Showing papers on "Polymer concrete published in 1978"

Cracking and toughening of concrete and polymer-concrete dispersed with short steel wires

Abstract: A fibre-strengthened brittle solid can crack and fracture in a number of ways and simple models can be used to describe quantitatively the fracture processes. This paper discusses some of these models and compares experimental measurements of cracking stress and toughness for two brittle fibrous composites with the theoretical predictions. The two brittle matrices are concrete and concrete impregnated with polymethylmethacrylate reinforced by discontinuous (short) high strength steel wires. It involved extracting a single steel wire from each brittle matrix to evaluate the debonding stress and pull-out stress as a function of fibre embedded length. These key material parameters and the energetics of cracking determined in three-point flexural experiments, together with the cracking and toughening equations are then used to characterize the fracture behaviour of fibrestrengthened concrete and polymer-concrete composites.

Use of polymers in highway concrete

Abstract: This report describes a series of laboratory and field studies undertaken to demonstrate the feasibility of polymer impregnation of concrete bridge decks from the upper surface to depths that will encase the top layer of reinforcement to arrest or prevent spall- and pothole-causing corrosive action. Deep impregnation of typical salt-contaminated concrete was achieved in the laboratory when the concrete was brought to a bone-dry condition. Impregnation was found to arrest the corrosion of reinforcing steel, virtually eliminate freeze-thaw damage, and substantially increase the resistance of the concrete to chemical attack. Water absorption and loss by abrasion were reduced severalfold. Using gas-fired infrared heaters for drying the concrete, moderate pressure to aid monomer impregnation, and hot water to achieve polymerization, deep penetration (up to 4 in. (10 cm)) was achieved on two bridge decks, one of which was heavily salt-contaminated. The equipment and techniques developed for the field demonstration are believed to be of a nature to permit scaling up for practical use. The research employed a methyl methacrylate mixture.

Polymer concrete compositions and cured products thereof

Abstract: This application concerns compositions comprising a mixture of air-drying dicyclopentenyl acrylate or methacrylate binder and a granular or particulate aggregate material, which may comprise a hydraulic cement, and is adapted to be formed by casting, extruding, or molding in any fashion into any desired shape and air-drying and resulting shaped article, thereby producing an integral, solid article of unitary mass and structure. The dicyclopentenyl (meth)acrylate may be used as an impregnant, polymerizable in situ, for already formed articles of porous nature, e.g., concrete, wood, pressed boards, and powdered pressed metal, such as aluminum, iron, steel, etc., to reduce the permeability at their surfaces and provides hard, continuous, hydrophobic, wear-resistant, and weather-resistant surfaces thereon.

Styrene-butadiene latex modifiers for bridge deck overlay concrete

Abstract: Styrene-butadiene (S/B) latex modified concrete overlays are being used to protect new bridge decks from rapid deicer-borne chloride intrusion and also in bridge deck rehabilitation efforts. The purposes of this research were to evaluate several commercially-available S/B latex modifiers for bridge deck overlay concrete; and to develop chemical specifications for the material, a prequalification program to permit evaluation of other S/B latex modifiers which become available, and a certification program to insure the user receives a prequalified product. The chemical and physical properties of the latex emulsions were studied (percent solids, percent butadiene, particle size, surface tension, viscosity, etc.) and the material from each manufacturer was finger printed using infrared spectroscopy. The physical properties of concrete made with each material were also determined (workability, strength-compressive, flexural and bond, freeze-thaw and scaling resistance, and chloride permeability). In general, the studies showed that the following materials similar properties and thus would be expected to perform similarly as bridge deck overlays: Modifier A--Dow Chemical Company; Deco-Rez 4776--General Polymers Corporation; Thermoflex 8002--Reichhold Chemicals, Inc.; and Arco Dylex 1186--Arco Polymers, Inc. The prequalification procedures given in the report are suggested for use in evaluating other S/B latex emulsions offered by industry. The certification procedures are suggested for use to insure that each production batch of emulsion is similar to an emulsion which was prequalified. /FHWA/

