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Showing papers on "Cement published in 1993"


Journal ArticleDOI
TL;DR: In this article, the general model for CSH gel described by Richardson and Groves (1) was extended to incorporate elements other than Ca, Si, O and H which have been detected by X-ray microanalysis of gels in hardened Portland cement and blended cement pastes.

253 citations


Journal ArticleDOI
TL;DR: In this paper, the authors describe the laboratory and field studies of the development of Magnesium Phosphate Cement, an advanced material for speedy repair of concrete pavements, and highlight special considerations on the use of the material and its procedure of application.

232 citations


Journal ArticleDOI
TL;DR: The results of a series of tests of the physical properties and durability of pastes, mortars, and concretes made with silica fume replacements for part of the portland cement were presented in this paper.
Abstract: The results are presented of a series of tests of the physical properties and durability of pastes, mortars, and concretes made with silica fume replacements for part of the portland cement: silica fume reduced the permeability of cement pastes and concretes; silica fume reduced the size of pores and total porosities of both cement and concretes; silica fume reduced the leachable calcium hydroxide contents of cement pastes; silica fume reduced the level of alkalies leached from the pastes; silica fume improved the resistance of ASTM C 441 Pyrex mortar bars to deleterious expansion; silica fume provided resistance superior to that of a sulfate resistant portland cement in ASTM C 1012 tests for sulfate resistance; and silica fume provided resistance to freezing and thawing to a series of high-strength, non-air-entrained concretes.

230 citations


Patent
05 Oct 1993
TL;DR: An apparatus for mixing bone cement and containing the mixed bone cement preparatory to dispensing is described in this paper, where the mixing chamber has an outlet for the mixed cement and a cartridge has an inlet releasably coupled to the outlet.
Abstract: An apparatus for mixing bone cement and containing the mixed bone cement preparatory to dispensing. The mixing chamber has an outlet for the mixed cement. A cartridge has an inlet releasably coupled to the outlet of the mixing chamber for receiving mixed bone cement therefrom. Structure is provided for moving cement from an upper region of the mixing chamber down into a lower region thereof to mix same and for moving such mixed cement off an inner surface of the mixing chamber and into the cartridge.

179 citations


Journal ArticleDOI
TL;DR: In this paper, uniaxial compressive strength measurements taken on 1210 unsealed cement paste and concrete specimens heated to temperatures up to 600°C are reported; they show that both material and environmental factors have a significant influence during the heat cycle and afer cooling.
Abstract: Results of uniaxial compressive strength measurements taken on 1210 unsealed cement paste and concrete specimens heated to temperatures up to 600°C are reported; they show that both material and environmental factors have a significant influence during the heat cycle and afer cooling. The best results were obtained using firebrick aggregate and a cement blend containing 65 % slag replacement of OPC by weight. At 600°C the “hot” compressive strength of this material was 85% of the value measured before heating.

163 citations


Patent
01 Feb 1993
TL;DR: In this article, fine particle size hydraulic cement compositions and methods of using such compositions for cementing in a subterranean zone penetrated by a well bore are provided, which are basically comprised of a fine particle-size hydraulic cement, a fine-particle size pozzolanic material and sufficient water to form a pumpable slurry.
Abstract: Fine particle size cement compositions and methods of using such compositions for cementing in a subterranean zone penetrated by a well bore are provided. The compositions are basically comprised of a fine particle size hydraulic cement, a fine particle size pozzolanic material and sufficient water to form a pumpable slurry.

161 citations


Journal ArticleDOI
TL;DR: In this article, an electrical conductivity model for hydrating portland cement systems has been developed and the high frequency a.c. impedance technique for characterizing the microstructure of cement paste and the hydration process of cement has been rationalized quantitatively.

