Abstract:
The objective of this research is to study stabilization of rice husk ash and sand mixed with lime admixture. Rice husk ash was mixed with sand at the ratio 100:0, 90:10, 80:20, 70:30, and 60:40 and then stabilized with lime at the percentage of 3, 5, 7, and 9 by weight of dry RHA and sand, and compacted by Modified Proctor method. Then, they were tested to determine the Unconfined Compressive Strength and California Bearing Ratio (both Soaked CBR and Unsoaked CBR) at different ages of curing. The test result shows that UCS, Soaked CBR and Unsoaked CBR for all rice husk ash-sand mix proportions varied wiht the amounts of lime and age of curing. On the other hand, Soaked CBR tends to the higher than Unsoaked CBR, associated with swelling of rice husk ash. Experiments were conducted to obtain the optimum rice husk ash-sand mix proportion at the percentage of 60:40 mixing with lime in the range of 3 to 9 percent by weight, tend to have the maximum dry density (MDD) in the range of 0.960 to 1.100 ton/m3. After 7 days curing the stabilized mixture tends to induce the unconfined compressive strength in the range of 9.90 to 17.70 ksc., with the Soaked CBR in the range of 38.3 to 73.4 percent and the Unsoaked CBR in the range of 35.9 to 70.8 percent. After 14 days curing the unconfined compressive strength tends to be in the range of 13.25 to 22.13 ksc., with the Soaked CBR in the range of 51.7 to 88.1 percent, and the Unsoaked CBR in the range of 44.3 to 82.4 percent. The result of research indicated that RHA mixed with sand is the proportion of 60:40 and stabilized with 8.5 percent of hydrated lime will induce the unconfined compressive strength 17.50 ksc. after 7 days curing.The relationship between UCS and Unsoaked CBR, UCS and Soaked CBR, Soaked CBR and Unsoaked CBR, percent sand and MDD, percent sand and UCS, percent sand and Unsoaked CBR, and percent sand and Soaked CBR all,. tend to be linear. Increasing the percentage of sand to the mix can cut down the amount of lime, but the density or unit weight of the mixture tends to be increased. The unconfined compressive strength of the RHA-sand mixture stabilized with lime tends to increase after 14 days curing, this indicates the effect of pozzolanics relation occurring in the mixture.