Cement calcium chloride

Portland cement Calcium chloride Phosphonium complexone Water 69-70 2.0-3.5 0.020-0.035 up to 100... 

N. B. Savenok, N. A. Mariampolskij, P. N. Mariampolskij, and L. A. Loshmankina. Plugging solution—contains Portland cement, calcium chloride, phosphonium complexone containing amine-group and water and has high adhesion to stratal rock. Patent SU 1802088-A, 1993. 

In the hydration of portland cement, although initially larger amounts of heat are developed in the presence of Ca formate, at later ages the heat may be slightly lower or equal to that of the reference material. Calcium formate accelerates the hydration of all types of cement. Figure 18 gives the relative amounts of heat produced by adding 0.18 molar calcium chloride, calcium nitrite, and ealeium formate to Type V cement. Calcium chloride is the best accelerator followed by calcium formate. ... 

For concrete work in cold weather a specially rapid-hardening cement may be made by addition of calcium chloride to the cement. 

In concrete, triethanolamine accelerates set time and increases early set strength (41—43). These ate often formulated as admixtures (44), for later addition to the concrete mixtures. Compared to calcium chloride, another common set accelerator, triethanolamine is less corrosive to steel-reinforcing materials, and gives a concrete that is more resistant to creep under stress (45). Triethanolamine can also neutralize any acid in the concrete and forms a salt with chlorides. Improvement of mechanical properties, whiteness, and more even distribution of iron impurities in the mixture of portland cements, can be effected by addition of 2% triethanolamine (46). Triethanolamine bottoms and alkanolamine soaps can also be used in these type appUcations. Waterproofing or sealing concrete can be accompUshed by using formulations containing triethanolamine (47,48). 

Galvanised steel provides increased corrosion resistance in carbonated concrete. In concrete with more than 0.4% chloride ion with respect to the cement content, there is an increased risk of corrosion and at high chloride contents the rate of corrosion approaches that of plain carbon steel. In test conditions the rate of corrosion is greater in the presence of sodium chloride than calcium chloride. Fusion-bonded epoxy-coated steel performs well in chloride-contaminated concrete up to about 3.9% chloride ion in content. 

Three other compounds of s-block elements—calcium oxide (CaO, known as lime ), sodium hydroxide (NaOH), and sodium carbonate (Na2 CO3)—are among the top 15 industrial chemicals in annual production. Lime is perennially in the top 10 because it is the key ingredient in construction materials such as concrete, cement, mortar, and plaster. Two other compounds, calcium chloride (CaCl2 ) and sodium sulfate (Na2 SO4 ), rank just below the top 50 in industrial importance. 

The ZOE impression paste is essentially a two-paste ZOE cement. One paste is formed by plasticizing the zinc oxide powder with 13 % of mineral or vegetable oil. The other paste consists of 12% eugenol or oil of cloves, 50% polymerized rosin, 20% silica filler, 10% resinous balsam (to improve flow) and 5 % calcium chloride (accelerator). 

Cement accelerators are shown in Table 10-12. The most common accelerators are calcium chloride and sodium chloride. Calcium chloride may be used in concentrations up to 4% by weight in wells with bottom-hole temperatures less than 50° C. Calcium chloride tends to increase the final strength under pressure conditions. 

Antifreezing agents for cement consist mainly of salts such as calcium chloride, magnesium chloride, sodium chloride, and soda. Calcium chloride is highly corrosive and very restricted in use. Some salts, especially potassium chloride, will affect the curing time of cement. The latter chemical is in fact used to increase the pot life of cement. Likewise, alcohol freezing-point depressants, such as ethylene glycol, can be also included in the composition [1022]. 

Small amounts of phosphonium complexone [1560] are sufficient to increase adhesion to the stratal rock. Table 18-4 illustrates an example for plugging solution with Portland cement and phosphonium complexone. Calcium chloride acts as a regulator of the setting time in the suggested composition. More precisely, phosphonium complexone stands for certain chelating phosphorous compounds (e.g., oxyethylidene diphosphonic acid, nitrilo-trimethyl phosphonic acid, sodium tripolyphosphate, or amiphol) [1540]. The mixture is applicable at low temperatures from 20° to 75° C. 

V. B. Kvashenkin. Plugging solution for cementing low pressure oil and gas wells—contains plugging Portland cement, waste of silicon production as the lightening additive and calcium chloride as mineral salt, and water. Patent SU 1832149-A, 1993. 

P. F. Tsytsymushkin, S. R. Khajmllin, A. P. Tamavskij, Z. N. Kudryashova, P. V. Kovalenko, V. N. Levshin, and B. V. Mikhajlov. Plugging solution for cementing oil and gas wells in salt-bearing strata—contains plugging cement, sodium chloride, calcium chloride, additional preparate bakteritsid, and water. Patent SU 1803531-A, 1993. 

