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The autogenous shrinkage strain and restrained stress due to autogenous shrinkage and heat of hydration effects in high strength concrete were investigated experimentally. It was clear that at early age the autogenous shrinkage strains develop more rapidly in concrete without the admixture, and in concrete containing silica fume, than in concrete containing blast-furnace slag. The final autogenous shrinkage strains in concrete containing blast-furnace slag are largest, and are smallest in concrete without admixtures. The autogenous shrinkage strains under the environment with temperature of 40 “C develop faster at early age and slower in the late than 20 “C . In correspondence with autogenous shrinkage, the stresses due to autogenous shrinkage in concrete containing blast-furnace slag is greatest. The restrained stresses due to autogenous shrinkage in concrete tends to be smaller at early age and to be greater in the late at 20°C than that at 40°C. The numerical analysis results by FEM agreed comparatively well with experimental stresses.

High performance concrete can be used as a vault sealing material in nuclear fuel waste chambers deep in the rock mass and can then be subjected to a triaxial-stress state and a maximum temperature in excess of 200 OC. Triaxial compression measurements at high temperature and pressure have been carried out on high performance concrete specimens. The experiments consisted of measuring in cylindrical specimens subjected to several conditions involving four triaxial loading conditions (03 = 0, 10, 20, and 40 MPa), two testing temperatures (T = 20 and 200 “C), two curing periods (28 and 90 days), a saturated moisture condition, two types of concrete mixtures (type H and type K). Testing was carried out to determine the way in which the physical stability, strength, and deformability of HPC subjected to ambient and high temperature conditions. The testing program shows that the triaxial strength increases with the increasing of the confining pressure and cure period at a constant temperature. The effect of confining pressure and cure period become less critical at high temperature and confining pressure. With increasing temperature at a constant confining pressure, the triaxial strength decreases especially at higher confining pressure ( a3 = 40 MPa). When the temperature and confining pressure were raised, the angles of internal friction !D and the Hoek Brown material constant m decrease, but the cohesive strength increase. High performance concrete at room and high temperature conditions shows elastic-brittle and quasi-elastic-brittle properties, respectively.

The present study was to develop high-durability concrete(HDC) and to apply it to actual structures. For the improvement of durability of concrete structures, the appropriate mixture proportions with mineral admixtures or slag (fly ash, silica fume, blast-furnace slag) have been selected and applied to various experimental studies. Two ievels of strength such as high and normal strength concretes have have been considered. Various durability tests including resistance to freezing and thawing, resistance to steel corrosion, resistance to sulfate attack, and permeability were performed and the durability characteristics for each mixture proportion have been analyzed to develop high-durability concrete. In addition, several in-situ applications of HDC, i.e., tetrapod at Tangjin power plant, a reinforced concrete slab bridge at Euwang, and sewage treatment structure at Gayang, were executed and investigated. Then, the results of field applications were discussed with those of laboratory tests.

A research program was carried out to evaluate the chloride-ion penetration of both air and non-air entrained concretes made with mineral admixtures as partial replacements of cement. Two series of investigations (Series 1 and Series 2) were carried out. The mixtures were proportioned to have 28-day strengths of 35 MPa for Series 1 and 69 MPa for Series 2. Chloride-ion penetration was determined in accordance with ASTM C 1202. Series 1 mixtures contained a Class C fly ash whereas Series 2 mixtures contained the fly ash and silica fume. In general, all the concrete mixtures, with or without mineral admixtures, exhibited low values of chloride-ion penetration. In this work, a concrete containing 37% Class C fly ash showed results comparable to a concrete containing 11% Class C fly ash plus 8 % silica fume with respect to chloride-ion penetration. The chloride-ion penetration of high-quality concrete system was found to be unaffected when silica fume concentration was increased from 8 % to 11% .

Foamcrete, also known as foamed or cellular concrete is a lightweight material that can be used for the development of infrastructure to the benefit of disadvantaged communities. The objective of this paper is to discuss the tests conducted on foamcrete using South African materials. The cost of foamcrete can be reduced by replacing large percentages of the cement with ungraded ash. This replacement does not lead to noticeable reductions in compressive strength, but the shrinkage is markedly reduced. Reinforcing bars can be used in foamcrete but although no problems have been encountered with bond, the low shear strength of foamcrete can lead to premature failure. The use of chopped polypropylene fiber improves the shear behavior of small structural elements to the extend that the load-deflection behavior of foamcrete beams are similar to that of comparable normal concrete beams.