Showing papers on "Cement published in 1968"

A model for hydrated Portland cement paste as deduced from sorption-length change and mechanical properties

Abstract: Recent findings in DBR and other laboratories has made it necessary here to revise the accepted model for hydrated portland cement paste. The model recognizes surface areas and porosities obtained by N2 adsorption as the most reliable values, and attributes many of the phenomena observed, to the behaviour of interlayer hydrate water. The bonds between and within individual “crystallites» are clearly defined; it is shown that the “inter-crystallite” bonds do not separate when exposed to physically adsorbed water. The paper describes some of the thermodynamic equations pertinent to the phenomena of adsorption, length change and creep, and some basic principles governing physical adsorption and types of hystereses. The results were obtained from two areas of work: A. Surface chemical experiments. B. Measurement of mechanical properties of compacted and cast systems of hydrated cement and gypsum. The experiments in (A) included sorption and length change scanning isotherms of water and methanol and led to the following conclusions: The experiments in (B) included measurements of modulus and strength versus relative humidity, and porosity, and led to the following conclusions:

Method and composition for stabilizing incompetent oil containing formations

Abstract: Improved method of and composition for the treatment of an oil-containing incompetent formation to prevent the movement of unconsolidated sand particles in an underground formation by forming a treating composition of sand, cement, silica flour and a sufficient amount of petroleum oil fraction containing an oil-wetting agent therein to oil-wet the sand, cement and silica flour particles suspending the resulting treating composition in an aqueous carrier medium, injecting the aqueous suspension against the unconsolidated formation at a pressure effective to force the treating composition into contact with the unconsolidated formation, contacting the placed treating composition with an aqueous curing solution to water wet the cement particles, permitting the cement to set and form a permeable cement and recovering oil through the cement.

Method and composition for cementing oil well casing

Abstract: 1,241,886. Cement compositions. DRESSER INDUSTRIES Inc. 5 May, 1969 [28 June, 1968], No. 22792/69. Heading C1H. [Also in Division E1]. A composition comprises cement and powdered Na 2 Siez glass (defined) of a Na 2 O/SiO 2 ratio 1:1A6: : 1:4A5 in a weight ratio of 6:1 : : 1:1. Optionals are Ca(OH) 2 , LiOH, Li 2 CO 3 , LiCl, NaOH and Na 2 CO 3 and up to 25% pozzuolana, e.g. volcanic ash, fly ash and some clays. Cement includes lime and pozzuolanic, high alumina, grappier and portland cements. The compositions are added to drilling fluids containing dispersants e.g. lignites (humates), tannates and lignosulphonates to give mud concretes.

Determining bond strength in fibre-reinforced composites

Abstract: Summary A pull-out technique suitable for determining the interfacial bond strength for various combinations of fibres and matrix is described. In this method, a thick fibre, 0·5 to 1·0 mm in diameter, is embedded perpendicularly through a matrix material contained in a special mould and is stressed on a tensile testing machine. The value of the maximum bond load corresponds to a sharp break in the load-extension curve. Results show that the bond strength between E-glass-fibre and cement is of the same order as that between steel and cement but higher than the values reported for asbestos and cement. The work has also shown that the strength of the bond between E-glass-fibre and gypsum plaster is of similar magnitude, but that it is affected significantly by variations in water/plaster ratio.

Aggregate-cement bond, cement paste strength and the strength of concrete

Abstract: A REVIEW IS GIVEN OF AVAILABLE DATA ON AGGREGATE-CEMENT BOND STRENGTH, CEMENT PASTE STRENGTH, AND THEIR INFLUENCE ON CONCRETE STRENGTH. MAJOR POINTS COVERED INCLUDE THE RELATIONSHIP BETWEEN BOND AND PASTE STRENGTHS OF DIFFERENT BRANDS OF CEMENT, THE EFFECT OF THE CHEMICAL COMPOSITION OF ROCK ON BOND TO NORMAL AGGREGATES TO THE INFLUENCE OF WATER/CEMENT RATIO AND MATURITY ON BOND AND PASTE STRENGTHS. OTHER VARIABLES CONSIDERED ARE VIBRATION, ADMIXTURES, SURFACE TEXTURE AND SURFACE CONTAMINATION OF AGGREGATES, SIZE OF AGGREGATE AND AGGREGATE ABSORBPTION. A SURVEY IS MADE OF THE RELATIVE IMPORTANCE OF MECHANICAL AND NON-MECHANICAL FACTORS IN BOND. /A/RRL/

