0000005140 00000 n (34.13 MPa) after one day and 6500 p.s.i. behavior of expansive clay soils can be modified and con­ trolled by stabilization methods. Unit Binder Content - The sum of cement and expansive admixture used for making 1 m3of expansive concrete, including the masses of fly ash and granulated blast-furnace slag fine powder when these are used as admixtures. Expansive cement shall conform to the physical requirements prescribed. More preferably, the amount is from about 5% to about 7%.

After curing in the stack for 7 25 days, samples of the boards were taken from the stacks and stored until they were 2 months old and then were placed in a carbonation chamber in which the atmosphere was 100% carbon dioxide except for the water vapor necessary to give a relative humidity of 95% at 73,F (23'C). The mix water temperature ranges from about 85'1 to about 1 40'F (30-60'C) 55 and the mortar temperature as it leaves the mixer is from about 65'F to about 11 O'F (18-43C), preferably about 90'F (32'C) or higher. Regrinding of the high alumina cement to a higher fineness allows the utilization of more of the alumina for the 60 production of ettringite within a short period of time. A preferred amount of calcium sulfate is from about 4% to about 8%. The amount of water is determined at least partially by the affinity for water by each of the components and by the surface area thereof, The cementitious compositions of this invention may also contain pozzolanic materials such as fly ash, montmorillonite clay, diatomaceous earth, 40 and pumicite. An expansive clinker containing a stable calcium alumino sulfate compound is separately ground to a selected surface area greater than about 4600 sq. 3,284, 980 (Dinkel) teaches a pre-cast, lightweight concrete panel having a cellular core, a thin, high density layer on each face, and a layer of fiber mesh embedded in each of the high density layers. Expanded polystyrene beads are also very useful as is the use of foaming agents to entrain air in the hardened mortar. Products and Services / Standards & Publications / Standards Products The high water demand of fly ash must be taken into account when determining the amount to be used. The expansion of the cement mortar or concrete is compensated for the shrinkage losses. A particularly preferred blend of powders consists essentially of about 74.8% type Ill portland cement, about 17% high alumina cement, about 7.5% landplaster (i. e., about 5.3% calcium sulfate), and about 0.65% slaked lime. 0000019476 00000 n Permissions to reprint documents can be acquired through 0000086303 00000 n Two batches of cubes, one as a control and one for testing of heat stability, were cast. trailer << /Size 275 /Info 237 0 R /Root 245 0 R /Prev 432789 /ID[<69be8dcc9b55414eb2525b3bd32639f1><69be8dcc9b55414eb2525b3bd32639f1>] >> startxref 0 %%EOF 245 0 obj << /Type /Catalog /Pages 239 0 R /Outlines 217 0 R /OpenAction [ 246 0 R /XYZ null null null ] /PageMode /UseNone /PageLabels << /Nums [ 0 << /S /D >> ] >> >> endobj 273 0 obj << /S 1227 /O 1419 /Filter /FlateDecode /Length 274 0 R >> stream The reaction of CA, C, and CS to yield ettringite proceeds rapidly when continuous saturation of the aqueous phase is promoted by the presence of very small aluminate particles and/or crystals formed at low fusion temperatures.

More particularly, it relates to a cement which will impart to such a panel the properties of high strength at an early age, high strength at high temperatures at a later age, and excellent resistance to carbon dioxide attack at such later age. <> 3 GB2150130A 3 The amount of calcium sulfate in the hydraulic cement of this invention is the controlling factor in the production of ettringite during hydration. ;u1����!bP��άT���\4?

Because calcium sulfate is the most soluble of the reactants in the hydration reactions, its particle size is not so critical to the speed of the hydration. <> Preferred cement compositions of the invention will set and develop strength fast enough after mixing with water to allow the production of cement board at about 20 to about 150 lineal feet 35 per minute (20 to 150 em/sec.). A cement compositions according to claim 6 in admixture with up to 25% by weight thereof of pozzolanic material.9. Azuma et al teaches that an aging and hardening process must be initiated within 4-8 hours after the cement mixture is shaped into an article. <> cements hydrating into ettringiteCEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIESLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. As important as the physical environment factors are to the behavior of expansive clay soils, the chemical environment around and inside clay particles affects their behavior much more profoundly. The term -hydraulic cement- as used herein, is understood to include any cement which has the characteristic of hardening under water, e.g., portland cement, blends of portland cement and high alumina cement, and mixtures of portland cement and blast-furnance slag. A method of forming a hydraulically set product from a composition according to claim 1 or 6, the method being substantially as hereinbefore described.6 GB2150130A 6 Printed in the United Kingdom for Her Majesty's Stationery Office, Dd 8818935. cements hydrating into ettringiteCEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIESLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. 0000086219 00000 n The set times and the GB 2 150 130A 5 compressive strengths are given in Table Ill. Compressive Strength (psi)' 5 Example Set (min.)