Physical nonlinearity of precast reinforced geopolymer concrete beams

Precast reinforced concrete includes a special category of building materials that aim at fast execution, low cost, and high quality. Although there is disagreement about the cost and quality of the geopolymer, its speed in execution would still be advantageous in relation to Portland. Geopolymer cements are being identified as a new class of low environmental impact or eco-efficient materials, emitting less CO2 during manufacturing than Portland cement. Its application in reinforced concrete requires high quality control of its constituents, which is a basic requirement in the precast industry. This work presents a pioneering analysis in Brazil of the mechanical behavior of precast beams of reinforced geopolymer concrete (CCG) and the comparison with their replicates of reinforced Portland cement concrete (CCP). The goal was to create an application precedent in the civil engineering field and find out if the mechanical behavior of CCG fits any criteria of physical nonlinearity developed for the CCP. To this aim, four models were compared: Branson, Ghali & Favre, Bischoff and the Brazilian Standard NBR 6118:2014. The results showed that CCG presents the same three classic stages on the Moment-Curvature relationship as the CCP, with reasonable approach to the Ghali & Favre and Bischoff models.