Slip Grooving,Anti Slip Step Treatment

Refractory Kiln Wrecking. Refractory kilns

Read more...

Monday, November 16, 2009

Test To Check Soundness Of Cement

SOUNDNESS
Soundness of cement is determined by Le-Chatelier method as per IS: 4031 (Part 3) – 1988.
Apparatus – The apparatus for conducting the Le-Chatelier test should conform to IS: 5514 – 1969
Balance, whose permissible variation at a load of 1000g should be +1.0g and Water bath.



Procedure to determine soundness of cement
i) Place the mould on a glass sheet and fill it with the cement paste formed by gauging cement with 0.78 times the water required to give a paste of standard consistency.
ii) Cover the mould with another piece of glass sheet, place a small weight on this covering glass sheet and immediately submerge the whole assembly in water at a temperature of 27 ± 2oC and keep it there for 24hrs.
iii) Measure the distance separating the indicator points to the nearest 0.5mm (say d1 ).
iv) Submerge the mould again in water at the temperature prescribed above. Bring the water to boiling point in 25 to 30 minutes and keep it boiling for 3hrs.
v) Remove the mould from the water, allow it to cool and measure the distance between the indicator points (say d2 ).
vi) (d2 – d1 ) represents the expansion of cement.

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Determining The Marshall Stability of Bituminous Mixture

This test is done to determine the Marshall stability of bituminous mixture as per ASTM D 1559. The principle of this test is that Marshall stability is the resistance to plastic flow of cylindrical specimens of a bituminous mixture loaded on the lateral surface. It is the load carrying capacity of the mix at 60oC and is measured in kg. The apparatus needed to determine Marshall stability of bituminous mixture is

i) Marshall stability apparatus
ii) Balance and water bath



The sample needed is
From Marshall stability graph, select proportions of coarse aggregates, fine aggregates and filler in such a way, so as to fulfill the required specification. The total weight of the mix should be 1200g.

Procedure to determine Marshall stability of bituminous mixture
i) Heat the weighed aggregates and the bitumen separately upto 170oC and 163oC respectively.

ii) Mix them thoroughly, transfer the mixed material to the compaction mould arranged on the compaction pedestal.

iii) Give 75 blows on the top side of the specimen mix with a standard hammer (45cm, 4.86kg). Reverse the specimen and give 75 blows again. Take the mould with the specimen and cool it for a few minutes.

iv) Remove the specimen from the mould by gentle pushing. Mark the specimen and cure it at room temperature, overnight.

v) A series of specimens are prepared by a similar method with varying quantities of bitumen content, with an increment of 0.5% (3 specimens) or 1 bitumen content.

vi) Before testing of the mould, keep the mould in the water bath having a temperature of 60oC for half an hour.

vii) Check the stability of the mould on the Marshall stability apparatus.

REPORTING OF RESULTS
Plot % of bitumen content on the X-axis and stability in kg on the Y-axis to get maximum Marshall stability of the bitumen mix. A sample plot is given

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Determine The Liquid Limit Of Soil

This test is done to determine the liquid limit of soil as per IS: 2720 (Part 5) – 1985. The liquid limit of fine-grained soil is the water content at which soil behaves practically like a liquid, but has small shear
strength. It’s flow closes the groove in just 25 blows in Casagrande’s liquid limit device. The apparatus used :-
i) Casagrande’s liquid limit device
ii) Grooving tools of both standard and ASTM types
iii) Oven
iv) Evaporating dish
v) Spatula
vi) IS Sieve of size 425µm
vii) Weighing balance, with 0.01g accuracy
viii) Wash bottle
ix) Air-tight and non-corrodible container for determination of moisture content

PREPARATION OF SAMPLE
i) Air-dry the soil sample and break the clods. Remove the organic matter like tree roots, pieces of bark, etc.
ii) About 100g of the specimen passing through 425µm IS Sieve is mixed thoroughly with distilled water in the evaporating dish and left for 24hrs. for soaking.



Procedure to Determine The Liquid Limit Of Soil
i) Place a portion of the paste in the cup of the liquid limit device.

ii) Level the mix so as to have a maximum depth of 1cm.

iii) Draw the grooving tool through the sample along the symmetrical axis of the cup, holding the tool perpendicular to the cup.

iv) For normal fine grained soil: The Casagrande’s tool is used to cut a groove 2mm wide at the bottom, 11mm wide at the top and 8mm deep.

v) For sandy soil: The ASTM tool is used to cut a groove 2mm wide at the bottom, 13.6mm wide at the top and 10mm deep.

vi) After the soil pat has been cut by a proper grooving tool, the handle is rotated at the rate of about 2 revolutions per second and the no. of blows counted, till the two parts of the soil sample come into contact for about 10mm length.

vii) Take about 10g of soil near the closed groove and determine its water content

viii) The soil of the cup is transferred to the dish containing the soil paste and mixed thoroughly after adding a little more water. Repeat the test.

ix) By altering the water content of the soil and repeating the foregoing operations, obtain at least 5 readings in the range of 15 to 35 blows. Don’t mix dry soil to change its consistency.

x) Liquid limit is determined by plotting a ‘flow curve’ on a semi-log graph, with no. of blows as abscissa (log scale) and the water content as ordinate and drawing the best straight line through the plotted points.

REPORTING OF RESULTS
Report the water content corresponding to 25 blows, read from the ‘flow curve’ as the liquid limit.
A sample ‘flow curve’ is given as

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REBOUND HAMMER TEST

Rebound hammer test is done to find out the compressive strength of concrete by using rebound hammer as per IS: 13311 (Part 2) – 1992. The underlying principle of the rebound hammer test is

The rebound of an elastic mass depends on the hardness of the surface against which its mass strikes. When the plunger of the rebound hammer is pressed against the surface of the concrete, the pring-controlled mass rebounds and the extent of such a rebound depends upon the surface hardness of the concrete. The surface hardness and therefore the rebound is taken to be related to the compressive strength of the concrete. The rebound value is read from a graduated scale and is designated as the rebound number or rebound index. The compressive strength can be read directly from the graph provided on the body of the hammer.

Procedure to determine strength of hardened concrete by rebound hammer.


i) Before commencement of a test, the rebound hammer should be tested against the test anvil, to get reliable results, for which the manufacturer of the rebound hammer indicates the range of readings on the anvil suitable for different types of rebound hammer.

ii) Apply light pressure on the plunger – it will release it from the locked position and allow it to extend to the ready position for the test.

iii) Press the plunger against the surface of the concrete, keeping the instrument perpendicular to the test surface. Apply a gradual increase in pressure until the hammer impacts. (Do not touch the button while depressing the plunger. Press the button after impact, in case it is not convenient to note the rebound reading in that position.)

iv) Take the average of about 15 readings.



Interpretation of Results
The rebound reading on the indicator scale has been calibrated by the manufacturer of the rebound hammer for horizontal impact, that is, on a vertical surface, to indicate the compressive strength. When used in any other position, appropriate correction as given by the manufacturer is to be taken into account.

