The primary aim of this research is to find an alternative for Portland cement using inorganic geopolymers. This study investigated the effect of steel and polypropylene fibres hybridisation on ternary blend geopolymer concrete (TGPC) engineering properties using fly ash, ground granulated blast furnace slag (GGBS) and metakaolin as the source materials. The properties like compressive strength, splitting tensile strength, flexural strength and modulus of elasticity of ternary blend geopolymer concrete. The standard tests were conducted on TGPC with steel fibres, polypropylene fibres and a combination of steel and polypropylene fibres in hybrid form. A total number of 45 specimens were tested and compared to determine each property. The grade of concrete considered was M55. The variables studied were the volume fraction of fibres, viz. steel fibres (0%, 0.5% and 1%) and polypropylene fibres (0%, 0.1%, 0.15%, 0.2% and 0.25%). The experimental results reveal that the addition of fibres in a hybrid form enhances the mechanical properties of TGPC. The increase in the compressive strength was nominal, and a significant improvement was observed in splitting tensile strength, flexural strength, and modulus of elasticity. Also, an attempt to obtain the relation between the different engineering properties was made with different volume fractions of fibre.
A material-tailored special concrete composite that uses a synthetic fiber to make the concrete ductile and imposes strain-hardening characteristics with eco-friendly ingredients is known as an “engineered geopolymer composite (EGC)”. Mix design of special concrete is always tedious, particularly without standards. Researchers used several artificial intelligence tools to analyze and design the special concrete. This paper attempts to design the material EGC through an artificial neural network with a cross-validation technique to achieve the desired compressive and tensile strength. A database was formulated with seven mix-design influencing factors collected from the literature. The five best artificial neural network (ANN) models were trained and analyzed. A gradient descent momentum and adaptive learning rate backpropagation (GDX)–based ANN was developed to cross-validate those five best models. Upon regression analysis, ANN [2:16:16:7] model performed best, with 74% accuracy, whereas ANN [2:16:25:7] performed best in cross-validation, with 80% accuracy. The best individual outputs were “tacked-together” from the best five ANN models and were also analyzed, achieving accuracy up to 88%. It is suggested that when these seven mix-design influencing factors are involved, then ANN [2:16: 25:7] can be used to predict the mix which can be cross-verified with GDX-ANN [7:14:2] to ensure accuracy and, due to the few mix trials required, help design the SHGC with lower costs, less time, and fewer materials.
Abstract. Concrete plays a vital role in the development of infrastructure and buildings all over the world. Geopolymer based cement-less concrete is one of the current findings in the construction industry which leads to a green environment. This research paper deals with the results of the use of Fly ash (FA), Ground Granulated Blast Furnace Slag (GGBS) and Metakaolin (MK) as a ternary blend source material in Geopolymer concrete (GPC). The aspects that govern the compressive strength of GPC like the proportion of source material, Molarity of Sodium Hydroxide (NaOH) and Curing methods were investigated. The purpose of this research is to optimise the local waste material and use them effectively as a ternary blend in GPC. Seven combinations of binder were made in this study with replacement of FA with GGBS and MK by 35%, 30%, 25%, 20%, 15%, 10%, 5% and 5%, 10%, 15%, 20%, 25%, 30%, 35% respectively. The molarity of NaOH solution was varied by 12M, 14M and 16M and two types of curing method were adopted, viz. Hot air oven curing and closed steam curing for 24 hours at 60°C (140°F). The samples were kept at ambient temperature till testing. The compressive strength was obtained after 7 days and 28 days for the GPC cubes. The test data reveals that the ternary blend GPC with molarity 14M cured by hot air oven produces the maximum compressive strength. It was also observed that the compressive strength of the oven cured GPC is approximately 10% higher than the steam cured GPC using the ternary blend.
Beam–column joints are extremely vulnerable to lateral and vertical loads in reinforced concrete (RC) structures. This insufficiency in joint performance can lead to the failure of the whole structure in the event of unforeseen seismic and wind loads. This experimental work was conducted to study the behaviour of ternary blend geopolymer concrete (TGPC) beam-column joints with the addition of hybrid fibres, viz., steel and polypropylene fibres, under reverse cyclic loads. Nine RC beam-column joints were prepared and tested under reverse cyclic loading to recreate the conditions during an earthquake. M55 grade TGPC was designed and used in this present study. The primary parameters studied in this experimental investigation were the volume fractions of steel fibres (0.5% and 1.0%) and polypropylene fibres, viz., 0.1 to 0.25%, with an increment of 0.05%. In this study, the properties of hybrid fibre-reinforced ternary blend geopolymer concrete (HTGPC) beam-column joints, such as their ductility, energy absorption capacity, initial crack load and peak load carrying capacity, were investigated. The test results imply that the hybridisation of fibres effectively enhances the joint performance of TGPC. Also, an effort was made to compare the shear strength of HTGPC beam-column connections with existing equations from the literature. As the available models did not match the actual test results, a method was performed to obtain the shear strength of HTGPC beam-column connections. The developed equation was found to compare convincingly with the experimental test results.
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