The Dow Chemical Company

Gale L Emig

R Douglas Eash

Daniel G Moldovan

Ronald H Cooper

Robert H Anspaugh

This invention relates to a latex-modified, pretensioned, and prestressed concrete structure having at least about a 50% reduction in bond transfer length as compared to a structure not modified by a latex. Such structure is composed of a cured concrete composition comprising a mixture of (1) portland cement, (2) mineral aggregate, and (3) a vinylidene chloride polymer latex, said latex being present in an amount sufficient to provide from about 5 to about 25 percent by weight of polymer solids.

Latex-modified, pretensioned and prestressed structures having enhanced

This invention pertains to improved shrinkage compensating portland cement concrete and mortar compositions comprising essentially an expansive portland cement, mineral aggregate, from about 5 to about 25 percent based on cement weight of a styrene-butadiene-1,3 copolymer having a styrene to butadiene weight ratio of about 30:70 to 70:30, water and certain minor amounts of nonionic and anionic surfactants, and a foam depressant. When properly restrained by either external restraints or internal restraints in the form of ordinary reinforcement or fibers of various lengths, these compositions possess improved mechanical and physical properties such as compressive and flexural strengths and unexpectedly enhanced freeze-thaw resistance. Such compositions are particularly suited for use in the construction of crack-free structures.

Shrinkage-compensating portland cement concrete and mortar compositions

A process for accomplishing a non-distressing accelerated heat cure of portland cement concrete systems comprising (1) admixing portland cement concrete with minor amounts of a vinylidene chloride polymer latex, than (2) heating the admixture to temperatures of from at least about 100.degree. F to about 250.degree. F under less than about 80 percent relative humidity for a period of at least about 4 hours. This process is particularly applicable for the preparation of portland cement concrete precasting and prestressing operations, where optimum strength is desired in the shortest possible time.

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Midland, MI, United States of America

Gale L Emig