XRD studies of portlandite present in hydrated Portland cement paste

Synopsis The effect of hydration time, water/solids ratio and addition of melamine sulphonate or naphthalene sulphonate resins on the I₍₀₀₁₎/I₍₁₀₁₎ XRD peak intensity ratio of portlandite formed in the hydration of pure tricalcium silicate or Portland cement was studied. It was found that this ratio does not remain constant and may change with variations of the above factors. As such variations are observed in bulk pastes they cannot be explained by an oriented crystal growth seen on pasteaggregate interfaces and appear to be characteristics of the material.