Abstract: An apparatus for non-destructively testing the response of a specimen to temperature change. An embodiment temperature cycles a specimen, such as a wet mortar beam, dynamically measuring change in dimension and the temperature of the specimen during the cycle. Among other elements, the apparatus employs an accelerometer, a thermistor, a thermocouple, a temperature controller, linear variable differential transducers (LVDTs), an FFT device, a data logger and a heat tape controller. A typical cycle involves using liquid nitrogen to reduce the temperature in an insulated test chamber from ambient to less than ?60° C. and returning to ambient by dispersing the nitrogen with a source of ambient air. Further, in select embodiments, the apparatus measures fundamental frequencies induced by a micro-hammer as measured transversely along a dimension of a specimen during the cooling-warming cycle. Also provided is a method for testing specimens using devices representative of embodiments of the present invention.

Abstract: A method and composition for making concrete includes an antifreeze admixe which is added to the concrete to prevent the freezing of water in the concrete when the concrete is cured during the winter or other cold conditions. The concrete admixture includes sodium nitrate and sodium sulfate combined with one another in a predetermined ratio. In a preferred a embodiment the ratio of sodium nitrate to sodium sulfate equals 3:1. A dosage of greater than 2% by weight of cement of the above described admixture was found to significantly increase the compressive strength of concrete cast of cold (below freezing, or 0 degrees celsius) temperatures, and dosages of 6% and 8% by weight of cement of the specified admixture were found to be particularly effective.

Abstract: A valve is disclosed for venting and relieving pressure within a blister in built-up, multiple layer roof structure, which includes a hollow shaft having one open end adapted to be inserted into the blister and the other end covered by an air permeable, water impermeable membrane protected by a housing. The exterior of the shaft is threaded to permit penetration into the blister and holding of the valve. Air is vented through the membrane and out a passage provided in the housing.