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Showing papers on "Cement published in 1978"


Journal ArticleDOI
TL;DR: The character of the liquid phase in contact with hydrating portland cement is significantly affected by the presence of alkalies as discussed by the authors and the effects of increased alkali contents on the hydration processes are manifested in the engineering properties of cement pastes and concretes produced from it.

263 citations


Book
01 Jan 1978
TL;DR: In this article, a comprehensive treatment covering the basic theory, properties, production, and application of a wide range of fiber cements and concretes is provided, with practical examples using theoretical treatment for typical real composites are appended.
Abstract: This book provides a comprehensive treatment covering the basic theory, properties, production, and application of a wide range of fibre cements and concretes. The subject matter is presented under the following chapter headings:-Introduction; Properties of Materials; Theoretical Principles of Fibre Reinforcement in Uniaxial Tension; Theoretical principles of fibre reinfercement in Flexure; Steel-Fibre Concrete-Properties in the Fresh State and Mix Design for Workability; Steel-Fibre Concrete-Properties in the Hardened State; Polypropylene Fibres in Concrete, Mortar, and Cement; Glass Fibres in Cement and in Concrete; Asbestos Cement; Fibres Other than Asbestos, Glass, Polypropylene and Steel; Applications of Steel, Polyprogylene, Glass and Asbestos Fibres; Steel-Fibre Concrete in Road and Airfield Pavements. Practical examples using theoretical treatment for typical real composites are appended. /Author/TRRL

250 citations


Journal ArticleDOI
TL;DR: The morphology of the contact zone developed between Portland cement paste and glass slide "aggregates" has been explored using SEM and other techniques as mentioned in this paper, where a duplex film of about 1 μm total thickness is rapidly deposited on the glass surface.

134 citations


Journal ArticleDOI
TL;DR: In this article, the properties of cement, lime and bitumen stabilized lateritic soils and made recommendations for field trials for road construction, the recommended percentages of cement are 3 percent for A1 and A2 soils; 5 percent for a4 soils and 7 percent for an A6 and A7 soil.
Abstract: Summary This paper is the final of a series concerned with work conducted at the Ahmadu Bello University on lateritic soils. It summarizes the properties of cement, lime and bitumen stabilized lateritic soils and makes recommendations for field trials. For road construction, the recommended percentages of cement are 3 percent for A1 and A2 soils; 5 percent for A4 soils and 7 percent for A6 and A7 soils. Only A2 soils are recommended for stabilization with lime as base materials and a minimum of 6 percent lime should be utilized for field trial. Bituminous stabilization should be used for the sub-base course only on lightly trafficked roads. The recommended soils are A1, A2 and A3; and 2 to 4 percent of bitumen is recommended for field trial in the first instance. Soil cement stabilization for low cost one storey buildings is advocated. 5 percent cement content is recommended in the first instance but this could be reduced depending on laboratory results. Reasons for the better success of cement stabilization with lateritic soils are discussed.

125 citations


Journal ArticleDOI
17 Mar 1978
TL;DR: In this paper, the authors used electron microscopy and conduction calorimetry to study the hydration of Portland cement and found that the reaction involves two stages: (a) the rapid initial formation of gelatinous hydrate coatings around the cement grains and, (b) after a dormant period, the growth from these coatings of fine fibrillar calciumsilicate-hydrate (C-S-H) gel material into a reticulate network between the cement grain.
Abstract: Electron microscopy and conduction calorimetry have been employed to study the hydration of Portland cement. In situ studies of wet cement pastes in an environmental cell in the high voltage microscope confirm that the reaction involves two stages: ( a ) the rapid initial formation of gelatinous hydrate coatings around the cement grains and, ( b ) after a dormant period, the growth from these coatings of fine fibrillar calciumsilicate-hydrate (C-S-H) gel material into a reticulate network between the cement grains. Detailed electron microscopy indicates that the individual fibres are not solid but consist of fine hollow tubes. Attention is drawn to the striking visual analogy between the sequence of hydration of cement and the tubular growth forms that are obtained in ‘silicate gardens’. The latter are known to depend on the development of osmotic pressure as a driving force and, in spite of obvious differences in the scale and rate of growth, the basic parallels are close enough to suggest that a similar osmotic mechanism probably applies to the hydration of cement. On this basis, a model is proposed which explains the two-stage nature of the hydration process and provides a viable mechanism for the transport of the silicate material during growth of the secondary, fibrillar C-S-H product.

