Showing papers on "Cement published in 1979"
Patent•
18 May 1979TL;DR: A low-density, high-strength cement composition useful in a high temperature environment, such as in thermal wells, which includes hydraulic cement, a siliceous material and a relatively low density inorganic material was proposed in this article.
Abstract: A low-density, high-strength cement composition useful in a high temperature environment, such as in thermal wells, which includes hydraulic cement, a siliceous material and a relatively low-density inorganic material.
131 citations
Patent•
10 May 1979TL;DR: In this paper, a process for cementing adjacent a gas-containing zone is described, in which process a cement slurry containing stabilized, dispersed gas is placed adjacent the zone, in order to prevent connate formation gas under pressure from passing into or around the cement before the time the cement has set up.
Abstract: A process for cementing adjacent a subterranean gas-containing zone, in which process a cement slurry containing a stabilized, dispersed gas is placed adjacent the zone. Sufficient gas is present in the cement slurry or is capable of being generated within the slurry to prevent the connate formation gas under pressure from passing into or around the cement prior to the time the cement has set up.
128 citations
Patent•
11 Jun 1979
TL;DR: A 9 to 12 ppg (1.08 to 1.4 kg/liter) cement slurry for use in oil well type completions which comprises hydraulic cement about 10 to about 30 weight percent hollow glass microspheres based on the weight of the cement and sufficient water to form a pumpable slurry with an API free water content of no more than about 2 volume percent.
Abstract: A 9 to 12 ppg (1.08 to 1.4 kg/liter) cement slurry for use in oil well type completions which comprises hydraulic cement about 10 to about 30 weight percent hollow glass microspheres based on the weight of the cement and sufficient water to form a pumpable slurry with an API free water content of no more than about 2 volume percent. This slurry is preferably mixed with an amount of water required to produce a slurry with the hydraulic cement having at least an API minimum water content and an API free water content of no more than about 2 volume percent and an additional amount of water equal to about 1.3 to about 1.8 weight percent water based on the weight of the hydraulic cement for each weight percent of the microspheres. The microspheres have true particle densities of about 0.2 to about 0.5 gm/cm 3 , hydrostatic collapse strengths of at least 500 psi (3447 kPa) and average particle diameters of less than about 500 microns.
123 citations
TL;DR: In this paper, the shrinkage and compressive strength of autoclaved aerated concrete were measured under varying conditions, mainly with cement and lime as binders, and the reaction products belonged to the tobermorite group of calcium silicate hydrates.
115 citations
TL;DR: Pulp tissue reaction showed no significant difference between glass ionomer and zinc oxide-eugenol cement from in vivo experiments using monkeys, and biological properties of a new dental cement of glass ionomers were compared with other types of conventional cement.
Abstract: Biological properties of a new dental cement of glass ionomer cement were compared with other types of conventional cement. The biological test was carried out by tissue culture method and animal examination. The culture cells showed weaker reaction to the glass ionomer cement than zinc oxide-eugenol or polycarboxylate cement. Pulp tissue reaction showed no significant difference between glass ionomer and zinc oxide-eugenol cement from in vivo experiments using monkeys.
112 citations
LGC1
TL;DR: The G-200 glass of the glass-ionomer cement has two phases: a continuous calcium aluminosilicate matrix and partly crystalline calcium fluoride-rich droplets, the nature of which depend on the thermal history of theGlass.
Abstract: The G-200 glass of the glass-ionomer cement has two phases: a continuous calcium aluminosilicate matrix and partly crystalline calcium fluoride-rich droplets, the nature of which depend on the thermal history of the glass. The setting process of the cement takes place when the glass is mixed with poly(acrylic acid). It has two overlapping stages corresponding to the rapid leaching of calcium ions from the uncrystalline part of the droplets, followed by the slower release of aluminum (and some calcium) from the main glass phase. These processes are affected by the microstructure and microcomposition of the glass.
109 citations
Patent•
27 Jul 1979TL;DR: In this article, a masonry cement is prepared by blending portland cement, kiln dust, and fly ash, which exhibits no efflorescence, good board life, workability, and acceptable color for use with such construction materials as brick, cinder block, and concrete block.
Abstract: A masonry cement is prepared by blending portland cement, kiln dust, and fly ash. The cement of this invention exhibits no efflorescence, good board life, workability, and acceptable color for use with such construction materials as brick, cinder block, and concrete block.
99 citations
TL;DR: Cement dermatitis is connected with chromate sensitivity and it can be expected that “elimination” of chromate in cement would decrease the number of cases of cement dermatitis.