142 citations


Journal ArticleDOI
TL;DR: The physical and chemical effects of small additions of two different tertiary alkanolamines to portland cement were investigated in this article, and the results indicated that the increased mortar strength resulted from an increased degree of hydration of the cement.
Abstract: The physical and chemical effects of small additions of two different tertiary alkanolamines to portland cement were investigated. The strengths of standard test mortars moist cured for more than 1 day were found to be enhanced in some cases by addition of triisopropanolamine, but not by similar amounts of triethanolamine. Thermogravimetric and X-ray diffractometric data indicate that the increased mortar strengths resulted from an increased degree of hydration of the cement. Calorimetry and aqueous-phase analysis show that the higher alkanolamine, triisopropauo-lamine, remains in solution for a sufficient time to catalyze hydration of C4 AF after all of the free gypsum has been consumed to form calcium sulfoaluminate hydrates, In contrast, the lower alkanolamine, triethanolamine, is mostly adsorbed by the cement within the first hours of hydration. It is hypothesized that the catalytic mechanism involves facilitated transport of ferric ions through the aqueous phase in the form of ferric-alkanolamine complexes.

140 citations


Journal ArticleDOI
TL;DR: In this paper, an accelerated test using an atmosphere containing 10% CO2, the evolution of some parameters of concrete caused by the carbonation processes at different levels of relative humidity is studied.

133 citations


Journal ArticleDOI
TL;DR: Using sham replacement of the proximal femur in adult mongrel dogs, shear strength at the interface between polymethylmethacrylate bone cement and cancellous bone has been found to be linearly dependent on the depth of penetration of the cement into the bone.
Abstract: Using sham replacement of the proximal femur in adult mongrel dogs, shear strength at the interface between polymethylmethacrylate bone cement and cancellous bone has been found to be linearly dependent on the depth of penetration of the cement into the bone. Shear strength at the interface was increased by 82% and penetration by 74% when distal bone plugging, pressure lavage, and pressurized insertion of cement were employed. Use of a lower-viscosity cement gave a further 18% increase in penetration and shear strength

131 citations


Journal ArticleDOI
TL;DR: In this paper, the influence of silica fume on impedance behavior of hydrating cement has been carefully investigated, and the results demonstrate that impedance measurement is very sensitive to changes in hydration kinetics and microstructure development due to the presence of Silica Fume.

Patent
07 Jun 1993
TL;DR: A low cost cement composition that can be admixed with water and hydrothermally closed cured to give acid-resistant products of high compressive strength consisting essentially of, in parts by weight, 1 to 1.5 parts of a calcium oxide material containing at least about 60% CaO, 10 to 15 parts of pozzolanic material and 0.025 to 0.075 parts of an alkali metal catalyst and building materials made therefrom as well as the method of making such building materials by closed curing as discussed by the authors.
Abstract: A low cost cement composition that can be admixed with water and hydrothermally closed cured to give acid-resistant products of high compressive strength consisting essentially of, in parts by weight, 1 to 1.5 parts of a calcium oxide material containing at least about 60% CaO, 10 to 15 parts of pozzolanic material containing at least about 30% by weight amorphous glass or vitreous silica, and 0.025 to 0.075 parts by weight of an alkali metal catalyst and building materials made therefrom as well as the method of making such building materials by closed curing.

Journal ArticleDOI
TL;DR: A bioactive bone cement consisting of silane-treated CaO-SiO 2-P 2O 5-CaF 2 glass powder as the filling particles and BIS-GMA diluted with triethylene-glycol dimethacrylate (TEGDMA) as the organic matrix is developed.
Abstract: We have developed a bioactive bone cement consisting of silane-treated CaOSiO2P2O5CaF2 glass powder as the filling particles and bisphenol-a-glycidyl methacrylate (BIS-GMA) diluted with triethylene-glycol dimethacrylate (TEGDMA) as the organic matrix. Histological examination demonstrated direct bonding between the cement and bone along the circumference of the cement at 4 weeks after implantation in rat tibia. The compressive strength and toughness of the cement were two and four times greater than those of polymethylmethacrylate (PMMA) cement, respectively. The inflammatory reaction of the skin caused by the new cement was not as intense as that for PMMA 3 days after subcutaneous implantation. This new cement may be applicable as a bioactive bone cement with high mechanical strength. © 1993 John Wiley & Sons, Inc.

