Length Change and Strength Development of Candidate Cement-Based Sealing Mixturesfor the WIPP

摘要

The purpose of some of the research was to describe quantitatively how placingand early-age properties of candidate grouts and concretes are affected by temperature, humidity, and properties of component materials. Previous work had investigated the effect of changing cement and pozzolan sources on length-change and early strength development. Changing cement source was found to have some effect on early length change, but later-age length change tended to converge on a common value. Type K cement-based mixtures expanded more than Class H oil-well cement-based mixtures. Changing pozzolan source appeared to have a strong effect on expansion. Changes in w/c also appeared to be important. The effects of temperature and relative humidity have not been systematically investigated. Previous work on expansive behavior reported numerous instances when expansion mechanisms apparently failed. These events were attributed to poor sealing of specimens soon after casting, which allowed them to dry and consequently shrink. Companion specimens stored in water or in fog expanded. Clearly moisture availability is important, but the effect has not been quantified.