MECHANICAL AND PHYSICAL PROPERTIES OF FIRED CLAY BRICKS STABILIZED WITH THE RICE HUSKS IN ORDER TO ASSESS THEIR DURABILITY AND RESILIENCE FOR A SUSTAINABLE HOUSING MODEL ADAPTED TO FLOOD RISKS IN THE LOCALITY OF TCHATIBALI, MAYO DANAY DIVISION, FAR NORTH REGION OF CAMEROON

Abstract

In the Far North Region of Cameroon, recurrent floods weaken rural housing built with water-sensitive local materials, particularly Karal clay, abundant and accessible. This study addresses the low hydraulic and mechanical durability of local bricks by assessing the potential of rice husks as a bio-based additive in fired clay bricks. Karal samples were collected in Tchatibali at depths ranging from 0.3 to 0.8 m, while rice husks were obtained from the same locality. The raw materials were characterised through natural water content, particle size distribution, Atterberg limits, specific gravity, modified Proctor and CBR tests. Bricks were mixed using partial replacement of 0%, 1%, 3%, 5%, 7%, 10%, 12% and 15% by weight of rice husk contents in karal materials, then moulded, dried and fired. The performance was assessed using compressive strength, flexural strength, water absorption and capillary rise tests. The results showed that Karal is a fine-grained, moderately plastic and water-sensitive soil, with 85% fine fraction and a plasticity index of 25%. The 1% rice husk bricks gave the best mechanical performances, reaching 1.94 MPa in compression and 0.32 MPa in flexure after 4 days and 4.30 MPa in compression and 0.35 MPa in flexure after 8 days. The same mix maintained low water absorption of 9.94% in 24 hours and a capillary rise time close to that of the control brick. Higher rice husk contents increased porosity, reduced mechanical strength and accelerated water migration. This study showed that controlled incorporation of 1% rice husks can valorise a local agricultural by-product while improving the balance between strength, absorption and durability of fired clay bricks.