Effect of mechanical processing on the pozzolanic efficiency and the microstructure development of wheat straw ash blended cement composites

Abstract

Mechanical processing significantly affects the pozzolanic efficiency of mineral admixtures. In this study, wheat straw ash was subjected to various stages of grinding and used to make mortar and paste samples. The cement was replaced (by weight) with ash at various replacement levels up to 30% maximum and studied for different parameters. The effect of mechanical processing on the pozzolanic efficiency of ashes was investigated via compressive strength test, isothermal calorimetry, Thermogravimetric analysis, Fourier transform infrared spectroscopy, X-ray diffraction analysis, scanning electron microscopy, and ultrasonic pulse velocity test. The results showed that the pozzolanic efficiency of the ash particles profoundly increased due to the mechanical processing. Mechanical processing reduced the particle size of the ash which enhanced the hydration reaction and improved the microstructure of the cement composites due to pozzolanic and filler effects. An enhanced quality blended cement composite can be obtained by replacing cement with 20% wheat straw ash ground for at least 60 min.