Effects of Cement-Rice Husk Ash Mixtures On Geotechnical Properties of Lateritic Soils

Soil Stabilization with Rice Husk Ash

“…The type of ash suitable for pozzolanic activity is amorphous rather than crystallized [2]. The structural transformations of the silica affect the ash reactivity since the larger surface area of the silica the greater the extent of the chemical reactions with the Ca(OH) 2 [2,6]. Incineration of rice husk in the temperature range of 550-700°C is generally found to produce amorphous silica in the ash while temperatures in excess of 900°C produce unwanted crystallized forms [2].…”

“…The RHA and lime have lower specific gravity and finer grain size distribution than those of the soil, so when added to a soil the specific gravity and the grain size distribution of the mixture are reduced resulting in the DUW decreasing [6,7]. As a result the MDD of soil-RHA-lime materials are less than those of the soils ( Table 3).…”

“…The burning volatilizes the organic compounds and water of the rice husk, and about 20% of the mass remains as rice husk ash (RHA) [2,[4][5][6][7][8][9]. If all rice husks had been burned, it would annually produce about 20 millions of tons of RHA worldwide.…”

“…The RHA contains around 90% of silica [4,5], which is the highest concentration of all plant residues [2]. Based upon this, RHA has been used to improve properties of soil either when added alone or when mixed with a hydraulic activator such as the cement and lime [1,[6][7][8][11][12][13][14][15][16]. Soil stabilization by the addition of RHA and lime is particularly attractive for road pavements because it leads to cheaper construction and lesser disposal costs, reduces environmental damage and preserves the most highly qualified materials for priority uses [7,8].…”

“…Development of UCS has been observed when clayey, clayey sandy, silty clayey and silty sandy soils were treated with RHA and lime or cement [1,7,8,12,13]. In the case of cement, it was observed that little or insignificant increases of UCS in lateritic and clayey soils stabilized with RHA and cement with respect to its increase when they were treated with cement alone [6,12]. For a given lime or cement content there is an optimum value of RHA content which corresponds to the maximum UCS, which varies depending on the type of soil, ash characteristics, hydraulic activator and curing time [1,7,8].…”