International Concrete Abstracts Portal

Treatments of AR glass fibers in silica fume slurry prior to their incorporation in cementitious matrix was found to be an effective means for improving the durability performance of GFRC composites. The improvement was found to be dependent on the extent of penetration of the silica fume particles into the spaces between the filaments during the slurry treatment. In a glass fiber fabric, heavily coated with polymer, the penetration was hindered and therefore the advantage offered by the silica fume treatment was not as great as in continuous glass fiber strands that were more readily wetted by the slurry.

Strength properties of steel fiber reinforced concrete and plain concrete specimens subjected to normal atmospheric exposure and accelerated cyclic testing in marine environment were examined. The concrete mix design consisted of cement:sand:aggregate in ratio of 1:1.96:3.01 with water-cement ratio of 0.6. The steel fibers, 10 mm in length, were added in volume of 0.0, 0.6, and 1.2 percent of the mix. Strength properties--compressive, flexural, and tensile strength of the concrete specimens containing steel fibers--showed considerable improvement over those obtained in the plain concrete exposed to the normal atmospheric condition. Both steel fiber reinforced and plain concrete specimens subjected to accelerated cyclic testing at 60 C, 24-hr cycle in marine environment, showed that the addition of fibers provided considerable improvement in strength properties. However, corrosion of the fibers was observed at or near the surface, and continued to worsen after 20 cycles. Specimens with 1.2 volume percent of steel fibers exhibited the largest increase in compressive and flexural strength in both test conditions, normal atmospheric and accelerated cyclic testing.

The background to the development of two types of thin, fabric-reinforced, portland cement concrete sheets is described and range of properties given. Both normal weight and lightweight mortars (including cellular mortars) were used as a matrix. Glass or synthetic fiber continuous reinforcement in the form of fabric scrims and/or nonwoven three-dimensional fabric were used. The materials developed are potential substitutes for plywood, cement asbestos, and other types of sheet material that require the properties of weather resistance, incombustibility, nonbiodegradability, and economy. The test results also suggest that the matrix and reinforcement concepts developed will lead to applications in other reinforced concrete uses. The thin sheet materials lend themselves to easy manufacture in a comparatively simple plant.

Thin-walled glass fiber reinforced concrete (GFRC) panels are used as facade systems for commercial structures. Wind load and gravity load are primary load cases typically considered in panel design. However, since the GFRC skin is relatively thin, it responds rapidly to thermal and moisture variations. Therefore, minimizing restraint of the GFRC skin movement under varying environmental conditions and/or determination of stresses resulting from restrained movement are also primary considerations in GFRC facade panel design. Paper addresses concepts for design of GFRC panels including material behavior, design strengths, and loading combinations. Discussions of load conditions and recommended design considerations are presented for the effects of manufacturing, handling, and erection loading, gravity loading, wind loading, and loading due to external and internal restraint of moisture and thermal movements. Paper is based on the authors' experiences during their involvement in the design process for several new GFRC installations along with observations made and lessons learned in evaluation of GFRC facade failures

Thin-walled, nonload-bearing exterior building facade panels of glass fiber reinforced concrete (GFRC) are manufactured by the spray-up process. Controlled factory conditions with strict attention to quality control are essential to help assure manufacture of a high-quality product. Furthermore, careful attention to installation and erection procedures cannot be overlooked. Paper describes the authors' experiences during their involvement in several major GFRC facade installations. Observations made during successful GFRC panel applications, and lessons learned in evaluation of GFRC facade failures, have formed the basis for development of an effective Quality Control/Quality Assurance (QC/QA) program that has been successfully implemented. Paper addresses QC/QA aspects of panel manufacture and installation that go beyond guidelines given in the PCI Recommended Practice. Methodologies presented in this paper will be a valuable tool for owners, designers, manufacturers, and contractors participating in the manufacture and installation of GFRC facades.