Showing papers on "Polymer concrete published in 1988"

Factors Affecting Bond Between New and Old Concrete

Abstract: When new concrete is placed next to old concrete, attempts are usually made to bond the two concretes together: ofen a cement paste or mortar joint is used, as in masonry. The service stress states in bonds can vary tremendously so no single test method can replicate all these states. A method of test for bond should reflect a typical in-service stress state yet also be sensitive to variation in the strength of the bond. Four tests were evaluated, and a slant shear test was found to be the most appropriate. The effects of various parameters were evaluated theoretically with the finite element and/or experimentally. A bond material with a modulus of elasticity similar to the adjacent concrete was found to be desirable, as was consistency in the bond material properties. Thick bond layers were found to reduce bond strength considerably and copolymer polyvinyl acetate was found to be a poor bonding agent over a wide range of curing conditions and mortar mix designs.

Mechanical behaviour of polymer concrete systems

Abstract: The mechanical behaviour of epoxy and polyester polymer concrete systems was studied under different loading conditions at various temperatures, resin content, and glass fibre content. While polymer content varied between 10 and 20% of the total weight of polymer concrete, the fibre content was limited to 4% by weight. The temperature was varied between 22 and 110°C, depending on the glass transition temperature of the resin. Compared to vibration, the compaction method of preparation reduces the void content and enhances the strength and modulus of polymer concrete. The compressive and flexural strength and stiffness of the polymer concrete systems increase up to a certain limit of polymer content at which they exhibit maximum strength and stiffness. They subsequently decrease or remain almost constant with further increase in polymer content. The strength and stiffness of polymer concrete are very much dependent on the temperature. The stiffness model, based on inclusion theory, yields satisfactory results for the three-phase polymer concrete. Using this model, the compression and flexural modulus of polymer concrete can be predicted from the properties of the constituents and their composition. Incremental strength and stiffness models developed in this study are effective in predicting the increase in strength and stiffness of glass-fibre-reinforced polymer concrete.

Concrete construction units and multi-ply concrete composites made therefrom

Abstract: Generally mat shaped concrete construction units provide novel, versatile building materials particularly for flexible multi-ply concrete composites in pavement or floor construction, roadbeds, driveways, waste disposal sites, etc. The mat-like structures comprise an outer shell subdivided into parallel tubular compartments which are filled with dry concrete mix so as to provide controlled chemical hydration for greater strength and durability. The multi-ply structures fabricated with the concrete construction units exhibit enhanced resistance to fracturing and possess residual structural values not found in equivalent poured concrete structures.

Equipment support pad and method

Abstract: A method of constructing an equipment pad and the resultant pad is disclosed. The method comprises the steps of providing a mold with fiberglass material laminated to the interior walls of the mold, providing a layer of polymer concrete in the base of the mold, covering the layer of concrete with a sheet of fiberglass material, covering the fiberglass material with an additional layer of polymer concrete, placing honeycomb material on the additional layer of concrete, filling selected cells of said honeycomb material with a polymer concrete, laminating a fiberglass sheet to the upper surface of the honeycomb material and sealing the upper sheet of fiberglass to the fiberglass laminated to the walls of the mold. The finished pad is then removed from the mold and inverted. If desired, an opening may be molded into the pad.

Setting Stress Distribution in Particle Reinforced Polymer Composites

Abstract: The effect of the geometric arrangement of spherical aggregates in a highly filled polymer composite (such as polymer concrete) on the setting stresses, due to resin shrink age during cure was investigated using three-dimensional finite element analysis. Simple cubic and face-centered cubic arrangements of perfect spherical aggregate were con sidered as well as a hexagonal-close-packed arrangement of hexagonal, prism-shaped aggregate. The shape of the aggregate has a very significant effect on the setting stresses. The effects of packing factor of aggregate particles were investigated. The higher the pack ing factor of spherical particles the lower the magnitude of setting stresses throughout the polymer composite system.

Electrically conductive polymer concrete coatings

Abstract: A sprayable electrically conductive polymer concrete coating for vertical d overhead applications is described. The coating is permeable yet has low electrical resistivity (<10 ohm-cm), good bond strength to concrete substrates, and good weatherability. A preferred formulation contains about 60 wt % calcined coke breeze, 40 wt % vinyl ester with 3.5 wt % modified bentonite clay. Such formulations apply evenly and provide enough rigidity for vertical or overhead structures so there is no drip or sag.

Expandable polymer concretes and mortars utilizing low cure temperature polymers

Abstract: An expandable polymer concrete or mortar composition, and process for producing it, which allows the use of low temperature cure resins by incorporating a substituted mineral which is able to expand in the polymer concrete mix so that the dilation of the mineral will counteract the shrinking effect of the curing resin. The substituted mineral may be selected from the montmorillonite group and is produced by substituting its water of hydration with a higher volatility composition such as ammonia.

