Showing papers on "Cement published in 1974"

Waste Glass as Coarse Aggregate for Concrete

Abstract: The paper reports on the performance of 34 different concrete mixes containing glass crushed to ¾-in. (19-mm) maximum size as coarse aggregate and six reference mixes made with gravel of the same size. Two cements of alkali equivalent 0.58 and 1.13, classifiable as low and high alkali (ASTM C 150-72), in amounts ranging from 400–900 lb/yd3 (237–534 kg/m3 were used in combination with glass both with the fines removed and in the as-crushed condition. Partial cement replacement with fly ash and mixing of glass with gravel aggregate were included in an attempt to find a suitable method of overcoming the expected adverse effects of the reaction between glass and cement alkalis. On the basis of compressive strength, flexural strength, expansion, and visible surface deterioration recorded up to an age of one year, the results show that in many cases the direct combination of glass with portland cement yields concrete which exhibits marked strength regression and excessive expansion due to alkali-aggregate reaction. The conditions under which performance is satisfactory appear to relate to limiting maximum values of cement content and alkali equivalent. Replacement of 25 to 30 percent by weight of the cement, whether low or high alkali, appears to be an effective and widely applicable method of ensuring good long-term concrete performance, although the minimum required in any given case may be related to cement composition.

Reactions in Glass Ionomer Cements I. Decomposition of the Powder

Abstract: The initial stages of the reaction between the glass ionomer cement powder and polyacrylic acid solutions (aluminosilicate polyacrylate cement) are described. Polyacrylic acid rapidly decomposes the ion-leachable powder, possibly aided by some metal comPlex-forming function. The amount of fluoride extracted, which is related to its molecular condition in the glass, is of considerable importance.

Drilling mud-cement compositions for well cementing operations

Abstract: A low clay content aqueous drilling mud or a magnesium saltbased aqueous drilling mud may be transformed into cement for well cementing by addition of magnesium oxide, magnesium sulfate and dolomite or magnesium carbonate to produce a magnesium oxysulfate cement.

Reactions in Glass Ionomer Cements: III. The Precipitation Reaction:

Abstract: Water-soluble ions in dental cements of different ages were studied. The cement is formed by the reaction between aqueous polyacrylic acid and an aluminosilicate glass. Electrical conductance measurements were made on cements up to three months after formation. Calcium polyacrylate is formed before aluminum polyacrylate. Calcium ions are fully combined within three hours, whereas aluminum ions continue to react for at least 48 hours.

Foamed cementitious compositions and method of producing same

Abstract: A cellular product useful for such purposes as fire resistance, thermal insulation, and acoustical sound proofing may be produced from a mineral cement, such as gypsum cement, portland cement, calcium aluminate cement, or magneisa cement, an organic film former such as guar gun, or an inorganic film former such as bentonite, a mixture of nonionic and anionic surfactants, a lightweight aggregate, such as perlite, vermiculite, or hollow silicate spheres, and air in amount substantially in excess of that used in air entrainment of cement, whereby the product has a density which is only a small fraction of the density of the mineral cement and aggregate composition per se.

Dry light-weight cement composition

Abstract: A dry mix for a light-weight cement comprises powdered cement mixed with bitumen particles of which more than 90% have sizes of less than 700 microns and aluminum silicate particles of which more than 90% have sizes of less than 30 microns

No-fines concrete - its properties and applications

Abstract: No-fines concrete consists solely of normal portland cement, water and coarse aggregate. It has been used in Europe and the United Kingdom since the 1930s for the building of single story and multistory dwellings, but had found little acceptance in North America. In recent years, however, due to increased awareness of the need for conservation of nonrenewable mineral resources, increased consideration is being given to the use of no-fines concrete in Canada and the United States. The compressive strength of no-fines concrete is considerably lower than that of conventional portland cement concrete and varies between 200 to 2000 psi (1.37 to 13.73 MN/square meters ). Young's modulus of elasticity is usually between 1.0 x 10,000,000 to 1.5 x 10,000,000 psi (0.7 x 100,000 to 1.2 x 100,000 MN/square meters) depending on the strength level of the concrete. The ratio of modulus of rupture to compressive strength expressed as a percentage varies between 10.8 and 42.0 percent. The shrinkage of no-fines concrete made with crushed limestone or river gravel, is of the order of 200 x 0.000001. This is about half for that of conventional concrete. Investigations at CANMET have indicated that no-fines concrete prisms with no air-entraining agent had poor resistance to freeze-thaw cycling; the corresponding prisms incorporating an air-entraining agent were able to withstand up to 274 freeze-thaw cycles compared with 56 for prisms without an air-entraining agent. The principal advantages claimed for no-fines concrete are economy in materials, somewhat higher thermal insulating values, lower shrinkage, and lower unit weight. The major disadvantages are its low compressive, flexural, and bond strength, and higher permeability. The principal applications of no-fines concrete are for load-bearing cast-in-place external walls of single story and multistory housing, small retaining walls and as a dampproofing subbase material for concrete floors cast on grade. This type of concrete is also eminently suitable for construction in northern Canada because of its somewhat higher thermal insulating property and low cement content.

