Employing quicklime in stabilizing earth

A method of treating subsurface layers of earth for controlling movement of subsurface water and building strength of the subsurface layers comprising the steps of:

• a. admixing in a slurry mixing tank unslaked lime called quicklime and water and including the step of at least initially adding said quicklime at a predetermined distance below the surface of the water in the mixing tank while simultaneously stirring the water and quicklime to obtain a more nearly uniform distribution of said quicklime and temperature throughout than would other-be obtained to assure maximum slaking and form a hot hydrated lime slurry at the elevated temperature above ambient temperature;
• said final slurry being passed through a screen for removing unslaked limestone particles that are not efficacious in an injection procedure before the final slurry is injected;
• and
• b. injecting said hot lime slurry before cooling below ambient temperature and at an elevated temperature above ambient at a plurality of predetermined, spaced apart locations and at a plurality of depths
• such that said subsurface layers are treated in situ to obtain added strength and to obtain stabilized moisture content.

In an apparatus for injecting slurry containing hydrated lime and water and including injection apparatus and interconnecting conduits, the improvement comprising:

• a. a mixing tank having a predetermined water level for filling to said level with water before making the slurry;
• b. mixing means for admixing into the water lime particles, both quicklime and hydrated lime that results from slaking of the quicklime;
• c. means for heating the water in order to speed slaking of quicklime;
• d. means for adding quicklime to the water in the mixing tank;
• e. suction line for connecting with said injection equipment and disposed adjacent the bottom of said mixing tank;
• and
• f. screening means connected serially with said suction line for screening out large solid particles that are not efficacious in the injection process.

In an apparatus for injecting slurry containing hydrated lime and water and including injection apparatus and interconnecting conduits, the improvement comprising:

• a. a mixing tank having a predetermined water level for filling to said level with water before making the slurry;
• b. mixing means for admixing into the water lime particles, both quicklime and hydrated lime that results from slaking of the quicklime;
• said mixing means comprising:
• i. spirally arranged paddles so sloped as to pull along the bottom of the mixing tank toward one end the particles of lime;
• said paddles being affixed to a rotatable shaft;
• and
• ii. rotating means for rotating said shaft;
• said rotating means being connected with said rotatable shaft;
• c. means for heating the water in order to speed slaking of quicklime;
• said means for heating the water comprising the exothermic slaking reaction and including first inlet conduit extending for a second predetermined distance below said predetermined water level for admixing the quicklime below the water level to form an elevated temperature dilute lime slurry;
• d. means for adding quicklime to the water in the mixing tank;
• the means for adding the quicklime including second inlet conduit and formainous baffle for distributing said quicklime into and forwardly and rearwardly onto the surface of the hot dilute lime slurry after it has been formed, until a final elevated temperature lime slurry is formed;
• e. suction line for connecting with said injection equipment and disposed adjacent the bottom of said mixing tank;
• and
• f. screening means connected serially with said suction line for screening out large solid particles that are not efficacious in the injection process.