International Concrete Abstracts Portal

Very little research has been done on the structural behavior of steel-reinforced polymer concrete (PC). In all the previous studied, it was generally assumed that the structural behavior of reinforced PC is similar to the structural behavior of reinforced portland cement concrete because both are composite materials consisting of a binder and inorganic aggregates. However, the design equations developed for steel-reinforced portland cement concrete yield very conservative results when applied to reinforced PC. The objective of this paper is to report on the shear and flexure properties of steel-reinforced PC beams using unsaturated polyester resins based on recycled polyethylene terephthalate (PET) plastic waste. The effects of the shear span-to-depth ratio, reinforcement ratio, and compressive strength were investigated with the shear beams, while the effect of reinforcement ratio was investigated with the flexure beams. New design equations were also developed to predict the shear and flexural strength of steel-reinforced PC beams.

There is an interest in developing better performing (high strength and ductility) composite structural elements for construction and repair of onshore and offshore structures. In this study, composite structural elements that consist of filled columns and sandwich columns (two concentric circular steel tubes with polymer concrete sandwiched in between) were investigated as potential compression members. High-strength (480 Mpa) and low-strength (200 MPa) steel tubes conforming to ASTM A513 Type 5 and ASTM A500 Grade B, respectively, were used. The polymer concrete was polyester based with a compressive strength of 60 Mpa. Short composite columns, made of steel tubes of diameter-to-thickness ratios ranging from 16 to 170, were tested under monotonically increasing axial compression. It was observed that the composite columns had compressive strengths of 10 to 30 percent higher than that of the summation of the individual components. The ductility was much higher than that of the corresponding steel tubes. Relationships for predicting the initial modulus and peak load and corresponding strain of the sandwich column have been developed. A simple model was used to predict the load-strain history up to the peak load of the composite elements. The predictions agreed well with the test results.

A methodology has been developed for designing precast, fiber reinforced polymer concrete (FPC) vaults to be used in underground applications. The approach used in the design was to consider the vault as a series of plates: cover, walls, and foundation slab. Each plate was subjected to loads resulting from soil pressure, live loading, and dead weight and was analyzed using classical plate theory. This approach was verified by testing two quarter-scale models of a typical vault. Upon completion of the laboratory evaluation, two vaults were designed for use as underground, natural gas regulator stations. The vaults were manufactured and subsequently placed into service by Brooklyn Union Gas Company, and the Consolidated Edison Company of New York.

A major problem confronting transportation departments is the surface deterioration of portland cement concrete (PCC) pavements and bridge decks. Some of these defects include cracking, spalling, polishing, and surface erosion. Each of these defects contributes to further deterioration within the concrete structure by allowing an infiltration of moisture, oxygen, deicing salts, chlorides, and other contaminants. Upon contact with the reinforcing steel, rusting occurs, causing internal tensile stresses that result in further surface spalling, hollow plane delamination and cracking. One effective technique used since the middle 1950s is to retard this corrosion process by preventing the penetration of chlorides and moisture into the concrete with in impermeable epoxy polymer concrete (EPC) overlay. These overlays also provide wear-resistant surfaces and extend the service life of the pavement or deck. Documented experience indicates that EPC overlays are cost effective, reduce overall annual maintenance costs, and provide a safe driving surface. This paper presents two project tracking studies. The first is a comparison of a new PCC slab placement to a thin EPC overlayment on an existing PCC pavement installed 15 years ago; the pavements are side-by-side. The documentation compares traffic volumes and surface deteriorations, such as wearability, spalling, polishing, and cracks. The second study involves a thin EPC overlay placed on a badly deteriorated PCC bridge deck 10 years ago to improve skid properties and provide an overall safer driving surface.

Given the breakthrough technology creating nonshrinking unsaturated polyester resin, this paper examines what this new technology might do if utilized in polymer concrete. The paper defines the criteria for success for polymer concrete in cast metal applications and, utilizing these criteria, compares the performance of the newly developed, low-shrink, polyester-based systems with an accepted standard epoxy. Criteria examined include (1) stiffness-to-weight ratio equal to cast iron, (2) low coefficient of thermal expansion, (3) temperature insensitive mechanical properties, (4) adhesion to insert materials, (5) low shrinkage, (6) good composite flow and consolidation characteristics, and (7) comparable cost to machined cast metals. The data tends to show that for most applications, these new low-shrink, polyester-based polymer concretes may, in fact, be a new polymer-based alternative for cast metals. Given the lower costs of these low-shrink polymer concrete systems, an exciting new opportunity may be defined. Observations on initial field trials are also noted.