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Non-Hydraulic Macro-Detect-Free Cementitous Products

IP.com Disclosure Number: IPCOM000034033D
Original Publication Date: 1989-Jan-01
Included in the Prior Art Database: 2005-Jan-26
Document File: 2 page(s) / 14K

Publishing Venue

IBM

Related People

Shafer, MW: AUTHOR [+2]

Abstract

A technique is described whereby a non-hydraulic process is implemented for macro-detect-free (MDF) type of cements so as to obtain stronger cement products than polyelectrolyte cements. The process is totally compatible with current MDF processes. Generally, Portland cements have been used as structural materials due to the low cost. In an effort to improve tensile strength of cements, MDF cements have been initiated and to eliminate the relatively large pores in the set cement, certain polymers have been added and unique processing conditions used. Although these steps effectively reduces the pore size in the hardened cement paste and increases the strength, through the Griffith criterion, the cements are still hydraulic and most of the water added to the pastes remains in the hardened cements as structural water.

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Non-Hydraulic Macro-Detect-Free Cementitous Products

A technique is described whereby a non-hydraulic process is implemented for macro-detect-free (MDF) type of cements so as to obtain stronger cement products than polyelectrolyte cements. The process is totally compatible with current MDF processes. Generally, Portland cements have been used as structural materials due to the low cost. In an effort to improve tensile strength of cements, MDF cements have been initiated and to eliminate the relatively large pores in the set cement, certain polymers have been added and unique processing conditions used. Although these steps effectively reduces the pore size in the hardened cement paste and increases the strength, through the Griffith criterion, the cements are still hydraulic and most of the water added to the pastes remains in the hardened cements as structural water. On the other hand, polyelectrolyte cements have been developed for use in areas such as used in dental materials. Inorganic materials, such as zinc oxide or calcium phospho-aluminosilicate glass products are reacted with a polyelectrolyte, such as poly(acrylic acid) to form basically non-hydraulic solid products. Water is also used in the paste, but the water is used to function as a transport media rather than a structural constituent of the final cement. The poly(acrylic acid) dissolved in water reacts with cations leached out to the surface of the solid powder and forms an insoluble solid. Such cements have been shown to be durable in a mildly hostile environment and to be adhesive to some metals including copper and stainless steel. However, the polyelectrolyte cement is not as strong as the MDF cement and is found to be difficult to remove the water used in the reaction of the polyelectrolyte cement formation. The concept described herein provides a non-hydraulic process for MDF-type cements so as to obtain products which are much stronger, tougher and less expensive than the polyelectrolyte cements. The process is totally compatible with current MDF cement processes in that the paste can be mixed, kneaded, sheared, pressed, or molded before setting. A typical application would be circuit boards made from these cements, which can be bonded with conductive layers of metal, on one or both sides, at or near room temperature. The process essentially consists five steps: 1) Weighing the commercial Portland cement and the

poly(acrylic acid) by the weight ratio, generally in the

range of 100/5 and 100/50.

2) Mixing them in dry or in an inert liquid, such as

hexane.

3) Kneading the mixture with acetone.

4) Passing the high shear process such as a roller mill

5) Mold and/or press to the final form before setting. The combination of the Portland cement an...