Journal Article
TL;DR: In this paper, the authors discuss the properties and limitations of fly ash, slag, condensed silica fume and rice-husk ash in the production of ready-mixed and precast concretes.
Abstract: Environmental problems associated with waste product disposal, resource conservation considerations, and the cost of portland cement will demand the increasing use of of fly ash, slag, condensed silica fume and rice-husk ash in the production of cement and ready-mixed and precast concretes. This article discusses this issue, the properties and limitations of these materials, and the effects that this will have on concrete properties. It is noted that North American trends indicate preference for the separate batching of these materials at concrete-batching plants rather than the intergrinding with portland cement clinker at a cement plant. This, however, is not advised in developing countries. It is also noted that recent developments in chemical admixtures, especially the introduction of superplasticizers, will increasingly facilitate the incorporation of supplementary cementing materials in concrete. Technology transfer needs are also noted.

Journal ArticleDOI
TL;DR: Ettringite was formed during the hydration of C3A with gypsum at temperatures between 25 and 80°C as mentioned in this paper, but the formation was retarded when hydration was carried out in KOH solutions whose concentrat...
Abstract: Ettringite was formed during the hydration of C3A with gypsum at temperatures between 25 and 80°C. Ettringite formation was retarded when hydration was carried out in KOH solutions whose concentrat...

Journal ArticleDOI
TL;DR: In this paper, the authors show that the rate of capillary absorption of water in cement-based materials is anomalous when compared with that of other liquids, including other liquids.
Abstract: The paper shows that the rate of capillary absorption of water in cement-based materials is anomalous when compared with that of other liquids.

Journal ArticleDOI
TL;DR: In this paper, the chemical activation of lime-pozzolan cement (LPC) has been studied and it was shown that the addition of 4% Na2SO4 can significantly improve the early strength of this cement.

Journal ArticleDOI
TL;DR: In this article, a mixture of highly hydrophobic proteins which are cross-linked through cysteine residues were identified in the cement of three balanid barnacles (Crustacea: Cirripedia) and the proteins were separated using SDS-PAGE and blotted onto polyvinylidene difluoride membrane for sequencing.
Abstract: Solidified adhesive (cement) of three balanid barnacles (Crustacea: Cirripedia) was dissolved using different concentrations of sodium dodecyl sulphate containing a reducing agent. The proteins were separated using SDS-PAGE and blotted onto polyvinylidene difluoride membrane for sequencing. Commonly occurring bands in the cement of each species were identified. One particular protein of 39 kD, found in the cement of Balanus perforatus, has the following N-terminal sequence: TYFPVLSYG?SSSLAPVI, where the? is most likely cysteine. Quinones were not identified in the cement by either infra-red, ultraviolet-visible or solid-state nuclear magnetic resonance spectroscopy and the successful dissolution and sequencing of cement proteins mitigates against their presence. Cement contains a mixture of highly hydrophobic proteins which are cross-linked through cysteine residues. It is the combination of these two components which makes cement highly resistant to chemical degradation. As a result bacteria are usually absent from the cement, possibly further excluded from the porous core of the cement by its smooth outer crust.

