Showing papers on "Polymer concrete published in 1989"

Acid resistant concrete articles, especially sulfur concrete pipes, and a method of manufacturing said articles

Abstract: Acid resistant concrete articles, especially sulfur concrete pipes manufactured from a material formulated on the basis of a composition of portland cement concrete suitable for the manufacture of pipes by means of the dry casting method, the volume of portland cement, filler and water being replaced by a substantially equivalent volume of sulfur cement and filler, while the amount of other components remains substantially unchanged. The sulfur concrete pipes are manufactured by mixing the components of the material and adjusting the mixture to a temperature, where sulfur cement is liquid. At this temperature the mixture is cast while being subjected to vigorous vibration, using a casting mould preheated to a temperature of up to 160° C. The cast pipes can be removed from the mould immediately after casting. After only 24 hours they have obtained sufficient strength for being delivered to a building site. Sulfur concrete pipes are most suitable in aggressive environments since they are resistant to acid and salt attacks.

Laboratory investigation of concrete sealers

Abstract: Laboratory studies are described that were performed to assist specifiers in the selection of sealers for the protection of concrete traffic surfaces of existing parking garages that have been exposed to chlorides. The study is limited to products marketed in Canada and include the following generic types: acrylics, oligomeric alkoxysiloxanes, epoxies, blends, urethanes, alkoxysilanes, silicates/ siliconates, polysiloxanes and silicones, stryrene-acrylate copolymers, chlorinated rubbers, oils, siloxane/methacrylate, and synergistic system. Considerable differences were found in the effectiveness of the various sealers; they were more effective on good concrete than on inferior concrete. Thus, the properties of concrete must be considered in selecting a sealer. Only 35% of all sealers penetrated the concrete to a measurable extent. Air entrained concrete has a higher water absorption and chloride penetration of coated and uncoated concrete.

Optimum use of pozzolanic materials in steel fiber reinforced concrete

Abstract: The effects on fresh and hardened material properties for fly ash caused by substituting cement with fly ash and silica fume in steel fiber reinforced concrete were studied experimentally. The percentage substitution of cement ranged from 0 to 40% and from 0 to 20% for silica fume. The workability of fresh fibrous mixtures was characterized by measuring the inverted slump cone time. The hardened material was tested at 28 days under compression and flexural loads. The development of compressive strength with time was also assessed in steel fiber reinforced concrete incorporating fly ash. The generated test data were used to decide the optimum ranges of cement substitution with fly ash or silica fume in steel fiber reinforced concrete for achieving desirable fresh mix and hardened material characteristics.

Polymer concrete composition for cementitious road repair and overlay

Abstract: A composition which is useful in road overlay and repair comprises aggregate and a binder. The binder comprises a liquid epoxy resin, triethyleneglycol diamine or tetraethylene glycol diamine as curing agent, and piperazine as accelerator. The binder-aggregate system is relatively flexible, has excellent compression and flexural strength and adheres well to the substrate. Th esystem undergoes a fast cure to a compression strength of 3000 psi (210.9 kg/cm²) which will support automotive traffic.

Durability of concrete - a measurable quantity?

Abstract: This paper considers the durability of concrete, and presents a test method for its evaluation. Durability depends mainly on the resistance of concrete to the ingress of aggressive substances. Although there are several different mechanisms for the transport of these substances, the author investigates whether a single parameter, the air permeability of concrete, is suitable for the general characterisation of concrete durability. The absorption of water by concrete may occur in one of the following ways: (1) permeation of water under an external pressure; (2) capillary suction of water; (3) diffusion of water vapour. In the Schoenlin concrete air-permeability test method, the concrete sample is cast directly into a rubber ring, cured for a suitable period, and then stored in a constant environment up to the time of testing at age 56 days. Test results are presented on: (1) the effect of water-cement ratio and curing duration; (2) air permeability and concrete micro-structure; (3) permeability and carbonation; (4) permeability and capillary suction; (5) permeability and other concrete durability properties. The author concludes that Schoenlin's test procedure can be used to determine rapidly and reliably the characteristic air permeability coefficient of a standard concrete specimen that has been cured and preconditioned in a standardised way. For the covering abstract of the conference see IRRD 858334. The French title of this paper is:- Durabilite du beton - quantite mesurable? The German title of this paper is:- Die Dauerhaftigkeit von Beton - Eine messbare Groesse?