Cement grinding aid and pack set inhibitor

Abstract: Additive compositions for use as grinding aids and pack set inhibitors in the manufacture of hydraulic cement composed of a water-soluble polyol, particularly a glycol, and a water-soluble salt of an aliphatic acid having no more than three carbons, said additive compositions being used either alone or in combination with water-soluble salts of a sulfonated lignin, a water-soluble hydroxyalkyl amine and urea, the hydraulic cement product of this addition and the method for making the cement product.

Quick-setting cement composition containing portland cement,alpha gypsum and a dispersant

Abstract: CRATERS AND EARTH VOIDS ARE QUICKLY FILLED WITH A HIGHSTRENGTH, QUICK-SETTING CEMENT COMPOSITION COMPRISING A MIXTURE OF CEMENT MATERIAL CONSISTING ESSENTIALLY OF FROM ABOUT 9.5 TO ABOUT 4 PARTS BY WEIGHT OF CALCIUM SULFATE HEMIHYDRATE TO ABOUT 0.5 TO ABOUT 6 PARTS BY WEIGHT OF PORTLAND CEMENT AND WATER WHICH IS PRESENT IN A QUANTITY OF FROM ABOUT 22% TO ABOUT 70% BY WEIGHT. ACCORDING TO THE DESIRED USES THEREFOR, ACCELERATORS, RETARDANTS OR DISBURSANTS ARE ADDED TO THE MIXTURE. THE PREFERRED QUICK-SETTING CEMENT COMPOSITION OF THIS INVENTION CONSISTS OF FROM 9.5 TO 7 PARTS BY WEIGHT OF ALPHA GYPSUM TO 0.5 TO 30 PARTS BY WEIGHT OF PORTLAND CEMENT ALONG WITH FROM ABOUT 22% TO ABOUT 40% WATER BY WEIGHT, BASED UPON THE CEMENT MATERIAL.

Dental Silicate Cements: VI. Infrared Studies

Abstract: Infrared studies have shown that silica gel and H2PO4-1 ions are formed in fresh cement paste. Subsequently, during setting and hardening, H 2PO4-1 ions further react to form covalent phosphates and are removed from the system. In an uncertified cement, H2PO 4-1 ions were found in substantial amounts even in the set cement, which accounted for poor strength and durability.

Dental Silicate Cements: IV. Phosphoric Acid Modifiers

Abstract: The effects of aluminum, zinc, and boric acid modifiers of the phosphoric acid liquid on the properties of the final cement are discussed, and conclusions are drawn as to the optimum conditions required for a good cement. Several commercial brands are examined in the light of the constitution of the liquids.

Expanded magnesia cement

Abstract: AN EXPANDED MAGNESIA CEMENT CONTAINING A VOLUME OF GAS AT LEAST EQUAL TO THE VOLUME OF THE CEMENT IN ITS UNEXPANDED STATE. THE CEMENT IS FORMED BY MIXING MAGNESIUM OXIDE, MAGNESIUM CHLORIDE AND WATER IN THE PRESENCE OF A FOAM-FORMING SURFACE ACTIVE AGENT AND IN THE PRESENCE OF A FOAM STABILIZING WATER-SOLUBLE SILICONE, ENTRAINING A GAS INTO THE RESULTING MIX TO FORM A FLOWABLE FOAM AND ALLOWING THE FOAM TO SET. PARTICULARLY USEFUL CEMENT FROM AN ECONOMIC AND STRUCTURAL POINT OF VIEW HAVE THREE TO TWELEVE TIMES THE VOLUME OF GAS PRESENT. A METHOD FOR THE PRODUCTION OF THESE EXPANDED CEMENTS IS ALSO CLAIMED.