Journal ArticleDOI
TL;DR: In this article, a new interpretation and classification of such features is proposed, based on backscatter mode scanning electron microscopy, and the microstructure is seen to consist of distinct grains of the order of 10 μm and larger (phenograins) set in a cellular groundmass of smaller particles and pores.
Abstract: Morphological features of hydrated portland cement paste exhibited on carefully polished surfaces have been critically examined using backscatter mode scanning electron microscopy. A new interpretation and classification of such features is proposed. The microstructure is seen to consist of distinct grains of the order of 10 μm and larger (“phenograins”) set in a cellular groundmass of smaller particles and pores. Most of the phenograins are dense pseudomorphs of the larger cement grains, but some are large calcium hydroxide crystals, and in some cements a few may represent inert filler grains added to the cement. The phenograins that are pseudomorphs of cement particles may be solid, gapped, or hollow; and, at a given age, various stages of hydration are represented in different grains. While many pseudomorph phenograins consist of a simple core of unhydrated material surrounded by a uniform shell of hydration product, more complex and irregular structures are also found. Relationships between these features and earlier classifications of cement hydration product particles are discussed, and implications with respect to difficulties in image analysis of hardened cement paste are examined.

Journal ArticleDOI
TL;DR: The cement was easily shaped and allowed a perfect filling of any defect, resulting in close contact of the whole implant surface with the host bone at the time of surgery, associated with appreciable mechanical strength.
Abstract: A quickly setting calcium phosphate-based hydraulic cement mixed with particles of tricalcium phosphate (TCP) ceramic was implanted in 56 metaphysial defects made in the long bones of ten adult mongrel dogs. Microradiography, histology and scanning electron microscopy (SEM) demonstrated the slow resorption of the cement and the bony incorporation of the calcium phosphate ceramic particles which were consistently embedded in bone. The original structural pattern of the bone tended to be restored 7 months after implantation. The cement did not hinder the incorporation of the calcium phosphate ceramic particles, neither did it elicit any inflammatory or foreign-body response. The cement was easily shaped and allowed a perfect filling of any defect, resulting in close contact of the whole implant surface with the host bone at the time of surgery, associated with appreciable mechanical strength. Most of the practical problems associated with the use of calcium phosphate ceramics in the repair of bone defects could be overcome with the cement.

Journal ArticleDOI
TL;DR: In this paper, measurements of the velocity of ultrasonic longitudinal and shear waves in ordinary Portland cement undergoing hydration were reported, and they were prepared in accordance with the American Petroleum Institute (API) specification for class G oil-well cement with various additives.

Journal ArticleDOI
TL;DR: This laboratory study compared the retention of prefabricated posts in well-fitting and loose-fitting post canals using different cement materials with greater resistance to dislodgment than posts cemented into well- fitting canals irrespective of the type of cements used.
Abstract: This laboratory study compared the retention of prefabricated posts in well‐fitting and loose‐fitting post canals using different cement materials. Eighty‐three human teeth were prepared for post placement. One of zinc phosphate cement, polycarboxylate cement, glass ionomer cement or resin cement was used to cement each post in place. A tensile force was applied to remove each post and the separation force was recorded. Posts cemented with the resin cement were the most difficult to dislodge. Posts cemented into loose‐fitting canals exhibited greater resistance to dislodgement than posts cemented into well‐fitting canals irrespective of the type of cements used. 1993 Australian Dental Association

Journal ArticleDOI
TL;DR: In this article, the amount of unreacted cement, Ca(OH) 2, and residual silica fume was quantitatively estimated using TMS-GPC, TGA, and 29 Si NMR.
Abstract: Cement pastes densified with small particles (DSP) containing up to 48% silica fume by weight of cement, and hydrated to up to 180 d at room temperature, have been analyzed using TMS-GPC, TGA, and 29 Si NMR to quantitatively estimate the amount of unreacted cement, Ca(OH) 2 , and residual silica fume, respectively. Using a mass balance approach, the CaO/SiO 2 and H 2 O/SiO 2 molar ratios of the C-S-H in the samples were calculated. For samples containing silica fume, the values of CaO/SiO 2 lie between 0.9 and 1.3, depending on the degree of hydration and silica fume content, whereas for samples without silica fume they were 1.6. Silicate polymerization analysis using TMS-GPC suggests that the molecular structure of the C-S-H is similar to that formed in conventional hydration. No cross-linking species were found, but the fraction of higher polymers (above octamer) increases as the CaO/SiO 2 ratio decreases

Journal ArticleDOI
TL;DR: In this article, the results obtained using the Langavant Calorimeter method on portland cements with different addition materials that are commonly used in the manufacture of commercial cements were studied.

