International Concrete Abstracts Portal

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.

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.

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.

An analytical procedure was developed by which thermally-induced stresses in polymer concrete overlays can be quantified. The distribution and the magnitude of thermally-induced stresses can be determined using the proposed procedure. The main variables which influence the thermal stress development are found to be the thickness ratio and the modular ratio of the polymer concrete to the portland cement concrete, the difference in the coefficients of thermal expansion, and the temperature change. The relationships between the variables and the thermal stresses are determined and presented. Analyses reveal that thermally-induced interface stresses decrease as the elastic modulus and the thickness of the overlay decrease for the thin polymer concrete overlays. The analyses assumed isothermal conditions.

Flexural behavior of a polyester polymer concrete was investigated by varying the polymer and fiber contents. The polymer content was varied up to 18 percent of the total weight of polymer concrete (PC). The chopped glass fibers were 13 mm long and the fiber content varied up to six percent (by weight of PC). The fine aggregates were well graded, with particle size varying from 0.1 to 5.0 mm and were mainly quartz. The fine aggregates and glass fibers were also pretreated with a coupling agent ( -MPS) to improve flexural and fracture properties of PC. In general, addition of fibers increased the flexural strength, failure strain (strain at peak stress), and fracture properties, but the flexural modulus of PC remained almost unchanged. Addition of six percent fiber content and silane treatment of aggregates and fibers increased the flexural strength of 18 percent PC to 41.6 MPa (6,040 psi), almost doubling the strength of unreinforced 18 percent PC system. Crack resistance curves based on stress intensity factor (K R-curve) have been developed for the fiber reinforced PC systems. A two- parameter relationship was used to predict the complete flexural stress- strain data. There is good agreement between the predicted and measured stress-strain relationships.