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Water/ Cemetitous Materials Ratio

The water / cementitious (w/c) ratio is used in both tensile and compressive strength analyses of Portland concrete cement. This ratio is found from

w / c = w m / w c

where w m = weight of mixing water in batch, lb (kg); and w c = weight of cementitious materials in batch, lb (kg).

The ACI Code lists the typical relationship between the w/c ratio by weight and the compressive strength of concrete. Ratios for non-air-entrained concrete vary between 0.41 for a 28-day compressive strength of 6000 lb/in 2 (41 MPa) and 0.82 for 2000 lb/in 2 (14 MPa). Air-entrained concrete w/c ratios vary from 0.40 to 0.74 for 5000 lb/in 2 (34 MPa) and 2000 lb/in 2 (14 MPa) compressive strength, respectively. Be certain to refer to the ACI Code for the appropriate w/c value when preparing designs or concrete analyses.

Further, the ACI Code also lists maximum w/c ratios when strength data are not available. Absolute w/c ratios by weight vary from 0.67 to 0.38 for non-air-entrained concrete and from 0.54 to 0.35 for air-entrained concrete. These values are for a specified 28-day compressive strength f ’ c in lb/in 2 or MPa, of 2500 lb/in 2 (17 MPa) to 5000 lb/in 2 (34 MPa). Again, refer to the ACI Code before making any design or construction decisions.

Maximum w/c ratios for a variety of construction conditions are also listed in the ACI Code. Construction conditions include concrete protected from exposure to freezing and thawing; concrete intended to be watertight; and concrete exposed to deicing salts, brackish water, seawater, etc

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Concrete Mix Design As Per Indian Standard Code

Introduction
The process of selecting suitable ingredients of concrete and determining their relative amounts with the objective of producing a concrete of the required, strength, durability, and workability as economically as possible, is termed the concrete mix design. The proportioning of ingredient of concrete is governed by the required performance of concrete in 2 states, namely the plastic and the hardened states. If the plastic concrete is not workable, it cannot be properly placed and compacted. The property of workability, therefore, becomes of vital importance.
The compressive strength of hardened concrete which is generally considered to be an index of its other properties, depends upon many factors, e.g. quality and quantity of cement, water and aggregates; batching and mixing; placing, compaction and curing. The cost of concrete is made up of the cost of materials, plant and labour. The variations in the cost of materials arise from the fact that the cement is several times costly than the aggregate, thus the aim is to produce as lean a mix as possible. From technical point of view the rich mixes may lead to high shrinkage and cracking in the structural concrete, and to evolution of high heat of hydration in mass concrete which may cause cracking.
The actual cost of concrete is related to the cost of materials required for producing a minimum mean strength called characteristic strength that is specified by the designer of the structure. This depends on the quality control measures, but there is no doubt that the quality control adds to the cost of concrete. The extent of quality control is often an economic compromise, and depends on the size and type of job. The cost of labour depends on the workability of mix, e.g., a concrete mix of inadequate workability may result in a high cost of labour to obtain a degree of compaction with available equipment.
Requirements of concrete mix design
The requirements which form the basis of selection and proportioning of mix ingredients are :

a ) The minimum compressive strength required from structural consideration

b) The adequate workability necessary for full compaction with the compacting equipment available.
c) Maximum water-cement ratio and/or maximum cement content to give adequate durability for the particular site conditions

d) Maximum cement content to avoid shrinkage cracking due to temperature cycle in mass concrete.
Types of Mixes
1. Nominal Mixes
In the past the specifications for concrete prescribed the proportions of cement, fine and coarse aggregates. These mixes of fixed cement-aggregate ratio which ensures adequate strength are termed nominal mixes. These offer simplicity and under normal circumstances, have a margin of strength above that specified. However, due to the variability of mix ingredients the nominal concrete for a given workability varies widely in strength.
2. Standard mixes
The nominal mixes of fixed cement-aggregate ratio (by volume) vary widely in strength and may result in under- or over-rich mixes. For this reason, the minimum compressive strength has been included in many specifications. These mixes are termed standard mixes.
IS 456-2000 has designated the concrete mixes into a number of grades as M10, M15, M20, M25, M30, M35 and M40. In this designation the letter M refers to the mix and the number to the specified 28 day cube strength of mix in N/mm2. The mixes of grades M10, M15, M20 and M25 correspond approximately to the mix proportions (1:3:6), (1:2:4), (1:1.5:3) and (1:1:2) respectively.
3. Designed Mixes
In these mixes the performance of the concrete is specified by the designer but the mix proportions are determined by the producer of concrete, except that the minimum cement content can be laid down. This is most rational approach to the selection of mix proportions with specific materials in mind possessing more or less unique characteristics. The approach results in the production of concrete with the appropriate properties most economically. However, the designed mix does not serve as a guide since this does not guarantee the correct mix proportions for the prescribed performance.
For the concrete with undemanding performance nominal or standard mixes (prescribed in the codes by quantities of dry ingredients per cubic meter and by slump) may be used only for very small jobs, when the 28-day strength of concrete does not exceed 30 N/mm2. No control testing is necessary reliance being placed on the masses of the ingredients.
Factors affecting the choice of mix proportions
The various factors affecting the mix design are:
1. Compressive strength
It is one of the most important properties of concrete and influences many other describable properties of the hardened concrete. The mean compressive strength required at a specific age, usually 28 days, determines the nominal water-cement ratio of the mix. The other factor affecting the strength of concrete at a given age and cured at a prescribed temperature is the degree of compaction. According to Abraham’s law the strength of fully compacted concrete is inversely proportional to the water-cement ratio.
2. Workability
The degree of workability required depends on three factors. These are the size of the section to be concreted, the amount of reinforcement, and the method of compaction to be used. For the narrow and complicated section with numerous corners or inaccessible parts, the concrete must have a high workability so that full compaction can be achieved with a reasonable amount of effort. This also applies to the embedded steel sections. The desired workability depends on the compacting equipment available at the site.
3. Durability
The durability of concrete is its resistance to the aggressive environmental conditions. High strength concrete is generally more durable than low strength concrete. In the situations when the high strength is not necessary but the conditions of exposure are such that high durability is vital, the durability requirement will determine the water-cement ratio to be used.

