Sustainable Incorporation of Lime-Bentonite Clay Composite for Production of Eco-Friendly Bricks

Abstract

Global earth atmosphere is degrading due to abundant use of fossil fuel for fulfilling energy demands of rapid growing economies. Brick manufacturing process contribute its part by consuming energy in its firing process, therefore, increase concentration of affluent greenhouse gasses and hazardous particulate matter, which causes global warming and cardio-respiratory diseases respectively. Therefore, proposed research aims to provide eco-friendly solution to the stated problems by incorporating locally available powdered lime-bentonite composite in compressed, unfired and fired clay brick. Characterization of lime, bentonite and its composite was determined individually by conducting scanning electron microscopy, X-ray diffraction, oxide composition, while gradation, atterberg limits and standard proctor test was conducted on composite level. Bricks for all three cases i.e. compressed, unfired and fired by replacing clay with 0, 5, 10, 15, 20% of bentonite keeping 5% quick lime constant. Bricks were then tested for compressive strength, flexure strength, unit weight, water absorption and thermal conductivity. Results indicated that calcium rich quick lime and silica rich bentonite being incorporated in clay brick decreased the D50 values, increased the plasticity from low to higher values and decreased the values of optimum moisture content of lime-bentonite clay brick. Incorporation of lime-bentonite composite in compressed, unfired and fired bricks resulted increased compressive strength and flexure strength attributed to pozzolanic activity, decreased water absorption and unit weight due to swelling/healing property and enhanced microstructure by dissolution of silica and alumina to form calcium silicate hydrate and calcium aluminate hydrate. Strength gain of compressed bricks observed due to reduction in voids, pozzolanic activity, geo-polymerization reaction and interlocking of clay minerals, whereas, strength gain in fired bricks resulted due to bonding of micro sized clay minerals due to optimal sintering achieved at 1000°C. Thermal conductivity reduced from 0.51 to 0..38 resulting 15.45% reducing in cooling load and carbon foot prints for B20 compressed brick composite, which proved it an energy efficient and ecofriendly construction material. Corrosion resistance of compressed bricks increased from 0.72 to 0.81 with bentonite inclusion. Conclusively, lime-bentonite compressed clay bricks provides eco-friendly, energy efficient and sustainable options for production of green clay bricks.