Ash of vegetable waste used for economic production of low to high strength hydraulic binders

Abstract

Some vegetable wastes contain relatively large amounts of silica. One of the most promising examples is rice husk. Since rice is a major crop among many of the developing countries, it is available in large quantities. Its ash can be produced without using expensive fuels - such as in the case of Portland cement. During incineration, heat is released which could eventually be transformed into mechanical energy for grinding the ash. An artificial pozzolan is obtained, which can be combined with lime to yield a hydraulic binder of lower quality. Kaolin clay, when available, could be added during incineration to improve the binder quality. At the other end of the spectrum, Portland cement can be blended with finely-ground rice husk ash to produce high strength concretes with a water reducing agent at low water to cement ratios. Blending with the incinerated kaolin can further increase cost effectiveness. This study concentrates on RHA technology but also gives a survey of obtained strength data. © 1998 Elsevier Science Ltd.