Thermo-mechanical and moisture absorption properties of fly ash-based lightweight geopolymer concrete reinforced by polypropylene fibers

Abstract

An experimental investigation on the thermo-mechanical and moisture absorption properties of lightweight geopolymer concrete prepared with fly ash, NaOH, sodium silicate and Polypropylene Fibers (PF) is presented in this study. The effects of dry density, NaOH, PF, aggregates and hydrophobic agent on the compressive strength, thermal properties and moisture absorption were studied. Results indicate that thermo-mechanical properties of Fly ash-based Lightweight Geopolymer Concrete (FLGC) strongly depend on the dry density, NaOH, PF and aggregates contents. The increase in dry density and fine aggregate contents resulted in higher compressive strength and thermal conductivity. NaOH within mass ratio of 0-10% is able to enhance thermo-mechanical properties. The optimal compressive strength was achieved when the length and content of the PF was 12 mm and 0.5% respectively. Meanwhile, PF in the range of 0-1% can also increase thermal conductivity and enhance moisture absorption. The increase in coarse aggregate ranging from 0 to 15% led to reduced dry density and thermal conductivity and enhanced moisture absorption, but did not affect compressive strength. Interestingly, the decrease in fine aggregate with the same content had the opposite impact to the moisture absorption in comparison to the coarse aggregate. However, the moisture absorption can be considerably weakened by surface *Revised Manuscript Click here to view linked References waterproofing treatment which makes the enhanced thermal performance durable. Therefore, the FLGC reinforced by PF has excellent thermo-mechanical properties and can also be engineered to be an environmentally friendly and durable thermal insulation material with the assistance of waterproofing treatment.

Influence of Polypropylene, Glass and Steel Fiber on the Thermal Properties of Concrete

“…This may affect the workability of mixtures. The same conclusion was reported by Wang et al [47], who determined that fiber addition higher than 0.5% caused poor workability and the incomplete compaction of concrete. However, in this study, in the mixing process, no such impact was noted.…”

“…However, in this study, in the mixing process, no such impact was noted. This was probably due to a higher admixture content used compared to Wang's study [47].…”

“…Therefore, many studies focus on the modification of concrete mixtures using a byproduct [39,40] or waste material [41] as its current main building material. A wide range of recycled fibers available on the market, e.g., steel, glass and polypropylene, can be used not only as distributed reinforcement [42,43] but also to change the thermal properties of concrete [44][45][46][47][48]. Most studies focus on achieving higher mechanical properties of hardened concrete, such as compressive strength, flexural strength and split tensile strength, as they are crucial for construction sustainability [49].…”

Mechanical Properties of Short Polymer Fiber-Reinforced Geopolymer Composites

“…This type of composite also has significant resistance to cracking at high temperatures, which allows it to be used as fireproof barriers in construction [9,39]. This kind of material could be used as lightweight construction and isolation materials [39]. Wang et al have studied foamed geopolymers reinforced by PP fibers [39].…”

“…This kind of material could be used as lightweight construction and isolation materials [39]. Wang et al have studied foamed geopolymers reinforced by PP fibers [39]. As a raw material, the fly ash from the Chinese coal mine company has been used (Class II according to the Chinse Standard of GB/T1596-2017).…”