Geopolymer mixtures (such as concrete, mortar, and paste) were used as sustainable alternatives to Portland cement, and enhancement the mechanical properties by addition fibers, due to their great potential in reducing environmental pollution and reducing consumption of raw materials. In this paper, verified the effect of different fibers added to slag based geopolymer paste, on compressive strength development. Ten mixes were preparing and curing at ambient condition. The variables included; type of fibers added (i.e. micro steel fiber, carbon fiber, or polypropylene fiber), and volumetric ratio of fibers included, (1%, 2%, or 3%) of micro steel fiber, and (0.2%, 0.4%, or 0.6%) of carbon fiber and polypropylene fiber. The alkaline solution was combination of sodium silicate (Na2SiO3), and sodium hydroxide (NaOH) with concentrically 10 molar. The results were found that the addition of fibers led to improving significant of the compressive strength. Generally, the development of compression was estimate by about (30% and 23%) at ages (7 and 28) days, respectively. Finally, the slag based geopolymer paste is more suitable to use in construction sites as alternative sustainable of Portland cement.
The problems of global warming and environmental pollution with gaseous and solid wastes, made researchers think of finding effective alternatives to reduce the proportion of carbon dioxide in the atmosphere and make use of solid waste for iron manufacturing stations and power production stations. Thus, geopolymers are considered one of the most promising solutions in the field of structural engineering. Therefore, this paper presents a review of previous studies on geopolymer mixtures, which were investigated in three main parameters, included: slag addition, solution ratios, adding fibers, and Nano silica. The results of the previous investigation showed that the compressive strength increased with the increase in the slag ratio. At certain proportions, the compressive strength increases with increasing the sodium silicate to sodium hydroxide and increasing the sodium hydroxide concentration (M). While it was reduced fresh properties such as flow-ability and setting time. It was also found that the addition of fibers or Nano silica improved the microstructures of geopolymers, and thus a significant improvement in tensile strength and compressive strength. Finally, the addition of external water was found to improve flow-ability but reduce compressive strength, while the addition of the superplasticizer in certain proportions improves fresh properties.
Researchers studied a lot of strengthening techniques of concrete, one of which is the technology of concrete confinement. This technique is common to utilize fiber fabric impregnated with epoxy resin adhesive. Relevant applications mainly include strengthening the existing structure and new structural construction. This paper presents a review of previous studies on the confinement of concrete using fiber-reinforced polymer (FRP) tubes. Four main parameters were investigated in this study: the number of layers of FRP tubes, cross-sectional shape and slenderness ratio, material types of FRP tubes, and concrete types. The results of the investigation showed that increasing the number of FRP tubes resulting in a significant improvement in the behavior of confined specimens, circular cross-section specimens exhibited better behavior than square. Also, the behavior of confined square specimens improvement with increasing the angular radius. A carbon fiber reinforced polymer tube is better than (aramid, glass, and basalt) fibers. Finally, the concrete confining technique significantly improved the behavior of specimens regardless of the type of concrete confined, and the effect of confining decreases with the increase of compressive strength of the concrete confined.
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