Method of production of injection mortar or porous concrete

Abstract: THE METHOD FOR PRODUCING INJECTION MORTAR OR POROUS CONCRETE COMPRISES ADDING TO A CEMENT CONTAINING MIXTURE A NITROGEN DELIVERING COMPOUND IN AN AMOUNT OF OF 0.1% TO 6% OF THE WEIGHT OF THE CEMENT CAUSING AN EXPANSION OR FORMATION OF PORES IN SAID MIXTURE. THE NITROGEN DELIVERING COMPOUND PREFERABLY WILL BE A HYDRAZINE DERIVATIVE, SUCH AS HYDRAZINE SULFATE OR DIHYDRAZINE SULFATE, OR A BENZENE-SULFOHYDRAZINE, A STABILISED DIAZONIUM SALT, OR A DIAZOTIZED NITRO-ANILINE, AND AN ACTIVATOR FOR THE NITROGEN DELIVERING COMPOUND MAY ADDED.

Well cementing composition

Abstract: A CEMENT SLURRY COMPOSITION ESPECIALLY DESIGNED FOR THE SETTING OF MULTIPLE STRINGS OF TUBING IN A MULTIPLE COMPLETION WELL WHEREIN THE SETTING OF THE CEMENT IS RETARDED FOR AT LEAST 10 HOURS, COMPRISING AN OIL-WELL CEMENT AND FROM 10 TO 16 PERCENT OF CLAY TOGETHER WITH RELATIVELY SMALL PROPORTIONS OF RETARDING AND DISPERSING AGENTS, NO FLUID LOSS ADDITIVES, AND NO MORE THAN ABOUT 100 PERCENT WATER, BASED ON THE DRY WEIGHT OF CEMENT.

Proportioning Fly Ash Concrete Mixes For Strength and Economy

Abstract: A METHOD IS PRESENTED FOR PROPORTIONING FLY WITH CEMENT TO PRODUCE CONCRETE OF EQUAL STRENGTHS AT 28 AND 90 DAYS TO CONCRETE WITHOUT FLY ASH. THE METHOD WAS DEVELOPED BY THE TENNESSEE VALLEY AUTHORITY (TVA) AS A RESULT OF USING FLY ASH IN ALL CLASSES OF CONCRETE FOR THE PAST 12 YEARS. EFFECTS OF DIFFERING PROPORTIONS OF FLY ASH ON WATER REQUIREMENTS, STRENGTH, AND ECONOMY ARE GIVEN. THE EFFECTS OF FINENESS AND CARBON CONTENT OF FLY ASH AND VARIATIONS IN STRENGTH OF CEMENTS ON CEMENT REQUIREMENTS ARE DISCUSSED. COMPARISONS ARE MADE BETWEEN THE CEMENT REQUIREMENTS AS DETERMINED BY THIS METHOD WITH THE CEMENT ACTUALLY REQUIRED BY TESTS FROM THE CORPS OF ENGINEERS, TVA, AND BAYS MOUNTAIN CONSTRUCTION COMPANY. THE COMPARISONS WERE MADE USING AT LEAST NINE DIFFERENT SUPPLIERS OF CEMENT AND EIGHT DIFFERENT FLY ASHES, FOUR OF WHICH WOULD NOT MEET FEDERAL AND ASTM SPECIFICATIONS. /AUTHOR /

Hydration and strength of neat Portland cement

Abstract: Summary In order to examine the relationship between some of the mechanical properties and the degree of hydration of Portland cement, two different methods were used to prepare samples of hydrated cement paste. One method involved hydrating the cement in suspension for different lengths of time in rotating polyethylene bottles (water/cement ratio = 5). The dried powder was then compacted to different porosities. In the other method, the dry unhydrated cement was mixed with plastic beads in the ratio of l:3 by weight and compacted at 10,000 lb/in2 to give a porosity oJ about 38%, and then hydrated by immersion in water. These compacts, which were in the shape of discs of 1·25 in. diameter, were used to measure the modulus of elasticity, fracture strength and indentation hardness. This work indicated that these types of sample can be used to follow the characteristic change in mechanical properties with time and degree of hydration of the cement.

