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.

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.

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.

Shrinkage is a form of dimensional change which, if restrained, can produce stresses similar to those caused by the contraction of a material subjected to a temperature drop. However, a significant portion of total shrinkage takes place during the first few hours after mixing when the polymer concrete mix is still viscous. In addition, shrinkage is typically a one-time occurrence with effects extending over a long period of time. The significance of this difference is associated with a property known as stress relaxation. Research eventually led to the development of a test method for determining shrinkage-induced stresses in overlays. The basic idea behind this method is to accumulate shrinkage-induced stresses in a restrained polymer concrete overlay, to remove the restraint, and to measure the total released strain. To perform the proposed test, the middle region of a portland cement concrete beam is covered with several layers of plastic sheets that act as a bond breaker. Once overlay placement is complete, a DuPont device is positioned within the limits of the unbonded central region. Restraint provided by the substrate through the end regions is then removed by cutting the overlay transversely near one end of the unbonded central region. Test results indicated that shrinkage-induced stresses are not encountered with the use of slow curing systems, such as the epoxy concrete considered in this study. As for systems with high unrestrained shrinkage, it was observed that a residual amount of shrinkage-induced stress was sustained. The stress, however, was much lower than the level indicated by the unrestrained shrinkage results.

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.