International Concrete Abstracts Portal

Reports the development of a premixed electrically conductive polymer concrete overlay for use on bridge decks and other concrete members, in conjunction with cathodic protection systems. The development of a conductive overlay culminated in the installation of such an overlay on a full-bridge deck in Pulaski, Virginia; the active cathodic protection system has operated for 8 months and is being monitored on a monthly basis. The monitoring shall continue for about 18 months. The conductive overlay was placed by a local contractor with technical assistance. The cathodic protection system was designed by a corrosion engineering firm. The installation of the conductive overlay and cathodic protection system cost less than $18.00 a square foot.

Liquified natural gas (LNG) is usually stored in large tanks surrounded by impounding dikes. If an accidental spill occurs, the LNG boils off and the vapors form a hazardous, explosive mixture with the atmosphere. The rate of evaporation of the LNG depends on the rate of heat transfer from the dike surface to the liquid gas. If the rate of heat transfer is reduced, the rate of evaporation of the LNG and the creation of hazardous conditions are also reduced. Reduction in heat transfer can be achieved by installing and insulating polymer concrete (IPC) overlay on the surface of the containing dikes. The IPC described in this paper was installed on approximately 56,000 ftý of the floor and 18,000 ftý of the sloped wall areas of the dike. It was based on a special moisture insensitive epoxy polymer concrete binder mixed with multicellular glass beads and ceramic-like shell fines to obtain insulating properties. A flame retardant agent was also added to improve fire resistance. The IPC was mixed in a continuous polymer concrete mixer and spread by vibrating screed. The different application techniques are described.

Polymer concrete (PC) has attracted significant interest in the past 15 years. It began primarily as a repair material for portland cement concrete, particularly bridges and pavements, and has now attracted considerable interest for other applications. A survey was conducted to determine the predicted needs and trends in the industry. The respondents, representing a wide range of backgrounds, indicated that precast products would have the greatest impact and, among precast products, utility components would lead the way. The greatest needs in the industry were deemed to be lower cost and improved monomers and resins. Many opinions were presented on the needed developments in materials properties. The author also presents his predictions on future trends in monomers and resins, aggregates, equipment, repair, precast products, and overlays. Future needs including improved training, public awareness, and research are discussed.

Fracture behavior of polyester polymer concrete was investigated at room temperature using single edge notched beams loaded in four-point bending. To investigate the effect of particle size distribution on the fracture properties, polyester polymer concrete systems were formulated using both uniform Ottawa 20-30 sand and well graded blasting sand. The notch sensitivity of polyester polymer concrete systems was investigated by varying the notch-to-depth ratio up to 0.7. The results are analyzed to examine the applicability of fracture parameters such as critical stress intensity factor KIC and critical J-integral JIC, to characterize the fracture behavior of polyester polymer concrete. This concrete is a notch sensitive material, and if it contains well-graded aggregate, it has better fracture properties than the uniformly graded aggregate system.

Results are presented from the preliminary phase of a laboratory test program conducted to identify and evaluate materials for converting hazardous geothermal residues to a nonhazardous and potentially usable form. Laboratory test results indicate that geothermal residues can be effectively incorporated as a fine aggregate into polymer concrete (PC) and portland cement mortar (PCM) composites. PC composites made using an emulsifiable polyester resin and a methyl methacrylate (MMA)-based monomer system exhibited compressive strengths varying between 3700 and 16,500 psi (25.5 and 113.8 MPa), depending upon the type of binder used and the moisture content of the residue. Waste extraction tests (WET) performed on ground samples of the composites indicate elemental levels of leachable heavy metals are below specified soluble threshold limit concentrations (STLC). PCM composites exhibited compressive strengths varying between 2875 and 5530 psi (19.8 and 38.1 MPa), depending upon the type, amount, and moisture content of the residue. WET analysis indicates elemental levels of leachable heavy metals are below specified STLC values for all but one of the PCM composites evaluated.