Water in hardened cement paste

Abstract: Some properties of adsorbed water in hardened cement paste and in the three completely hydrated main constituents of portland cement have been examined by means of differential thermoanalysis, thermo-gravimetry and nuclear magnetic resonance. When a dried specimen is re-wetted, the adsorbed water first contributes to the build-up of a mono-layer. Only in the higher humidity range is the sorbed water partly bound as inter-layer hydrate water and as hydrate water. According to the first results of the nuclear magnetic resonance measurements the water adsorbed in the monolayer behaves like a two-dimensiional Van-der-Waals-gas.

Method and apparatus for distributing bulk material such as cement

Abstract: A wheeled vehicle for storing and dispensing pulverized or granular material such as fertilizer, grain, etc., and more particularly cement, especially mortar cement, at a place where the material is to be used, such as, a residence or a construction site and the like, and which dispenses the material in portions of predetermined size or amounts.

How chlorides affect concrete used with reinforcing steel

Abstract: THE CORROSION BEHAVIOR OF STEEL IN CONCRETE HAS BEEN ATTRIBUTED TO CONCRETE ABSORPTION AND TO SALT IN THE CONCRETE. THIS STUDY REPORTS THE RESULTS OF MEASURING RESISTIVITY AND ABSORPTION OF CONCRETE WHEN THE CHLORIDE ION AND CEMENT CONTENT OF CONCRETE ARE VARIED. THE RESULTS INDICATE THAT RESISTIVITY OF CONCRETE IS RELATED TO THE AMBIENT MOISTURE LEVEL IN THE CONCRETE AS WELL AS TO THE AMOUNT OF WATER AND CEMENT USED IN CONCRETE MANUFACTURE. SIGNIFICANT ADDITIONS OF CHLORIDE ION TO THE MIX ONLY AFFECTED RESISTIVITY BY VIRTUE OF INCREASING CONCRETE ABSORPTION. HOWEVER, WHEN CHLORIDE CONTAINING CONCRETE WAS OVEN DRIED AND RESOAKED, ITS RESISTIVITY DECREASED WITH INCREASING SALT CONTENT. THE INSTRUMENTS FOR MEASURING RESISTIVITY IN THE FIELD AND THE LABORATORY ARE SHOWN AND DESCRIBED. AN EMPIRICAL FORMULA IS GIVEN WHICH RELATES ABSORPTION TO CONCRETE MIX VARIABLES. /AUTHOR/

Aluminous cement-tricalcium silicate binders

Abstract: Aluminous cements are disclosed containing tricalcium silicate. The tricalcium silicate acts as a delayed-action water-binding agent, which removes water from cement mortars in excess of that required to hydrate aluminous cement to the stable crystalline form of tricalcium aluminate hexahydrate.

