M-Y. Lin, P. Grandgeorge, A.M. Jimenez, C. Quiroz-Arita, E. Roumeli
University of Washington,
Keywords: algae, cement, construction, mechanical properties
Summary:As 5-8% of global CO2 emissions is attributed to the concrete industry, increasing attention is drawn toward the environmental impacts of cementitious materials. A wide variety of biobased fillers, including hemp fibers, cellulose microfibrils, and nanocellulose, has been studied and shown great potential in reducing carbon footprint of cementitious materials. Although incorporating such biobased materials to cementitious materials shows improvement on the mechanical properties, as well as thermal and acoustic insulation properties, limitations involving using costly food crops and energy-intense processing methods for extracting and pretreating have impeded their further applications. Algae-based materials, due to their high capacity of carbon fixation, rapid growth rate, and capability of growing on non-arable land, represent a promising biomass resource for construction materials. In this work, we investigated the effects of adding a photosynthetic algae, Spirulina, in forms of dry powder into Type I/II ordinary Portland cement (OPC) at concentrations ranging from 0.5-15 wt.%. The compressive strength evolution across 3-91 days is studied and associated with the development of microstructure by scanning electron microscopy (SEM). We observe minimal differences in strength with spirulina substitutions up to 1 wt%. However at concentrations 5 wt% and higher, there is a drastic decrease in strength. Finally, we estimate the environmental impact of our cement-chlorella composites with life-cycle analysis, for a variety of the produced materials and show reductions in the order of 10 % carbon footprint with the addition of 5-15 wt.% chlorella.