119 citations


Journal ArticleDOI
TL;DR: In this article, it is proposed that the hydrated, calcium-depleted surface of grains consists of low molecular mass silicic acids and that these interact with dissolved hydroxylated calcium species (principally Ca(OH) 2 ) to produce a semi-permeable membrane of "calcium silicate hydrate " at the surface of a grain.
Abstract: When Portland cement is contacted with water, calcium ion is rapidly leached from the solid to form calcium hydroxide solution but only traces of silica are found in the aqueous phase. It is proposed that the hydrated, calcium-depleted surface of grains consists of low molecular mass silicic acids and that these interact with dissolved hydroxylated calcium species (principally Ca(OH) 2 ) to produce a semi-permeable membrane of ‘ calcium silicate hydrate ’ at the hydrated grain surface. Osmotic pressure within this membrane causes its rupture and hence the growth of excrescences from the grain as the contents are extruded into the surrounding calcium hydroxide solution. The interstitial solid material is best regarded as a coagulum resulting from the combination of low molecular mass silicate anions with dissolved calcium hydroxide. It is proposed that the low tensile strength of Portland cement paste results from microstructural features consequent upon this mechanism of hydration and setting.

116 citations


Journal ArticleDOI
TL;DR: The results showed that the retentive ability of both cements increased with increasing surface roughness, and the increase in retention was greater for brass than for dentine, but on rough surfaces the opposite relationship was observed.
Abstract: Summary Two series of brass cones and two series of dentine posts with varying surface roughness were produced. Maximum roughness value and arithmetical mean roughness were recorded for each cone. Brass crowns were cemented either with zinc phosphate cement (De Trey's Zinc Cement Improved®) or with polycarboxylate cement (Durelon®). A tensile stress was applied until the crown and the cone separated. The retentive force in relation to retention area was measured. The results showed that the retentive ability of both cements increased with increasing surface roughness. The increase in retention was greater for brass than for dentine. Differences were also found between the two cements; on smooth surfaces the zinc phosphate cement had a lower retentive ability than the polycarboxylate cement, but on rough surfaces the opposite relationship was observed.

95 citations


Patent
24 May 1978
TL;DR: The additive essentially contains at least one sulfate such as aluminum sulfate, alum or iron sulfate as mentioned in this paper, and at least two alkaline metal salt, such as carbonate, bicarbonate or silicate.
Abstract: Solidification or consolidation, for fixation of various kinds of waste matter, soil etc. containing toxic contaminants affecting ecological system of the environment, by use of composition made up of hydraulic cement and particular additive. The additive essentially contains at least one sulfate, such as aluminum sulfate, alum or iron sulfate, and at least one alkaline metal salt, such as carbonate, bicarbonate or silicate.

72 citations


Patent
19 Oct 1978
TL;DR: Oily wastes which are immiscible with water are treated by mixing them with powdered chalk or other absorbent substance and a liquid hazardous waste as mentioned in this paper, and the mixture thus obtained then has added to it cement and fly ash thereby producing a slurry which sets into a detoxified rock.
Abstract: Oily wastes which are immiscible with water are treated by mixing them with powdered chalk or other absorbent substance and a liquid hazardous waste. The mixture thus obtained then has added to it cement and fly ash thereby producing a slurry which sets into a detoxified rock.

71 citations


Patent
26 Jun 1978
TL;DR: In this article, a rapid hardening cement is also provided which contains the above cement retarder, which comprises 5 to 20% by weight, based on the weight of said retarder of gluconic acid, of citric acid and/or an alkali carbonate.
Abstract: A cement retarder is provided which comprises 5 to 20% by weight, based on the weight of said retarder, of gluconic acid and/or tartaric acid and/or a water soluble salt thereof, 30 to 10% by weight, based on the weight of said retarder, of citric acid and/or an alkali salt thereof, and 50 to 85% by weight, based on the weight of said retarder, of an alkali carbonate. A rapid hardening cement is also provided which contains the above cement retarder.

60 citations


Journal ArticleDOI
TL;DR: In this paper, it was shown that C2ASH8 has strength giving properties and that it can give a significant increase in strength using Commercial HAC and prehydrated ordinary Portland cement.

Journal ArticleDOI
TL;DR: In this paper, the authors describe a study of the structure, composition and strength of cement paste near the cement-steel interface of an embedded wire and show that the interface does not change appreciably for curing times greater than a week and suggests enrichment of the interface with Ca(OH)2 X-ray diffraction.

