Showing papers on "Cement published in 1995"
TL;DR: In this paper, the effect of the sand content on the development of pore structure, the permeability to water, and the diffusivity of chloride ions was studied on portland cement mortars.
435 citations
TL;DR: In this paper, the compressive strength of mortars based on the raw clays is affected by structure of clays, and a close correlation exists between the clays' pozzolanic activity and the particle size distribution of dehydroxylated clays.
384 citations
Book•
31 Dec 1995
TL;DR: Polymer-modified or polymer cement mortar (PCM) and concrete (PCC) are materials that deal with concrete-polymer composites as mentioned in this paper, they are made by partially replacing the cement hydrate binders of conventional cement mortar or concrete with polymers, such as polymeric admixtures or cement modifiers, and by strengthening the binders with the polymers.
Abstract: Polymer-modified or polymer cement mortar (PCM) and concrete (PCC) are materials that deal with concrete-polymer composites. They are made by partially replacing the cement hydrate binders of conventional cement mortar or concrete with polymers, such as polymeric admixtures or cement modifiers, and by strengthening the binders with the polymers. The polymeric admixtures or cement modifiers include latexes, emulsified polymers, redispersible polymer powders, water-soluble polymers, liquid resins, and monomers. The composite concrete and mortars are currently used as popular construction materials. This book brings together the current knowledge and information of PCMs and PCCs and discusses or reviews the following items in detail: principles of polymer modification for cement composites, process technology of PCMs and PCCs, properties of PCMs and PCCs, applications of PCMs and PCCs, and special polymer-modified systems such as MDF cements, antiwashout underwater concretes, polymer-ferrocements, and artificial woods. An index and chapter references are included.
298 citations
TL;DR: In this paper, a comprehensive investigation undertaken to assess the influence of soil characteristics and cement content on the physical properties of stabilised soil blocks is presented, including dry density, compressive and flexural strength, durability and drying shrinkage of over 1500 block tests.
Abstract: The paper outlines results of a comprehensive investigation undertaken to assess the influence of soil characteristics and cement content on the physical properties of stabilised soil blocks. The dry density, compressive and flexural strength, durability and drying shrinkage of over 1500 block tests are outlined in the paper. Experimental results are compared with current specifications and used to develop empirical guidelines for cement content requirements for a range of soil plasticity characteristics. An empirical relationship between compressive and flexural strength is proposed as a simple means of field assessment.
282 citations
01 Jan 1995
TL;DR: In this article, Cement-based composites are used to construct high-strength concrete and high performance concrete and concrete-like composites, including high performance concretes.
Abstract: Introduction Composites and Multiphase Materials Concrete-Like Composites Components of Cement Based Composites Reinforcement of Cement-Based Composites Structure of Cement Composites Interfaces Strength and Deformability Under Short-Term Static Load Cracking in Cement Matrices and Propagation of Cracks Fracture and Failure of Material Structures Behaviour of Cement Matrix Composites in Various Service Conditions Design and Optimization of Cement Based Composites High-Strength Concrete and High Performance Concretes Application and Development of Cement-Based Composites
277 citations
TL;DR: In this article, influences of cement, chemical admixture, mineral admixture and water-cement ratio on the autogenous shrinkage of cement paste were experimentally studied, and some admixtures which were able to reduce autogeneous shrinkage were found.
264 citations
TL;DR: In this paper, the suitability of a particular binder system for an application based on fresh concrete properties and mechanical properties was evaluated for concrete mixes having a fixed waterbinder ratio of 0.35 and a constant total binder content of 430 kg/m3.
251 citations
TL;DR: In this article, the authors focus on the evolution of the heat of hydration of hardening concrete or cement based materials and propose a new general hydration model based on isothermal and adiabatic hydration tests, valid for portland cement and blast furnace slag cement.
247 citations
TL;DR: In this paper, a spectrum of thermal and XRD analysis results from ancient, Byzantine, post-Byzantine and later historic mortars from Greece is presented and relevant information concerning the characterization of traditional mortars is validated.
231 citations
TL;DR: In this paper, the current status of interfacial chemistry at the solid-liquid boundary and places it in perspective with present and future s s processes based on Portland cement and pozzolanic materials.
211 citations
TL;DR: In this paper, chemical shrinkage of cement was calculated from chemical equation of hydration, it was compared with observed one and relationship between them was clearly described and defined by definition of chemical shrinkages and autogenous shrinkage was made.
TL;DR: In this article, a new mechanism has been proposed to explain the delayed expansions due to the presence of dead-burnt CaO or MgO, of Portland cement based materials, based on the crystal growth pressure, the solubility of hydroxide crystals, their growth habits and diffusion of Ca2+ and Mg2+ through the electrical double layer which forms round cement hydration products.
