International Concrete Abstracts Portal

A major problem confronting transportation departments is the surface deterioration of portland cement concrete (PCC) pavements and bridge decks. Some of these defects include cracking, spalling, polishing, and surface erosion. Each of these defects contributes to further deterioration within the concrete structure by allowing an infiltration of moisture, oxygen, deicing salts, chlorides, and other contaminants. Upon contact with the reinforcing steel, rusting occurs, causing internal tensile stresses that result in further surface spalling, hollow plane delamination and cracking. One effective technique used since the middle 1950s is to retard this corrosion process by preventing the penetration of chlorides and moisture into the concrete with in impermeable epoxy polymer concrete (EPC) overlay. These overlays also provide wear-resistant surfaces and extend the service life of the pavement or deck. Documented experience indicates that EPC overlays are cost effective, reduce overall annual maintenance costs, and provide a safe driving surface. This paper presents two project tracking studies. The first is a comparison of a new PCC slab placement to a thin EPC overlayment on an existing PCC pavement installed 15 years ago; the pavements are side-by-side. The documentation compares traffic volumes and surface deteriorations, such as wearability, spalling, polishing, and cracks. The second study involves a thin EPC overlay placed on a badly deteriorated PCC bridge deck 10 years ago to improve skid properties and provide an overall safer driving surface.

Epoxy asphalt concrete is a polymer concrete with a 25-year history of application as a bridge deck surfacing. Since 1967, over 100 million pounds (50,000 tons) have been installed on 22 bridge decks totaling 6.5 million square feet. Most installations have exhibited excellent performance. The epoxy asphalt binder is a two-phase, thermoset chemical system in which the continuous phase is an acid cured epoxy and the discontinuous phase is a mixture of asphalts. The aggregates and gradation are similar to those used in asphalt concrete. The epoxy asphalt binder components are premixed before being combined with the heated aggregate in a conventional asphalt batch plant and applied through conventional asphalt paving equipment. Epoxy asphalt concrete has found use as a pavement for new orthotropic steel bridge decks and as an overlay for existing concrete bridge decks. Epoxy asphalt has also been applied as a chip-seal. On one project, the epoxy asphalt concrete was shop applied to steel plates that were later installed as a bridge deck. Several installations have not performed as expected. Successful installations require close temperature control of aggregates and careful attention to early compaction. This paper also provides a history of the commercial use of epoxy asphalt in the United States and Canada.

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 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.