Pozzolanic Activity of Rice Husk Ash : Comparison of Various Electrical Methods

The great abundance of rice husk ash (RHA) as low-cost agricultural waste in Thailand makes it the most suitable material for cement-based applications. However, the use of RHA as a supplementary cementitious material (SCM) is not yet widespread in Thailand due to the poor pozzolanic activity of most agricultural RHA. Most RHA is incinerated at too high temperatures (usually in excess of 1000 degrees C) or under uncontrolled conditions as biomass fuel. This reduces the amount of amorphous SiO2 and hence worsens the pozzolanic activity of the resulting RHA. To enhance the use of RHA as an SCM in Thailand, a proper method to evaluate its pozzolanic activity is necessary. In this work, the two most simple electrical methods proposed in the literature to evaluate the pozzolanic activity of different pozzolans (not necessarily RHA) will be applied to RHA. Their applicability is discussed in comparison with the strength activity index method, and other physical properties believed to influence the pozzolanic activity of RHA.