Performance of ACI code for predicting the flexural capacity and deflection of reinforced geopolymer concrete beams

Abstract

A conventional Portland cement can be considered as the most consumed energy material, since it isresponsible on about 1.35 billion tons annually, occupying is approximately 6% of global CO2 emissions. It can be stated that the emission related to CO2 is the main reason of global warming and greenhouse effect. For this reason, studies have been devoted to find a clean source of material to be an alternative for the traditional cement. Geopolymer concrete is being emerged as a promised construction material that acts as an ecofriendly material. Geopolymer is an inorganic material that can be produced from geological origin or by-product waste, mainly from Silicon (Si) and Aluminum (Ai) in addition to the alkaline activator required for geopolymerization process. Research conducted to assess the performance of the existing design guidelines (e.g. ACI code) for moment and/or deflection calculations of Geopolymer concrete beams is scarcely available in literature. Therefore, this research is devoted to evaluating the applicability of ACI 318-2019 code for flexural and deflection calculations. For this purpose, a total of 40 simply supported geopolymer concrete beams embedded with steel reinforcement bars were compiled from different sources of literature. The experimental results collected from the samples were compared to those calculated by ACI 318-2019 in terms of moment capacity and deflection. It was found that the calculated moments of the ACI were conservative with a mean value and the variation of coefficient of 1.16 and 15 %, respectively. On the other hand, the deflection results were much lower than those measured experimentally. Essentially after the formation of the first crack, highlighting the need of a suitable model for precisely predicting the flexural strength and deflections of geopolymer concrete beams to reflect the main parameters that control the behavior of such elements.

Shear Behavior of Geopolymer Concrete Slender Beams

“…Alex et al [57] reported that GPC beams exhibited 9% greater midspan deflection than OPC beams. Zinkaah et al [22] also reported that midspan deflections of GPC beams were greater than OPC beams. The nominal moment capacity (𝑀 𝑛 ) of shear reinforced beams expected to fail in flexure was computed using Equation (1).…”

“…Alex et al [57] reported that GPC beams exhibited 9% greater midspan deflection than OPC beams. Zinkaah et al [22] also reported that midspan deflections of GPC beams were greater than OPC beams.…”

“…Mamdouh et al [21] reported that slag-based ambient cured GPC beams exhibited 7.4% greater flexural strength and 17.5% reduced cracking moment than the OPC beams of similar compressive strengths. Zinkaah et al [22] reviewed data from forty GPC beams and found that OPC and GPC beams exhibited similar flexure failures with similar crack width and crack propagation. GPC and OPC beams exhibited similar ductility.…”

Experimental investigation of the effect of longitudinal tensile reinforcement ratio on ductility behaviour in GPC beams

“…Another study for bending and deflection calculations evaluated the applicability of the ACI 318-2019 code for geopolymer concrete beams. It has been stated that a suitable model is needed to calculate the flexural strengths and deflections of geopolymer concrete beams after the first crack formation [30]. When adding glass fiber or steel fiber and hybrid propylene while manufacturing fly ash-based geopolymer-reinforced concrete beams, the bending capacity increased by 30-35% [31,32].…”

Performance of Beams Incorporating Geopolymer and FRP Bars: A Review

“…Alumina and silica undergo rapid reactions in an alkaline environment during polymerization, forming a three-dimensional network of polymeric chains [13,14]. Furthermore, the performance of GPC is greatly influenced by the type of activators employed and the availability of aluminosilicates [15]. Compared to conventional concrete, GPC exhibits significantly lower CO2 emissions, with reduction rates ranging from 9% [16] to over 80% [17].…”