4. Maximum nominal size of aggregate
In general, larger the maximum size of aggregate, smaller is the cement requirement for a particular water-cement ratio, because the workability of concrete increases with increase in maximum size of the aggregate. However, the compressive strength tends to increase with the decrease in size of aggregate.
IS 456:2000 and IS 1343:1980 recommend that the nominal size of the aggregate should be as large as possible.
5. Grading and type of aggregate
The grading of aggregate influences the mix proportions for a specified workability and water-cement ratio. Coarser the grading leaner will be mix which can be used. Very lean mix is not desirable since it does not contain enough finer material to make the concrete cohesive.
The type of aggregate influences strongly the aggregate-cement ratio for the desired workability and stipulated water cement ratio. An important feature of a satisfactory aggregate is the uniformity of the grading which can be achieved by mixing different size fractions.
6. Quality Control
The degree of control can be estimated statistically by the variations in test results. The variation in strength results from the variations in the properties of the mix ingredients and lack of control of accuracy in batching, mixing, placing, curing and testing. The lower the difference between the mean and minimum strengths of the mix lower will be the cement-content required. The factor controlling this difference is termed as quality control.
Mix Proportion designations
The common method of expressing the proportions of ingredients of a concrete mix is in the terms of parts or ratios of cement, fine and coarse aggregates. For e.g., a concrete mix of proportions 1:2:4 means that cement, fine and coarse aggregate are in the ratio 1:2:4 or the mix contains one part of cement, two parts of fine aggregate and four parts of coarse aggregate. The proportions are either by volume or by mass. The water-cement ratio is usually expressed in mass
Factors to be considered for mix design
ð The grade designation giving the characteristic strength requirement of concrete.
ð The type of cement influences the rate of development of compressive strength of concrete.
ð Maximum nominal size of aggregates to be used in concrete may be as large as possible within the limits prescribed by IS 456:2000.
ð The cement content is to be limited from shrinkage, cracking and creep.
ð The workability of concrete for satisfactory placing and compaction is related to the size and shape of section, quantity and spacing of reinforcement and technique used for transportation, placing and compaction.
Procedure
1. Determine the mean target strength ft from the specified characteristic compressive strength at 28-day fck and the level of quality control.
ft = fck + 1.65 S
where S is the standard deviation obtained from the Table of approximate contents given after the design mix.
2. Obtain the water cement ratio for the desired mean target using the emperical relationship between compressive strength and water cement ratio so chosen is checked against the limiting water cement ratio. The water cement ratio so chosen is checked against the limiting water cement ratio for the requirements of durability given in table and adopts the lower of the two values.
3. Estimate the amount of entrapped air for maximum nominal size of the aggregate from the table.
4. Select the water content, for the required workability and maximum size of aggregates (for aggregates in saturated surface dry condition) from table.
5. Determine the percentage of fine aggregate in total aggregate by absolute volume from table for the concrete using crushed coarse aggregate.
6. Adjust the values of water content and percentage of sand as provided in the table for any difference in workability, water cement ratio, grading of fine aggregate and for rounded aggregate the values are given in table.
7. Calculate the cement content form the water-cement ratio and the final water content as arrived after adjustment. Check the cement against the minimum cement content from the requirements of the durability, and greater of the two values is adopted.
8. From the quantities of water and cement per unit volume of concrete and the percentage of sand already determined in steps 6 and 7 above, calculate the content of coarse and fine aggregates per unit volume of concrete from the following relations:


where V = absolute volume of concrete
= gross volume (1m3) minus the volume of entrapped air
Sc = specific gravity of cement
W = Mass of water per cubic metre of concrete, kg
C = mass of cement per cubic metre of concrete, kg
p = ratio of fine aggregate to total aggregate by absolute volume
fa, Ca = total masses of fine and coarse aggregates, per cubic metre of concrete, respectively, kg, and
Sfa, Sca = specific gravities of saturated surface dry fine and coarse aggregates, respectively
9. Determine the concrete mix proportions for the first trial mix.
10. Prepare the concrete using the calculated proportions and cast three cubes of 150 mm size and test them wet after 28-days moist curing and check for the strength.
11. Prepare trial mixes with suitable adjustments till the final mix proportions are arrived at.

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CONCRETE MIX DESIGN (GRADE M60)

(a) DESIGN STIPULATION:-
Target strength = 60Mpa
Max size of aggregate used = 12.5 mm
Specific gravity of cement = 3.15
Specific gravity of fine aggregate (F.A) = 2.6
Specific gravity of Coarse aggregate (C.A) = 2.64
Dry Rodded Bulk Density of fine aggregate = 1726 Kg/m3
Dry Rodded Bulk Density of coarse aggregate = 1638 Kg/m3

Step-1
Calculation for weight of Coarse Aggregate:
From ACI 211.4R Table 4.3.3 Fractional volume of oven dry Rodded C.A for 12.5mm size aggregate is 0.68m3
Weight of C.A = 0.68*1638 = 1108.13 Kg/m3

Step-2
Calculation for Quantity of Water:
From ACI 211.4R Table 4.3.4
Assuming Slump as 50 to 75mm and for C.A size 12.5 mm the Mixing water = 148 ml
Void content of FA for this mixing water = 35%
Void content of FA (V)
V = {1-(Dry Rodded unit wt / specific gravity of FA*1000)}*100
= [1-(1726/2.6*1000)]*100
= 34.62%

Adjustment in mixing water = (V-35)* 4.55
= (34.62 – 35)*4.55
= -1.725 ml
Total water required = 148 + (-1.725) = 146.28 ml
Step-3
Calculation for weight of cement
From ACI 211.4R Table 4.3.5(b)
Take W / C ratio = 0.29
Weight of cement = 146.28 / 0.29 = 504.21 kg/m3

Step-4
Calculation for weight of Fine Aggregate:

Cement = 504.21 / 3.15*1000= 0.1616
Water = 146.28 / 1*1000= 0.1462
CA = 1108.13 / 3*1000= 0.3690
Entrapped Air = 2 / 100= 0.020
Total = 0.7376m3
Volume of Fine Aggregate= 1-0.7376
Weight of Fine Aggregate= 0.2624*2.6*1000= 683.24 kg/m3

Step-5
Super plasticizer:
For 0.8% = (0.8 / 100)*583.53 = 4.668 ml

Step-6
Correction for water:
Weight of water (For 0.8%) =146.28 – 4.668 =141.61 kg/m3

Requirement of materials per Cubic meter
Cement = 504.21 Kg/m3
Fine Aggregate = 683.24 Kg/m3
Coarse Aggregate = 1108.13 Kg/m3
Water = 141.61 Kg/ m3
Super plasticizers = 4.6681 / m3

So the final ratio becomes
Cement : Fine agg (kg/m3) : Coarse agg (kg/m3) : Water (l/m3): Superplasticizer (l/m3)

1: 1.35 :2.19 :0.29 :0.8

This concrete mix design has been submitted to us by Natarajan. We are thankful to him for this valuable contribution.

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Mix Design For M35 Grade Of Concrete

The mix design for M35 Grade Of Concrete for pile foundations provided here is for reference purpose only. Actual site conditions vary and thus this should be adjusted as per the location and other factors.