Some applications of infrared and raman spectroscopy in cement chemistry. Part 3 - hydration of portland cement and its constituents

Abstract: Infrared spectroscopy was used to study the hydration process of portland cement. The course of hydration for different types of portland cement was followed by observation of changes in the infrared wavebands associated with silicate, sulphate and water groups. The results obtained with ordinary portland cement were compared with those given by the technique of differential thermal analysis.

An informal report of cold mix research using emulsified asphalt as a binder

Abstract: The characteristics were studied (by the Marshall method) of emulsified asphalt mixtures treated with various amounts of cement cured at predetermined temperatures and periods of time. Two grades of emulsified asphalt were used: CSS-1 and CSS-1h. The crushed aggregate used (from a commercial source) had a rough texture with low absorption, and 85 percent of the material retained in the No. 4 sieve was fractured. Stability and flow analyses were performed on each cured specimen (cured at 40F, 50F, and 120F) at room temperature (70 to 72 F). Two specimens from each group were tested for moisture content by drying for a 24-hour period in a 302 F oven. A sample was immersed in water for visual observation. Immersion compression investigations were also performed. The study indicates that emulsified asphalt mixtures requre the addition of cement to prevent moisture-induced deterioration and provide immediate stability. Although emulsified asphalts derived from low penetration asphalt cements (CSS-1h), when used in emulsion mixes produced high stability mixes, it is felt that the resultant mixes would become brittle with age causing ravelling of the surface. Moisture, either natural or induced, is necessary to activate the cement. The water available from the emulsion is either inadequate or otherwise unusable. The study also shows that dense graded, cement modified, emulsified asphalt cold mixes when properly proportioned, placed and compacted appear to be satisfactory for local service and secondary roads with low traffic count.

Method for execution of quick hardening cement

Abstract: A method for working quick hardening cements comprising preparing (A) a composition comprising a cement paste, mortar or concrete and (B) a composition comprising a powder or suspension composition of calcium aluminate and inorganic sulfate, mixing the composition (A) and the composition (B) and quickly executing the mixture immediately after the admixture.

Pulpal Response of Monkeys to a Composite Resin Cement

Abstract: A composite resin cement is shown to be stronger and less soluble than the cementing materials that are commonly used today. The acidic cavity cleanser that is recommended to improve the adhesive properties of this resin cement considerably enhanced the pulpal response to the cement.

Additive for improving hydraulic cement compositions

Abstract: An additive for imparting water repellancy to, and retarding the set of hydraulic cement compositions (e.g., Portland cement compositions such as masonry cements) is described which is an aqueous oil-in-water emulsion containing water, a water-insoluble, water-repelling acid component (e.g. tall oil), an emulsifier (e.g. a salt of such acid), and a setting time-retarding agent (e.g. sucrose). The additive is ideally dispersible in water and preferably contains an air-entraining agent as an additional optional component. Intergrinding the emulsified additive with the cement component is the preferred manner of incorporating the additive in the cement composition.

Process for making artificial rocks

Abstract: A light-weight simulated rock is made by molding a composition comprising cement, a light-weight filler, water, a curing agent for the cement and an acrylic resin latex in a flexible mold and thereafter nonuniformly coloring the hardened rock body so formed with cement dyes and/or pigments.

Calcium aluminate cement

Abstract: A refractory cement is made by combining a clinker which is substantially all CaO.Al 2 O 3 (CA) with a roughly equal weight amount of an alumina which has been calcined to produce a carefully controlled morphology, particularly specific surface and pore size within relatively narrow ranges. Both materials are very finely divided, at least 80% passing a 325 mesh screen.

On the Stability of the Mechanical Properties of Self-Curing Acrylic Bone Cement.

Abstract: : The effect of storage for periods up to two years in bovine serum at 37C on the mechanical properties of Simplex and CMW bone cements was studied. No significant deterioration was detected either in static properties or in compressional fatigue behavior. The data on compressional fatigue suggest that working stresses in the cement be limited to less than 1.4 x 10 to minus eight dynes/sq cm to insure long-term viability of any design or implantation technique. (Author)

Hypothesis for Reinforcement of Portland Cement by Polymer Latexes

Abstract: Vinylidene chloride and styrene-butadiene copolymer latexes are used commercially to reinforce portland cements. Although the technology is well developed, the mechanism of reinforcement is not well understood. A hypothesis is proposed to explain this reinforcement, i.e. (1) latex substitutes for all or part of the water to give the same fluidity at a lower water/cement ratio; (2) latex particles coalesce around each unhydrated (or slightly hydrated) cement grain and aggregate particle to form an interpenetrating network of polymer throughout the structure; (3) microcracks form throughout the structure to relieve the strain introduced by the shrinkage of the portland cement that occurs when the relative humidity falls below 100%; and (4) a propagating microcrack intersects the interpenetrating polymer network to form microfibers spanning the microcrack, sometimes so effectively that propagation is halted, but always so that the microcrack is held together. This hypothesis was supported by scanning electron microscopy of latex-modified cement specimens, as well as by other experiments. More work is needed to determine how each part of the hypothesis contributes to the physical properties of latex-modified cement.