Efficiency Factors for Condensed Silica Fume in Concrete

Abstract: This paper presents how the term "efficiency factor" for condensed silica fume in concrete can be defined as the number of parts of cement that may be replaced by one part of silica fume without changing the property studied. This factor was first introduced for concrete compressive strength after 28 days curing in water at 20 C. In this situation, factors around 3 to 4 are reported. However, if the concrete is exposed to other temperatures, other curing conditions, or other curing periods, the factor may be as low as zero. This is very important information for the practical application of silica fume, especially when forms have to be stripped very early in winter concreting. The durability of concrete structures is more in focus than ever. When studying durability, the efficiency factors of silica fume in concrete can be calculated at the same time. Durability efficiency factors are also affected by the curing conditions. A comprehensive research program has enabled efficiency factors to be calculated for different conditions. This has covered strength and durability parameters such as permeability, carbonation, and chloride penetration. This work will be a helpful indication of how silica fume can be used in the most efficient way in concrete structures.

A hard look at concrete

Abstract: Concrete has been looked upon as something fixed and unchanging, a generic, nondescript mass, But it demands specific engineering attention. Because many existing concrete studies are outdated, it's time to address today's conditions. There are new products and processes, and such concrete types as admixtures, fly ash, pulverized slag and silica fume are here to stay.

The use of penetrating sealers for the protection of concrete highways and structures

Abstract: This study investigated a variety of different penetrating sealers for their potential to provide increased protection and durability for concrete in highways and structures. It was found that the best protection was provided by a two-coat penetrating sealer system comprised of a silane (OAS) primer and an acrylic resin-based topcoat. Test results showed that the system provides good protection against water, chloride, and carbon dioxide ingress yet still allows the concrete to breathe by the passage of water vapor. Recommendations are presented that help to ensure satisfactory surface preparation and application.

Evaluation of Cold-Weather Concrete Patching Materials

Abstract: The results are presented of an investigation of patching materials suitable for winter maintenance operations of bridges and pavements at subfreezing temperatures. Four materials, identified by a preliminary screening investigation as potentially suitable, were tested extensively for strength and durability. The four materials are methyl methacrylate-based polymer concrete, two types of magnesium phosphate-based concretes, and polyurethane-based concrete. Methyl methacrylate emerges as superior to the other materials in terms of performance, but environmental considerations mitigate in favor of the magnesium phosphates. The water-based magnesium phosphate has relatively poor freeze-thaw durability when cast at subfreezing temperatures, but the liquid-activated variety offers a reasonable compromise between performance and environmental factors.

High-strength concrete for pacific first center

Abstract: Strict testing and quality control insured successful placement of high-strength concrete in the construction of a buliding in Seattle, Washington. The design strength of the concrete was 14,000 psi, and the actual strength achieved was measured at 18,000 psi. The article describes various methods for testing and production to accommodate this very high-strength mix. The high-strength concrete mix used a 3/8-inch pea gravel aggregate and a coarse sand with a fineness modulus of 3.2. Admixtures consisted of a water reducer/retarder, superplasticizer, and condensed silica fume. The cementitious portion fo the mix was made up of Type I cement having low water demand characteristics, together with one sack of fly ash per cubic yard. 4 x 8 inch test specimens were determined to yield the best results. Compressive test results are described. Modifications to conform to field conditions are also described. Quality control, and problems in production and handling are described.

Marine durability of steel fibre reinforced concrete of high water/cement ratio. fibre reinforced cements and concretes: recent developments. proceedings of an international conference held at the university of wales, college of cardiff, school of engineering, united kingdom, september 18-20, 1989

Abstract: An assessment of the corrosion potential of steel fibres in concrete, on the basis of knowledge on rebar corrosion in concrete, raises serious doubts about the marine durability of steel fibres in concrete owing to their large surface area and low cover. Recent research, however, has shown that under splash/tidal zone exposure fibre corrosion does not occur provided they are embedded in uncracked concrete or in concrete with very fine crack widths. These conclusions are generally based on research using "marine" mixes of high cement contents and low water/cement ratios. This paper reports the results of a marine durability investigation on a mix of steel fibre reinforced concrete which had a cement content of 428 kg/m3 and a relatively high water/cement ratio of 0.58. The concrete was reinforced with melt extract fibres or galvanised corrosion resistant fibres. The test samples were exposed to a marine environment simulating the splash/tidal zone. The results show that resistance of steel fibres to C1 induced corrosion is equally satisfactory in mixes made with relatively low cement and high water/cement ratio as it is in rich mixes of high cement content and low water/cement ratio.(A) For the covering abstract of the conference see IRRD 827953.

Fracture Properties of Epoxy Polymer Concrete

Abstract: Epoxy polymer concrete beams with varying polymer content and notch depth were tested at two temperatures. The results were analysed to examine the applicability of various fracture parameters such as critical stress intensity factor, J-integral and fracture surface energy to characterize the fracture behavior of epoxy polymer and polymer concrete. The notch sensitivity of polymer and polymer concrete are also investigated.

