Effects of rice husk ash on itself activity and concrete behavior at different preparation temperatures

This paper aims to investigate the effects of rice husk ash (RHA) on itself activity and its concrete performance at different preparation temperatures for which three temperatures of 650 °C, 800 °C, and 900 °C were considered. To find a reasonable particle size, the effect of the particle size of the RHA on the workability of concrete at various grinding times was studied. A series of experiments were carried out to study the characteristics of the RHA, including X-ray fluorescence, XRD, ESEM, and an activity test. The carbonation resistance and frost resistance of concrete incorporating RHA were also investigated, where 10 and 30 wt.-% of cement was considered. The results show that the surface area of the RHA first increases and then decreases with grinding time. When the RHA is ground for 30 min, its surface area is largest and the workability of its mixture is also best. The burning temperature has little effect on the amount of SiO₂. Although the structure and activity of SiO₂in RHA change at different burning temperatures, the performance of concrete incorporating RHA is higher than that of control concrete without RHA. With the same content of RHA, both carbonization resistance and frost resistance decrease with an increasing burning temperature of RHA. At the same burning temperature, both carbonization resistance and frost resistance increase with an increasing amount of RHA. Among all types of mixtures, the mixture incorporating 30 % RHA burned at 650 °C (i. e., RHA₆₅₀) yields the best performance.