Partial replacement of cement by combination of fly ash and metakaolin in bamboo bioconcretes
Abstract
During the Portland cement manufacture, it is known that an average of one ton of CO2 is released per ton of cement produced. Consequently, the materials with high cement consumption have negative environmental impacts. One of these materials is the bio-concrete of bamboo, which is basically constituted of bamboo particles, an average of 800 kg/m3 of cement, and presents around 9 MPa of compressive strength. In this work, a partial replacement of cement with fly ash and metakaolin was realized, with the purpose of reaching compressive strength closer to a bio-concrete containing only cement. Mixtures with partial substitution of 0, 40, 50, 60 and 70% of cement by mass were produced with a volumetric fraction of bamboo set as 40%. The water-to-cement ratios varied gradually from 0.30 to 0.40, while the fly ash inversely varied from 40 to 10% of cement replacement by weight and the metakaolin were kept constant (30%). The compressive behavior of the bio-concretes was analyzed at 7, 28, 60 and 90 days. The results revealed that it was possible to reach between 60% and 90% of the reference strength, producing workable bio-concretes using binders with low CO2-emission.
