Abstract
Despite their drastically different chemical ingredients and interactions, geopolymer concrete exhibits many of the same features as ordinary concrete. Among these properties is drying shrinkage. As in normal concrete, dry shrinkage in geopolymer concrete may cause cracking if the geopolymer concrete is bound, which affects the integrity of the structure in the future. It's important to measure drying shrinkage as soon as possible because it's the cause of early age cracking, which happens when the concrete isn't very strong. The purpose of this study is to determine how to reduce the dry shrinkage value of geopolymer concrete by using different types of fibers. Three types of fibers were used to determine their effect on the dry shrinkage of geopolymer concrete when compared with a reference mixture without the fibers. Metakaolin was used as a binder for the concrete geopolymer. As for the fibers, steel, carbon and polypropylene fibers were used in proportions of (0, 0.5, and 1%). The results showed an improvement in dryness shrinkage when adding fibers in general, with a difference in values between the different types of fibers. Steel fibers had the lowest amount of dry shrinkage. The temperature had a direct influence on the decrease in the extent of the shrinking, since the samples handled at higher temperatures had less dryness to begin with. Doi: 10.28991/cej-2021-03091780 Full Text: PDF
Highlights
Raw material characteristics, mixing ratios, processing methods, and other factors all influence shrinkage
All mixes show that the dry shrinkage of metakaolin-based and heat-cured geopolymer concrete is significantly lower than that of room-temperature-cured concrete
The addition of fibers helped in developing the mechanical properties of metakaolin-based geopolymer concrete compared to non-fibrous ones
Summary
Raw material characteristics, mixing ratios, processing methods, and other factors all influence shrinkage. Only a few attempts have been made to assess the drying shrinkage of geopolymer concrete. Wallah & Rangan (2010) studied the drying of ocean-treated samples in the order of 1,500 microstrain, two to three times higher than that required for OPC-based parabolic cement [4, 5]. A thermo-thermo-treated fly ash-based geopolymer concrete has dried after 3 months. Water is not directly integrated into the geopolymer gel product, unlike Portland cement. Only a small amount of the mixing water remains as interstitial water [6, 7]. Because MK-geopolymer pastes take a lot of water to mix, there is a lot of unbound or free water in the hardened paste that can evaporate at room temperature under low relative humidity circumstances. Despite the lack of chemically bonded water, structural stability is still required
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