THE SETTING and hardening of portland cement can be influenced by chemical additives. Several kinds of retarders and accelerators are known. A special committee of the American Concrete Institute summarized the effect of additives upon the properties of concrete (1). The most widely used accelerator is calcium chloride, which almost all commercially manufactured accelerators contain.
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We investigated the effects of hydrogenrich water (HRW) on the strength and durability of Portland cement mortars. We comparatively assessed the performances of HRWbased mortars (HWMs) with respect to cement mortars fabricated from control water (CWM). The results indicate that the use of HRW significantly improves the compressive, flexural, and splitting tensile strength of mortars at .
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Jun 21, 2017· gypsum is a type of mineral and a hydrated calcium sulfate in chemical form. It plays a vital role in compensating the rate of hardening of the cement. It is used to control the setting time of cement but if it is in excess it may unsound the ce...
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may also cause an incompatibility between the cement and certain types of admixtures such as superplasticisers. Such incompatibility may cause false set or quick set of the fresh cement pastes [13,14]. Mork and Gjoerv used three different gypsumhemihydrate ratios, namely 80/20, 50/50 .
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Portland cement is the most common of the "hydraulic" cements, which set and develop strength through hydration, not by drying out. Hydration involves chemical reactions between water and the cement It therefore sets and hardens whether left in air or submerged in water. Once set, it has low permeability and resists
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title = "Effect of additives on the compressive strength and setting time of a Portland cement", abstract = "Improvements in strength and setting time of Portland cements (PC) are needed to enhance their performance as endodontic and load bearing materials.
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Chemical Properties of Cement. Silica fumes Silica fume is added to cement concrete in order to improve a variety of properties, especially compressive strength, abrasion resistance and bond strength. Though setting time is prolonged by the addition of silica fume, it .
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Numerous ref erences were found on the subject of acceleration of the setting time of portland cement or on special rapid setting mixes, However, almost all of these references pertain to methods of shortening the setting time of cement 10 to 20 percent.
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By replacing the pozzolana in cement content ball bearing effect and particle packing effect can be reduced in the concrete. Pozzolanic materials generally used for manufacture of Portland cement are calcinated clay (lS: 1489 part 2 of 1991) or fly ash (IS: 1489 part 1 of 1991) Composition and manufacturing of pozzolana Portland cement (PPC):
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Manufacturing of Portland Cement The details of the cement making process vary widely. However, the fundamental stages in cement production are all the same and as follow. A schematic diagram of the cement manufacturing is shown in • 1. The raw materials are reduced to fine particle size. • 2.
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Based on that, it was assumed that 5% (in weight) of Portland cement represented the concentration that exerted less influence on the experimental cement's properties (setting time and color). Glycerol salicylatebased cement is set by an acidbase reaction .
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and humidity which influence setting and hardening of Portland cement. Setting is important in concrete work to keep fresh concrete plastic for enough time which helps the processes of .
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which the initial set of test specimens for apparent viscosity, bond to concrete, softening point, resilience, asphalt compatibility, fingerprinting and cone penetration will be prepared. The sealant material remaining in the melter will be kept at the manufacturer's maximum heating temperature
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Aug 01, 2000· To verify the effect of insoluble residue on the properties of Portland cement, artificial insoluble residue was prepared and replaced in Portland cement type I. Finely crushed sand was extracted to represent artificial insoluble residue. Setting times and compressive strengths of cement mortar mixed with insoluble residue were investigated.
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all. Instead of drying, Portland cement sets. Setting results from a chemical reaction known as hydration, which occurs when Portland cement and water mix, forming a third substance. And because the chemical reaction creates a completely different third substance, Portland cement that has set is no longer soluble by water.
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Portland cement clinker is made by heating, in a cement kiln, a mixture of raw materials to a calcining temperature of above 600 °C (1,112 °F) and then a fusion temperature, which is about 1,450 °C (2,640 °F) for modern cements, to sinter the materials into clinker.
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