Abstract: Cement dermatitis is connected with chromate sensitivity. It can therefore be expected that "elimination" of chromate in cement would decrease the number of cases of cement dermatitis. Iron sulfate added to cement reduces the chromate completely and the 3-valent chromium is precipitated. An amount of 0.35% (w/w) iron sulfate, FeSO4 . 7H2O, is enough to reduce 20 microgram Cr6+/g cement. There is no technical side effect to the concrete. The iron sulfate is preferably added to cement when there is an intimate contact with skin, e.g. at floor laying, repairs and hand-made casting.
94 citations
TL;DR: In this paper, the thixotropic behavior of fresh Portland cement pastes is examined on the basis of the stress transients determined at constant shear rate, and significant quantities are considered: the difference between maximum and equilibrium shear stresses, the breakdown area and the density of the energy absorbed by material for the breakdown of the structure.
76 citations
LGC1
TL;DR: A linear relationship was found to exist between strength and the degree of hydration of dental cements, and all the cements were found to become more highly hydrated and stronger as they aged.
Abstract: A study was made of the hydration of dental cements, water being classified as "non-evaporable" and "evaporable". The ratio of these two types of water was found to vary greatly among different cement types, being lesser in zinc oxide and ionic polymer cements and greater in ion-leachable glass and phosphoric acid cements. The cement with the least "non-evaporable" water, i.e., showing least hydration (the zinc polycarboxylate cement), had the lowest strength and modulus and the greatest deformation at failure. A linear relationship was found to exist between strength and the degree of hydration of dental cements. All the cements were found to become more highly hydrated and stronger as they aged.
73 citations
TL;DR: In this paper, DTA is applied to estimate Ca(OH) 2 in cementitious phases by determining the peak areas caused by the decomposition of Ca(O) 2 to CaO+H 2 O.
TL;DR: In this article, the effects of heavy metal oxides and hydroxides on the formation of hardened ettringite and microstructure of hardened Ettringites were studied.
Patent•
16 Feb 1979TL;DR: The compressive strength of a hydrated hydraulic cement composition such as Portland cement concrete is enhanced by the addition of a very small amount of certain select synthetic non-ionic surface active agents to the compositions.
Abstract: The compressive strength of a hydrated hydraulic cement composition such as Portland cement concrete is enhanced by the addition of a very small amount of certain select synthetic non-ionic surface active agents to the compositions.
Patent•
18 May 1979TL;DR: Cement is produced by feeding residue solids containing carbonaceous material and ash constituents obtained from converting a carbonaceous feed material into liquids and/or gases into a cement-making zone and burning the carbon in the residues solids to supply at least a portion of the energy required to convert the solids into cement as mentioned in this paper.
Abstract: Cement is produced by feeding residue solids containing carbonaceous material and ash constituents obtained from converting a carbonaceous feed material into liquids and/or gases into a cement-making zone and burning the carbon in the residue solids to supply at least a portion of the energy required to convert the solids into cement
TL;DR: In this paper, a comprehensive investigation on physical and mechanical properties of alite mortars and concretes, large quantities of monoclinic alite were produced at the University of California at Berkeley.
Patent•
20 Nov 1979
TL;DR: In this paper, a manufacturing process for converting coal ash slag from a slagging coal gasifier into a marketable cement product having the characteristics and qualities of portland cement is described.
Abstract: Disclosed is a manufacturing process for converting coal ash slag from a slagging coal gasifier into a marketable cement product having the characteristics and qualities of portland cement. This process comprises the steps of transferring molten slag from a slagging coal gasifier to a melt chamber and reacting it with a mineral containing lime, for example: calcium oxide, calcium hydroxide or calcium carbonate, to form a homogeneous cement product. This cement product is then transferred to a quench chamber where it is allowed to cool and solidify in the form of clinkers, which are later reduced to powder form. This process also provides an efficient means to conserve energy when producing a portland cement and provides an effective and economical way to dispose of a waste product while increasing the cost efficiency of a slagging coal gasifier.
TL;DR: The retentive capacity of the Whaledent Parapost system utilizing ASPA cement was compared at two lengths, three diameters, and with respect to the effect of both medication and citric acid pretreatment, and the greatest single factor influencing retention was embedment depth into dentin.
Abstract: The retentive capacity of the Whaledent Parapost system utilizing ASPA cement was compared at two lengths, three diameters, and with respect to the effect of both medication and citric acid pretreatment. The greatest single factor influencing retention was embedment depth into dentin. No significant differences were observed between the retention values for medicated and unmedicated teeth. Finally, no increase in retention was noted over previously reported values for zinc phosphate, carboxylate, and epoxy resin cements. The glass-ionomer cement tested offers no advantage for post retention.
Patent•
20 Mar 1979
TL;DR: The disclosed process for making cast vegetable/mineral structural products having flame retardant properties utilize a major volume portion of ligneus plant fragments such as soft and hardwoods, sugarcane, cereal and fiber plant stalks, and a minor volume proportion of a mineral binder deposit comprised of magnesium or calcium oxyphosphates and inert filler particles as mentioned in this paper.
