Abstract
The environmental impact of Portland cement production and utilization in the construction sector has led to the global call for the use of eco-friendly construction materials for the production of cleaner and sustainable products. Therefore, this study explored agro-industrial wastes, slag and corncob ash, for the production of geopolymer concrete (GPC). Corncob was dehydroxylated at 600 °C for 3 h and partially used as a replacement for slag at 0%, 20 %, 40 %, 60 %, 80 %, and 100 %. A 12 M, 14 M, and 16 M of both sodium silicate (SS) and sodium hydroxide (SH) were used as activators. The chemical moduli of each and mixed binder were quantified and evaluated based on the major reactive oxides, hence leading to the evaluation of reactivity indexes (RIs). Moreover, the RIs and mix design properties (MDPs) of concrete were used for the prediction of flexural strength while the chemical resistance of each concrete sample was investigated. Compared with the experimental results, the predictive flexural strengths based on the RIs and the MDPs yielded a high precision with R2 ranging from 88–92 % at 7–90 days, respectively. Moreover, the GPC, unlike Portland cement concrete (PCC), resisted the more acidic attack. Therefore, the use of GGBFS−CCA blended concrete would be more advantageous in a highly acidic environment than PCC. Ultimately, the models proposed by this study can be useful in the concrete mix design procedure for the flexural strength development of GPC incorporating agro-industrial provided the oxide compositions of each and mixed material were obtained.
Highlights
In the construction sector, the utilized rate of concrete is high, owing to the rapid industrialization and urbanization [1]
The results could be associated with the reaction between the aluminosilicate glassy phases of ground granulated blast furnace slag (GGBFS), as shown in Fig. 5(b), and the alkaline solutions, resulting in x-ray amorphous aluminosilicate paste (X-RAAP)
The study examined the GGBFSÀCCA-based geopolymer concrete (GPC), and its effects on the activity indexes and the acidic attacks were evaluated. Both experimental and statistical methods were used in the course of the study, and the results were compared with Portland cement concrete (PCC)
Summary
The utilized rate of concrete is high, owing to the rapid industrialization and urbanization [1]. The production of PC, apart from its negative impact on the environment, requires a massive industrial process [2]. A ton of PC production, which emits 1 ton of carbon dioxide (CO2) into the atmosphere, requires 4000 MJ energy, 1.5 tons of raw materials, and 140 kW h of electricity [3]. A 7–9 % of CO2 is emitted yearly into the atmosphere following the massive requirements of energy in PC production, contributing to the serious global warming [4]; this poses huge threats to human and ecosystem survival and development. The yearly utilization of PCC in the construction industry is estimated to be 20 billion tons globally [6].
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