Sustainable incorporation of lime-bentonite clay composite for production of ecofriendly bricks

Abstract

The global earth atmosphere is degrading due to the abundant use of fossil fuel for fulfilling the energy demands of rapidly growing economies. The conventional brick manufacturing process contributes its part by consuming energy in its firing process, which causes global warming and cardio-respiratory diseases attributed to increasing concentration of affluent greenhouse gases and hazardous particulate matter. Therefore, the proposed research aims to provide eco-friendly solutions to the stated problems by incorporating locally available powdered lime-bentonite composite in compressed and unfired bricks, whereas properties of fired bricks were examined for comparison purpose. For compressed, unfired and fired bricks, clay was replaced by 0, 5, 10, 15, and 20% of bentonite content while keeping 5% quick lime constant for each dosage level. Characterization results indicated that the calcium-rich quick lime and silica-rich bentonite being incorporated in clay bricks decreased its average particle size and optimum moisture content values, whereas increased the plasticity of lime-bentonite clay composite. Incorporation of lime-bentonite composite in compressed, unfired bricks yield the increased compressive and flexure strength, whereas reduction in water absorption and unit weight was observed. However, compressed bricks type appeared as the most desired one out of all brick types with the compressive strength value of 10.40 MPa, which satisfied the strength requirement for building code of Pakistan and ASTM specifications C62-13 for building bricks along with negligible weathering. Durability in terms of corrosion resistance of compressed bricks increased from 0.72 to 0.81 with bentonite inclusion. However, thermal conductivity reduced from 0.72 to 0.38 W/m-K comparative to conventional fired brick used in the construction industry, resulting 31.91% reduction in cooling loads and carbon footprints for B20 compressed bricks, which suggests its energy-efficient and ecofriendly nature. Conclusively, lime-bentonite compressed clay bricks provide eco-friendly, energy-efficient and sustainable options for the production of green clay bricks.