International Concrete Abstracts Portal

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.

Industrial floors of asphalt concrete or other bituminous products are deformed under sustained concentrated loads. They are also dark in color and difficult to clean. Consequently, they need to be renovated. The use of polymer-modified concrete (PMC) overlays is an interesting alternative. Reinforced and unreinforced overlays were subjected to static and rolling wheel loads. Reinforced PMC overlays on asphalt showed a high load-carrying capacity. Shrinkage tests were carried out on PMC prisms and on concrete and bituminous overlaid with PMC. A two-layer overlay with wear and leveling layers was less prone to shrinkage than an overlay solely consisting of awear layer.

This research concerns the release of liquid methyl methacrylate from inside of the porous fibers into hardened concrete matrices to reduce permeability. Low heat is applied to the composite. It melts the wax coating on the fibers and dries the matrix, both of which act to move the methyl methacrylate and wax out into the matrix surrounding the fiber. The heat is increased, and the monomer becomes polymerized in the dispersed state into the matrix. Research results showed reduction in matrix permeability.

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.