Influence of Fineness Modulus Values, Polypropylene Fibers Contents, and Air Foam Contents on Dry Unit Weight and Strengths of Lightweight Geopolymer Reinforced Polypropylene Fibers

Abstract

This paper investigated the influence of fineness modulus on dry weight, compressive strength and flexural strength of lightweight geopolymer reinforced polypropylene fibers. Geopolymer fly ash was used as a cementitious material. The fineness modulus of sand was determined at 1.6, 1.45, and 1.3, polypropylene fibers contents of 0, 0.5, 1, 1.5, 2, 2.5, and 3% by weight of fly ash, air foam contents (AF) of 0, 1, and 2% by weight of binder, fly ash to sand ratio was 1, the alkaline solution to binder ratio was 0.55, and the sodium silicate (Na2SiO3) to sodium hydroxide solution (NaOH) was 50:50. The results showed that the dry weight decreased with increasing polypropylene fiber contents and air foam contents. The lowest dry weight was found at a fineness modulus of 1.6, a polypropylene fiber content of 3% by weight of fly ash, and an air foam content of 2% by weight of binder. The maximum compressive strength and flexural strength were found at a fineness modulus of 1.45. The flexural strength increased by the enhancement of polypropylene fiber content due to fiber-controlling cracks and reduced crack width. The flexural strength decreased by increasing the polypropylene fiber contents up to 3% by weight of fly ash because the excess fibers induced the friction in sample. The dry weight and compressive strength of lightweight geopolymer reinforced polypropylene fibers was by the Thai Industrial Standards (TIS 2601-2013). The dry weight was between 701-1,600 kg/m3 and the compressive strength was more than 5.0 MPa (51.0 kg/cm2).