TL;DR: In this paper, the authors measured the fluidity, setting time and time dependency of fluidity using fresh cement paste prepared with four kinds of organic admixtures, polycar-ylic acid-based, aminosulfonic acid based, β-naphthalenesulfonic acids-based and lignin sulfonic acidbased, by two different methods of addition, together with mixing water (simultaneous addition) and specified time after mixing with water (later addition).
Patent•
22 Aug 1995TL;DR: In this paper, the junction of multi-lateral wells is caked with a slurry of styrene/butadiene aqueous latex, a latex stabilizer, hydraulic cement and appropriate cementing additives.
Abstract: The present invention provides methods of cementing the junction of multi-lateral wells whereby the set cement can withstand impacts and shocks without shattering. A cement slurry composition which sets into a high strength impact resistant solid mass is utilized comprised of a styrene/butadiene aqueous latex, a latex stabilizer, hydraulic cement and appropriate cementing additives.
TL;DR: The results obtained in this investigation indicate that the use of sodium alginate composite FSCPC as nd-FSCPC should be of value in orthodontics and oral and maxillofacial surgery where the cement is exposed to blood.
TL;DR: In this article, the composite mechanism of polymer modified cement (PMC) and mortar has been studied by using particle dispersion of polymer and the formation of polymer films as a composite mechanism.
TL;DR: In this paper, both the raw and calcined illite samples, before and after being mixed with Ca(OH) 2 in the presence of simulated cement pore solution, were studied by DTA, TG (for raw illite), XRD, SEM, EMPA and chemical solubility.
TL;DR: In this paper, a calcium phosphate cement consisting of tetracalcium phosphate (TTCP) and dicalcium phosphate anhydrous (DCPA) was reduced from 30 to 5 min by use of a cement liquid that contained a phosphate concentration of 0.25 mol/l or higher.
Abstract: The setting time of a calcium phosphate cement consisting of tetracalcium phosphate (TTCP) and dicalcium phosphate anhydrous (DCPA) was reduced from 30 to 5 min by use of a cement liquid that contained a phosphate concentration of 0.25 mol/l or higher. The diametral tensile strength and conversion of the cement ingredients to hydroxyapatite (OHAp) during the first 3 h were also significantly increased by the phosphate. However, the phosphate produced no significant effects on the properties of the 24-h cement samples. Results from additional experiments in a slurry system verified that the high phosphate concentration in the solution accelerated the formation of OHAp in the TTCP + DCPA system, and this reaction could explain the fast-setting properties of the cements.
TL;DR: In this article, the physical and engineering properties of various no-fines concrete mixtures are investigated under unconfined compression, indirect tension, and static modulus of elasticity; and the results are interpreted as functions of mixture proportions.
Abstract: In this study the physical and engineering characteristics of various no-fines concrete mixtures are investigated. No-fines concrete mixtures subjected to impact compaction are studied under unconfined compression, indirect tension, and static modulus of elasticity; and the results are interpreted as functions of mixture proportions. The effect of impact-compaction energies, consolidation techniques, mixture proportions, curing types, and testing conditions on physical and engineering properties are presented. The abrasion characteristics and resistance to freezing and thawing of no-fines concrete are also discussed. It was found that the strength of no-fines concrete is strongly related to its mixture proportion and compaction energy. A sealed compressive strength of 20.7 MPa (3,000 psi) can readily be achieved with an aggregate cement ratio of 4.5:1 or less and a minimum compaction energy of 165 J/m 3 (4,303 ft-lb/cu ft). The splitting tensile-compressive relationship followed a pattern similar to that ...
TL;DR: In this article, the performance of plain and blended cements in both environments was evaluated by measuring expansion and determining reduction in compressive strength, and the results indicated that the performance was not satisfactory in the magnesium-sulfate environment.
Abstract: In this investigation, mortar specimens made with two plain cements, Type I and V, and blended cements, made with fly ash, silica fume, and blast furnace slag, were exposed to sodium-sulfate and magnesium-sulfate solutions. The performance of these cements, in both the environments, was evaluated by measuring expansion and determining reduction in compressive strength. The data indicate that while the performance of all blended cements, particularly those made with silica fume, was generally excellent in the sodium-sulfate environment, their performance in the magnesium-sulfate environment was not satisfactory. A similar trend was observed in mortar specimens made with a water-cement ratio of 0.35. The type of cement did not have any significant influence on the performance of either plain or blended cements in both environments. The deterioration of plain and blended cements in sodium-sulfate and magnesium-sulfate environments is attributed to the initial reaction of sodium sulfate and magnesium sulfate with calcium hydroxide. The reduction of calcium hydroxide in blended cements provides an opportunity to magnesium sulfate to react more directly with the primary and secondary calcium silicate hydrate due to the destabilization of these phases by magnesium hydroxide. Comparatively, lower deterioration of blended cements exposed to the sodium-sulfate environment is attributed to the reduced calcium hydroxide, which significantly mitigates the sulfate attack in these cements.