Odot experience with silica-fume concrete

Abstract: Two bridge-deck-overlay projects placed in 1984 and 1987 are the basis for Ohio's specifications on the use of silica fume; they are reviewed along with a full-depth silica-fume structure placed in 1987. Data on mixing, placing, curing, compressive and flexural strengths, resistance to freezing and thawing, and permeability are presented. An assessment of these results shows that Ohio's 15 percent by mass of cement silica-fume requirement could be reduced, retaining high compressive and flexural strengths, good resistance to freezing and thawing, and favorable permeability characteristics. At present silica-fume-modified concrete appears to be a satisfactory and cost-competitive method of extending the life of bridge decks.

New concepts in polymer concrete insulation

Abstract: The author deals with polymer-concrete insulation, a technically viable, low-cost alternative to energy-intensive porcelain for high-voltage electrical applications both indoors and outdoors. He briefly describes the advances in polymer-concrete insulation made to date and presents new concepts for further utilizing this versatile material advantageously in present and future electric power system applications. >

High speed construction method of semi rigidity pavement

Abstract: PURPOSE: To shorten the construction hours by injecting polymer cement grout in gaps among concrete frame materials while open grading asphalt concrete with which pavement has been finished still maintains its heated state. CONSTITUTION: Pavement is carried out with open grading asphalt concrete. Then, while concrete maintains its heated state, polymer cement concrete grout which is formed by compounding the holmaldehide condensate of aminotriagin containing sulfonic acid radical in polymer cement grout by 0.5 - 10.0wt.% in the cement weight standard, is injected into the gaps among concrete frame materials. COPYRIGHT: (C)1990,JPO&Japio

Influence of Water Cement Ratio and Curing on the Permeability and Structure of Hardened Cement Paste and Concrete

Abstract: Curing affects sincerely the durability of concrete especially in surface regions. This is reflected in the pore structure and in the permeability. In a systematic research the structural changes due to water cement ratio and curing have been studied by mercury porosimetry, by nitrogen adsorption, by oxygen diffusion and by oxygen permeability. Due to these results diffusion and permeability are connected by a power law. Structural changes alter the permeability by four orders of magnitude. The results can be well explained by pore size distribution both for hcp and for concrete. Carbonation and frost action as well as strength and elastic modulus are closely correlated to permeability and therefore to pore structure. For practical application it is possible to give advice for concreting and curing. Service life can be predicted by permeability measurements in an early stage. The results are comparable with Nyames /20/.

Peat fly ash as a supplementary cementing material in concrete . nordic concrete research. publication no 7

Abstract: The study was performed as a comparison test on superplasticized peat and coal fly ash concretes with or without an air-entraining agent. Reference concretes with pure portland cement were used. The fly ash contents varied between 20 -60 % by mass of the total amount of binder. The non-air-entrained concretes were used for studying the compressive strength, drying shrinkage, watertightness and water absorption properties. With the air-entrained concretes the frost-resistance properties were additionally studied by means of protective pore ratio, freezing dilation, freeze-thaw resistance and frost-salt resistance tests. The test data indicate that with proper mix design, and choice of admixtures, peat fly ash can be used as a supplementary cementing material to produce a high-quality, frost-resistant concrete. (Author/TRRL)

Practical considerations for using silica fume in field concrete

Abstract: Ready-mixed silica-fume concrete is currently used in the United States on a regular basis. During 1986, approximately 350,000 cu yd (270,000 cu m) of silica-fume concrete were placed. The silica fume is used as a cement replacement material or as a performance-enhancing admixture. This paper reviews the practical aspects of working with silica fume in ready-mixed concrete, with emphasis on the use of silica fume in the performance-enhancement role. Availability of silica fume and of products containing silica fume is described first. The current lack of specifications for silica fume, admixtures containing silica fume, and concrete incorporating silica fume is examined. Aspects of concrete production including measuring, adding, mixing, using high-range water-reducing admixtures, and controlling concrete temperature are discussed. Transporting, placing, finishing, and curing are reviewed to determine how silica-fume concrete differs from conventional concrete in these areas. Finally, several specific considerations for using silica fume in concrete for bridge decks are discussed. Ready-mixed silica-fume concrete has been placed successfully in a wide variety of applications. The price for a successful placement is strict adherence to the fundamentals of good concrete practice.

Relation between creep and performance of pc --the production, performance and potential of polymers in concrete. 5th international congress on polymers, brighton, september 24-27, 1987

Abstract: Creep (increase of material deformations under constant stress and environmental conditions in the course of time) has particular significance for bearing polymer concrete (pc) structures. It influences the value of long-term strength, the possibility of utilization in different service conditions, etc. Creep of pc depends on many factors, mainly: parameters of compositions, load history, kind of environment. The paper deals with the influence of some composition parameters (e.g. Chemical character of resin, filler/binder ratio, maximal diameter of filler grains) on pc creep. It analyses the effect both of the relative value and of the sign of stress as well as of loading history on the behaviour of the material. From the results it follows that it is possible to attain creep compliance of pc similar to that of cc, if the resin, filler/binder ratio and granulometric composition are correctly selected. For the covering abstract of this congress see IRRD 814075.

