Abstract: Pseudoelastic elements are shaped in order to form springs which exhibit relatively constant force levels over a major fraction of maximum deflection capacity during loading and also during unloading. The shape of sail pseudoelastic elements is chosen to concentrate at least one of flexural and torsional deformations within limited regions. The element may be braced outside said regions in order to further concentrate deformations within said regions. Loading of said pseudoelastic springs thus produces strains within said regions which are largely corresponding to the upper pseudoelastic stress plateau where strain variations cause relatively small changes in stress. Unloading of said pseudoelastic springs also produces strains within said regions which are largely corresponding to the lower stress plateau of the pseudoelastic stress-strain curve where stress is subject to relatively small changes with strain variations.

Abstract: Concrete materials are impregnated with liquids which harden within concrete pores and microcracks, and develop a sharp contrast with the body of concrete in microscopic images. The impregnation process involves vacuum application to remove air from concrete pores and microcracks, followed by the introduction of liquids under pressure. The sharp contrast between the impregnated (and hardened) liquid and the body of concrete facilitates distinction of pores and microcracks in microscopic images for the purpose of automated image analysis.

Abstract: Pseudoelastic elements are subjected to pre-strains and restrained in order to form springs which exhibit relatively constant force levels over a major fraction of maximum deflection capacity during loading and also during unloading. Pre-straining of pseudoelastic elements subjects them to strains which approach or reach the upper stress plateau of the pseudoelastic stress-strain curve. Loading of said pseudoelastic springs thus produces strains largely corresponding to the upper pseudoelastic stress plateau where strain variations cause relatively small changes in stress. Unloading of said pseudoelastic springs also produces strains largely corresponding to the lower stress plateau of the pseudoelastic stress-strain curve where stress is subject to relatively small changes with strain variations. Said psueodoelastic springs can be used in brush holders which can benefit from a relatively constant level of force as deflections occur due to brush wear.

Abstract: Shape-memory fibers are incorporated into a metal matrix material with a level of fiber-to-matrix bonding so that upon localized failure of matrix under load, the strains in fibers debond them from the matrix to the extent that fibers do not all rupture at the location of matrix failure. The pull-out process of fibers ruptured away from the matrix failure location provides the composite material with substantially increased ductility and energy absorption capacity after localized failure of the matrix. Pre-tensioning of shape-memory fibers impose sustained stresses on matrix which enhance the strength and energy absorption capacity of the composite material. The shape-memory fibers may be incorporated into a metal matrix at their end so that fibers pull out from the matrix under load and provide an energy-absorbing assembly.

Abstract: A CO.sub.2 pre-curing period is used prior to accelerated (steam or high-pressure steam) curing of cement and concrete products in order to: (1) prepare the products to withstand the high temperature and vapor pressure in the accelerated curing environment without microcracking and damage; and (2) incorporate the advantages of carbonation reactions in terms of dimensional stability, chemical stability, increased strength and hardness, and improved abrasion resistance into cement and concrete products without substantially modifying the conventional procedures of accelerated curing. Depending on the moisture content of the product, the invention may accomplish CO.sub.2 pre-curing by first drying the product (e.g. at slightly elevated temperature) and then expose it to a carbon dioxide-rich environment. Vigorous reactions of cement paste in the presence of carbon dioxide provide the products with enhanced strength, integrity and chemical and dimensional stability in a relatively short time period.

Abstract: Pulp fibers derived from wood or non-wood plants or recycled paper products are individualized and dispersed in water, and mixed into cement-based mixtures using conventional mixing procedures at relatively low dosages of about 0.3-30 kg of fiber per cubic meter of concrete. Once individualized, the affinity of plant pulp fibers for water facilitates their dispersion in normal cement-based mixtures. Fresh cement-based materials incorporating the dispersed individualized plant pulp fibers provide desirable workability, resistance to segregation and bleeding, pumpability, finishability, and reduced rebound when pneumatically applied. Hardened cement-based materials incorporating the dispersed individualized plant pulp fibers provide improvements in crack resistance, toughness, impact resistance, fatigue life, abrasion resistance, and other mechanical, physical and durability characteristics.

Abstract: A method and an apparatus is provided for accelerated processing of cement-bonded particleboard or fiberboard under pressure through the injection of a diluted carbon dioxide gas. The method and apparatus yield controlled, thorough and efficient acceleration of the curing process, reduce the cost and raw material consumption in the process, broaden the raw materials basis for the production of cement-bonded particleboard and fiberboard, and yield end products with improved mechanical, physical and durability characteristics. Streamlined processing plants with improved productivity and efficiency can be based around this invention for the production of cement-bonded particleboards and fiberboards with improved performance characteristics.

Abstract: Pulp fibers derived from wood or non-wood plants or recycled paper products, which are about 0.1-30 mm long and about 0.001-0.1 mm in diameter with length-to-diameter ratio of about 30-3000, are dispersed in conventional concrete mixtures using conventional mixing equipment for effectively improving fresh and hardened concrete properties at relatively low cost. Dispersion is achieved by individualizing the plant pulp fibers so that they are not fully bonded to each other, and dispersing the individual fibers in concrete at relatively low dosages of about 0.3-30 kg per cubic meter. Once individualized, the affinity of plant pulp fibers for water facilitates their dispersion in conventional concrete mixtures. Fresh concrete mixtures incorporating the dispersed individualized plant pulp fibers possess desirable workability, resistance to segregation and bleeding, pumpability, finishability, and reduced rebound when pneumatically applied.