Abstract
Geopolymer concrete, also known as an earth-friendly concrete, has been under continuous study due to its environmental benefits and a sustainable alternative to conventional concrete construction. The supplies of many source materials, such as fly ash (FA) or slag (SG), to produce geopolymer concrete (GPC) may be limited; however, quarry rock dust (QRD) wastes (limestone, dolomite, or silica powders) formed by crushing rocks appear virtually endless. Although significant experimental research has been carried out on GPC, with a major focus on the mix design development, rheological, durability, and mechanical properties of the GPC mixes; still the information available on the structural behavior of GPC is rather limited. This has implications in extending GPC application from a laboratory-based technology to an at-site product. This study investigates the structural behavior of quarry-rock-dust-incorporated fiber-reinforced GPC columns under concentric and eccentric loading. In this study, a total of 20 columns with 200 mm square cross-section and 1000 mm height were tested. The FA and SG were used as source materials to produce GPC mixtures. The QRD was incorporated as a partial replacement (20%) of SG. The conventional concrete (CC) columns were prepared as the reference specimens. The effect of incorporating quarry rock dust as a replacement of SG, steel fibers, and loading conditions (concentric and eccentric loading) on the structural behavior of GPC columns were studied. The test results revealed that quarry rock dust is an adequate material that can be used as a source material in GPC to manufacture structural concrete members with satisfactory performance. The general performance of the GPC columns incorporating QRD (20%) is observed to be similar to that of GPC columns (without QRD) and CC columns. The addition of steel fibers considerably improves the loading capacity, ductility, and axial load–displacement behavior of the tested columns. The load capacities of fiber-reinforced GPC columns were about 5–7% greater in comparison to the CC columns. The spalling of concrete cover at failure was detected in all plain GPC columns, whereas the failure mode of all fiber-reinforced GPC columns is characterized with surface cracking leading to disintegration of concrete cover.
Highlights
Environmental pollution has been a major concern around the world today
The columns were divided into three groups depending upon their mix proportions, i.e., CC, GC, and GCD
In the third group ‘GCD’, quarry rock dust (QRD) was incorporated as a partial replacement (20%) of SG, alongwith SG (30%), and fly ash (FA) content (50%) in all the column specimens
Summary
Environmental pollution has been a major concern around the world today. The primary reasons are the emission of CO2 in the atmosphere, depletion of natural resources and uncontrolled production of wastes that are dumped eventually in the environment. There has been a significant increase in the generation of waste materials from industries, such as fly ash (FA) from coal power plants; molten slag (SG) from steel and iron industries; red mud from the alumina industry; dolomite, silica powders, and limestone dust from quarrying operations; ceramic wastes from the ceramic industry; and mine tailings from the mineral industry This has become a challenging task for the environmentalists and researchers to dispose of or manage these wastes and develop alternatives to traditional ordinary Portland cement (OPC) concrete [5]. The annual global supply of SG is fairly limited in comparison to the annual requirement of concrete for the global construction activities It is important, to find alternatives for FA and SG to be used as precursors in the production of GPC, to promote commercialization of GPC and lessen the costs, as well as to meet the increasing infrastructural demand.
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