The appropriate mixing of rice husk and sand with Saraburi series to make adobe brick for earth construction

Abstract

This study aimed at finding the appropriate ratio of rice husk and sand to mix with Saraburi series (Very-fine, mixed, active, nonacid, isohyperthermic Vertic (Aeric) Endoaquepts) in order to make adobe brick. This soil series comprises of high content of smectite which would make the brick easily be cracked under dry condition. The experiment design was CRD (Completely Randomized Design) with 5 treatments and 10 replications. Treatments were control treatment, T1 (soil 100% by weight), and T2, T3, T4 and T5 were soils mixed with rice husk and sand at rates of 10, 14, 16 and 20% by weight, respectively. Adobe bricks were analyzed for their stable properties such as number of cracks, degree of volumetric shrinkage, compressive strength and mass water content. These properties were used as indices to identify the most appropriate mixing ratio. Results showed that increasing contents of rice husk and sand increased brick’s compressive strength and water content, but decreased number of brick’s cracking and degree of volumetric shrinkage. Thus, contents of rice husk and sand mixers at the rate of 20% by weight (T5) was the most appropriate ratio in order to make adobe brick. With the aforementioned mixture, the brick product has no crack, 41.81 kg/cm2 compressive strength, 0.31 θ_m and 3.96% volumetric shrinkage.