Petrographic examination of several four-year-old laboratory developed grout mixtures

Five different grout mixtures that were approximately 4 years old were examined by x-ray diffraction and SEM. Variables between the mixtures included type of cement, presence or absence of a natural pozzolan, and presence of salt in two of the mixtures. Specimens from each mixture were stored dry at ambient laboratory temperature while companion specimens were stored in simulated brine groundwater, also at about 730F. The following conclusions were made: most of both wet and dry storage specimens showed cracking for all five mixtures. This was attributed to moisture or temperature changes or both in the laboratory environment; specimens from all mixtures made with salt or stored in the simulted brine groundwater showed conversion of ettringite to C3A(CaCl2)H10; the use of portland rather than shrinkage-compensating cement or shrinkage compensating plus expansive cement was not usually detectable, probably because of the ettringite conversion in the presence of salt; the use of a natural pozzolan in one grout mixture was not detectable; and the phase composition and microstructure of the grout mixtures was normal for the materials involved, ages, and storage conditions