Effect of zeolite and bamboo biochar as CO2 absorbant in concrete

Abstract Carbon dioxide (CO2) is one of the major air pollutants that enter the atmosphere. There is a large release of carbon dioxide into the atmosphere as a result of burning fossil fuels in the cement manufacturing industries and many other industries, as well as emissions from gridlock. This increase in CO2 concentration in the atmosphere leads to various ill effects and global warming. To reduce the CO2 level in the atmosphere, efforts were made to prepare concrete that can absorb CO2 by addition of zeolite and bamboo biochar. These materials were chosen because zeolite and bamboo biochar have large pore volume and large specific surface area and so they can absorb more CO2. Zeolite is having more oxygen content and bamboo biochar is having more carbon content which helps in CO2 absorption. In this work, Zeolite is substituted for fine aggregate in the varying ratios of 25% and 50% and bamboo biochar is substituted for cement in the ratios of 0.5%, 1% and 1.5%. The strength properties and CO2 absorbing capacities of various zeolite and bamboo biochar concrete ratios were compared and it was found that concrete with 50% zeolite and 1% bamboo biochar (ZB5) was the optimal mix. The optimal mix was found based on compressive strength, split tensile strength, water absorption, impact strength, amount of CO2 absorption and depth of CO2 penetration in concrete. This optimal mix has a compressive strength of 38.49 MPa which is 7.48% higher than conventional concrete and also has a split tensile strength of 4.39 MPa which is 15% higher than conventional concrete. It was also found that the optimal mix absorbed 1.2 g of CO2 per day and that the depth of CO2 penetration was 15 mm when the concrete cube was kept in the carbonation chamber for 7 days. This study provided necessary information on the addition of zeolite and bamboo biochar in the concrete which enhances both strength properties and CO2 absorption. This study is important because now-a-days the current CO2 emission in the atmosphere is mainly due to several man-made activities. This ZB concrete provides a solution to reduce the amount of CO2 in the atmosphere and can be used in the concrete pavements, sewer pipelines, parapet walls and the environments with higher CO2 concentration and emission. Graphical Abstract