Device for injecting polymer concrete into a mould, in order to enable it to be filled

Abstract: The invention relates to a device making it possible to manufacture, rapidly by injection, components made from polymer concrete or synthetic marble which contain no or few trapped air bubbles The device is constituted by a hopper 1 fitted with a pressure-withstanding lid 2 A pressurised gas tends to push the polymer concrete through the injection orifice 3 of the hopper The polymer concrete fills the mould 5 and 6 up to a gasket 7 Indicators 8 make it possible to ensure that the mould is completely filled The device according to the invention is particularly intended for the manufacture of sanitary ware, tiling, various components for a dwelling and for urban furniture

Criteria for polymer concrete on airport pavements

Abstract: : The subject of polymer concrete (PC) has generated a lot of interest among researchers during the past decade. This is due to the many advantages that polymer concrete pavement offers compared to regular portland cement concrete. The advantages of polymer concrete, when compared to portland cement concrete include, quick curing and setting, reduced moisture sensitivity and permeability and improved mechanical properties resulting in reduced pavement thickness to support the same load. These advantages will lead to attractive life cycle cost benefits. Material properties and mix designs for PC with epoxy, methylmethacrylate (MMA) and Polyester as the binder material have been investigated and presented in part I of this report. Part II contains pavement thickness design charts, developed for various aircraft, quality control methods, construction procedures and cost analysis. It has been shown in this study that increased material cost of PC can be offset by the reduced thickness of the pavement. In order to develop life cycle cost information, it is necessary to obtain field performance data of PC pavement, especially in the composite design mode. (kr)

Set Time Control Studies of Polymer Concrete

Abstract: : Set time data were obtained for polymer concrete made with a proprietary polyurethane resin for a wide range of aggregate and resin temperatures. Catalysts concentrations were adjusted so that setting occurred within a required time range. The effected of presence of water and ice on set time were also studied. Set time data were also obtained from pilot tests using another polyurethane and catalyst for various aggregate and resin temperatures and moisture and conditions. Considerably more catalyst was required in the pilot tests to obtain comparable set times. The impact of temperature variations on flexural strength was investigated. The flexural strength and failure mechanism at early ages depended on the temperature of aggregate and resin at the time of casting the polymer concrete. A model for the prediction of set time of polymer concrete was developed based upon thermodynamic and kinetic principles. The model parameters were determined experimentally from auxiliary laboratory tests conducted separately from the set time tests. Reasonable agreement was found between the model and the data from the set time since observed set times and resin temperatures generally agreed with those predicted by model.

Properties and application of steel polypropylene and polyester fibre reinforced concrete. fibre reinforced cements and concretes: recent developments. proceedings of an international conference held at the university of wales, college of cardiff, school of engineering, united kingdom, september 18-20, 1989

Abstract: The use of steel, polypropylene and polyester fibres to improve engineering properties of concrete has been investigated. The properties investigated are compressive, flexural and split tensile strength, modulus of elasticity, shear and impact strength. Steel fibres were used at 1.0, 1.5 and 2.0 percent by volume of concrete. Polypropylene fibres were used at 0.75, 1.0 and 1.5 percent by volume of concrete whereas polyester fibres at 0.75 and 1.0 percent by volume of concrete were used. The addition of fibres in concrete indicated favourable effect on ductility, toughness, impact resistance and tensile strength. The energy dissipators of spillways are prone to damage due to abrasion and cavitation which may cause heavy damage. Hence, fibre reinforced concrete which has relatively better ability to resist abrasive action was used in energy dissipation arrangements for repairs. It has given excellent performance which has shown that fibre reinforced concrete has wide scope for use in runways, penstocks, spillways and energy dissipators.(A) For the covering abstract of the conference see IRRD 827953.

Teflon-lined paver places polymer concrete surface

Abstract: Two bridges in Chillicothe, Ohio, and six in Columbus, Ohio, were repaired using an asphalt paver modified by a 12-ft.-long, teflon-coated auger to distribute the mix and teflon linings on all exposed surfaces of the machine. The $400,000 Chillicothe job involved 4000 sq. yd. of deck, while the $900,000 Columbus job totalled 7500 sq. yd. Mobilization, traffic control and patching of the old decks accounted for about 3/4 of the cost of each project. The 3/4-in. polymer concrete deck overlays cost about $30 per sq. yd., including all preparatory and placement work. This article provides information on deck preparation, polymer concrete mixing, and overlay placement.

Properties of No-Fines Concrete Containing Silica Fume

Abstract: This paper will discuss how cement paste with silica fume was used to improve strength and other characteristics of no-fines concrete. The results showed that by using cement paste with silica fume and superplasticizer, apparent viscosity and yield value of the paste in the fresh stage can be controlled. The compressive strength of no-fines concretes with silica fume is in the range of 20 to 47 MPa. Other characteristics such as flexural and splitting strengths, modulus of elasticity, and frost resistance of no-fines concrete are improved. The coefficient of water permeability varies depending on the amount of the continuous void and binder. A value of 2 to 50 mm/sec can be obtained.