The injection of cement grout in water-saturated medium and the sealing of anchorages require the use of grout with high resistance to water dilution to enhance in-situ performance. This can be achieved by reducing the W/C and incorporating an antiwashout admixture (AWA) to enhance the stability. Such admixture can increase the viscosity and yield stress and necessitate higher dosage of high-range water-reducer (HRWR) to maintain the desired fluidity. Cement-based grouts with 0.30 to 0.50 W/C and different combinations of AWA and HRWR were evaluated. The study was undertaken to highlight the influence of W/C and dosage of chemical admixtures on fluidity, washout resistance, and residual compressive strength (RCS) of the underwater-cast grout. Statistical models established using a statistical design of experiments indicate that the W/C has greater effect on changes in minislump flow, washout, and RCS than the concentrations of HRWR and AWA. On the other hand, for mixtures prepared with a fixed W/C of 0.40, the models show that measured responses are highly affected by the dosages and interaction of both admixtures. Trade-off between fluidity and washout resistance and means to optimize mixture proportioning to enhance the resistance to water dilution without adversely affecting fluidity are discussed.
[1]
K. Khayat,et al.
Simple field tests to characterize fluidity and washout resistance of structural cement grout
,
1998
.
[2]
Virgilio A. Ghio,et al.
The rheology of fresh cement paste containing polysaccharide gums
,
1994
.
[3]
Phillip S. Kott,et al.
Wiley Series in Probability and Mathematical Statistics
,
1995
.
[4]
Ravindra K. Dhir,et al.
Concrete durability and repair technology : proceedings of the International Conference held at the University of Dundee, Scotland, UK on 8-10 September 1999
,
1999
.
[5]
Kamal H. Khayat,et al.
Effect of Welan Gum-High-Range Water Reducer Combinations on Rheology of Cement Grout
,
1997
.
[6]
R. H. Myers,et al.
Response Surface Methodology: Process and Product Optimization Using Designed Experiments
,
1995
.