• Korean Journal of Agricultural Science
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• v.6 no.1
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• pp.45-55
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• 1979

This study made to find the variation of strengths of briquette ash which were hardened into cement. The briquette ash were mixed with the cement, ((cement (90%)+slaked lime (10%)) and ((cement (80%)+fly ash (20%)) in the ratio of 1:2, 1:3, 1:4, 1:5, 1:7 and 1:9, respectively, and these were compared with the one made of cement plus standard sand in the strengths of compression, tension and bending at the ages of 7 days and 28 days. The results from the study conducted preliminary without studying the economical aspects or duration of the products are summarized as follows: 1. The compressive strengths of mortar made of 1 to 2 ratios of cement to briquette ash, (cement+slaked lime) to briquette ash and (cement+fly ash) to briquette ash were 84%, 90% and 75% at the age of 7 days and 84.9%, 73.5% and 69.8%, respectively of those of Korean Standard values. 2. The compressive strength s of mortar made of 1 to 2 ratios of cement to briquette ash, (cement+slaked lime) to briquette ash and (cement+fly ash) to briquette ash were 69.3%, 75.1% and 41.3% at the age of 7 days and 56.4%, 49%, and 46.5% at the age of 28 days, respectively of the mortar made of standard sand. 3. The tension strengths of mortar made of 1 to 2 ratios of cement to briquette ash, (cement+slaked lime) to briquette ash, and (cement+fly ash) to briquette ash were 64.4%, 47.1% and 35.4% at the age of 7days and 69.6%, 64.8%, and 57.3%, respectively of that of the mort ar produced with standard sand. 4. The bending strengths of mortar made of 1 to 2 ratios of cement to briquette ash, (cement+slaked lime) to briquette ash, and (cement+fly ash) to briquette ash were 46.3%, 65.9% and 39.1% at the age of 7 days and 89.9%, 96.7%, and 85.1%, respectively of that of mortar produced with standard sand. 5. The bending strength of the mortar was lower than that of cement mortar, when the briquette ash were harqened into cement. However, the mortar produced by such method seemed to be used as the secondary products of cement or concrete. The additional usefullness of the hardened biquette ash can be found in contributing toward the solving the various pollution problems, the saving the labor costs needed to clean-up waste materials, and the saving the construction materials.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.1 no.1
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• pp.53-68
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• 1981

Most clays under sustained load exhibit time-dependent deformation because of creep movement of soil particles and many investigators have attempted to relate their findings to the creep behavior of natural ground and to the long-term stability of slopes. Since the creep behavior of clays may assume a variety of forms depending on such factors as soil plasticity, activity and water content, it is difficult and complicated to analyse the creep behavior of clays. Rheological models composed of linear springs in combination with linear or nonlinear dashpots and sliders, are generally used for the mathematical description of the time-dependent behavior of soils. Most rheological models, however, have been proposed to simulate the behavior of secondary compression for saturated clays and few definitive data exist that can evaluate the behavior of non-saturated clays under the action of sustained stress. The clays change gradually from a solid state through plastic state to a liquid state with increasing water content, therefore, the rheological models also change. On the other hand, creep is time-dependent, and also the effect of thixotropy is time-function. Consequently, there may be certain correlations between creep behavior and the effects of thixotropy in compacted clays. In addition, the states of clay depend on water content and hence the height of the specimen under drained conditions. Futhermore, based on present and past studies, because immediate elastic deformation occurs instantly after the pressure increment without time-delayed behavior, the factor representing immediate elastic deformations in the rheological model is necessary. The investigation described in this paper, based on rheological model, is designed to identify the immediate elastic deformations and the effects of thixotropy and height of clay specimens with varing water content and stress level on creep deformations. For these purposes, the uniaxial drain-type creep tests were performed. Test results and data for three compacted clays have shown that a linear top spring is needed to account for immediate elastic deformations in the rheological model, and at lower water content below the visco-plastic limit, the effects of thixotropy and height of clay specimens can be represented by the proposed rheological model not considering the effects. Therefore, the rheological model does not necessitate the other factors representing these effects. On the other hand, at water content higher than the visco-plastic limit, although the state behavior of clays is visco-plastic or viscous flow at the beginning of the test, the state behavior, in the case of the lower height sample, does not represent the same behavior during the process of the test, because of rapid drainage. In these cases, the rheological model does not coincide with the model in the case of the higher specimens.