Abstract: The disclosed process for making cast vegetable/mineral structural products having flame retardant properties utilize a major volume portion of ligneus plant fragments such as soft and hardwoods, sugarcane, cereal and fiber plant stalks, and a minor volume proportion of a mineral binder deposit comprised of magnesium or calcium oxyphosphates and inert filler particles. Fragments having thicknesses ranging from 0.3 mm to 8 mm including chips, shavings, strips, strands, fibre bundles, slivers, fibres and peeled and sawn veneer sheets, have applied to their surfaces an aqueous solution of ammonium polyphosphate or soluble acid phosphate salt supplying from 0.15 to 0.40 parts of P 2 O 5 as phosphate ion per part of fragments by weight, and particulate cement solids comprised of MgO or CaO or Mg(OH) 2 or Ca(OH) 2 or MgCO 3 or CaCO 3 ranging from 0.25 to 1.0 part per part of fragment, and from 0.01 to 0.80 parts of inert filler particles and the mixture is molded and held under predetermined compaction pressure until the product has rigidified, in about 10 minutes' time. The process is practically immune to cement poisoning sugars and polyphenolics which were found to be detrimental to other cement mixes.
TL;DR: The early diagenetic deformation of lime mud can be traced to the dissolution of 0.25 to 2 µm sized metastable grains and precipitation of calcite crystals up to 8 µm in size.
Abstract: Diagenesis of lime mud involves mineralogic stabilization, addition of large amounts of porosity-reducing cement and/or compaction, and grain shape changes, processes that may occur rapidly when fresh water invades the sediment pore systems. Scanning electron microscopy of lithified and semilithified Pleistocene lime mudstone from a subsurface location on Barbados (Borehole #17) illustrate some of these early diagenetic processes. Mineralogically stable muds that have resided in fresh water phreatic lenses are well cemented with porosity less than 15%. Mud particles are 0.5 to 2 µm in diameter Three to 8 µm grains of cement occur in aggregates lining irregular coarse silt- and sand-sized cavities (molds?). In the modern zone of mixing of fresh and marine ground water. mineralogically metastable muds contain 20-30% calcite crystals, 3 to 5 µm in size, partially filling micropores and cementing 0.25 to 2 µm mud particles; porosity is 20-40%. These data indicate that early cementation of lime mud can occur in fresh and brackish phreatic environments. Mineralogic stabilization of the muds involves dissolution of 0.25 to 2 µm sized metastable grains and precipitation of calcite crystals up to 8 µm in size. Interpretation of the scanning electron micrographs indicates that aggrading neomorphism has not been an important process in the early evolution of the mud fabric.
TL;DR: In this article, the influence of this dust on cement strength and mortarbar expansion is described, and pozzolanic use of silica fume from a ferrosilicon plant now under erection is discussed.
Patent•
20 Jul 1979
TL;DR: In this article, a cement-based powdered water-repellent composition was proposed, consisting of 20-60% of a cement, 30-70% of an inorganic or organic filler, 2-10% of fiber selected from zirconium, hafnium, vanadium and cesium silicate fibres, 0.2-1% of plasticizers for cement, 1-3% of adhesive, and 0.1-2% alkalinity reducing buffer salts.
Abstract: This invention relates to a cement-based powdered water-repellent composition, comprising, expressed as dry weight: (a) 20-60% of a cement, (b) 30-70% of an inorganic or organic filler, (c) 2-10% of a fibre selected from zirconium, hafnium, vanadium and cesium silicate fibres, (d) 0.2-1% of plasticizers for cement, (e) 1-3% of an adhesive, (f) 0.1-0.5% of a water-repellent. This composition is useful for the production of coatings and molded products, having very high mechanical strength and water-repellent properties. This composition may additionally contain 0.1-2% alkalinity-reducing buffer salts.
Patent•
24 Jan 1979
TL;DR: An improved fluid loss additive for use in well cements, preferably comprising from about 30 to about 70 weight percent polyvinylpyrrolidone, from about 5 to about 19 weight percent carboxymethylhydroxyethyl cellulose, and the sodium salt of naphthalene sulfonate, is presented in this article.
Abstract: An improved fluid loss additive for use in well cements, preferably comprising from about 30 to about 70 weight percent polyvinylpyrrolidone, from about 5 to about 19 weight percent carboxymethylhydroxyethyl cellulose, and the sodium salt of naphthalene sulfonate. Improved cement slurries comprising the subject fluid loss additive and an improved method for cementing well bores through use of the novel slurries are also provided. The improved cement slurries of the invention preferably comprise from about 26 to about 60 percent water and from about 0.75 to about 2 percent of the improved fluid loss additive, by weight of the cement.