Studies of the role of calcium sulphate in the manufacture of portland cement clinker

Abstract: SULPHATE IN PORTLAND CEMENT CLINKER MAY ORIGINATE FROM THE CLAY OR CALCIUM SULPHATE OF THE RAW MIX, FROM THE FUEL, OR FROM THE USE OF MINERALIZERS ITS RETENTION IN THE CLINKER IS INFLUENCED BY THE KILN ATMOSPHERE STUDIES ARE IN PROGRESS OF THE ROLE OF SULPHATE IN THE CEMENT MAKING PROCESS AND THE WAYS IN WHICH IT MAY ALTER EITHER THE COMPOUND COMPOSITION OF THE CLINKER OR THE CEMENTING PROPERTIES OF IMPORTANT CEMENT COMPOUNDS SINCE THE UTILIZATION OF INDUSTRIAL BY-PRODUCTS AND LOW-GRADE LIMESTONES, CONTAINING IMPURITIES RARELY PRESENT IN CEMENT IN ANY QUANTITY, IS CURRENTLY INCREASING, AN UNDERSTANDING OF THE FUNCTION OF SUCH MINOR COMPONENTS AS MAGNESIA AND SULPHATE IS ACQUIRING NEW IMPORTANCE /AUTHOR/

Improved vermiculite and uses thereof

Abstract: 1,202,097. Delaminated, exfoliated vermiculite; cement compositions. MANDOVAL Ltd. 24 Feb., 1969 [21 March, 1968; 10 April, 1968 (2); 6 June, 1968], Nos. 13825/68, 17415/68, 17418/68 and 27019/68. Headings CIA and ClH. [Also in Division C4] Delaminated, exfoliated vermiculite is claimed per se. It has a flake like form with a width to thickness ratio preferably 3 : 1. It may be prepared by treating exfoliated vermiculite in a sheer action mill such as a hammer mill, the exfoliated vermiculite being preferably fed to the mill by way of an Archimedes screw. The product leaves the mill preferably by way of a herringbone pattern slotted screen. By mixing with binder(s) and optionally filler(s) a sealing or coating composition is obtained (see Divisions A5 and C4). The average largest dimensions of the vermiculite particles in these compositions is preferably not greater than “-inch. The binder may be a clay binder or an hydraulic binder, and the filler may be selected from ground chalk or limestone, pulverized fly ash, and lime. Coatings of delaminated exfoliated vermiculite have the laminµ substantially parallel to the coated surface and are consequently gas and liquid impermeable. Such compositions contain up to 50% by volume of a binder which may be ordinary Portland cement, white, sulphate resisting or rapid hardening Portland cement, lime or high alumina cement or mixtures thereof.

Significance of total and water-soluble alkali contents of portland cement

Abstract: THE PORTION OF THE ALKALIES IN THE CLINKER THAT ARE WATER SOLUBLE DEPENDS ON THE FORM OF THE ALKALIES, WHICH IN TURN DEPENDS ON THE CHEMICAL COMPOSITION OF THE RAW MIX AND THE CONDITIONS DURING THE BURNING OPERATION. IT WAS FOUND THAT THE AMOUNT OF THE ALKALIES THAT ARE WATER SOLUBLE CAN VARY FROM LESS THAN 10 TO OVER 60 PER CENT OF THE TOTAL ALKALI CONTENT. IN SOME CASES A BETTER CORRELATION WAS OBTAINED BETWEEN THE SOLUBLE ALKALI CONTENT AND THE AMOUNT OF MORTAR EXPANSION THAN BETWEEN THE TOTAL ALKALI CONTENT AND THE AMOUNT OF EXPANSION. SOLUBLE ALKALIES WERE FOUND TO HAVE A SIGNIFICANT EFFECT ON THE RATE OF HYDRATION BUT NOT ON THE PH OF THE AQUEOUS EXTRACT FROM CEMENT PASTES. EVEN AFTER HYDRATION AT ROOM TEMPERATURE FOR ONE YEAR, A CONSIDERABLE PORTION OF THE ALKALIES IN CEMENT MAY NOT BE WATER SOLUBLE. /AUTHOR/

