PNNL

Abstract

Algal biochar, as the solid residue of biofuel production from algal biomass, are reported to explore disposition options, aiming to lessen the liability or obstacles to biofuel production process. However, landfill and open combustion lead to adverse environmental impacts. One way to add value to such wastes is by using them as admixtures in cementitious construction materials. This study aims to investigate the feasibility of algae-derived biochar as supplementary cementitious materials at different water content and solid addition ratio. Performance of algal biochar-cement composites are compared with control composites with commercial silica fume as admixture. The findings suggest that algal biochar is a promising candidate to supplant the existing admixtures, like silica fume. Algal biochar-cement composites can reach comparable compressive strength and Young’s Modulus to commercial cement-pozzolan materials. However, the tensile strength of algal biochar-cement composites is lower and requires further investigations to improve their performance. The mechanical properties are negatively impacted by the high retention of mixing water by the char. Valorization of algae-derived solid waste provides great potential to reduce carbon footprint and brings credit to biofuel production and cement-based construction.