Grade of Concrete : M35
Characteristic Strength (Fck) : 35 Mpa
Standard Deviation : 1.91 Mpa*
Target Mean Strength : T.M.S.= Fck +1.65 x S.D.
(from I.S 456-2000) = 35+ 1.65×1.91
= 38.15 Mpa

Test Data For Material:
Aggregate Type : Crushed
Specific Gravity
Cement : 3.15
Coarse Aggregate : 2.67
Fine Aggregate : 2.62

Water Absorption:
Coarse Aggregate : 0.5%
Fine Aggregate : 1.0 %

MIX DESIGN

Take Sand content as percentage of total aggregates = 36%

Select Water Cement Ratio = 0.43 for concrete grade M35

(From Fig 2. of I.S. 10262- 1982)

Select Water Content = 172 Kg

(From IS: 10262 for 20 mm nominal size of aggregates Maximum Water Content = 186 Kg/ M3 )

Hence, Cement Content= 172 / 0.43 = 400 Kg / M3

Formula for Mix Proportion of Fine and Coarse Aggregate:

1000(1-a0) = {(Cement Content / Sp. Gr. Of Cement) + Water Content +(Fa / Sp. Gr.* Pf )}

1000(1-a0) = {(Cement Content / Sp. Gr. Of Cement) + Water Content +Ca / Sp. Gr.* Pc )}

Where Ca = Coarse Aggregate Content

Fa = Fine Aggregate Content

Pf = Sand Content as percentage of total Aggregates

= 0.36

Pc = Coarse Aggregate Content as percentage of total Aggregates.

= 0.64

a0 = Percentage air content in concrete (As per IS :10262 for 20 mm nominal size of

aggregates air content is 2 %) = 0.02

Hence, 1000(1-0.02) = {(400 /3.15) + 172 +(Fa / 2.62 x 0.36)}

Fa = 642 Kg/ Cum

As the sand is of Zone II no adjustment is required for sand.

Sand Content = 642 Kg/ Cum

1000(1-0.02) = {(400 /3.15) + 172 +(Ca / 2.67 x 0.64)}

Hence, Ca = 1165 Kg/ Cum

From combined gradation of Coarse aggregates it has been found out that the proportion of 53:47 of 20 mm & 10 mm aggregates produces the best gradation as per IS: 383.

Hence, 20 mm Aggregates = 619 Kg

And 10 mm Aggregates = 546 Kg

To obtain slump in the range of 150-190 mm water reducing admixture brand SP430 from Fosroc with a dose of 0.3 % by weight of Cement shall be used.

Hence the Mix Proportion becomes:

Cem
W/C
Water
Sand
20mm
10mm
Admix

400
0.43
172
635
619
564
1.2

1

0.43
1.6
1.547
1.36
0.003


Units – Kg/ M3

Cement : Sand: Coarse Aggregates = 1 : 1.6 : 2.907

We are thankful to Er. Ishan Kaushal for this valuable information.

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Who's exhibiting at the 2009 World Steel Bridge Symposium?

The 2009 National Steel Bridge Alliance (NSBA) World Steel Bridge Symposium is just around the corner. Here's a look at the some of the sessions you can expect, as well as the companies exhibiting:

Tuesday, November 17, 2009
Pre Fabricated Bridge Elements and Systems Workshop
--Fabricators Perspective on PFBESRonnie Medlock, High Steel Structures
--Introduction to Tubular Steel PiersWill Reeves, TuboCo
--PreFabricated Connections forAccelerated Construction - Michael Culmo, CME Associates
--Folded Plate Technology for Accelerated Bridge Fabrication and Construction - Atorod Azizinamini, University of Nebraska
--Orthotropic Deck Girders Bridges for Rapid & Long-Lasting Solution - Brian Kozy, Parsons Brinckerhoff
SSPC Workshop: Bridge Coatings – Today’s Systems, Tomorrow’s Performance

Wednesday, November 18, 2009
Accelerated Construction Technologies Workshop
--Desoto Bridge—Fast Track Replacement Bridge Project - Manjula Louis, Minnesota DOT
--A Complete Bridge using an AcceleratedBridge Construction Method - Roe Enchayan, Nebraska DOR
--CSX Transportation Rehabilitates & Rebuilds with Steel - Michael Leonard, HDR, Inc.
--Simple for Dead Load/Continuous for Live Load for Modular Construction - Atorod Azizinamini, University of Nebraska
--Roll-In/Float-In of a PreFabricated Truss Bridge - Robert Cisneros, High Steel Structures
--Owners Perspective on ABC - Jim McMinimee, Utah DOT
8:00 a.m. – 11:30 a.m.AISC Certification: The Importance and the Process

WSBS Technical Sessions
In addition to the workshops listed above, WSBS attendees can attend 15 technical sessions featuring 50 presentations that focus on steel’s long-life, low maintenance costs, quick erection, and environmentally sound attributes. If you need CEU credits, you may find something of interest in the list of session topics below:
--Steel bridge erection
--Steel bridge analysis
--Texas Topics
--BridgeSecurity
--Signature bridges
--Practical Solutions
--Skewed bridges
--Fabricator interest
--Curved steel girders
--Cost reduction
--Fatigue/Fracture
--Potpourri of many other bridge-related topics

There are over 50 exhibitors attending this year’s Symposium:

Exhibitor Booth Website
Acrow Corporation 100 www.acrowusa.com
AISC - Certification 407 www.aisc.org/certification
AISC - Steel Solutions Center 415 www.aisc.org
Allied Sales & Service Co., Inc. 305 www.allied-sales.com
Amercian Galvanizers Association 300 www.galvanizeit.org
Atema 102 www.atema.com
Bendco Inc. 416 www.bendco.com
BendTec 209 www.bendtec.com
BGFMA 313 www.bgfma.org
Big R Bridge 105 www.bigrbridge.com
Bureau Veritas 206 www.us.bureauveritas.com
Computers & Structures Inc. 418 www.csiberkeley.com
Controlled Automation 111 www.controlledautomation.com
CSi - Bridge Dek 207 www.csisteel.com
D.S. Brown Company, The 318 www.dsbrown.com
Delta Rigging & Tools 201 www.deltarigging.com
ENERPAC 309 www.enerpac.com
Fabreeka International, Inc. 202 www.fabreeka.com
FabSuite, LLC 307 www.fabsuite.com
Ficep Corporation 301 www.ficepcorp.com
G.W.Y., Inc. 107 www.gwyinc.com
Hercules Bolt Company 208 www.herculesbolt.com
InfoSight Corporation 200 www.infosight.com
Kentex 302 www.gokentex.com
KTA - Tator, Inc. 400 www.kta.com
LARSA, Inc. 219 www.larsausa.com
LeJuenue Bolt Co 101 www.lejeunebolt.com
LUSAS 119 www.lusas.com
Mabey Bridge & Shore, Inc. 404 www.mabey.com
McClain & Co, Inc. 408 www.mcclainandcompany.com
MDX Software 112 www.mdxsoftware.com
Michelman-Cancelliere Iron Works 109 www.mcironworks.com
NACE International 308 www.nace.org
National Steel Bridge Alliance (NSBA) 409 www.steelbridges.org
Non-Destructive Testing Services 410 www.nondestructivetesting.com
Peddinghaus Corporation 104 www.peddinghaus.com
Pieresearch 113 www.pieresearch.com
Quickmill, Inc. 406 www.quickmill.com
R.J. Watson, Inc. 212 www.rjwatson.com
Rebuilding America's Infrastructure 304 www.rebuildamericasinfrastructure.com
Scougal Rubber Corporation 205 www.scougalrubber.com
Seismic Energy Products 412

List of Expected Exhibitors as of 11/2/2009

It is not too late to register for the 2009 WSBS - please visit www.steelbridges.

