Air entraining agent for concrete and mortar mixtures

Details Air entraining agent for concrete and mortar mixtures Air entraining agent for concrete and mortar mixtures

1996-09-26

1998-06-02

Marcantoni, Paul

Compositions: coating or plastic

Coating or plastic compositions

Inorganic settable ingredient containing

106696, 106727, 106808, 106822, C04B 2434

Patent

active

057592594

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

Many concrete buildings and concrete structures are exposed to constant stress due to environmental influences. For example, cement concrete road surfaces are subjected to frequent changes between frosts and thaws during winter, and possibly an additional effect of chemical thawing agents that can lead to premature destruction of the concrete. This is also the case for concrete buildings or parts thereof, which are subjected to similar conditions, for example in the air-placed-concrete regions of road surfaces or in hydraulic structures. Concrete can be damaged or destroyed by frequent changes between frosts and thaws if its pores are filled with water to the extent that the concrete has a critical degree of saturation. The mechanisms that cause this type of damage are only partially understood. Because of the influence of surface forces in the fine capillary pores of the cement stone, as well as the lowering of the freezing point due to dissolved substances in the pore water, the water in the cement stone does not yet freeze at 0.degree. C. Instead, the proportion of freezable water increases steadily as the temperature continues to drop. Hydrostatic pressures in the water that has not yet frozen, which are triggered by the increase in the volume of the frozen water, as well as osmotic pressures and a redistribution of the water in the pore system of the cement stone can lead to such high internal tensions that the concrete is destroyed. However, concrete buildings and structures can be produced to have a high resistance to frost if a sufficient expansion space is created through the artificial introduction of finely-distributed air pores. These finely-distributed air pores can be introduced artificially by the addition of suitable substances that create defined expansion spaces in the hardening mixture to concrete and mortar mixtures; for their part, these expansion spaces reduce or prevent damaging tensions caused by freezing water. A wide variety of substances has been proposed for this purpose, such as: concrete by triggering a chemical reaction, plastics or inorganic materials, or mixtures of these materials.
All of these methods have known disadvantages, and cannot be used in every application. In particular, the method described under 1) has been used in numerous cases because of the extraordinary simplicity and good reproducibility of the metering of the surfactant. Examples of these air entraining agents include alkali salts from resin acids, sulphonated resin acids, alkali sulphonates, alkyl sulphonates, alkylarenesulphonates, fatty acid salts, etc.
The surface-active substances used range from anion-active to non-ionic to cation-active substances, as described in, for example, EP 0 054 175, U.S. Pat. Nos. 4,019,916, 4,249,948, 4,453,978 or SU 629 185.
The aforementioned resin acids or their derivatives were used especially frequently as air entraining agents. For example, the use of a wood rosin called "Vinsol" is generally regarded as prior art, and "Vinsol Resin" is also accepted as a standard in ASTM Specification C-226-86, "Air Entraining Additions for Use in the Manufacture of Air Entraining Portland Cement" and is cited by name.
Moreover, a wide range of other modified resins or their soaps are known which act as air entraining agents. The use of a resin modified with an adduct of ethylene oxide laurylamine as an air entraining agent is known from JP 58 01057.
An air entraining agent based on a tall resin methylolized with paraformaldehyde is described in DD 291901.
Another method, as described in SU 800 157, provides that, prior to being saponified, the resin acids used are subjected to a thermal oxidation, the result of which is a dimeric product.
JP 57 166352 describes the use of a colophony as an air entraining agent, the resin having been reinforced with maleic anhydride and esterified with polyethylene glycol and subsequently saponified with KOH.
The proportion and quality (pore diameter, spacing factor) of the air pores entrained in the concrete, as wel

REFERENCES:
patent: 2510776 (1950-06-01), Gabrielson
patent: 4019916 (1977-04-01), Golightly et al.
patent: 4046582 (1977-09-01), Kawamura et al.
patent: 4249948 (1981-02-01), Okada et al.
patent: 4453978 (1984-06-01), Okimura et al.
patent: 4948429 (1990-08-01), Arfaei
patent: 5156679 (1992-10-01), Gartner et al.
patent: 5522927 (1996-06-01), Hegge
"Gum rosin Salt Air Entraining Hydraulic Cement Admixture . . . " Jeknavorian US Open App. No. 09503688W Published Oct. 12, 1995.

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