Fracture toughness measurements of polymer concretes

Abstract: SYNOPSIS This paper describes the use of linear elastic fracture mechanics to examine the behaviour of premix and impregnated polymer concretes. Results are given for three monomers, viz. styrene, methyl methacrylate and butyl methacrylate, and two strengths of concrete, as well as for appropriate control series. The notched-beam technique is used to determine fracture parameters, together with compliance measurements to determine slow crack growth. Experimental results indicate that thermal treatment to polymerize the monomer in the premix concrete has a marked influence upon fracture toughness. Irradiation on the other hand has little influence. Polymer impregnation increases the stress-intensity factor and the strain at failure, the latter increase being influenced by the extensibility of the polymer. The results also show that the plain and the premix polymer concretes are partially notch-sensitive, whereas the impregnated polymer concrete is a notch-sensitive material.

Polymer concrete materials for use in geothermal energy processes

Abstract: The feasibility of using polymer concretes as materials of construction in geothermal processes has been demonstrated and tests to determine the practicability are in progress. High temperature polymer concrete systems have been formulated and laboratory and field tests are being performed in brine, flashing brine, and steam at temperatures up to 500/sup 0/F (260/sup 0/C). Results are available from field exposures of up to 18 months in four geothermal environments. Good durability at temperatures > 392/sup 0/F (200/sup 0/C) is obtained with samples containing portland cement-silica sand aggregate. Based upon these results, potential applications for polymer concrete in geothermal processes have been identified and the effects of its use on the cost of electric power generation have been estimated. Reductions in the cost of power delivered to the distribution system of approx. 10% were calculated. Redesign of the plants for the optimum utilization of polymer concrete would be expected to result in greater savings.

Rapid patching of concrete using polymer concrete

Abstract: One of the major problems confronting the highway industry today is the need for a rapid repair material for deteriorated concrete structures. High maintenance costs and traffic delays have created the need for a long lasting, rapid setting, concrete patching material. The use of polymer concrete (PC) as a repair material is discussed. Materials used to make polymer concrete composites are described, as is the procedure for placing polymer concrete patches. The placement of polymer concrete patches in the field by highway maintenance personnel using conventional concrete mixing equipment and techniques is also described.

Optimum Polymer Content in Concrete Modified by Liquid Epoxy Resins

Abstract: The investigation discussed used low viscosity resin with hardner, mixed under normal temperature condition in the concrete mix. After the best combination of resin and hardner was developed, the effect of water/cement (W/C) ratio and the polymer/cement (P/C) ratio were studied on the tensile and other properties. The investigation showed that the rate of increase of slump due to the increase in the polymer/cement ratio is less than that due to increasing the water/cement ratio. It also showed that the P/C optimum ratio within the workable range varies between 0.3 and 0.45 for any practicable W/C ratio below 0.6.

Rapid patching of deteriorated concrete using polymer concrete

Abstract: The increased use of deicing salts is resulting in rapid deterioration of portland cement concrete bridge decks. Corrosion of the reinforcing steel by the chlorides results in an increase in the volume of the steel. This expansion produces stresses in the concrete which result in delaminations and surface spalling. The repair of spalls with conventional durable patching materials can only be made if traffic can be diverted from the patched areas for several days. Therefore, a durable patching material which will allow traffic to be resumed over the repaired area in a few hours is needed. These criteria can be met by the use of polymer concrete. Polymer concrete (PC) is a composite material in which the aggregate is bound together in a dense matrix with a polymeric binder. The aggregate is mixed with a monomer mixture and subsequently cured in place. PC combines the premix characteristics of portland cement concrete with high strength, long-term durability, and short cure time. The high early strength of PC is suitable for use in the repair of highway structures where traffic conditions allow closing of the area for only a few hours.

Special aspects of resin mortars for cement concrete pavement repairs. in: polymers in concrete. international symposium

Abstract: Synthetic resins have gained popularity for rapid repairs of cement concrete pavement by combining the properties of rapid hardening, good adhesion, abrasion resistance and strength. This paper reviews work of the Central Road Research Institute, New Delhi, associated with the use of synthetic resins for repair of pavement structures in India. The Insitute has paid special attention to the effect of climatic changes on the bond of cement concrete-resin mix composites through accelerated tests. While the study clearly indicated differential performance of composites using polyester and epoxy resins, the indications point to higher values of curing shrinkage and moisture absorption by polyester resin mortars as the likely causes.