Method for stabilizing aluminous cements and cements obtained

Abstract: A process for the stabilization of aluminous cements is disclosed wherein a substance is added to the anhydrous cement mixture to prevent the formation of cubic aluminate and free water in the cement. Substances capable of forming alkaline earth carbonates, or hydroxy carbonates or precursors thereof, the natural and synthetic calcium borates, organic complexing agents for aluminum, diamino-benzene, and o-aminophenol and ethers, esters, ammonium salts and anhydrides of the complexing agents, diamino-benzene, and o-aminophenol may be used. The amount of carbonate-containing or carbonate-forming substance which is added should be sufficient to correspond to an addition of alkaline earth carbonate of about 10 percent by weight based upon cement. The amount of calcium borates which may be added ranges from 2 percent to 5 percent and the amount of organic complexing agent, diaminobenzene and o-aminophenol or the respective ether, ester, ammonium salt or anhydride which are added should be about 0.1 percent to 0.5 percent.

The effect of mix proportions and aggregate dust upon the compressive strength of concrete

Abstract: Summary The compressive strength of concrete at a constant cement/water ratio is shown to decrease with increasing cement contents and therefore confirms earlier work in Europe. This decrease, however, is generally quite small especially for the uniaxial compressive strength. Two exceptions are possible, depending upon the sand content: at high sand contents a critical maximum sand/cement ratio is exceeded such that air voids become unavoidable and the strength decreases with decreasing cement content; at low sand contents a critical minimum sand/cement ratio is not attained and large losses in strength then occur with increasing cement contents. The critical minimum sand/cement ratio depends upon the type and grading of the aggregate and the mix proportions. It is due to the onset of very extensive ‘water gain’ and to the lack of adequate restraint to shrinkage of the cement paste. These effects can (and should) be avoided in normal concretes. The presence of dust in the fine aggregate can be beneficial....

Polymer modified mortars

Abstract: Aqueous polymer dispersions admixed to cement concretes or mortars affect their properties. Some research work has been made to find the optimum type and proportion of polymer dispersion admixture, and to see how concrete and mortar properties are thereby modified.

Effect of cement hydration of concrete form pressure

Abstract: THE PRESSURE OF CONCRETE ON FORMS AS AFFECTED BY CEMENT HYDRATION AND INDIVIDUAL CONCRETE INGREDIENTS AT 70 F (21 C) WAS STUDIED. THE EFFECT OF CEMENT HYDRATION WAS INVESTIGATED BY COMPARING THE BEHAVIOR OF CONCRETE WITH AND WITHOUT A WATER-REDUCING, SET RETARDING AGENT TO THE NONHYDRATING MIXTURE CONTAINING FLY ASH WHICH HAD ABOUT THE SAME PLASTIC PROPERTIES AS CONCRETE. OIL FILLED PRESSURE CELLS WERE ADAPTED TO MEASURE PRESSURE IN A FORM 10 FT. (3.05M) HIGH X 3 FT. (0.91 M) WIDE X 1 FT. (0.30 M) THICK. RESULTS INDICATE THAT UNDER THESE CONDITIONS, A WORKABLE CONCRETE HAVING A 2 TO 4 IN. (76 TO 102 MM) SLUMP DOES NOT BEHAVE AS FLUID FOR ANY APPRECIABLE TIME WITHOUT SOME OUTSIDE ENERGIZING FORCE SUCH AS VIBRATION. THE ARCHING ACTION OF THE AGGREGATE IS THE EARLIEST FACTOR TO LIMIT THE LATERAL PRESSURE TO 5 TO 6 PSI (0.35 TO 0.42 KG/CM2) EQUIVALENT TO 5 TO 6 FT. (1.52 TO 1.83 M) OF HEAD, WITH THE METHOD OF PLACEMENT AND VIBRATION USED. HYDRATION OF THE CEMENT TENDED TO LIMIT FORM PRESSURE UNDER THE NORMAL VIBRATION USED, BUT DID NOT PREVENT AN INCREASE IN PRESSURE BROUGHT ABOUT BY REVIBRATION UNTIL AFTER 4 HOURS. THE EFFECT OF SET RETARDING AGENT ON CEMENT HYDRATION DID NOT SIGNIFICANTLY ALTER THE PRESSURE. /AUTHOR/