Effect of Polypropylene Fiber on Properties of Alkali‐Activated Slag Mortar

Abstract

Alkali-activated slag (AAS) is becoming an increasingly popular building material due to its excellent engineering properties and low CO 2 emissions, but its large shrinkage is an important reason to restrict its application and popularization. is work is aimed to study the possibility of inhibiting the shrinkage of AAS mortar by incorporating polypropylene fiber (PPF). For this, an experimental study was carried out to evaluate the effects of PPF content on setting time, fluidity, physical properties, mechanical properties, impact resistance, and microstructure of AAS mortar. e volume content of PPF is 0.05%, 0.1%, 0.15%, and 0.2%. e working, physical (porosity, water absorption, and bulk density), mechanical, shrinkage, and impact resistance properties of the AAS mortars were evaluated. e results show that incorporating PPF effectively reduces the shrinkage deformation of AAS mortar, significantly improves its impact resistance, enhances its toughness, and slightly improves its compressive strength in the later stage. At the same time, PPF delays the initial setting time of AAS mortar and reduces the fluidity, density, porosity, and water absorption of AAS mortar. SEM results show that the bridging effect of PPF between AAS mortars can inhibit the generation and propagation of cracks, improve the internal microstructure, and enhance the performance of AAS mortar.

Analysis of Concrete Failure on the Descending Branch of the Load-Displacement Curve

“…Numerous studies are focused on improving the technical, economic and environmental characteristics of concrete, the continuous flow of which confirms the relevance and complexity of the problems of increasing the competitiveness of this material . As a result of research, there are more economical components of concrete, new materials for reinforcement, and improved technologies for the manufacture of concrete as a multicomponent composite material [5][6][7]. Experimental studies are required to ensure sufficient structural reliability, but the cost remains high.…”

Effect of fiber type and content on the mechanical properties and shrinkage characteristics of alkali‐activated kaolin

“…The high integrity failure in fiberreinforced samples points at the effective aluminosilicate matrix-fiber bond which allows fibers to resist transverse tension forced, enabling the composite to carry further stresses. [30][31][32] strength was more significant than those on the compressive strength. HS fiber showed a substantial increase in the flexural strengths at all fiber content when compared to other fibers, enhancing the flexural strength by more than 200% when 1.5% fiber volume content is added.…”

“…The specimens with 1% PP, 1% DSS, 1.5% BCS, and 1% HS had better integrity with fewer fragments and more ductile behavior, the failure pattern agrees with the compressive strength trends results observed in Figure 2. The high integrity failure in fiber‐reinforced samples points at the effective aluminosilicate matrix‐fiber bond which allows fibers to resist transverse tension forced, enabling the composite to carry further stresses 30–32 …”

“…44 Besides, (iv) the incorporation of fibers into the aluminosilicate matrix may refine the micropores and producing more discontinuous pores, which has been recently reported to effectively block the moisture migration within the matrix and resulting in less shrinkage. 31 HS was found to be the most effective fiber to reduce the drying shrinkage compared to other fibers, with shrinkage of fewer than 60 microstrains. The presented results are in agreement with the literature on the effectiveness of different fibers on reducing drying shrinkage.…”

“…45,46 Based on the SEM visual observations, no obvious deformation was detected on the surface of the fiber, which could indicate that fiber-reinforced alkali-activated mortar may have excellent durability characteristics. 14,31 The presence of fibers within the aluminosilicate matrix was reported to help in relieved the stress that has been transferred to the fiber through the matrix-fiber boundary; thus prevent cracks propagation. 29 The basic geopolymer structure comprises (i) amorphous aluminosilicate gel, (ii) unreacted kaolin particles, and (iii) pores.…”