Concrete polymer materials for geothermal applications

Abstract: The feasibility of using a copolymer composed of styrene, acrylonitrile, and acrylamide or methacrylamide in the formation of a high-strength thermally and chemically stable polymer concrete for use in geothermal environments has been demonstrated. Specimens produced with the copolymer in conjunction with an aggregate containing sand and portland cement had compressive strengths in the range 25,000 to 30,000 psi at 20/sup 0/C and were thermally stable up to approximately 240/sup 0/C. A study of the effect of monomer concentration on the properties of the polymer concrete indicated that the optimum concentration is in the range 12 to 13 wt %. Increased monomer concentrations lead to a nonuniform polymer distribution within the composite, resulting in a deterioration of the properties. The optimum properties are obtained when the monomer is used in conjunction with an aggregate containing 70 to 80 wt % silica sand and 20 to 30 wt % portland cement. The results from laboratory and field evaluations in progress indicate that the materials can be used for pipe or as protective liners on pipe and vessels in electric generating and direct utilization geothermal processes.

Building structural restoration using monomer impregnation. in: polymers in concrete. international symposium

Abstract: The paper discusses the application of the newly developed techniques of polymer impregnated concrete (PIC) in conjunction with existing epoxy repair technology to restore severely deteriorated, low quality concrete to an adequate structural material. Described are the problems of handling techniques and safety of PIC used in a closed building environment. Also discussed are costs of commercial use of PIC. The paper reports on testing, analysis, and design leading to a restoration contract for a condemned, structurally deteriorated jail building. The contract achieved restoring a cracked and crumbling reinforced concrete slab with a compressive strength of less than 800 psi by injecting an acrylic monomer.

Concrete for earth-covered structures

Abstract: : Low permeability to water is a primary consideration in the design and construction of earth-covered concrete structures. Factors affecting the permeability of concrete are generally classified into three groups: (1) constituent materials; (2) methods of concrete preparation; and (3) subsequent treatment of the concrete. Each group of factors is examined in this paper and recommendations are made on how to obtain concrete that is virtually impermeable. Also, some specialized concretes with potential applications in earth-covered structures are discussed briefly. These include polymer-impregnated, polymer, and fiber-reinforced concretes and ferro-cement. (Author)

An investigation of the properties of polymer concrete. in: polymers in concrete. international symposium

Abstract: The purpose of this study was to investigate the formulation of various composite materials that consist of a polymeric matrix with mineral fillers that could be used for building materials. Combinations of sand, gypsum, gravel, clay and chopped glass fibers were mixed with a number of polyester-styrene-methyl methacrylate resin systems, cast and cured, and the resulting materials were then tested. The study found that the addition of a chlorendic anhydride improved polymerization at both ambient and elevated temperatures. Specimens from the most promising formulations were tested in compression and flexure and compared with respect to physical properties and cost with ordinary concrete.

The degree of cement hydration in concrete

Abstract: • A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers.

Polymer impregnation used in concrete repairs of cavitation/erosion damage. in: polymers in concrete. international symposium

Abstract: Discussed is the use of polymer impregnation in the repairs of concrete damaged by cavitation/erosion forces at Dworshak Dam in Idaho Based on the work completed, the following conclusions can be made: polymer impregnation can be accomplished even under very difficult field conditions; polymer impregnation of horizontal surfaces is relatively simple; an accurate depth of impregnation can be determined using an infrared pyrolysis technique; polymer impregnation of dry-pack patches will strengthen the patch; and preliminary indications are that polymer impregnated concrete will provide excellent resistance to cavitation, erosion, and impact forces

Polymer Impregnation Used in Concrete Repairs of Cavitation/Erosion Damage

Abstract: Discussed is the use of polymer impregnation in the repairs of concrete damaged by cavitation/erosion forces at Dworshak Dam in Idaho. Based on the work completed, the following conclusions can be made: polymer impregnation can be accomplished even under very difficult field conditions; polymer impregnation of horizontal surfaces is relatively simple; an accurate depth of impregnation can be determined using an infrared pyrolysis technique; polymer impregnation of dry-pack patches will strengthen the patch; and preliminary indications are that polymer impregnated concrete will provide excellent resistance to cavitation, erosion, and impact forces.