International Concrete Abstracts Portal

Addition of epoxy components to portland cement concrete before or during mixing is a special form of polymer modification of concrete. The polymerization of the epoxy components takes place subsequently in the concrete along with the cement hydration, resulting in a strong, durable polymer inside the hardened concrete. Therefore the process may be called post-mix polymerization. The purpose of the modification is to improve certain properties of a mortar or concrete in the fresh as well as hardened state, such as workability, flexural and compressive strengths, impermeability, etc. In this paper first the properties of the epoxy components and epoxy are discussed that are pertinent to the polymerization and concrete modification. Then the polymerization process is described along with the principles of epoxy modification of concrete. A brief description of mix design for epoxy modified concrete closes the paper.`

There is a growing interest in rapid-setting and high-strength materials of construction that can also reduce the rising costs of maintenance and improve productivity. The Sulphur Institute, in cooperation with the Bureau of Mines and a small group of dedicated construction contractors, has encouraged research and development activities to devise new and advanced sulfur construction materials. Sulfur polymer cement concrete (SC) is used in hostile chemical environments where corrosion due to acid and/or salt exposure results in failure of such conventional materials as portland cement concrete. SC is also finding valuable uses in other applications. SC is gaining recognition in the increasing market for corrosion-resistant materials. Examples of construction and maintenance projects utilizing SC are described for chemical environments encountered during production of sulfuric acid, ammonium sulfate, phosphoric acid, potash, and other fertilizer materials, and compared with the performance of conventional construction materials. SC materials show no signs of deterioration due to acid and salt corrosion after approximately 9 years of industrial testing. New and expanding applications for SC are also explored. In addition to the summary of industrial projects, newly developed construction equipment, SC precast production, and other new and innovative applications are presented. 140-393

Discusses the lessons learned from 66 Alberta bridge sites, where thin polymer wearing surfaces have been placed by contractors on existing concrete bridge decks. The repair is intended to be a retrofit surface membrane designed as preventive maintenance for use on existing decks where deterioration has not progressed too far. It is intended to reduce the rate of deterioration caused by the penetration of chlorides and water to extend the service life of the bridge deck. The climatic exposure conditions of the decks vary from deck temperatures of 45 C to -45 C and average freeze-thaw cycles from 69 to 135 per year. Case histories are presented from the 87,000 m 2 of installed polymer wearing surface systems. Permeability, skid resistance, and CSE test data are reported as a measure of the success of the systems in stabilizing reinforcing bar corrosion in salt-contaminated existing decks. Observations are made on the cause and prevention of typical localized failures and their frequency of occurrence at typical sites. Comments on life expectancy and cost are presented, based on actual performance in a severe climate.

There is no reported work on the placing or bonding of polymethyl methacrylate (PMMA) mortars underwater. In this paper, PMMA mortars with and without coupling agents are prepared, and the applicability of underwater placing and bonding of PMMA mortars is examined, with the objective of performing underwater construction, which has gained popularity in recent years. PMMA mortars are tested for adhesion in flexure and tension to preplaced PMMA mortar substrates, and for flexural and tensile strength. It is concluded from the test results that the strength properties of PMMA mortars placed and bonded underwater are somewhat improved by the addition of a silane coupling agent, permitting the mortars to develop suitable strength and adhesion. PMMA mortars are applicable for underwater concreting if their appropriate binder system formulations are selected.

Matching certain properties of polymer concrete overlays and repair materials more closely with those of concrete can produce better compatibility between the resin-based material and the cementitious substrate. The key parameters of polymer concretes that are significant to this end include the resin type and loading, shrinkage properties, coefficient of thermal expansion, and modulus of elasticity. The approach used most often has been to minimize the resin loading requirements. This approach, by itself, imposes certain limitations on the type of products that can be formulated. In the course of work to develop shrinkage-controlled polymer concrete utilizing an unsaturated polyester binder, it was discovered that the shrinkage control agent contributes in an important way to the thermal and elastic properties of the material. This paper describes how this finding was used to develop polymer concrete that is more compatible with portland cement concrete.