Flexural design of alkali-activated reinforced concrete beams: Evaluating model errors using standards for Portland concrete

The article examines the potential of utilizing existing standard codes, although originally designed for Portland cement, in the flexural design of geopolymer (GP) concrete beams. In particular, the article collects experimental data from the literature on the cracking and ultimate moment of reinforced GP concrete beams, with and without steel fibers (SFs). The experimental moments are compared with those calculated using different standard codes for Portland cement (2nd generation EC2, ACI318, ACI363, AS3600) and GP concrete (SATS199). The purpose of this comparison is to evaluate the model error obtained with the different codes. The same procedure is applied on experimental data from RC beams made with Portland cement. To study the model error, the results obtained with different precursor materials (granulated blast furnace slag or fly ash), concrete compressive strengths, and reinforcement percentages are analyzed. The different codes have different levels of conservatism, resulting in different average model errors. However, within the same code, the average model errors for GP and Portland concretes are similar. Therefore, the existing codes can be used to calculate the cracking moment and ultimate moment of GP concrete beams. However, some uncertainty remains for the ultimate moment of over-reinforced beams, for which the number of experimental data is still limited.