Improvements in and relating to board products

Abstract: A fire-resistant board product is comprised of a hydraulic cement binder reinforced by a mixture of long and short staple vitreous fibres, silica in an amount at least sufficient to react with the free lime in the cement, together with from 1 to 10% by weight of a cellulosic fibre. Optionally, the board product further includes at least one low density filler which may provide at least part of the silica component.

Cementitious compositions having fast-setting properties and inhibited shrinkage

Abstract: A cementitious composition which when mixed with water is capable of setting rapidly into a hard mass of high compressive strength without substantial shrinkage during setting and early hardening, which exhibits reduced long-term shrinkage, and which possesses a high degree of impermeability to liquid and vapor, is composed of a particulate mixture of portland cement, a calcined gypsum, and high alumina cement. Alternatively, such a cementitious composition can be composed of a particulate mixture of a high alumina cement and pressure calcined gypsum. Additional components such as surface active agents, gas generating or releasing agents and aggregate can be employed, if desired, for the selective improvement of specific properties.

Admixtures for reducing slump loss in hydraulic cement concretes

Abstract: In freshly mixed portland cement concrete, slump loss, which normally occurs during transportation and handling, can be either prevented or considerably reduced by admixing small amounts of styrene-butadiene latices, e.g., 0.01 to 0.15% of latex (on solid basis) by weight of concrete or 0.1 to 1.5% of latex by weight of cement. Thus, by maintaining plasticity of fresh (unhardened) concrete for prolonged periods of time, the small amount of latex admixture can permit transportation of pre-mixed concrete over longer hauling distances, or permit longer handling time for placement, consolidation, and finishing of concrete in formwork.

Mortar of inorganic binder and sulfonic acid group-containing formaldehyde condensation product with cycloalkanone

Abstract: A mortar comprising an inorganic binder such as anhydrite, gypsum or cement is rendered more flowable and processible by incorporating therein a sulfonic acid group-containing formaldehyde condensation product with a cycloalkanone, e.g. preferably about 0.05 to 5% by weight of the binder of the condensation product of sodium sulfite, formaldehyde and cyclohexanone. There may also be present an auxiliary such as FeSO4,7 H2 O,Al2 (SO4)3.18 H2 O or KAl(SO4)2, as well as an additive such as a plasticizer, hardening accelerator, retarder, air-entraining agent, thickener, activator, anti-foam agent or synthetic resin dispersion, and/or an aggregate such as sand, silica, perlite, pumice or foamed plastic beads.

Absorption and reflection infra-red spectra of major cement minerals, clinkers and cements

Abstract: The infra-red spectra of the major cement minerals, synthetic mixes of the four important clinker phases and commercial clinkers and cements have been studied both by the absorption technique as well as by the attenuated total reflectance technique of powder samples. The possibility of general application of infra-red spectrometry in the quality control of clinkers and cements has been indicated especially with reference to the relative proportion of the tricalcium and dicalcium silicate phases. In this context the potentiality of the attenuated total reflectance technique in cement characterization has been especially emphasized.

Method for solidifying sludge

Abstract: A sludge having a water/solid high ratio and containing a substance having a harmful influence upon the setting of portland cement is solidified by mixing the sludge with rapid hardening cement containing calcium haloaluminate

Study of Portland cement fracture surfaces by scanning electron microscopy techniques

Abstract: An extensive scanning electron microscopy study was carried out with respect to the fracture surfaces of Portland cement hydrated for various times. It is shown that the two major products of hydration are calcium silicate hydrate spherulites, which consist of radiating fibres and calcium hydroxide platelets. These fibres bond with one another to hold the spherulites together. The volume between the spherulites consists of calcium hydroxide platelets. The fracture is frequently found to be across the weakly bonded basal planes of the calcium hydroxide, and is believed to limit the strength of the Portland cement.

High-alumina cement

Abstract: A high-alumina cement composition is disclosed which has thermal stability over a wide temperature range and which develops strength at an early age. The cement composition comprises a high-alumina cement, a halide salt and calcium sulfate. This composition when added to water provides a hydraulic cement composition which can be employed in environments subject to wide temperature fluctuations below and above freezing (e.g. 32° F).

Method for placing cement in a well

Abstract: The integrity and strength of cement placed in a well drilled with a drilling fluid containing an ingredient that deleteriously affects curing of the cement can be improved by (1) displacing the drilling fluid from the well with a highly gelled aqueous suspension of a hydrated clay that is substantially free of deleterious agents and that has a density at least equal to that of the drilling fluid, (2) introducing a cement slurry into the well, and (3) displacing the cement slurry to the proper location in the well with an additional quantity of highly gelled, aqueous hydrated clay suspension. The gelled preflush fluid can contain an abradant solid to facilitate the removal of the filter cake from the wall of the borehole. Also, filter cake removal can be facilitated by jetting the gelled preflush fluid against the borehole wall.