Development of Compressed Earth Blocks using Local Materials

Abstract

Earth has been used for thousands of years for the purpose of construction. Even today about 30% of the world population lives in earthen buildings. The main type of earthen construction material is brick. Fired bricks are one of the most used construction materials around the world with around 1.391 trillion bricks produced each year at 800℃ with baking time of 3 to 14 days. This brick firing process is energy intensive as well as hazardous for the environment. Around 3.7 million people died in the world due to air pollution according to World Health Organization. During production Bricks produce around 200 kg CO2/ton, Concrete blocks produce 143 kg CO2/ton and Aerated concrete blocks produce 280 - 375 kg CO2/ton. To address these problems, Interlocking Compressed Earth Blocks are proposed as an alternative to these construction materials. ICEBs are produced using cement as stabilizer. Materials properties were investigated using particle size gradation analysis, Atterberg limits, Modified proctor test and X-ray diffraction of soil samples. Due to inherent variability of soil as well as absence of any standard mix design for CEB production, different mix ratios with varying amounts of cement, sand and water were initially tested. The mix ratio that demonstrated the best results was then selected to produce ICEBs for further testing. Optimized ICEBs were tested for Wet compressive strength, Flexural strength test, Drip erosion test, water absorption test, Masonry prism test and Masonry wallet tested for compression. Later SEM and FTIR analysis were also conducted to analyse the hydration products. Compression test results showed that Compressive strength of ICEBs increases with increase in cement content due to the formation of CSH gel in the ICEBs. Increasing the water content from 12 % to 21 % resulted in increased compressive strength for same cement and soil/sand ratios. This increase in strength could be observed to be present till around 18 % water content, after that the strength decreases. The increase of sand percentage resulted in decreased compressive strength for low cement and water percentages whereas the strength increased for higher percentages of cement. Masonry prism and wallet test results showed that ICEBs could be used as eco-friendly and sustainable alternative to conventional brick masonry.