Title:
Evaluation of Polypropylene Fiber Reinforced High-Volume Fly Ash Shotcrete
Author(s):
D. R. Morgan, N. Mcaskill, G. G. Carette, and V. M. Malhotra
Publication:
Materials Journal
Volume:
89
Issue:
2
Appears on pages(s):
169-177
Keywords:
compressive strength; flexural strength; freeze-thaw durability; fly ash; polypropylene fibers; shotcrete; Materials Research
DOI:
10.14359/2254
Date:
3/1/1992
Abstract:
Paper describes the results of a test program undertaken to evaluate the use of polypropylene fiber reinforced high-volume fly ash shotcrete for the specific purpose of capping and sealing large areas of exposed pyritic slate. The study was performed in two phases. In Phase I of the investigation, 12 mixtures with varying fly ash contents and polypropylene fiber addition rates were investigated. Samples from each of the 12 mixtures were tested for compressive strength, flexural strength, and toughness. Based on the results of these tests, six shotcrete mixtures were selected for investigation in a Phase II study. These mixtures covered two cementitious contents of 400 and 450 kg/m3 (674 and 758 lb/yd3) with polypropylene fiber addition rates of 0, 3, and 6 kg/m3 (0, 5.1, and 10.1 lb/yd3). Twelve large panels and twelve small panels were shotcreted. The large panels were used for restrained shrinkage tests. Cores were drilled and prisms were cut from the smaller panels for determining the compressive strength, flexural strength, flexural toughness, and freezing and thawing resistance of the shotcrete mixtures. The results of the investigation have shown that polypropylene fiber reinforced high-volume fly ash concrete can be satisfactorily shot using conventional wet-mix shotcrete equipment. The shotcrete mixtures require a certain minimum amount of cementitious material and water content, and these appear to be of the order of 420 and 150 kg/m3 (710 and 253 lb/yd3), respectively. The polypropylene fiber content required to provide satisfactory flexural toughness index is between 4 and 6 kg/m3 (6.7 and 10.1 lb/yd3). The shotcrete mixtures investigated have adequate strength development characteristics and excellent durability on exposure to freezing and thawing cycling. The mixtures investigated should find use in applications such as capping exposed rock susceptible to degradation and for covering mine waste dumps.