Effect of nanolimestone particles on hydration and flexural strength of Portland limestone cement pastes

In this study the effect of nanoparticles of limestone (nLS) hydration and flexural strength of Portland limestone cement pastes was investigated. nLS with an average primary particle size of 70nm and a surface area of 17 to 29m2/g were added to three different blended cement systems. nLS content ranged from 0% to 10% by mass of solids at water to binder ratio (w/b) of 0.3. Specimens were wet cured at 20oC and 60oC. The blended cement combinations comprised of binary and ternary systems (based on Portland cement and micro-sized limestone). The microstructure characterisation was carried out using thermal gravimetry (TG) and scanning electron microscopy (SEM); isothermal conduction calorimetry was used to investigate the effects of nLS on the heat of hydration. Results showed that nLS accelerated hydration of Portland cement, increased the quantity of C–S–H and calcium hydroxide produced, and altered aluminate hydration possibly through formation of calcium carboaluminates.