Foundation, Concrete and Earthquake Engineering

Cement-Related Parameters Controlling the Rate of Strength Gain of Concrete

Many parameters relating to the composition of the cement constituents and their proportions in the cement can affect the rate of strength gain and the final strength achieved. These include:

1. Alite content (Tri-Calcium silicates) & Belite contents (Di-calcium silicates) 

2. Alite & belite reactivity

3. Sulfate contents

Alite is the most reactive cement mineral that contributes significantly to concrete strength. More Alite should give better early strengths ('early' means up to about 7 days). 

Sulfate in cement, both the clinker sulfate and added gypsum, retards the hydration phase. If there is insufficient sulfate, a flash set (rapid hardening of freshly mixed cement paste with noticeable heat evolution) may occur. on the other hand too much sulfate contents can cause false-setting(rapid hardening of freshly mixed cement paste with minimum heat evolution) 

Strength gaining-time graph with different type cement
Some physical parameters of cement also play role in strength gain of concrete like Cement surface area and particle size distribution. 

Fineness is often expressed in terms of total particle surface area. More fine is cement; greater will be its hydration rate. Particle size distribution is also very important prospect in strength gain of concrete. Cement with very finely-ground gypsum and clinker particles results in slower hydration.

No comments:

Post a Comment