Ryan J. Carda

Document Type

Thesis - University Access Only

Award Date

2006

Degree Name

Master of Science (MS)

Department / School

Mechanical Engineering

Abstract

In the past, the production of the bentonite-based grouting product Thermal Grout Select has been done without a comprehensive understanding of the interactions and effects of each chemical ingredient used to form the product with respect to the actual quantities necessary. The objective of this research was to first observe through testing and then statistically verify the relationships between chemical content in the product and the measurable properties of Thermal Grout Select used to evaluate its performance, then, based on the research performed, make recommendations as to the actual chemical content necessary to make an acceptable product. The ultimate goal was to determine the adequate amount of each chemical ingredient to use in order to manufacture a desirable Thermal Grout Select product while minimizing its total production cost. One hundred twenty-eight different bentonite -chemical combinations were generated and mixed to evaluate the overall effect of each ingredient used. Laboratory tests were performed to determine characteristics and properties which were relevant to the evaluation of pumpability and et hardness of bentonite-based grout as well as their ability to hold sand in suspension prior to bentonite hydration and flocculation. All data obtained over the course of this research was used to try to determine a range for the amount of each chemical ingredient to u, e. The desired end result of such chemical use is production of a bentonite-based grouting product suitable for field u e while meeting all imposed environmental and thermal performance criteria. While viscosity testing and hardness testing were deemed to be adequate indicators of grout pumpability and behavior after bentonite flocculation, respectively, gel strength testing was not a good measure of the ability of each bentonite-chemical combination to hold sand in suspension prior to setting up. Simply monitoring each sample during viscosity testing turned out to be a better indicator of the presence or lack of sand settling in each combination studied. Definite trends and difference could be noted in the different samples that were tested. As cement content in the grout increased, assuming all other things constant, so did its overall viscosity, gel strength, and hardness. Hydration and flocculation time was also detrimentally affected by heightened levels of cement in the mixtures. Most of the grout sample that unfavorably set up early during viscosity testing had very high levels of Portland cement in them, among other thing. The addition of cement to a grout mixture requires the addition of soda ash and SAPP in order for the mixture to be pumpable. Both soda ash and SAP P significantly cut grout gel strength and final set hardness, even in the presence of increased cement contents. When there was even a small amount of either in a sample, the gel strength and hardness value were significantly lower. Values for grouts with all levels of Portland cement were all similar when soda ash and SAPP were present in the mixtures. In was found not to be economically feasible to increase cement content to increase gel strength and set hardness because of the fact that such increase would required heightened levels of soda ash and SAPP as well without reaping much benefit of the desired effect. These overall trends were verified by the Pearson correlation coefficients found during analysis with respect to the overall effects that each chemical ingredient had on the grout properties. According to the equations given by the stepwise regression analysis performed, manufacturing Thermal Grout Select using 50% MWB, 50% MWY, 2% cement, I% soda ash, and 2% SAPP, a 1.00 Btu/hr-ft-°F thermal conductivity mixture would have approximately a 851.75 cp viscosity after IO minutes, a 85.2 dyne/cm IO minute gel strength, and a 0.45 hardness number. In addition, a l .20 Btu/hr-ft-°F thermal conductivity mixture would have approximately a 65.93 dyne/cm2 IO minute gel strength and a 0.37 hardness number. All values predicted by the stepwise regression analysis would be acceptable values for actual use in the field in addition to being comparable to the actual results of the testing that was performed. Based on all testing performed throughout the course of this research, recommendations were made for a range of the level of each chemical ingredient to use in order to make an acceptable Thermal Grout Select product at a reasonable cost. The range of each combination that is believed to make an acceptable product is 62.5-50% MWB content, 37.5-50% MWY content, 2-3% Portland cement content, 1.0-1.5% soda ash content, and l .5-2.0% SAPP content.

Library of Congress Subject Headings

Ground source heat pump systems -- Design and construction

Grouting (Soil stabilization)

Bentonite

Format

application/pdf

Number of Pages

179

Publisher

South Dakota State University

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