Polymer impregnated concrete (PIC) was overlaid with a low slump dense concrete (LSDC) or a latex modified concrete (LMC). Flexure strength, compressive strength, and freeze-thaw durability data were obtained on the composite specimens. Flexural data indicated a strong bond was established between LSDC, LMC, and PIC. Compressive strength data indicated the bond was weaker for the LMC than the LSDC. Freeze-thaw data showed that a durable bond was established between the PIC and the LSDC whereas the bond failed between the PIC and the LMC.

An epoxy resin system has been developed for modificat-ion of concrete providing handling and performance advantages over other polymer types. Description of two applications are pro-vided. Estimated costs of applied epoxy modified concrete are presented.

Polymer concrete has been successfully developed for use as an electrical insulating material. Work done at the Instituto de Investigaciones Electricas in Mexico has resulted in formulations using native materials and manufacturing techniques which promise to replace electrical porcelain in many instances. The technology and materials are especially suited to Mexico's requirements for electrical system expansion.

Every segment of the transportation industry is experiencing maintenance problems with rapidly deteriorating portland cement concrete structures. The Federal Highway Administration, aware of such problems, has sponsored research and development work to find a rapid-setting durable composite that can be used to repair deteriorated concrete and/or to effectively reduce chloride and moisture penetration into concrete.

The feasibility of using the products of free-radical copolymerization of cyclic and linear organosiloxanes in the formation of polymer concrete (PC) composites for use in the completion of geothermal wells has been demonstrated. The PC contained a mixture of tetramethylvinylcyclotetrasiloxane and polydimethylsiloxane used in conjunction with aggregate materials such as silica flour and portland cement. The use of these compounds resulted in composites with high strength and with thermal and hydrolytic stability. Thermogravimetric analyses and compression strength tests at elevated temperatures have been used to determine the thermal stability of the composites. The results from these studies indicate that over the temperature range 25 to 350°C, the compressive strength is essentially constant at a value of -72 MPa and there is also a relatively low weight loss of polymer (-1.0 wt%). The hydrolytic stability of the composites was determined by using infrared spectroscopy on a variety of free and bonded OH functional groups before and after the samples were exposed to a 25% brine solution at 300°C. These results showed that the inclusi on of various additives such as Ca or Mg compound inorgan i c phase affects the hydrothermal stability. s in the Pumpability tests were also performed, and the results indicated that a PC slurry containing 35.5 wt% organosiloxane mixed with 64.5 wt% silica flour and cement as an aggregate did not change viscosity at temperatures of 150° to 165OC and a pressure of 36.5 MPa for at least 4.5 hr. Increasing the temperature to 205OC resulted in increased viscosity after 4 hr. The results from these studies indicated that this system can be used as a geothermal well-completion material.