TL;DR: In this article, the physical and mechanical properties of the fibres from water reed, elephant grass, plantain and musamba are discussed and the effect of elephant grass fibres upon the strength of reinforced cement sheets and the consistence of the mortar is shown to be beneficial.
Abstract: Synopsis Some relevant physical and mechanical properties of the fibres from water reed, elephant grass, plantain and musamba are discussed. The effect of elephant grass fibres upon the strength of reinforced cement sheets and the consistence of the mortar is shown to be beneficial.
TL;DR: In this article, the effects of surface treatment of discrete wood fibres incorporated into cement have been studied by measuring the fracture energy and flexural strength of the derived composite materials, and the results confirm that the mechanical performance of a wood fibre reinforced cement composite can be altered by the use of coupling agents.
LGC1
TL;DR: The optically active isomers and the racemic (±) mixture are equally effective as accelerators, however, the meso-isomer retards the cement-forming reaction and adversely affects cement strength.
Patent•
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16 Oct 1979
TL;DR: In this article, a high calcium-content fly ash and calcium sulfate, and mortar and concrete compositions containing the fly ash are combined to create a new type of cement, called fly ash fly ash.
Abstract: A cement composition comprising a high calcium-content fly ash and calcium sulfate, and mortar and concrete compositions containing the cement.
Patent•
15 Jan 1979
TL;DR: In this paper, the additive was used either alone or in combination with at least one of a water-soluble glycol, a water soluble hydroxy-alkyl amine (HOA), a watersoluble salt of a sulfonated lignin, and a salt of an aliphatic acid having no more than three carbon atoms.
Abstract: Additives for use as grinding aids and set retarders in the manufacture of hydraulic cement composed of polyglycerol, preferably a polyglycerol selected from the group of di-, tri-, and tetraglycerol and mixtures thereof, the additive being used either alone or in combination with at least one of a water-soluble glycol, a water-soluble hydroxy-alkyl amine, a water-soluble salt of a sulfonated lignin and a water-soluble salt of an aliphatic acid having no more than three carbon atoms, the hydraulic cement product of this addition and the method for making the cement product.
Patent•
27 Apr 1979
TL;DR: An improved earthen composition suitable for building construction comprises soil, a sulfonic acid, cellulose and a cementing agent comprising a calcium cement such as Portland cement, lime or calcium carbonate as discussed by the authors.
Abstract: An improved earthen composition suitable for building construction comprises soil, a sulfonic acid, cellulose and a cementing agent comprising a calcium cement such as Portland cement, lime or calcium carbonate and/or an asphalt cement such as asphaltic concrete, asphalt, or tar. The compositions are prepared in an aqueous mixture, which is then tamped or consolidated, and dried.
01 Jan 1979
TL;DR: The more gradual transmission of load from implant to bone and "auto-centering" of implants during operation by pre-coating, are believed to be advantageous over conventional cement fixation method.
Abstract: A study on the feasibility of implants pre-coated with an acrylic bone cement has been performed. Four types of implants, an actual canine femoral prosthesis, a polished steel rod (0.49 cm dia. x 13 cm long) with and without pre-coating, and a sandblasted steel rod with pre-coating were implanted into canine femurs in vitro and in vivo to evaluate the interfacial shear strengths in addition to the bench test. After serial sectioning the samples in discs, push-out tests were made to evaluate the interfacial strengths of cement-bone-implant. The weakest interfacial shear strength was exhibited by the polished rod/cement interface (0.5 MPa) while the strongest was the "old" and "new" cement interface (23.4 MPa). The bone/cement interfacial strength was in between for in vitro (1.17 MPa) and in vivo (1.68 MPa). The shear strength of rod/cement interface increased substantially by sandblasting (6.84 MPa). The microscopic observation of the interface showed somewhat smaller gaps developed for the pre-coated rod than the uncoated rod due to the shrinkage effect. In addition to the overall increase in interfacial strength, the pre-coating may furthermore reduce the setting temperature, the shrinkage, and the amount of monomer released during operation due to the reduced amount of cement at the time of implantation. The more gradual transmission of load from implant to bone and "auto-centering" of implants during operation by pre-coating, are believed to be advantageous over conventional cement fixation method.
Patent•
14 Jun 1979
TL;DR: A poly(carboxylate) cement pack comprising a water soluble poly (carboxylic acid) having a relative viscosity of from 1.05 to 2.00, a chelating agent and a cement powder which will react with the poly(Carboxyric acid) in the presence of the chelation agent and water to give a plastic mass which rapidly hardens to form a poly(CARboxylates) cement.
Abstract: A poly(carboxylate) cement pack comprising a water soluble poly(carboxylic acid) having a relative viscosity of from 1.05 to 2.00, a chelating agent and a cement powder which will react with the poly(carboxylic acid) in the presence of the chelating agent and water to give a plastic mass which rapidly hardens to form a poly(carboxylate) cement.