Title: Glass Fiber Reinforced Concrete With Improved Ductility and Long Term Properties
Author(s): H. J. Molloy, J. Jones, and T. G. Harmon
Publication: Symposium Paper
Appears on pages(s): 79-90
Keywords: cement additives; ductility; durability; flexural strength; glass fibers; hydraulic cements; reinforced concrete; strains; Materials Research
Presents results of a development program to improve the properties of glass fiber reinforced concrete (GFRC). The current system is composed of portland cement, silica sand, 5 percent alkali-resistant glass, curing agent (5 percent acrylic copolymer solids by weight of cement), and a water-cement ratio of 0.32. Historically, this system has resulted in loss of some ductility due to the development of calcium hydroxide, which bonds the individual filaments together in the strand, reducing their reinforcing efficiency. A new system was developed to improve the performance of the composite. This system is composed of rapid-hardening hydraulic cement, silica fume, and additives to combine with any free lime, provide enhanced workability, and a degree of retardation, using a water-cement ratio of 0.45 and 5 percent alkali-resistant glass containing 20 percent zirconium oxide. Polymer curing agents are not recommended. The durability of the system was tested using the glass industry test of immersing the product in hot water (60 C) for up to 100 days and periodically measuring the flexural strength and strain capacity using ASTM C 947-89. Analysis of the results indicates a very high retention of both flexural strength and strain capacity for the new system, after being exposed to the hot water aging test.