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Eastern Ave. bridge to get taller replacement

The Eastern Avenue bridge, too old and so low that it gets whacked by tall trucks, is about to be demolished and replaced, a year-long job that will force 21,800 daily drivers to find another route over Kenilworth Avenue.

The project, funded by $10.4 million in federal stimulus money, is scheduled to begin this month.

The bridge has been a too-short player in a tall-truck world, resulting in many a crunching encounter that have caused backups to radiate through adjoining streets and highways.

One of the most memorable occurred four years ago, when a backhoe atop a flatbed trailer -- total height 15 feet -- rammed into the bridge, which has a clearance of 14 feet. The only things hurt were the bridge and the schedules of thousands of drivers caught in the ensuing traffic.

The new bridge will have a 16-foot clearance.

Big portions of the bridge will be precast, allowing them to be dropped into place and reducing the time to complete the project from two years to one.

"We're starting on those precasts before we demolish the old bridge," said John Lisle, spokesman for the D.C. Transportation Department. "That will save us lots of time."

Service roads adjacent to Kenilworth Avenue will remain open while construction is underway, except for a short period.

Lisle said the old bridge will not be demolished until late December or early next year.

"As we get closer to the actual start of this, we'll send out detailed detour directions," Lisle said.

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London 2012: Power of design

The London 2012 Olympics aims to be a beacon for sustainable delivery of the Games and the infrastructure behind it. And its Energy Centre − resembling a mini Tate Modern − is at the heart of its plans. Andrea Klettner reports.


With London 2012 aiming to be the greenest, most sustainable Olympics to date, it is only fitting that the first piece of usable legacy will be the park’s own Energy Centre.

The idea is that it will be a carbon neutral and efficient source of power, as well as a heating and cooling system across the site for the Games and for the new buildings and communities that will develop in the years after.

Work on the project, which is located at the western edge of the park on the former Kings Yard site, started towards the end of 2008.

John Coleman, project manager for contractor Cofely − which won a 40-year concession to design, build, finance and operate the Energy Centre in April 2008 − explains: “We effectively designed the building around the equipment. The site has a small footprint so we had to build up rather than out.”

Piling started in September 2008. In total 218 concrete continuous flight auger piles, the majority of which were 22m in length and varying in diameter between 450mm, 650mm and 750mm, were installed.

Then more than 500t of steel was used to erect the frame of the building, which is 45m tall at its highest point − resembling a miniature version of London’s iconic Tate Modern art gallery.

“We effectively designed the building around the equipment. The site has a small footprint so we had to build up rather than out.”

John Coleman, Cofely
Traditional construction methods tell you that now is the time to add walls and a roof to the building, but the team behind the Energy Centre decided to leave that until the very end, allowing them to install the equipment much more easily.

“The advantage of the construction is that it is very much demountable. It allows us to change the technology inside as it moves on,” says Coleman. “That’s the kind of flexible design we wanted.”

The ground floor holds spark ignition gas engines, ammonia electric chillers and the boilers that will drive the centre’s Combined Cooling, Heat and Power (CCHP) plant.

“The boilers weight 100t each and are transported down from Scotland,” explains Coleman.

“The gas engines weigh around 70t each. On the first floor are the two-stage waste heat boilers and on the top floor you have the air handling and ventilation, switchgear and double effect absorption chillers.

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Wednesday, November 4, 2009

Project Manager Job Description

Description

The role of the Project Manager is to plan, execute, and finalize projects according to strict deadlines and within budget. This includes acquiring resources and coordinating the efforts of team members and third-party contractors or consultants in order to deliver projects according to plan. The Project Manager will also define the project’s objectives and oversee quality control throughout its life cycle.
Responsibilities

• Direct and manage project development from beginning to end.
• Define project scope, goals and deliverables that support business goals in
collaboration with senior management and stakeholders.
• Develop full-scale project plans and associated communications documents.
• Effectively communicate project expectations to team members and stakeholders in a timely and clear fashion.
• Liaise with project stakeholders on an ongoing basis.
• Estimate the resources and participants needed to achieve project goals.
• Draft and submit budget proposals, and recommend subsequent budget changes where necessary.

• Where required, negotiate with other department managers for the acquisition of required personnel from within the company.
• Determine and assess need for additional staff and/or consultants and make the appropriate recruitments if necessary during project cycle.
• Set and continually manage project expectations with team members and other stakeholders.
• Delegate tasks and responsibilities to appropriate personnel.
• Identify and resolve issues and conflicts within the project team.
• Identify and manage project dependencies and critical path.
• Plan and schedule project timelines and milestones using appropriate tools.
• Track project milestones and deliverables.
• Develop and deliver progress reports, proposals, requirements documentation, and presentations.
• Determine the frequency and content of status reports from the project team, analyze results, and troubleshoot problem areas.

• Proactively manage changes in project scope, identify potential crises, and
devise contingency plans.
• Define project success criteria and disseminate them to involved parties throughout project life cycle.
• Coach, mentor, motivate and supervise project team members and contractors, and influence them to take positive action and accountability for their assigned work.
• Build, develop, and grow any business relationships vital to the success of the project.

• Conduct project post mortems and create a recommendations report in order to
identify successful and unsuccessful project elements.
• Develop best practices and tools for project execution and management.

Position Requirements

• University degree or college diploma in the field of […].
• […] years direct work experience in a project management capacity, including all
aspects of process development and execution.
• Certifications in […].
• Strong familiarity with project management software, such as […]
• Familiar with programming languages, including […].
• Database and operating systems experience with […].
• Competent and proficient understanding of platforms, such as […].
• Solid working knowledge of current Internet technologies, including […].
• Demonstrated experience in personnel management.
• Technically competent with various software programs, such as […].
• Experience at working both independently and in a team-oriented, collaborative environment is essential.
• Can conform to shifting priorities, demands and timelines through analytical and problem-solving capabilities.
• Reacts to project adjustments and alterations promptly and efficiently.
• Flexible during times of change.
• Ability to read communication styles of team members and contractors who come from a broad spectrum of disciplines.
• Persuasive, encouraging, and motivating.
• Ability to elicit cooperation from a wide variety of sources, including upper
management, clients, and other departments.
• Ability to defuse tension among project team, should it arise.
• Ability to bring project to successful completion through political sensitivity.
• Strong written and oral communication skills.
• Strong interpersonal skills.
• Adept at conducting research into project-related issues and products.
• Must be able to learn, understand, and apply new technologies.
• Customer service skills an asset.
• Ability to effectively prioritize and execute tasks in a high-pressure environment is crucial.

