Study on the pozzolanic properties of rice husk ash by hydrochloric acid pretreatment

Summary

The pozzolanic properties of rice husk ash pretreated with hydrochloric acid are reported.  Three methods were used to estimate the pozzolanic activity.  The heat evolution and the heat of hydration of the cement, the Ca(OH)2 content in the mortar, and the pore size distribution of the mortar were determined.  It was shown that, compared with untreated  ash, the pozzolanic activity of HCl pretreated rice husk ash  is not only stabilised but noticeably enhanced.  The kinetics of reaction of rice husk ash with lime is consistent with diffusion control and can be represented by the Jander equation.  A significant increase in the strength  of the pretreated specimen is seen.  Heat evolution results indicate that the pretreated rice husk ash shows an increase  in cement hydration. Cement mortar containing pretreated rice husk ash has a lower Ca(OH)2 content after 7 days, and its pore size distribution shows a tendency to shift towards  a smaller pore size.  15 refs.

Primary author(s): Feng Q; Yamamichi H; Shoya M; Sugita S

                            Hachinohe,Institute of Technology

Source: Cem.Concr.Res.

            34,No.3,2004,p.521-526