Journal ArticleDOI
TL;DR: In this article, the properties of silica fume concrete were investigated, including slump, air-content, compressive strength, flexural strength, permeability, and permeable void volume.
Abstract: The properties of silica fume concrete was studied. Various properties of silica fume cocnrete, including slump, air-content, compressive strength, flexural strength, permeability, and permeable void volume were investigated, and the effect of the silica fume replacement ratio of cement is described. The effects of aggregate content and graduation, water-binder (cement plus silica fume), and superplasticizer dosage rate also are discussed. In this investigation, silica fume-binder ratios ranged from 0.00 to 0.40, water binder ratios from 0.41 to 0.47, aggregate binder ratios from 1.0 to 4.0, and superplasticizer binder ratios from 0.01 to 0.05.

Journal ArticleDOI
TL;DR: In this paper, an experimental procedure is described to discriminate between the two predominant phenomena which are the increase of interstitial water viscosity and the decrease of cement cake permeability, and more particularly the efficiency of fluid loss control additives is related with a threshold concentration corresponding to the overlapping concentration of macromolecular chains in solution.

Journal ArticleDOI
TL;DR: In this paper, it has been found that a number of industrial wastes and by-products such as phosphogypsum, bauxite fines, fly ash and blast furnace slag, can be employed without negatively affecting the hydraulic behaviour of planned C 4 A 3 S :β-C 2 S : C S weight ratio 1.5:1:1.

Book
16 Sep 1993
TL;DR: SOMMAIRE as discussed by the authors : 1.Portland Cement. - 2.Mineral admixtures and Blended Cements. - 3.Workability. - 4.Durability of concrete. - 5.Early volume changes and cracking. - 6.Drying shrinkage.
Abstract: SOMMAIRE : 1.Portland Cement. - 2.Setting and Hardening. - 3.Mineral admixtures and Blended Cements. - 4.Workability. - 5.Early volume changes and cracking. - 6.Concrete strength. - 7.Drying shrinkage. - 8.Creep. - 9.Durability of concrete. - 10.Corrosion of reinforcement.

Journal ArticleDOI
TL;DR: The amount of porosity at the interface greatly exceeded the amount of general porosity found throughout the bulk cement and the presence of these pores may be explained by the rheological characteristics of the cement.
Abstract: This study is the first description of the extensive porosity which is preferentially located at the cement-prosthesis interface of cemented femoral components of total hip replacements. The observation is important because the interfacial porosity may decrease the strength of the cement-femoral prosthesis interface and jeopardize the mechanical integrity of the cement mantle. We examined the cement-metal interfaces from a multiplicity of in vivo and in vitro specimens using both optical and scanning electron microscopy. These samples included several stem designs, implants made from either Co-Cr or Ti alloy, implants made with a variety of surface finishes and both centrifuged and uncentrifuged cement. All in vivo and in vitro samples had marked porosity in the cement focally concentrated at the cement-metal interface. The amount of porosity at the interface greatly exceeded the amount of general porosity found throughout the bulk cement. Centrifuging did not affect the interfacial porosity, and neither did alloy nor surface finish. The presence of these pores may be expoained by the rheological characteristics of the cement. © 1993 John Wiley & Sons, Inc.

Journal ArticleDOI
TL;DR: Palacos R bone cement was mixed in a commercial vacuum mixing system (MITAB), and in an experimental system allowing evacuating air from the powder before mixing and collecting the cement under partial vacuum to test the effect on the porosity of mixing at different pressure levels.
Abstract: Palacos R® bone cement was mixed in a commercial vacuum mixing system (MITAB), and in an experimental system allowing evacuating air from the powder before mixing and collecting the cement under pa...