Work Conditions

• Overtime may be required in meet project deadlines.
• Sitting for extended periods of time.
• Dexterity of hands and fingers to operate a computer keyboard, mouse, and
other devices and objects.
• Physically able to participate in training sessions, presentations, and meetings.
• Some travel may be required for the purpose of meeting with clients,
stakeholders, or off-site personnel/management.

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History of project management

History of project management

As a discipline, Project Management developed from different fields of application including construction, engineering and defense. In the United States, the forefather of project management is Henry Gantt, called the father of planning and control techniques, who is famously known for his use of the Gantt chart as a project management tool, for being an associate of Frederick Winslow Taylor’s theories of scientific management[1], and for his study of the work and management of Navy ship building. His work is the forerunner to many modern project management tools including the work breakdown structure (WBS) and resource allocation.
The 1950s marked the beginning of the modern Project Management era. Again, in the United States, prior to the 1950s, projects were managed on an ad hoc basis using mostly Gantt Charts, and informal techniques and tools. At that time, two mathematical project scheduling models were developed: (1) the “Program Evaluation and Review Technique” or PERT, developed by Booz-Allen & Hamilton as part of the United States Navy’s (in conjunction with the Lockheed Corporation) Polaris missile submarine program[2]; and (2) the “Critical Path Method” (CPM) developed in a joint venture by both DuPont Corporation and Remington Rand Corporation for managing plant maintenance projects. These mathematical techniques quickly spread into many private enterprises.

At the same time, technology for project cost estimating, cost management, and engineering economics was evolving, with pioneering work by Hans Lang and others. In 1956, the American Association of Cost Engineers (now AACE International; the Association for the Advancement of Cost Engineering) was formed by early practitioners of project management and the associated specialties of planning and scheduling, cost estimating, and cost/schedule control (project control). AACE has continued its pioneering work and in 2006 released the first ever integrated process for portfolio, program and project management (Total Cost Management Framework).

In 1969, the Project Management Institute (PMI) was formed to serve the interests of the project management industry. The premise of PMI is that the tools and techniques of project management are common even among the widespread application of projects from the software industry to the construction industry. In 1981, the PMI Board of Directors authorized the development of what has become A Guide to the Project Management Body of Knowledge (PMBOK Guide), containing the standards and guidelines of practice that are widely used throughout the profession. The International Project Management Association (IPMA), founded in Europe in 1967, has undergone a similar development and instituted the IPMA Competence Baseline (ICB). The focus of the ICB also begins with knowledge as a foundation, and adds considerations about relevant experience, interpersonal skills, and competence. Both organizations are now participating in the development of an ISO project management standard

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Construction Management Study

Construction Management Study

Construction management is the study and practice of managerial and technological factors in the industry of construction. This includes construction, the science of construction, construction management and technology in construction. Construction management also refers to a business representation wherein a crew to a construction contract serves as a consultant to the construct, hereby providing design and advice of the construction.

The education for construction management has a wide array of formats; these are the formal degree programs, on the job trainings, and continuing education or professional development. Examples of formal degree programs are two year associate degree programs, four year baccalaureate degree programs and graduate degree programs. The accrediting body of construction management educational programs in the United Stats is the American Council for Construction Education. According to them the academic field of construction management covers broad array of topics. These topics range from general management skills, to skills that have specific relation to construction, to technical knowledge in the methods of construction and procedures.

In general, there are three groups involve in the industry of construction; the owner, architect or engineer or more known as the designer, and the builder or contractor. As these three groups plan, design and construct together, two contracts work between these groups. The first contract is known as the owner and designer contract. This first contract involves the planning, designing and some possible factors of construction. The second contract is known as the owner and builder contract. This contract involves the actual construction. On most cases, an indirect go-between relationship exists among the designer and the builder because of these contracts.

There is also a substitute contract or business representation that replaces the two contracts with three contracts. These three contracts are owner and designer contract, owner and construction manager contract, and the owner and contractor contract. The company that handles the construction management is the additional group engaged in the construction, acting as the advisor to the three groups. The function of the construction manager is to provide advice to the designer, design advice to the builder, and services (design and construction wise). Services include subcontracts and material if needed, to the owner.

One type of construction management service is the Agency Construction Management. Agency Construction Management is a fee based service by which the construction manager is accountable to the owner and operates in the interest of the owner on every phase of the project. Broad management of every phase of the project produces the furthermost possible advantage to the owners.

In the United Kingdom, the construction industry is regulated by the Construction Design Management. Hereby, reducing and preventing untoward events on the construction sites and the civil engineering structure once the construction is completed

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Concrete Blocks Used In Great Pyramids Construction

Michel Barsoum, professor of materials engineering, shows in a peer-reviewed paper published Dec. 1 in the Journal of the American Ceramic Society how the Egyptian builders of the nearly 5,000-year-old pyramids were exceptional civil and architectural engineers as well as superb chemists and material scientists. Barsoum wrote the paper with Adrish Ganguly, a an alumnus who received a doctoral degree in materials engineering from Drexel, and Gilles Hug of the National Center for Scientific Research in France.

Their conclusions could lead to a seismic shift in the kind of concrete used in construction and provide developing nations a way to build structures utilizing inexpensive and easily accessible materials.

The longstanding belief is that the pyramids were constructed with limestone blocks that were cut to shape in nearby quarries using copper tools, transported to the pyramid sites, hauled up ramps and hoisted in place with the help of wedges and levers. Barsoum argues that although indeed the majority of the stones were carved and hoisted into place, crucial parts were not. The ancient builders cast the blocks of the outer and inner casings and, most likely, the upper parts of the pyramids using a limestone concrete, called a geopolymer.

To arrive at his findings, Barsoum, an Egypt native, and co-workers analyzed more than 1,000 micrographs, chemical analyses and other materials over three years. Barsoum, whose interest in the pyramids and geopolymers was piqued five years ago when he heard theories about the construction of the pyramids, says that to construct them with only cast stone builders would have needed an unattainable amount of wood and fuel to heat lime to 900 degrees Celsius.

Barsoum’s findings provide long-sought answers to some of the questions about how the pyramids were constructed and with such precision. It puts to rest the question of how steep ramps could have extended to the summit of the pyramids; builders could cast blocks on site, without having to transport stones great distances. By using cast blocks, builders were able to level the pyramids’ bases to within an inch. Finally, builders were able to maintain precisely the angles of the pyramids so that the four planes of each arrived at a peak.

Although these findings answer some of the questions about the pyramids, Barsoum says the mystery of how they were built is far from solved. For example, he has been unable to determine how granite beams — spanning kings’ chambers and weighing as much as 70 tons each — were cut with nothing harder than copper and hauled in place.

