Distinct Effect of Hydration of Calcined Kaolinitic Clay–Limestone Blended Cement on Microstructure and Autogenous Shrinkage

Abstract

This paper investigates the microstructure and autogenous shrinkage of calcined kaolinitic clay-limestone (LC) blended cement paste composites up to 200 days. The calcined clay-limestone content ranged between 20% and 65%. The microstructural parameters were studied using X-ray diffraction (XRD), thermogravimetric analysis (TGA), nitrogen adsorption (NAD), and Fourier transform infrared (FTIR) spectroscopy. The results showed that calcined kaolinitic clay-limestone blends developed higher autogenous shrinkage, faster hydration, and finer pore structure compared to the reference cement mixture. Autogenous shrinkage was the highest at 27% cement replacement and then decreased with further increases in replacement level. Both hydration and pore size distribution led to the development of high autogenous shrinkage for all calcined kaolinitic clay-limestone (LC) blends.