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.

Recycled polyethylene terephthalate (PET) plastic wastes could be used in the production of unsaturated polyester resins. If specially formulated, these unsaturated polyester resins could, in turn, be mixed with inorganic aggregates to produce polymer concrete (PC). The results of an extensive research confirm that PC materials using resins based on recycled PET are comparable in strength to conventional PC materials. Resins based on recycled PET could also easily be altered to achieve a relatively wide range in the strength and flexibility properties of the PC, depending on the intended use of the material. PC using resins based on recycled PET may be utilized in the repair and overlay of portland cement concrete structures or in the production of various precast products, such as utility, transportation, and building components. The recycling of PET in PC would help decrease the cost of PC products, save energy, and alleviate an environmental problem posed by plastic wastes.

The use of porous materials as top layers of pavements is currently increasing in several European countries due to their noise absorption effect and an improvement in the drainage properties of the pavement. These effects are considered essential because of environmental and safety reasons. In this context, porous concrete is being studied as an alternative to porous asphalt. Since the porosity of this material significantly reduces its strength, some additions, in particular polymers, are required to obtain adequate mechanical properties and durability. These additions increase the cost of the pavement. To counteract this, the thickness of porous material is reduced to a thin layer; a bottom dense concrete, bonded to the porous top, must be laid. One such study was carried out by Dutch, German, and Spanish companies within the scope of a research project funded by the European Commission. This project included the analysis of noise production mechanism and noise measurement, the study of the behavior of porous concrete, the construction of test sections, the investigation of low noise by surface treatment, and the assessment and establishment of a practice code and guideline for the design and construction of porous concrete pavements. With respect to the laboratory research on porous concrete, the main objective was the definition of several mix compositions and a study of their characteristics of behavior. This paper presents the results obtained in the fatigue testing program carried out in this research project. It included compressive strength tests, the definition of the W÷hler curves (S-N diagrams) for several polymer contents and for different stress ratios, and the statistical analysis of experimental results.

A new family of latexes has been developed for use in portland cement that has a minimum film-formation temperature (MFFT) well above working temperature, eliminating the two major drawbacks of latex-modified mixtures: formation of a crust on the surface and difficulty in cleaning tools. Instead of coalescing to form a film, as do the typical latex modifiers for portland cement, these latex particles maintain their shape as spheres. Of the several formulations studied, two are reported here: a styrene polymer and a methyl methacrylate polymer, both carboxylated. In addition to extensive laboratory testing of both polymers, two field trials with the styrene latex formulation were conducted. These laboratory and field studies demonstrated that film formation is not necessary for latexes to contribute to the performance of portland cement mixes. The data from these studies are encouraging, but also revealed that much more work needs to be done to fully understand the capabilities and limitations of this family of latexes.

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.