EVALUATION OF CEMENT GROUTS FOR EMBEDDING ANCHORS UNDER WATER

Approximately 110 pull-out tests were conducted on grouted anchors cas t ill the laboratory to investigate the effects of the rheological and mechanical properties of cement grouts, the initial fi-eo drop distan ce of grout, as well as the age of testing on the behavior of anchorag es cast in dry and submerged conditions. The anchors consisted of 19mm , conventional steel bars with an embedment:length fixed at five times the bar diameter. Two different casting procedures corresponding to i nitial free drop of the grout in water of 20 and 200 mm were investiga ted. The cement grouts used in this investigation incorporated either a Type 10 or a blended silica fume cement and a fixed water-binder rat io of 0.40. The grouts incorporated various concentrations of a high-r ange water reducer, a rheology-modifying admixture, and silica fume. T he rheology-modifying admixture and high-range water reducer were join tly incorporated to enhance both fluidity and washout resistance. The test results indicate that properly designed grouts can be easily cast into place, and yet be cohesive enough to resist the washout of cemen titious materials. The spread in load-carr)ring capacity between ancho r bars cast in dry versus submerged conditions can decrease when cemen t grouts having a greater washout resistance level are used which can be secured by incorporating a rheology-modifying admixture and silica fume. The bond strength is known to increase when incorporating silica fume regardless of the casting condition.