Water absorption properties of sawdust lignin stabilised compressed laterite bricks

Abstract Lignin is reported to have good binding ability with soil particles especially in roadconstruction, however, its application and behavior in compressed bricks is being investigated. The water absorption property of lateritic bricks is essential to its durability as well as its bonding with cement mortar. This study is focused on the determination of the initial rate of absorption and the 45 min total water absorption of lignin stabilised compressed lateritic bricks. Two particle sizes of laterite namely those passing the 2.36 mm BS sieve and those retained on it were stabilised at 4%, 8% and 12% by mass with sawdust lignin extracted through alkaline hydrolysis. Fourier infra-red spectroscopy (FTIR) was used to identify the functional groups present in the lignin additives while the laterite sample was subjected to consistency, physical and mineralogical tests. The tests were carried out in order to determine the likely interaction and mechanism of reactions between the soil particles and the additives. The total water absorption after 45 min of full immersion and the initial rate of absorption after 5 and 60 min were determined at 14 and 28 days of air curing. The wood additives showed an improvement in the water absorption properties of the stabilised bricks compared to that of cement stabilised samples. The percentage water absorbed by cement stabilised samples ranges between 6% and 15% which is considered high while that of the wood additives ranges between 2% and 6%.