Drying shrinkage of fly ash geopolymeric mortars reinforced with polymer hybrid fibres

Abstract

Drying shrinkage performance is a very important factor for reinforced concrete composites because a high shrinkage performance is associated with a high cracking tendency, which leads to future durability problems. Geopolymeric mortars show much higher drying shrinkage than Portland cement-based composites because they use a low amount of structural water and thus have a higher pore content than ordinary Portland cement composites. Therefore, the use of fibres is especially interesting to counteract the drying shrinkage tendency of geopolymeric mortars. This paper provides results on the restrained and unrestrained shrinkage performance of fly ash-based geopolymeric mortars reinforced with short polymer hybrid fibres (SPHF). The results show that SPHF reduces the shrinkage cracking tendency. A content of SPHF as low as 0•08% was able to reduce the average crack width by four times when compared with non-reinforced mortars. Increasing the content of SPHF from 0•08 to 0•8% reduces the time of appearance of the first crack by 25 h and reduces the average crack width by two times.

Preparation, characterization, and evaluation of compressive strength of polypropylene fiber reinforced geopolymer mortars

“…Punurai et al [12] replaced the fly ash content with basalt fibers to synthesize hybrid geopolymer paste and evaluate the mechanical properties, microstructure, and drying shrinkage of the paste, resulting in high mechanical strength and decreased drying shrinkage reducing the total porosity and critical pore size of the paste. Likewise, Kheradmand et al [13] used hybrid polymer fibers to decrease shrinkage in the fly ash-based mortar matrix, obtaining results in reducing shrinkage cracking with only a minimum fiber content of 0.08%, reducing the width of typical crack four times, compared to unreinforced mortars. While Noushini [14] used polypropylene and polyolefin fibers to improve deformation and contraction performance in fly ash-based geopolymer concretes with low calcium contents, obtaining results in the decrease of drying contraction and an increase in the compression creep in the Geopolymer concrete, at both early ages and in the long term, through adding a volume fraction of 0.5% fiber.…”

A mini guideline study for fly ash-based alkali activated foam masonry units

“…It is a white powder, that is slippery and insoluble in water. Chopped polypropylene fiber was added to the samples to prevent cracks that may occur during drying (88)(89)(90)(91)(92)(93)(94), and expanded perlite was added to improve the thermal insulation properties (49,63,65,95).…”

Effect of the addition of waste basalt fibers on concrete shrinkage

“…Concrete shrinkage is an intrinsic phenomenon that occurs in materials with a porous structure [16,17]. It consists in reducing the volume of concrete through the loss of water contained in the pores due to physical and chemical phenomena.…”