Patent
25 Oct 1978
TL;DR: The dry wall joint compound can be used to completely close and fill joints between adjoining panel of gypsum dry wall board without a tape material, which comprises a powdered mixture of hydrated gypsus, calcium carbonate, plaster of paris, hydrated amorphous silica and talc as mentioned in this paper.
Abstract: The dry wall joint compound, which can be used to completely close and fill joints between adjoining panel of gypsum dry wall board without a tape material, comprises a powdered mixture of gypsum, hydrated gypsum, calcium carbonate, plaster of paris, hydrated amorphous silica and talc. The dry wall joint compound can be admixed with water to provide a dry wall joint cement and preferably is admixed with a liquid additive composition comprising an aqueous mixture of zinc oxide, sodium acetate, ammonium alum, and an acrylic resin.

Journal ArticleDOI
TL;DR: In this paper, the existence of hollow-shell or Hadley grains in bulk cement paste specimens has been investigated and it was found that almost all fractured grains observed seem to be of the hollowshell variety, similar to those previously established as occurring near interfaces with glass slides.

Journal ArticleDOI
TL;DR: In this article, it was shown theoretically and experimentally that the inclusion of continuous, opened polypropylene fibrillated films in cement mortar can more than double the load capacity of beams and can produce closely spaced multiple cracking.

Patent
17 Jul 1978
TL;DR: In this paper, the authors described thixotropic compositions for coloring cement or concrete or similar products comprising particulate pigment particles (about 20-80% by weight), at least one stabilizer (about 04-15%), a dispersent (about 01-30%), and water (about 12-77%).
Abstract: Thixotropic compositions for coloring cement or concrete or similar products comprise particulate pigment particles (about 20-80% by weight), at least one stabilizer (about 04-15%), a dispersent (about 01-30%) and water (about 12-77%) Methods of making these compositions are also explained

Journal ArticleDOI
TL;DR: In this paper, surface areas, total pore volumes and the microstructure of the hardened expansive cement pastes are discussed, and the results obtained are compared with each other using scanning electron microscopy.


Patent
18 Jul 1978
TL;DR: In this article, an article is cast from a composition comprising a binding agent comprising from 90% to 10% calcined gypsum and from 10% to 90% Portland cement mixed with water to produce a fluid mixture which is caused to flow into a mould or other supporting device and is there allowed to set.
Abstract: An article is cast from a composition comprising a binding agent containing, by weight, from 90% to 10% calcined gypsum and from 10% to 90% Portland cement mixed with water to produce a fluid mixture which is caused to flow into a mould or other supporting device and is there allowed to set. To increase the durability of the cast article in the presence of moisture, sodium carbonate in an amount up to 5% by weight of the dry weight of the cement is added to the composition. The sodium carbonate is preferably present in an amount between 0.1% and 0.5% of the dry weight of the cement and the composition preferably also contains an acrylic resin emulsion in an amount from 0.25% to 4% of the dry weight of the gypsum and cement in the composition and a pigment such as iron oxide, titanium oxide or cobalt oxide in an amount from 0.25% to 4% by weight of the dry weight of the gypsum and cement in the composition.

Patent
30 Jan 1978
TL;DR: In this paper, a portland cement with rapid strength gain having normal setting and volume change characteristics and its method of manufacture are disclosed. But the use of chlorides or other accelerators is unnecessary to obtain early high strength; although, these and plasticizers can be used if desired.
Abstract: A cement with rapid strength gain having normal setting and volume change characteristics and its method of manufacture are disclosed. The cement has substantially all particles over 20 microns removed which advantageously results in higher early strength than normal portland cements. This is important in the prestress and precast concrete industry, and early high-strength cement is desirable for other uses such as patching or resurfacing highways and airport runways or in operations where early form removal is desired. The use of chlorides or other accelerators is unnecessary to obtain early high strengths; although, these and plasticizers can be used if desired.

Patent
14 Apr 1978
TL;DR: In this article, 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.

Patent
09 May 1978
Abstract: An agent for accelerating hardening of cement for use in an underground mining installation employing concrete-like packs including run-of-mine coal. The agent comprises by weight one and a half parts triethanolamine, five parts sodium carbonate and one part potassium carbonate. Too rapid setting of quick setting cement is avoided by the agent because a slurry of cement in water is mixed with a slurry of agent and run-of-mine coal in bentonite in a mixer immediately before being added to a pack so that setting cement does not occur in pipes leading to the mixer.

Journal ArticleDOI
TL;DR: In this article, a study of the processes involved at and near the steel-matrix interface when an embedded steel wire is pulled out of a cement paste or mortar matrix is presented.

