Papers by Keyword: Calcium Silicate Brick

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Authors: Jiří Brožovský, Ámos Dufka
Abstract: Dynamic Young ́s modulus of elasticity can be determined by ultrasonic pulse method and resonance method. Because of the difference in the way of introducing tension into a test specimen, the values of modulus of elasticity differ. Dynamic Young ́s modulus of elasticity measured by ultrasonic pulse method is higher; the difference stated for concrete is 5 to 20%. It was found that the dynamic Young's modulus of elasticity of calcium silicate bricks and prisms measured by ultrasonic pulse method is on average higher by 9.5% than dynamic Young's modulus of elasticity measured by resonance method. If dynamic Young's modulus of elasticity is converted to static modulus of elasticity, this difference has to be taken into account by means of appropriate coefficient.
193
Authors: Ibrahim Mohamad H. Wan, B.H. Abu Bakar, M.A. Megat Johari, P.J. Ramadhansyah
Abstract: The aim of this study is to investigate the behaviour of the calcium silicate brick masonry wall exposed to sulphate condition. This paper presents some result about the effect of sodium sulphate attack on the elasticity of the calcium silicate brick masonry structures. All specimens were cured under polythene sheet for 14 days in environmental controlled room with temperature of 25± 2°C and 80 ± 5% relative humidity. After curing, the specimens were exposed to sodium sulphate solution before tested at 14, 28, 56 and 180 days respectively. As a result, the modulus of elasticity of the calcium silicate brick masonry wall reduces with the increase of sulphate concentration.
195
Authors: Jiří Brožovský
Abstract: Testing with rebound hammers is influenced by various factors, like composition and components of tested material, treatment of tested surface, moisture content of tested material, temperature of material and environment. Influence of these factors on measurement results during testing concrete is described in technical literature and standards. Calcium silicate body can be characterized as non-cement based fine grained concrete, however, with considerably higher water absorbing capacity compared to standard concrete: ca 12-14% (fine aggregate bonded by hydration products of lime). To use rebound hammers for testing calcium silicate bricks, influence of selected factors on measurement results was tested. It was proved, that content of moisture and temperature of calcium silicate brick has influence on results of measurements with rebound hammer, and therefore it is necessary to take into account these influences.
352
Authors: Ibrahim Mohamad H. Wan, B.H. Abu Bakar, M.A. Megat Johari, P.J. Ramadhansyah
Abstract: This paper presents the behaviour of moisture movement of calcium silicate brick masonry walls exposed to sodium sulphate environment. The walls were exposed to three sodium sulphate conditions with sulphate concentrations of5%, 10% and 15%. For comparison, some walls were also exposed to dry and wet condition which acts as a control conditions. All specimens were prepared and cured under polythene sheet for 14 days in a controlled environmental room and maintained at relative humidity and temperature of 80 ± 5% and 25 ± 2°C, respectively. After the curing period, the specimens were exposed to sodium sulphate as well as drying and water exposures, during which moisture movement was measured and monitored for a period of up to 7 months. As a result, the moisture expansion was observed and recorded for all masonry wall specimens after exposed to the sulphate condition.
201
Authors: Jiří Brožovský
Abstract: The rebound hammers of the Schmidt system belong among the non-destructive testing methods that are used for determining compressive strength of building materials, most often concrete and rocks. Calibration relations between the rebound number and compressive strength must be available to determine the compressive strength. Calibration relations are determined on the basis of destructive and non-destructive tests of test specimens. This paper deals with the effects of internal compressive stress in calcium silicate bricks on measurement results obtained using the L-type Schmidt hammer. Based on the obtained information, in order to process calibration relations, it is recommended to apply such force to the test specimens, which corresponds to the internal compressive stress 10-15% of the final compressive strength. We do not recommend measuring on firmly supported bricks only.
155
Authors: Jiří Brožovský
Abstract: Measuring with ultrasonic pulse method is influenced by various factors, like loading in particular inner tension when material built in a construction is tested. The paper researches influence of inner tension (load) on testing of calcium silicate bricks with ultrasonic pulse method. Calcium silicate bricks were loaded with force corresponding to 0 % (unloaded test specimens), 10 %, 20 %, 50 %, 60 % of ultimate compressive strength with various content of humidity (dried samples, w=2 %, w=8 % and samples saturated with water). It was found that ultrasonic pulse velocity is not considerably influenced at load of 10% and 20% of ultimate strength of bricks. However, ultrasonic pulse velocity considerably decreases after loading at 50% and 60% of ultimate compressive strength. Most of theoretical assumptions concerning mentioned concrete stated in technical literature were confirmed, however, particular values were different because of differences between concrete and calcium silicate bricks.
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