Bioactive PMMA bone cement prepared by modification with methacryloxypropyltrimethoxy silane and calcium chloride. Journal of Biomedical Materials Research, 67A, 1417-1423. 

Calcium chloride has several industrial applications. The major applications of this compound are in deicing of roads, dust control, imparting stability to roads and buildings, and to improve traction in tractor tires. It is mixed with ice to make freezing mixtures. Hexahydrate mixed with crushed ice can lower the temperature of the cooling bath to below -50°C. It also is used as a desiccant for dehydrating gases and liquids. It is added to cement in various proportions to manufacture different types of concrete. Other uses are in adhesives, to lower gel temperatures, and as a calcium source in liquid feed supplements for dairy cattle. Also, the compound is used to control particle size development and reduce coalescence in plastics. 

The action of an admixture in relation to attack on reinforcement can be considered either in direct chemical reaction with the steel or, alternatively, a breakdown of the passive layer imparted by concrete which normally prevents corrosion at the cement/steel interface. In this respect, any accelerating water-reducing admixtures containing calcium chloride can be considered hazardous as far as raising susceptibility of steel reinforcement to corrosion is concerned. It is particularly so at calcium chloride contents in the concrete at or above 1.5% by weight of cement as discussed in the section on accelerators. The use of such materials has been controlled by relevant codes of practice where embedded metal is present in the concrete. 

The data presented in this section illustrate that, with the exception of those accelerating water-reducing admixtures containing calcium chloride, there is an abundance of evidence to support the conclusion that water-reducing admixtures of lignosulfonate chemical form certainly will not accelerate any kind of corrosion with reinforcement and, when used to reduce the water-cement ratio, will form a more permeable and durable protective cover for the reinforcement. In view of the chemical nature of the other types of materials such as the hydroxycarboxylic acids and hydroxylated polymers, it seems most likely that these materials too would have no deleterious effect in this respect. 

The reactions between calcium chloride and the constituents and reaction products of Portland cement have been widely researched and are of importance in practice, since the risk of corrosion of reinforcement depends, at least in part, on the amount of chloride which is left in a free state in solution in the concrete [4]. 

The following points are relevant to the reactions occurring in pastes of Portland cement containing normal proportions of C3A, C3S, C2S, C4AF and gypsum in the presence of calcium chloride. 

Calcium chloride does not react significantly with cement pastes for a period of 2-6 h [1, 5] after mixing, although rapid setting can occur in this period. 

Fig. 5.9 The degree of hydration of cement pastes in the presence of calcium chloride in comparison to a plain paste measured by X-ray analysis (Young). 

The differences in chemical composition are accompanied by differences in the morphology of the tobermorite gel. Spicular or cigar-shaped rolled sheets are formed in the normal plain hydrated cement paste, whilst in the presence of calcium chloride, thin crumpled sheets or foils are formed. It has been suggested [16] that either the high lime content or adsorbed chloride prevents rolling of the sheets. 

Accelerating admixtures based on calcium chloride, formate, nitrate, and thiocyanate have no significant effect on the workability, air content, mix stability, or water-cement ratio of concretes into which they are incorporated. The only properties of plastic concrete which are affected are the heat evolution and setting time. 

The composition of the Portland cement in the concrete can also influence the effectiveness of both calcium chloride and calcium nitrate and a regression analysis [26] for data for 10 cements produced the equation... 

The resistance of concrete containing calcium chloride to attack by aqueous sulfate is reduced [22, 31, 33], A comprehensive study of concrete over a 5-year period [24] using various cements and cement content stored in high-sulfate-containing water, gave the results shown in Figs 5.24 to 5.29, for which the following conclusions can be reached ... 

The presence of calcium chloride at concentrations greater than about 1.5% by weight of cement can lead to breakdown of the passive layer of Fe203 normally present at the steel/concrete interface, rendering the... 

The general conclusion can be reached that in well-designed properly compacted concrete, the addition of up to 1.5% by weight of cement of calcium chloride and 0.5% of thiocyanate ion can be used without any significant detrimental effect on embedded ferrous metals. 

The drying shrinkage of concrete containing calcium chloride is increased in comparison to plain concrete, even though the amount of moisture lost is less [22]. This is illustrated in Fig. 5.37 and it is thought that the reduced moisture loss will be due to the more advanced state of hydration in the specimens containing calcium chloride. The increased shrinkage must, therefore, be a characteristic of the type of cement hydration products formed. Under saturated conditions, such as total water immersion, the amount of expansion of the concrete is reduced when calcium chloride is present. 

The creep of concrete under drying conditions is increased by the presence of calcium chloride in the mix [30], as shown in Fig. 5.38 for 1.5% calcium chloride by weight of cement. 

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