TL;DR: In this article, the compressive strengths of silica fume cement paste and mortar were evaluated at various water-cementitious ratios and it was shown that the increase in compressive strength of mortar containing silica-fume, as a partial replacement for cement, greatly contributes to strengthening the bond between the cement mixture and aggregate.
TL;DR: A new light-cured glass ionomer cement exhibited all the necessary qualities needed to bond brackets, without any etching and in the presence of saliva, and is now being routinely and successfully used on all patients.
TL;DR: It is concluded that chemical curing alone was not sufficient to achieve maximum hardening of the examined cements, and cement hardness was significantly reduced when inlay thickness was 2 to 3 mm or more.
Abstract: Dual-cure inlay resin cements polymerize both chemically and through light activation; however, clinically some aspects of the cement are not readily accessible to the light source. This study investigated the degree of cement hardening achieved through chemical curing only versus dual curing and the effect of inlay thickness on cement hardness. Disks 6×2.5 mm were prepared from seven commercially available cements. Eight specimens were prepared from each material; half of the specimens were cured chemically only, and the remainder were dual-cured. Knoop hardness measurements were then recorded at 1-hour, 1-day, and 1-week intervals. In addition, 24 specimens of the same dimensions were prepared from each cement. Twelve specimens were dual-cured through resin composite spacers of varying thicknesses (1 to 6 mm), and the others were cured through similar ceramic spacers, and hardness measurements were recorded. Multivariate analysis of variance revealed significant differences in hardness of chemically cured versus dual-cured specimens at the 5% level of significance for all examined cements. Significant differences were also found in the hardness of specimens dual cured through ceramic or resin composite spacers 2 to 3 mm in thickness or more versus those that were dual cured without spacer regardless of the spacer material. It is concluded that chemical curing alone was not sufficient to achieve maximum hardening of the examined cements. Cement hardness was significantly reduced when inlay thickness was 2 to 3 mm or more.
Patent•
16 May 1995TL;DR: An improved method for filing and sealing tooth cavities involves the use of a cement composition which exhibits several advantages over existing orthograde and retrograde filling materials, including the ability to set in an aqueous environment.
Abstract: An improved method for filing and sealing tooth cavities involves the use of a cement composition which exhibits several advantages over existing orthograde and retrograde filling materials, including the ability to set in an aqueous environment. In a preferred embodiment, the cement composition comprises Portland cement, or variations in the composition of such cement, which exhibit favorable physical attributes sufficient to form an effective seal against re-entrance of infectious organisms.
TL;DR: In this article, the authors investigated the influence of different parameters, such as the water to cement ratio, the type of cement, the age at loading and the use of fibre reinforcement, on the tensile creep of concrete.
TL;DR: In this article, a fracture mechanics study of high strength concrete (water-binder ratios of 0.32 and 0.23) with compressive strength in the range 80 to 115 MPa was performed.
TL;DR: In this paper, a literature review is presented, together with new test results obtained by means of improved test methods: for the determination of the specific heat of cement paste during hardening, test methods are developed based on existing methods.
Abstract: This paper focuses on the evolution of the thermal characteristics of early-age concrete as a function of the state of the hardening process. A literature review is presented, together with new test results obtained by means of improved test methods: For the determination of the specific heat of cement paste during hardening and of the thermal diffusivity of hardening concrete, test methods are developed based on existing methods. The specific heat is determined for hardening cement paste samples made with blastfurnace slag cement. It is concluded that the specific heat and thermal diffusivity decreases linearly with the degree of hydration.
TL;DR: In this article, the interaction of sodium salt of polynaphthalene sulfonate superplasticizer (PNS) with different cement types, its effects on the flow loss, and the chemistry of the pore solution at early time of hydration from mixing to presetting were reported.
TL;DR: In this paper, an original fly ash was ground, using a laboratory mill, for several times (from 10 to 60 minutes), and chemical properties of fly ash/water suspensions were studied and acid neutralization capacities measured.
Patent•
31 Oct 1995TL;DR: In this paper, the authors present lightweight, fast setting cement compositions and methods which can be utilized in performing a variety of well-cementing operations, which are basically comprised of slag cement, water sufficient to form a pumpable slurry, a gas sufficient to foam the slurry and a foaming agent.
Abstract: The present invention provides lightweight, fast setting cement compositions and methods which can be utilized in performing a variety of well cementing operations. The cement compositions are basically comprised of slag cement, water sufficient to form a pumpable slurry, a gas sufficient to foam the slurry and a foaming agent.