Lightweight Concrete Production

1. Introduction to light weight concrete

Lightweight concrete is mainly used as back-filling material. When talking about lightweight concrete, we refer to a concrete of which its specific gravity (density) is much more lower than normal concrete.

Basically normal concrete: 2.35 – 2.42 ton/m3 while lightweight concrete 0.80-1.40 t/m3.

Therefore final strength is not issue. Expected final strength would be usually lower 5 MPa at 28 dasy as such concrete contained of lot of air entrained.

The strength would be affected by type of lightweight aggregate to used.

2. Production Principle

Basically there are 2 ways to produce light weight concrete.

a. Cement/ Water/Sand/lightweight aggregate/ chemical additives (admixtures)

b. Cement/ Water/ Sand/ Chemical additives

By lightweight aggregate we can consider polystyrene balls, expanded clay for instance. Chemical additives, we mainly means special air entrained agent such as Sika Lightcrete 1-500VP. This admixture ca entrained safely up to 30% of air entrained into the mix.

As per the use of the special air entrained, usually, the mix is batched for a designed volume the air entrained is measured in order to determine final volume of the concrete batched. Indeed in term of concrete production it is important to know about about which volume we are talking, we are referring to:

For instance: Expected air entrained 30%

Volume of fresh batch 1000 liters -> initial ar development 30% –> final hard volume ~1.3 m3