Guidelines to select cement for concrete

GUIDELINES TO SELECT CEMENT FOR CONCRETE

J D Bapat

Concrete is used as a material to build varieties of structures under different surrounding conditions. Here are some guidelines to select appropriate cement or binding material for concrete used for different structural applications.

Sl No	Application	Comments
1	Conventional structural	Select cement for economy
2	Concrete in non-aggressive environment	Any cement as per the Standards. Blends of OPC with GGBS or FA or alternatively PPC or PSC, as per the Standards, have been extensively and successfully used in non-aggressive environment
3	Large placements where temperature rise, due to heat of reaction, is to be kept as low as possible	Best results are likely to be achieved with cements with mineral admixtures contents in excess of 50% GGBS or 25% FA.
4	Structural precast	Choice of cement for precast elements will depend mainly on strength requirements at early ages. High early strengths, without steam curing, will be achieved most economically with cements of strength Grade 43 and higher and with low mineral admixture content. Cements with higher mineral admixture content are better suited to steam curing. Where there is no requirement for rapid strength gain, the choice of cement should be based on economy
5	Precast bricks, blocks and pavers	Provided the elements have sufficient strength to allow handling at an early age, typically the day after casting, the choice of cement should be based on economy.
6	High-performance or High-strength concrete	Strength Grade 43 or higher may be used. The inclusion of about 8% silica fume is common practice in this application. Other mineral admixtures may also be used for durability or economic benefits. Superplasticiser is an essential ingredient in high-performance concrete. The compatibility of the cement/binder material and the Superplasticiser is important and needs to be checked.
7	Reinforced concrete in marine environment	Research and long-term field experience shows that best results in marine environment are obtained, using concrete with cement replacement > 50% by GGBS or FA around 30%
8	Concrete with alkali-reactive aggregates	Cement replacement should be > 40% GGBS or > 20% FA, for alkali-reactive aggregates
9	Concrete exposed to sulphate attack	OPC with 5-8% C3A possesses good resistance towards sulphate attack. Using high levels of GGBS as cement replacement (above 50%) improves sulphate resistance