Abstract: A height indicating instrument useful for preparing flat and level cementitious floors over an uneven sub floor. The instrument includes first and second rod assemblies, the first having a foot engagable with the surface of a sub floor and the second assembly operatively attached to and moveable axially with respect to the first assembly. The second assembly includes a height indicator to indicate the desired underlayment height, and carries a laser beam detector. A laser beam generator generates a horizontal laser beam detectable by the laser beam detector. Vertical movement of the second rod assembly with respect to the first rod assembly to horizontally align the detector with the generator simultaneously moves the height indicator to adjust elevation of the latter with respect to the foot. At a plurality of locations on the uneven sub floor, slurry is poured until the slurry rises into contact with the height indicator at each such location.

Abstract: Mixing machine for mixing cement components with water to provide a pumpable slurry, and a method for its use. The machine includes a mixing vessel having an inlet for water at an average flow rate and for dry cement components, and a water tank for supplying water at a high flow rate to the mixing vessel and having an internal diaphragm separating the tank into water and air compartments. The water tank includes an inlet for admitting water to the water compartment and a conduit communicating the water compartment with the mixing vessel and capable of accommodating the flow of water at an average flow rate substantially greater than the average flow rate of water into the water compartment. The conduit includes a water meter and valve to monitor and regulate, respectively, the quantity of water supplied to the mixing vessel.