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.

SP-166 This volume contains 11 symposium papers that were presented at the 10th and 11th symposia that were held in Minneapolis, MN and Tarpon Springs, FL in 1993 and 1994 respectively. There were a total of four sessions, the first titled "Polymer Concrete Overlays," the second "Recent Innovations in Polymer Concrete Technology", the third and fourth "Structural Properties of Polymer Concrete, Part I and II."

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.