Evaluation of the properties and carbon sequestration potential of biochar-modified pervious concrete

Adding biochar (BC) into cementitious materials to replace partial cement is a win-win strategy for both cement output reduction and hygrothermal properties improvement of cement-based composites. However, how to coordinate the different functions to achieve the optimized performance of BC-modified pervious concrete remains scarcely reported. This study is aim to explore the influence mechanism of BC prepared from construction wood waste on strength, water absorption, thermophysical properties and evaporative cooling performance of pervious concrete. The results show that when the BC content is 1.0-3.0 wt% (by weight), the compressive/flexural strength of BC-modified pervious concrete is higher than that of BC-free one, but the strength will be compromised if the content exceeds this value. The water absorption capacity of pervious concrete gradually increases with BC contents. Although the presence of these black carbonaceous particles will induce more solar radiation absorption, the increased solar absorption can be offset by the extra absorbed water via evaporative cooling. BC-modified pervious concrete performs a better cooling performance, with a maximum temperature reduction of 10 degrees C and a duration of about 12 h. Moreover, taking producing 1 m(3) concrete as an example, it reveals that CO2 emissions reduced 15% when 8.0 wt% BC is used instead of cement as compared to the control sample.