Cements waterproofing

Architectural Institute of Japan (AIJ) Recommendation and Guideline (Japan) PMC, PC and PIC Recommendation for practice of concrete-polymer composites Recommendation for practice of survey, diagnosis and repair for deterioration of reinforce concrete structures Guideline for polymer-modified cement waterproofing membrane work... 

Architectural Institute of Japan (AU) Guideline for Polymer-Modified Cement Waterproofing Membrane Work (in Japanese), AU, Tokyo (2006). 

Samples ofmaterials usedfor insulation, cementing, waterproofing of insulation and external cladding shouldl be preserved for future reference. 

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). 

In contrast to other polymers the resistance to water permeation is low due to the hydrolysis of the poly(vinyl acetate) (163,164). Ethylene copolymers have been developed which have improved water resistance and waterproofness. The polymer can be used in the latex form or in a spray-dried form which can be preblended in with the cement (qv) in the proper proportion. The compressive and tensile strength of concrete is improved by addition of PVAc emulsions to the water before mixing. A polymer-soHds-to-total-soHds ratio of ca 10 90 is best. The emulsions also aid adhesion between new and old concrete when patching or resurfacing. 

Water resistance is an important factor in concrete and masonry constmetion for the safety, health, and comfort of buUding occupants (see Cement). Several texts on concrete constmetion describe the methods for obtaining water resistance (72—76). The term waterproof describes concrete and masonry that is completely impervious to water and its vapor, whether or not the water is under pressure. Waterproof constmetion involves the use of some type of barrier that covers aU surface pores or capUlaries. Water repeUent describes concrete or masonry that repels water without significantly reduced permeabUity to water vapor. In this discussion, concrete and masonry are used synonymously. 

Water-Repellent. Three techniques used for water repeUency are modification of cement by the addition of waterproofers, use of repellent additives to the concrete mix, and surface treatment of concrete stmctures with repellents. The modification of portland cement by intergrinding with stearate salts or other water-repellent material can reduce the water permeabiUty of mortar. Considerable controversy exists, however, as to whether these cements produce concrete that is superior to carefully mixed concrete without such additives (79). 

Specifically, the improved solidification (cementation) technology involves the use of (a) a special dry powder admixture for the generation of a nonsoluble crystalline formation deep within the pores and capillary tracts of the concrete—a crystalline structure that permanently seals the concrete against the penetration or movement of water and other hazardous liquids from any direction (b) special nonmetal reinforced bars for enhancing the concrete block s tensile and compressive strengths and (c) a unique chemical crystallization treatment for the waterproofing and protection of the concrete block s surface. 

Surface bonding mortar or cement is mentioned in some building codes as an approved dampproofing treatment, but not as a waterproofing treatment. A number of manufacturers produce cements and mortars impregnated with fibrous glass or other fibers. Some of these may be chemically unstable in the alkaline environment of Portland cement. 

One technique of assembly using surface bonding cement is to dry stack blocks and apply the cement on both sides. As an alternative, the block wall is conventionally assembled with only an outside coating as a positive-side waterproofing. 

Hydraulic Cements. To build constructions submerged in a sea, lake, or river, it is necessary to use waterproof cements, generally known as hydraulic cements, which harden even in the presence of excessive amounts of water. In the past, such cements were prepared by heating a mixture of limestone and a considerable amount of clay or other powdered siliceous material. At high temperature (above 650°C), the quicklime, formed when the limestone... 

Celsius (°C) A scale for measuring temperatures, also known as the centigrade scale, where the freezing point of water is 0°C and the boiling point 100°C. cement A natural or artificial fluid or semifluid substance, or mixture of substances, that hardens to act as an adhesive for binding solid surfaces together, cement, hydraulic A type of waterproof stony cement that sets even under water see pozzolana. 

Herodotus (484-425 B.C.) mentioned the occurrence of many lumps of bitumen in the River Is, a small tributary of the Euphrates (10). The Babylonians heated this bitumen and used it instead of mortar for cementing together the bricks of their walls and buildings (11). Herodotus also spoke of a well near Susa (the Shushan of the Bible) which yielded bitumen, salt, and oil (11). Cornelius Tacitus, a friend of Pliny the Younger, described the bitumen of the Dead Sea (12). R. J. Forbes states in his book Bitumen and Petroleum in Antiquity that the ancients used tar and pitch for waterproofing pottery, for caulking ships, and for making torches, paint for roofs and walls, and lampblack for paints and ink (13). 

After loading Tetryl at the open end, a coat of waterproof cement is applied on the surface of Tetryl (Ref 23, pp 4-8 to 4-10)... 

The presence of the cement hydrate/polymer comatrix in LMM and LMC confers superior properties, such as high tensile and flexural strengths, excellent adhesion, high waterproofness, high abrasion resistance and good chemical resistance, when compared to ordinary cement mortar and concrete. The degree of these improvements however depends on polymer type, polymer-cement ratio, water-cement ratio, air content and curing conditions. Some of the properties affected by these factors are discussed below [87, 88, 93-95],... 

Three items are important in the storage of admixtures, namely, the ease of identification, humidity and temperature at which they are stored. To avoid confusion between different admixtures, drums should be delivered clearly labeled as to the contents identification can be made easier by a colorant which has no influence on the concrete. Powdered admixtures are more sensitive to moisture and carbon dioxide than are Portland cements. The materials should, therefore, be packed in waterproofed bags and always stored in areas free of high relative humidity and temperature extremes to avoid condensation. Storage tanks should be vented properly, and fill nozzles and any other tank openings should be capped when not in use to avoid contamination. 

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