Innovative Large-Scale Grout Research Simulating Karst and Hydraulic Conditions-PPT Presentation

PPT Presentation

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The research program, launched in 2017, developed large-scale laboratory testing to assess grout performance under conditions representative of karst foundations and hydraulic flow. The work supports ongoing grouting at Logan Martin Dam in Alabama, where well-developed karst features occur in dolomite, limestone, and chert.<br /><br />Initial static tests used a 30-foot chamber filled with stone to simulate karst. Researchers compared grout mixtures based on pressure development, bleeding, and normalized grout take. Results showed that mix design strongly affected performance: some mixtures bled excessively or failed to build pressure, while additive-containing mixes generally achieved better stability. A 1.5:1 water-cement mix with Glenium and diutan achieved the highest normalized grout take in the static tests; a bentonite-based mix was identified as the most cost-effective.<br /><br />The team then adapted the facility to simulate low-velocity crossflow through a primary conduit, secondary conduits, and fractures. Tests measured flow redistribution, pressure, temperature, and grout take. A 1:1 water-cement mix without additives successfully sealed the primary conduit and progressively filled secondary pathways and fractures, despite water crossflow. Post-test cuts confirmed grout closure throughout the simulated flow system.<br /><br />Findings also showed that temperature matters: the 1:1 mix performed under warmer conditions, while cold conditions delayed hydration and setting, limiting effectiveness. The research provides a quantitative approach for evaluating grout mixes and indicates that quick-setting designs may be needed in colder environments.

Keywords

karst foundations

grout performance

Logan Martin Dam

laboratory testing

water-cement mix

crossflow simulation

grout take

pressure development

diutan additive

cold conditions