Sulfate resistance

Type V (High Sulfate Resistance). Type V Pordand cement is used in concrete exposed to severe sulfate attack of 1,500 to 10,000 ppm. Low concentrations of tricalcium aluminate [12042-78-3] give Type V its sulfate resistance. The sulfate resistance is improved with air entrainment and low water to cement ratios in the wet concrete. U.S. production of Type V Pordand cement in 1989 was 0.9% of the total Pordand cement production. 

Other countries have similar types, some classifications, as in Germany, are based on age-strength levels by standard tests (70). A product made in Italy and Prance known as Perrari cement is similar to Type V and is sulfate-resistant. Such cements have high iron oxide and low alumina contents, and harden more slowly. 

Tetracalcium aluminoferrite (4CaO Al O, FeOj) has little effect on the physical properties of the cement. For high-sulfate-resistant (HSR) cements, API specifications require that the sum of the tetracalcium aluminoferrite content plus twice the tricalcium aluminate may not exceed a maximum of 24%. 

Class B Intended for use from surface to 6,000 ft (1,830 m) depth, when conditions require moderate to high sulfate resistance. Available in both moderate (similar to ASTM C 150, Type II) and high-sulfate-resistant types. 

Class E Intended for use from 10,000 to 14,000 ft (3,050 to 4,270 m) depth, under conditions of high temperatures and pressures. Available in both moderate and high-sulfate-resistant types. 

Class H Intended for use as a basic well cement from surface to 8,000 ft (2,440 m) depth as manufactured, and can be used with accelerators and retarders to cover a wide range of well depths and temperatures. No additions other than calcium sulfate or water, or both, shall be interground or blended with the clinker during manufacture of Class H well cement. Available in moderate and high- (tentative) sulfate-resistant types. 

Select the most appropriate API class of cement that meets the depth, temperature, sulfate resistance and other well limitations. Select the cement class that has a natural thickening time that most nearly meets the cementing operation time requirement, or that will require only small amounts of retarding additives. 

E Retarded 3000-4000 High temperature, high pressure moderately or highly sulfate resistant... 

Sulfate-resisting cement, 5 498 Sulfate surfactants, 24 145 Sulfate titanium dioxide production process, 29 388-391 Sulfathiazole, 28 684 Sulfation, 23 513, 514, 536-538 higher aliphatic alcohols, 2 4 in higher olefins, 27 713 Sulfation operations, industrial changes affecting, 23 515-516 Sulfation processes, general overviews of, 23 555... 

It was shown earlier that aggregate types do not materially affect the performance of water-reducing admixtures. This is not true for cement and mixes containing special cements require particular care. Examples here are increased retardation with low C3A cement (for example, sulfate-resistant cement) and... 

In view of the known deleterious effect of admixtures containing calcium chloride and the possibility of the same effect being found with calcium formate, it is suggested that accelerating water-reducing admixtures should not be used in those areas where sulfate resistance is of importance. 

Table 1.21 Sulfate resistance of concrete mixes containing water-reducing agents (no mix design changes other than addition of water-reducing admixture)...

Table 1.22 Sulfate resistance of reduced water-cement ratio and corresponding mix... 

Calcium chloride at 2% addition level contributed to a lowering of sulfate resistance in almost all cases. 

Fig. 5.26 CaCl2 is least detrimental to sulfate resistance with Type V cement (low C3A (Shideler). 

Dunstan, E. R. 1980. A possible method for identifying fly ashes that will improve the sulfate resistance of concrete. Cement, Concrete, Aggregates, 2, 22-30. 

Tikalsky, P. J. 1989. The Effects of Fly Ash on the Sulfate Resistance of Concrete. PhD dissertation, University of Texas at Austin, August. 

Another example of an important construction material in the Middle East is portland cement. For example, all-purpose Type I and sulfate-resisting Type V portland cements are manufactured in Saudi Arabia in three plants at Hofuf, Jeddah, and Riyadh. The cement production from the three plants totaled 1,790,000 tons in 1978 which is about a 38.5 percent rise over 1977. Portland cement is a basic construction material, and is primarily consumed by the construction industry. In Saudi Arabia cement does not seem to be encountering competition from any other building materials which are capable of endangering its present level of demand. 

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