The type of concrete pyramid builders used could reduce pollution and outlast Portland cement, the most common type of modern cement. Portland cement injects a large amount of the world’s carbon dioxide into the atmosphere and has a lifespan of about 150 years. If widely used, a geopolymer such as the one used in the construction of the pyramids can reduce that amount of pollution by 90 percent and last much longer. The raw materials used to produce the concrete used in the pyramids — lime, limestone and diatomaceous earth — can be found worldwide and is affordable enough to be an important construction material for developing countries, Barsoum said.

Source: Drexel University

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Second Fault On 'Squinty Bridge'

A crack has been found on Glasgow's Clyde Arc bridge just over a week after a support cable snapped.


The new bridge across the Clyde cost more than £20m to build


The £20m crossing, known locally as the Squinty Bridge, was closed while repairs were ongoing and the crack was found during an inspection.

It is expected that it will be closed for six months, rather than a couple of weeks as had been initially anticipated by engineers.

The River Clyde has now also been shut to all traffic travelling below it.
Glasgow City Council said that the crack was found in a similar component to the one which failed and was removed last week.

Impact unclear




The cables are an integral part of the bridge structure



Though the bridge was designed to allow for the removal of one of these supports, the impact of the failure of the second is still unclear.

The cable, one of 14 which supports the newest bridge over the River Clyde, came crashing down on 14 January.

Designers Halcrow and civil engineering contractor Edmund Nuttall Ltd, who built the bridge, are investigating the cause of the problems.

The bridge between Finnieston and Pacific Quay opened in 2006 and is still under contractor guarantee.

The structure, which spans 140m, is a tied arch design, carrying four traffic lanes. One lane in each direction is reserved for public transport and there are pedestrian and cycle paths.

Running at an angle across the water, it was the first new road bridge over the river to be built since 1969 when it was built at a cost of £20.3m.

A spokesman for Glasgow City Council said public safety was its number one priority and apologised for the inconvenience.

"The bridge was closed last week following the failure of a steel component that connected one of the hangers to the arch," he added.

"The casting that failed has been taken away for inspection and testing and the council, constructors and designers are still awaiting the results of this.

"In the course of an inspection today, a crack was found in another similar connector on a different hanger.

"The council has, as a precautionary measure, requested that all river traffic below the bridge be suspended until further notice."

Source : BBC News

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Garage Collapse Contractor Points Finger at Engineer

The pancake-style collapse on December 6, 2007, claimed the life of a laborer and injured 23 others. Atlanta-based Choate Construction Co. hired two forensic engineering firms, Wiss-Janney Elstner Associates, Inc., Atlanta, and Carl Walker of CW Consulting LLC, Kalamazoo, Mich., to review the design for the six-story, post-tensioned concrete garage that accompanies the Berkman Plaza II residential tower.

“Both studies independently conclude that the collapse was due to significant deficiencies in the design performed by the owner’s structural engineer, Structural Consulting Group LLC of Alpharetta, Ga.,” said the written release from Wm. Millard Choate, CEO of Choate Construction.

Choate didn’t immediately make available the full engineering reports.

Officials of the Structural Consulting Group could not be reached for comment. An employee who answered the phone in the firm’s office declined to comment.

Specifically, Choate’s statement says Wiss-Janney concluded, “The original design was deficient and inadequate to support the 50-psf design live load prescribed by the building code.” Mark Moore, a principal with Wiss-Janney, confirmed the accuracy of the statement but says he cannot comment further.

Neither the Will Janney or Walker report found any action or inaction by Choate to be the cause of the collapse, according to the Choate press release.

However, in June, the U.S. Occupational Safety and Health Administration cited Choate for three violations and proposed penalties totaling $56,700 against the contractor. OSHA also issued two willful violations with penalties totaling $125,000 against Southern Pan Services of Lithonia, Ga., the concrete formwork contractor.

Choate and Southern Pan each received a willful violation for failing to have a qualified person determine if the structure could support the additional three-quarters of an inch of wet concrete weight that was added to the 20-in floor slab. In addition, the agency proposed one willful violation against Southern Pan for failing to obtain a re-shoring drawing, including all revisions, for the reshoring design method used at the site.

Choate is vigorously contesting its citations, the release says, because the evidence shows Choate properly performed the work.

Mike Wald, a spokesman for OSHA, acknowledged that Choate has appealed the citations and declined to comment further.

The project’s developer, Harbor Cos., said in a statement that there was no surprise that Choate’s experts would point the finger at other project members. “Other experts will undoubtedly express very different opinions,” says Harbor’s statement. “The owner is committed to determining the true cause of the collapse and to making sure the responsible party or parties are held accountable for this tragic event, whoever they may be.”

Harbor says it won’t comment further until all investigations are complete. The developer has not set a date for resumption of construction and says it is taking steps to ensure no problems are encountered in completing the project and that the final product will be safe.

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BRIDGE INSPECTION RESIDUAL STRESS - NEW METHOD

BRIDGE INSPECTION RESIDUAL STRESS - NEW METHOD

Introduction

Internal stresses are to be considered as the following: 1) Operational strains referring to loads that the material is subject and calculated 2) Residual stresses in the material caused by heat treatments or stresses caused by welding, forging, casting, etc. The new technique is able to measure the applied load and residual stress that are balanced on the surface of the material, and in a relatively large volume, at times even the same size as the entire structures. This stress is part of the metal’s elasticity field and has a three axis spatial orientation.


Description

Elastic oscillations (also called vibrations) of an elastic material consisting of elementary masses alternately moving around their respective balance positions; these movements cause a transformation of the potential energy into kinetic energy. This phenomenon takes place due to reactions (elastic forces) that the aforementioned masses produce in opposition to elastic movements; these reactions are proportional according to Hooke’s Law to the same movements. The elastic waves that are produced propagate according to a fixed speed that depends on how rapidly the elemental masses begin to oscillate. Elastic waves of this type are called “permanently progressive”, and they propagate at a constant speed which is absolutely independent of the speed with which the elemental masses move during the oscillating motion, and therefore also their respective oscillations. It is easy to verify that the elastic oscillations, from a material point P (in which the elemental mass m is supposedly concentrated) are harmonic. In reality, due to the fact that in any moment the elastic force that is applied to P is proportional to the distance x of the point from its position of balance 0, P acceleration (caused by the proportionality between the forces and the corresponding accelerations) is also proportional to x; this is demonstrated in the harmonic movement. The impulse creates in the metallic mass a harmonic oscillation (vibration) which is characterized by a specific frequency ù² and by a width equal to dx (movement of the relative mass). If a constant impulse is produced in the metallic material, the elastic oscillation generated in the P point will also produce a sinusoidal wave with specific width, acceleration, speed and period values.
This wave is longitudinal when the direction of the vibration is equal to the P point movement, or is transversal, and in both cases the values of the results are identical; the only difference is the ¼ delay of the phase.


