Calcium Silicate Hydrate (C-S-H)

Summary

Calcium Silicate Hydrate (C-S-H) - is the main end-product of the hydration process of cement and provides concrete with most of its final strength.

Technical Information

In C-S-H there is no strict ratio of silicate to calcium (usually around 0.4-0.5). It is dependent on the ratio of alite to belite in the original cement mix, and also what proportion of the Portland cement, if any, has been replaced by a cement replacing material.

During hydration, C-S-H expands into any capillary pores present in the cement and forms much smaller gel pores within its structure; these don’t have a structural capacity but reduces porosity.

C-S-H is directly vulnerable to thaumasite sulphate attack in situations where sulphates, carbonates and water are present in cool temperatures.