Evaluation of physical and mechanical properties of porous clay brick manufactured with biochar

Abstract

In older buildings, clay bricks have been widely used as a primary construction material due to their excellent heat retention, erosion resistance, and fire-resistant properties. Biochar, produced by heating biomass without oxygen, has numerous benefits: insulation, air quality, emission reduction, humidity control, radiation shielding, water management, and environmental well-being. Clay, a versatile mineral substance, shapes effortlessly for art, pottery, construction, ceramics, agriculture, science, and industry. Clay bricks offer limited thermal insulation and hence the incorporation of biochar enhanced thermal insulation properties due to its porosity. The main objective of this research was therefore to evaluate the physical and mechanical properties of porous bricks made from biochar and clay soil. The Specific objectives included characterizing the properties of the materials, fabricating clay-biochar-bricks, evaluating the properties of the fabricated bricks and relating the properties of the clay-biochar bricks with pure clay bricks. This study utilized clay and maize biochar to create porous bricks for building. The methodology involved material collection, characterization, experimental design and brick fabrication through hydroplastic forming. The clay and biochar were blended by varying the biochar from 5% to 15%, firing temperature from 700 o C to 1000 o C and compacting pressure from 0.1 to 1.5N/m 2 . The clay used in the study had a plasticity of liquid of 49, plastic limit of 24.95, plastic index of 24.05, particle size of 2mm, main chemical composition of 69.45% (SiO 2 ), 21.29%, (Al 2 O 3 ),2.25% (K 2 O), 2.07% (TiO) and3.40% Fe 2 O 3 The biochar used had an average particle size of 2mm, moisture content of 0.0933% and 30% carbon. The fabricated porous clay brick was characterized by the bulk density value of 1.418g/cm2, water absorption of 24.009%, thermal conductivity of 0.688W/mK and compressive strength of 8.408N/mm 2 respectively. From the results of this study it was concluded that clay and biochar can be used as an alternative raw material for porous brick production. Further work should study on the effects of temperature, pressure and biochar on other bricks properties not studied and do the cost analysis involved in production of bricks.