Impact with the metallic surface results an elastic deformation energy.

Ed = Ei – ( Ek + Ep )
Ei = Impact energy Ek = Kinetic energy
Ed = elastic deformation energy Ep = plastic deformation energy + lost energy
Ed = ½ K dx² = ½ m ω² dx² K = constant elastic material (stiffness)



Behavior elastic metals, due to new discovery


Fig. 1 Fig.2

The system works through the accelerometer mounted with a magnetic base to generate the acceleration value of the vibrations created by the device impacting on the metal surface. The acceleration value, in combination with other parameters, permits obtaining the exact value of the residual stress or load applied in the desired point. This value will appear on the display directly in N / mm ². For non-magnetic metals, wax or gel will be used to mount the accelerometer.
The system doesn’t recognize the compressive from tensile stress.


Fig .3

Quality of surface The test method requires smooth surfaces free of oxides, paint, lubricants, oil. The indentation deep and the accurately of the test depend from the roughness of the surface. For the preparation of the surface, is necessary, must be careful not to alter the surface over certain values of heating or hardening. More practical results can be realized by using a high-speed grinder (> 12000 rpm).


Conclusion

Application of this type of non-destructive method NDT provides the possibility to measure residual stress and the effect of the service load in a very rapid and simple way on any point of the metallic surface. The testing method requires smooth surfaces free of oxides, paint, lubricants and oil. Precision depends on the roughness of the surface. This technology has demonstrated its validity over years of mechanical experimentation and has confirmed its theoretical basis. The new system provides a full-field, large area inspection, in real time to point-by-point inspection too rapid and easy

About residual stresses
The residual stress in a metal doesn’t depend on its hardness, but from the elasticity module or Young module and from its chemical composition. The hardness of a metal indicates its ability to absorb elastic or plastic energy, but through it not possible to determine the value of residual stress. In a metal with the same hardness we will have different values of this stress. . The residual stresses tend to equilibrate themselves in the surface of the material.
The measurement made with all the major methods, X-ray, string gauge (destructive), optical etc. the residual stress is determined between the measuring the displacement of the equilibrium point the reticule crystalline. The method discovered analyzes the value of frequency and vibratory acceleration generated by an impulse with the subsequent reaction elastic (elastic field) from the metal.

You will realize the convenience of this technique.
1) Portable system easy to use and very swift. 2) NDT non-destructive test.
3) Repeatable in unlimited number of points.
4) All metals type (a-magnetic)
5) Don’t expensive. Effective for welding, hardened treatments, vessels control,
bridges, pipes line, aeronautics, NDT inspection for every metal types.


p.i. Ennio Curto.

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Foundation types for multistorey

Hi I've to design an 11 storey building with a double basement. I'm stuck on my foundation design for my prelim design.Conditions:Basement 13 metres totalGroundwater @ 2 metres. existing buildings at both sides (city centre location)Rock @ 12m at one end of the building and 15m at the other end (80metres between both boreholes)Unable to blast rock due to location.Can anyone help me with the type of foundation to use and the construction of the basement with ref to the ground water? also how to remove the rock without blasting?Thanks

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Reinforcement of existing Truss frame

Reinforcement of existing Truss frame

Dear all,I am doing a project which involves reinforcing existing truss frame.. I have never done this before and personally do not know anyone who has done this. So if anyone having some experience in subject work can guide… refer to any book… preferable Code… Please note that, the already constructed frame is 3 years old and has undergone deformation due to wind load.I don’t know what is the code allowance for such structure? Design Methodology?Methodology to stress relieve the structure?Do we have to tack weld the new structure initially? Proposed methodology and sequence? Any other step/sequence or precaution needed to be taken during execution?

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COMPOSITE CONSTRUCTION

COMPOSITE CONSTRUCTION

Hello friends..,Let’s have something more in structural engineering...,Here, I have submitted links for some materials which I found very necessary while designing or analysing any composite structures..At a primary stage,I have submitted Links 4 some of important books, magazine, thesis, technical report, and handbook, and also one structural engineering report. Each of them have very good quality of content..Let me describe them..

1) COMPOSITE STRUCTURE OF STEEL AND CONCRETE.- By R.P.JOHNSON - (2nd edition, Blackwell Scientific Publication.)- (Volume 1 – Beams, Slabs, Columns & Frames for Building)(This book is the whole sole of this field. Most of the other author uses this book as a reference book. Sir Johnson has contributed a lot in this field.)If you are interested in this topic then don’t forget to refer this book

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Researchers Design Devices To Protect Buildings From Earthquakes

Researchers Design Devices To Protect Buildings From Earthquakes

Researchers from the Buildings and Hydraulic Engineering Department of the Granada University are working on the design of energy dissipaters, that is, devices that act as the fuses of an electrical system during an earthquake, causing the buildings to better withstand the movement.

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Properties Of Steel

Properties Of Steel

When steel first came into practical use, its distinguishing characteristic was its ability to harden if heated to a red heat and cooled suddenly, as in water or oil. Present methods of steel making have, however, brought out a product of iron containing too little carbon to harden when cooled suddenly, yet its composition differs from the old form of steel only in containing less carbon.
Primarily, the differences between wrought iron, the several grades of steel, and cast iron are due to the per cent of carbon in each class of metal, and for this reason steel is said to occupy a place between wrought iron and cast iron. However, the processes of manufacture give steel a composition and a molecular structure which affect its properties aside from this simple relation. The properties of steel depend primarily upon the carbon it contains, influenced by the kind and quantity of the other ingredients (or impurities, they may be called), and further influenced by the cooling of the steel from its molten state. This last-named influence determines the size and composition of the crystals which steel assumes upon cooling.
Despite the somewhat complex conditions determining the properties of steel, the grades of steel are classed according to their hardness due to their contained carbon. The higher the per cent of carbon, the greater the strength and brittleness, and the less the elongation before breaking. The grades of steel merge so gradually one into another that only two classes are distinguished, viz., mild steel which will not harden when suddenly cooled, and high-carbon steel which will harden when suddenly cooled from a red heat. This property of hardening begins to show when the steel contains .25% of carbon though is not of much practical use in hardening tools until the carbon has reached about .75% in the steel.
A quick means of showing whether a piece of iron is wrought iron or steel is to place it in a somewhat dilute mixture of sulphuric and hydrochloric acids, after it has been cleaned to show a metallic surface. Steel shows a granular and wrought iron shows a fibrous structure after a few minutes action of the acid.
The conditions determining the properties of iron and steel can only be touched upon lightly here, and the pursuit of this subject is in itself a special study.
III. The Manufacture of Wrought Iron.

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Cost of concrete

Cost of concrete

About $100 per yard, extra's cost more.Make the whole thing out of concrete, ICF's work real good.This is a good place to start.
Source(s):
http://www.cement.org/homes/ch_bs_icf.as…

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