The effectiveness of membrane curing compounds for Portland cement concrete pavements

Abstract: Membrane curing compounds are widely used to cure concrete in highway construction. The function of these compounds is to form a membrane that helps retain moisture in the concrete slab, otherwise lost through evaporation. The amount of evaporation loss varies as a function of the environmental conditions and the temperature of the concrete mass during the curing period. This report provides an evaluation of the performance of membrane curing compounds as related to concrete material properties such as tensile and flexural strength, stiffness, surface durability, and density. In addition to traditional testing methods, the non-destructive, in-situ, Spectral Analysis of Surface Waves method is also used to observe and measure material properties as a function of time. Testing can start at initial set or when the modulus of elasticity for concrete is about 10,000 psi (A).

A constitutive equation for creep in polymer concretes and their resin binders

Abstract: We present here a method for superposing creep measurements on polymer concrete (PC), taken at different temperatures, imposed stresses, and resin contents, onto master curves, which describe the respective responses of various PC systems and their resin binders, to compressive, tensile, and flexural loads. This treatment is extended to systems reinforced with chopped glass fiber and montmorillonite (MMT). The general applicability of this superposition is tested with creep measurements by other investigators under tensile, compressive, and flexural loads. The results make it possible to predict the long-term creep behavior of unfilled as well as reinforced glassy polymer systems at different temperatures and load conditions from limited, short-term data. Success of the multiple superposition suggests a generalized constitutive equation, which describes the creep compliance of these systems as a product of separable functions of each parameter in the form of shift factors for temperature (αT), stress (ασ), resin content (αυ), fiber reinforcement (αF), and MMT reinforcement (αM): J(PC) = JrαTασαυαFαMtm, where Jr is an appropriately chosen reference creep compliance. The time exponent m does not depend on the chemical nature of the polymer matrix.

Underwater concrete containing segregation controlling polymers --the production, performance and potential of polymers in concrete. 5th international congress on polymers, brighton, september 24-27, 1987

Abstract: As concrete is a mixture of materials consisting of different kinds of particles such as aggregates, cement, and water, it is inherently liable to segregate in water while fresh. However, by adding a water-soluble high-polymer segregation controlling agent as an admixture, cement and aggregates are imparted with cohesiveness which makes segregation difficult even when subjected to washing by water. The mechanism of segregation resistance in water of concrete containing a segregation controlling admixture is discussed, and the properties of this concrete in a fresh state such as flow self-levelling, and bleeding are explained. The setting and strength characteristics are also discussed.(a) for the covering abstract of this congress see IRRD 814075.

Static flexural behaviour of various polymer concrete beams --the production, performance and potential of polymers in concrete. 5th international congress on polymers, brighton, september 24-27, 1987

Abstract: This study was conducted to investigate the flexural behavior of various polymer concrete beams. Eighteen polymer concrete and control beams were tested using two symmetrically placed concentrated loads. Five polymers were used: polyester, methyl methacrylate (mma), polyesteramide resin (pear), epoxy, and vinyl ester. Some fundamental flexural characteristics of various polymer concrete beams were compared with portland cement concrete control beams as a function of the tensile steel ratios. The polymer concrete beams developed higher ultimate moment strength, greater deflection, curvature, ductility, and energy absorption, as well as lower effective beam stiffness than control beams having the same tensile steel ratio. Although the polymer concrete beams were stronger and tougher than the control beams, the deformation in polymer concrete beams was greater than that of the control beams. Those properties are also dependent on the amount of reinforcing steel. The polymers listed in order of their performance in reinforced polymer concrete beams were epoxy, methyl methacrylate, vinyl ester, polyester, and polyesteramide resin.(a) for the covering abstract of this congress see IRRD 814075.

Stress-strain behaviour of polymer concrete systems --the production, performance and potential of polymers in concrete. 5th international congress on polymers, brighton, september 24-27, 1987

Abstract: The stress-strain responses of polymer concrete systems with epoxy and polyester as binders were investigated at varying temperatures, resin content and void content to ascertain the influence of polymer properties on the polymer concrete behavior in compression, flexure and splitting tension. The strength and stiffness of the polymer concrete systems increase up to a certain limit of polymer content at which they exhibit maximum strength and stiffness and subsequently decrease or remain constant with further increase in polymer content. The strength and modulus of polymer concrete are very much dependent on the temperature. Compared to vibration, compaction reduces the void content and enhances strength and modulus of polymer concrete. The polymer concrete is treated as a three-phase composite material in developing stiffness models in terms of the constituent properties to predict the compressive and flexural moduli. A nonlinear elastic stress-strain relationship is used in modeling the compressive behavior of polymer concrete up to peak stress.(a) for the covering abstract of this congress see IRRD 814075.