Patent
27 Dec 1978
TL;DR: In this paper, a concrete or mortar mixture or concrete-or mortar on the basis of hydraulic binders and plastic materials for the production of building elements or coatings insensitive to shock and impact stress, abrasion, frost-thaw and defrosting salt and chemical attack is presented.
Abstract: A concrete or mortar mixture or concrete or mortar on the basis of hydraulic binders and plastic materials for the production of building elements or coatings insensitive to shock and impact stress, abrasion, frost-thaw and defrosting salt and chemical attack as well as for effecting repair work on building elements or coatings, wherein lime or cement selected from the group consisting of Portland cement of conventional composition, iron Portland cement, blast furnace cement, flue ash Portland cement, Ciment compose, puzzolane cement, high-alumina cement, modified Portland cement on the basis of 11CaO.7Al2 O3.CaF2, Brunauer cement, Grenoble cement and Roman cement and further at least one liquid-dispersed or dissolved plastic material selected from the group consisting of pure polymerizates, mixed polymerizates, and co-polymerizates, the plastic material having low-temperature adhesiveness and a Tmax value of less than -8° C. determined according to DIN 53445, are contained.

Patent
Joseph U Messenger1
15 Nov 1978
TL;DR: In this article, a method of preparing and using a cement slurry having water swellable clays therein as extenders for the cement is described, which method enhances the effectiveness of the water-swellable clay by preshearing aqueous suspensions thereof prior to mixing these suspensions with cement to form a pumpable cement slury.
Abstract: A method of preparing and using a cement slurry having water swellable clays therein as extenders for the cement is described, which method enhances the effectiveness of the water swellable clays by preshearing aqueous suspensions thereof prior to mixing these suspensions with cement to form a pumpable cement slurry. Also described is a particular technique for using bentonite as a cement extender in a cement slurry formed with salt water.

Journal ArticleDOI
TL;DR: In this paper, a non-destructive method is presented to study the combining properties of a number of hardened cement pastes for NaCl and CaCl 2, and the dependence of the amount of chloride combined by the cement on the total amount added to the cement is calculated.

Journal ArticleDOI
TL;DR: Sodium lignosulfonate in combination with sodium carbonate controls the setting of pure portland clinker pastes and exhibits a strong liquefying effect on both pure clinker and cement pastes as mentioned in this paper.

Journal ArticleDOI
TL;DR: The results showed that Durelon, EBAC, zinc phosphate, Epoxylite CBA, and Fynal had thinner film thicknesses than EBA and Fluro-Thin and no significant differences occurred with these two cements whether the crown was vented or not.
Abstract: Summary The results showed that Durelon, EBAC, zinc phosphate, Epoxylite CBA, and Fynal had thinner film thicknesses than EBA and Fluoro-Thin In addition, venting of a crown resulted in lower film thicknesses with all cements except Fynal and EBAC No significant differences occurred with these two cements whether the crown was vented or not Obviously many other factors besides film thickness, such as toxicity, strength, and solubility, have to be considered before selecting a cement for clinical use When only film thickness is to be considered, all of the cements in the study could be recommended for the cementation of crowns with the exception of EBA and Fluoro-Thin

Patent
15 Sep 1978
TL;DR: Expansive cement compositions and novel expansion agents containing free lime for use in such compositions are prepared by heating lime of particle size less than 250 microns in an atmosphere comprising water vapor at 100° to 400° C or carbon dioxide at 350° to 850° C, or by heating a partially hydrated lime at a temperature of at least 100° C as discussed by the authors.
Abstract: Expansive cement compositions and novel expansion agents containing free lime for use in such compositions. The expansion agents are prepared by heating lime of particle size less than 250 microns in an atmosphere comprising water vapor at 100° to 400° C. or carbon dioxide at 350° to 850° C., or by heating a partially hydrated lime at a temperature of at least 100° C. The encapsulated limes produced in this way are useful as expansion agents in hydratable cement compositions, the amount thereof generally being less than 30%, preferably 3 to 10%, based on the weight of the cement and additive. Cement compositions containing the novel expansion agents are useful in a wide variety of uses where shrinkage of the composition on drying has to be prevented or reduced.

Patent
22 May 1978
TL;DR: A surgical cement is a mixture of a concentrated non-gelling aqueous solution of polycarboxylic acid and an annealing suspension of metal oxide powder which when mixed together form a plastic mass which is formable into the desired shape before it hardens as discussed by the authors.
Abstract: A surgical cement comprised of a concentrated non-gelling aqueous solution of a polycarboxylic acid and an aqueous suspension of metal oxide powder which when mixed together form a plastic mass which is formable into the desired shape before it hardens. The surgical cement has particular utility for dental applications.