Partially Replacing Fly Ash with Limestone Powder in the Paste - Influence and Characterization
Paste filling is an important research direction of coalmine "green mining" which can dispose coalmines solid waste and achieve environmental protection. The mechanical properties such as compressive strength, workability, ulti- mate tension value, shear strength and splitting strength of paste, in which the fly ash was partially replaced by limestone powder, was studied. Adiabatic temperature rise, setting time, shear strength, permeability, frost resistance and dry shrinkage of different substitution rate were investigated and the results were compared with traditional paste. The test re- sults showed that the influence of limestone powder on workability, permeability and frost resistance performance of paste was slight, the setting time of paste were shortened, adiabatic temperature rise and mechanics performance of paste were decreased, dry shrinkage value was increased with limestone powder content increasing.
Cement design for underground gas storage well completion
In order to shave the peak demands during the cold seasons, underground gas storage (UGS), balancing the supply-demand chain throughout the year, has been accepted as a strategic method. During the successive UGS cycles, the well cement experiences cyclic mechanical, thermal, and hydraulic stress and may crack due to its low elasticity and ductility. This could lead to the transmission of stored gas through cementing behind casing, one of the major challenges experienced in UGS operations, so posing high workover costs on UGS wells. In addition to workover costs, the loss of inventory due to gas transmission makes the reservoir insufficient in proper gas supply during the high-demand season. In this work, a new formulation has been invented in order to prevent cement cracking, improve cement elasticity and ductility, and reduce the crack propagation in the cement used for completion of UGS well. The new formulation adds a polymer and an elastomer to cement composition. Results showed that addition of latex to cement decreases the density, hydration and fluid loss of cement; also, the rate of cement bonding decreases. On the other hand, addition of polypropylene fibers results in dramatic improvement of compressive strength and stress strain properties of the cement. In comparison with elastomer, this additive provides a higher threshold elasticity of cement. Also, the combined cohesive effect of latex and flexibility of microfibers brings about the best resistance against excessive pressures.
[Effects of dance exercise on exercise intention and exercise-related affect of postmenopausal women].
PURPOSE
A dance exercise program was performed to investigate the effects of exercise on exercise intention and exercise-related affect as these are important determinants of exercise behavior.


METHOD
The subjects were overweight (23< or =BMI< or =25) or obese (BMI> or =25) postmenopausal women (n=14), who participated in an exercise program from May, 2003 through November, 2003 at one public health center located in Kyong-gi Province. Data was analyzed with an SAS PC program.


RESULT
Exercise intention was significantly increased after the exercise program (t=-2.24, P=0.04). Exercise-related affect was also increased, but there was no statistically significant change (t=1.81, P=0.09).


CONCLUSION
This study suggests that exercise participation can increase the level of future exercise behavior by increasing exercise intention and exercise-related affect.