NAC534.065. “Cement-bentonite grout” defined.

“Cement-bentonite grout” means a mixture of sodium bentonite and portland cement that, when mixed with water, is specifically designed to seal and plug instrumentation boreholes and:

     1. Consists of a range of water to cement to bentonite ratios by weight of between 2.5 to 1 to 0.3 and 4 to 1 to 1. For example, the ratio by weight of 2.5 to 1 to 0.3 is obtained by mixing 30 gallons of water per 94-pound bag of portland cement with 25 pounds of bentonite and the ratio by weight of 4 to 1 to 1 is obtained by mixing 45 gallons of water per 94-pound bag of portland cement with 94 pounds of bentonite;

     2. Has hydraulic conductivity or permeability values of 10^-7 centimeters per second or less;

     3. Has a fluid weight of not less than 10 pounds per gallon; and

     4. Has a 28-day compressive strength of at least 100 pounds per square inch.

     (Added to NAC by St. Engineer by R039-12, eff. 6-29-2012)