Application of Enzyme to clay brick for low cost in-situ house construction

Abstract

In this research, the literature, theories and the test result from experiment were combined and verified to show the quality, economic and feasibility of enzyme application for clay brick. The first test was done to identify the curing time by compressive strength after 14, 21, 28 and 35 days. This is preliminary investigation. The test result after 28 and 35 days are the same, therefore 28days are the maximum curing time. Enzyme improve the strength of brick by 33%. After determining curing time, the application of an enzyme to clay bricks with different clay contents is described. The compressive strength test results for 7, 14, 21, and 28 days curing time, water absorption and dry density are reported. The enzyme brick with an 85/15 clay/silt ratio by weight exhibited higher strength in the 28-day test, with an average value of 6.89 MPa. Clay soil with a more specific surface area had a better chance of undergoing an ionic reaction with the enzyme to increase density and strength. Less water absorption, less porosity and higher density were also observed in brick with a higher clay proportion. Generally, the average compressive strength of the enzyme clay brick was over 5.50 MPa after a 28 day curing period and thus satisfied the specific limit of 5 MPa, which is the minimum standard for British common brick. After determining the applicability of enzyme brick with clay soil, investigation the enzyme dosage was very important. Compressive strength, water absorption, diffusivity capacity, pore area and the role of the enzyme on clay soil brick was verified. The higher compressive strength at enzyme/water ratio of 1/150, 1/250 & 1/350 was above 7MPa and lower water absorption at same state was below 16%. These value satisfied the ordinary clay brick standards which are a minimum strength of 7MPa and a maximum limit of 20% water absorption. The enzyme concentration affected the pore area of brick samples. Based on ImageJ analysis, the pore area of enzyme clay brick decreased when enzyme concentration increased. Cross-linking and matrix like bond structure formations are the role of enzyme on clay soil as it was observed by SEM with a couple of Matlab image processing. These structures are important for strength as well as immobilization properties of enzyme in clay soil. The enzyme brick might satisfied the clay brick standards which is above 7MPa. The basic processes of enzyme brick production are soil selection, grinding & sizing, stabilization & mix preparation, compaction, curing and finally packaging and or distribution. Enzyme brick is economical, low in energy consumption and molded by locally available clay material. Therefore, enzyme brick is applicable for housing construction particularly in developing countries to satisfy one of human basic needs.