Abstract
This research investigates the simultaneous impact of two different types of steel fibers, nanometakaolin, and nanosilica on the mechanical properties of geopolymer concrete (GPC) mixes. To achieve this aim, different geopolymer concrete mixes were prepared. Firstly, with and without nanomaterials (nanosilica and nanometakaolin) of 0, 2%, 4%, 6%, and 8% from ground granulated blast furnace slag (GGBFS) were used. Secondly, steel fiber (hooked end and crimped) content of (0, 0.5%, 1, and 1.5%) was used. Thirdly, optimum values of nanomaterials with the optimum values of steel fiber were used. Crimped and hooked-end steel fibers were utilized with an aspect ratio of 60 and a length of 30 mm. Geopolymer mixes were manufactured by using a constant percentage of alkaline activator to binder proportion equal to 0.45 with GGBFS cured at ambient conditions. For alkaline activator, sodium hydroxide molar (NaOH) and sodium hydroxide solution (NaOH) were used according to a proportion (Na2SiO3/NaOH) of 2.33. The hardened concrete tests were performed through the usage of splitting tensile strength, flexural, and compressive experiments to determine the impact of steel fibers, nanometakaolin, and nanosilica individually and combined on performance of GPC specimens. The results illustrated that using a mix composed of the optimum steel fibers (1% content) accompanied by an optimum percentage of 6% nanometakaolin or 4% nanosilica demonstrated a significant enhancement in the mechanical properties of GPC specimens compared to all other mixtures. Besides, the impact of using nanomaterials individually was found to be predominant on compressive strength on GPC specimens especially with the usage of the optimum values. However, using nanomaterials individually compared to using the steel fibers individually was found to have approximately the same splitting tensile strength and flexural performance.
Highlights
Concrete is considered as the most commonly used structural material because of the ease of shaping and the availability of raw materials
Crushed dolomite from Elmenia quarry was utilized as coarse aggregate (CA) to produce geopolymer concrete (GPC). e crushed granite was utilized in two sizes, whereas the maximum nominal dimension was 10 mm. e coarse aggregate was tested following ASTM C127
The improvement in fiber reinforced concrete compressive strength was associated to the capability of fibers to hinder and postpone the propagation of crack and to minimize the stress concentration extent at the crack tip [35]. e hooked-end steel fibers handle the existence of several microcracks in the concrete body in a better way due to the cracks’ microdimension as well as having smaller size in comparison with the crimped steel fibers
Summary
Concrete is considered as the most commonly used structural material because of the ease of shaping and the availability of raw materials. An environmentally friendly concrete such as geopolymer concrete appeared to be an alternative for OPC [5,6,7]. E usage of geopolymer concretes has grape the attention due to the worldwide need for reducing CO2 emission and natural resources consumption. Unlike OPC, a reduction in energy consumption was observed due to the fabrication of the raw materials which do not demand a calcining process. It was claimed in other research that the quantity of CO2 emitted from the Advances in Materials Science and Engineering geopolymer concrete is around 5 to 6 times lower in comparison with the concrete made by OPC [8, 9]. The geopolymer concrete could utilize the byproduct wastes of aluminosilicate composition to manufacture inventive construction materials besides reducing the emissions of CO2 significantly [10, 11]
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