Effect of cyanobacterial calcification mechanism on the solidification of bricks for green construction

• Main Author: Dawood Muhammad Iqbal, Mr.
• Format: text::Thesis
• Language: English
• Published: 2023
• Subjects: Effect of cyanobacterial calcification mechanism on the solidification of bricks for green construction

Global warming is the primary environmental concern due to carbon emissions. The increase in the population requires more building and infrastructure to be constructed. Building raw material such as cement, causes carbon emissions and still; it is widely used in the construction industry. Similarly, the cement-sand brick and fired clay brick consume a lot of energy in their production which leads to carbon emissions. The purpose of this study is to apply microbial induced calcium carbonate precipitation technology from cyanobacteria (Microcystis) to produce bio-brick to reduce carbon emissions. The first part of this study is to analyze the photosynthesis of cyanobacteria with respect to carbon capture. An optimum carbon capture of 22 mg L-1 was observed on 36-day of exposure with a urea concentration of 40 g L-1. The amount of cyanobacteria at the duration of urea exposure was used for casting the cyanobacterial bricks. The optimal mix design was proposed to be 0.8 water to binder ratio with the mixture content of 25% of calcium oxide, 30% kaolin and 45% sand are used. Experimental tests were conducted to evaluate the compressive strength, water absorption, residual compressive strength, surface temperature, scanning electron microscope and wavelength dispersive X-Ray fluorescence to characterize the mechanical and chemical behavior of the cyanobacterial bricks. Based on the 28-day of cyanobacterial calcification, 3 MPa of compressive strength, 0.198 MPa of modulus of rupture, 3.71 MPa of compressive strength at an elevated temperature of 400°C, and 5.14% of water absorption were observed for the cyanobacterial bricks designed at the optimal mixture. The surface temperature tests revealed that the cyanobacterial bricks were better in term of thermal insulation and they were lighter by weight compared to the cement-sand bricks. The findings showed that cyanobacterial bricks have the advantage to be used as non-load bearing materials due to the fact that they require less energy in their production compared to conventional cement-sand bricks. In summary, the results showed that the cyanobacterial bricks are compatible to commercially available cement-sand bricks and can be applied for the making of non- load bearing walls such as fence walls. This can provide a green solution to the brick manufacturing industry and key pave a way for the product commercialization.