W. R. Grace Co.-conn.

Karl D Taub

Dennis M Hilton

Keith Lipford

Michael D Morgan

Robert S Young

Robert Paul

Ricky N Bastarache

Michael Abbott

Philip A Zanghi

Mary E Driscoll

A system is adapted to automatically maintain a desired yield level for a slurry flow. Measurements of the electrical conductivity of a slurry are taken and corrected for the effects of temperature and pressure. The corrected conductivity measurements are used to arrive at a value for system yield. The system automatically determines if the yield is too high or too low relative to a desired level, and controls the rate at which accelerator is added to the slurry in order to increase or decrease yield.

Automated yield monitoring and control

Method and device for ensuring high yields during spraying of a settable slurry composition. The slurry is conveyed through a length of hose to a nozzle spray-orifice, and a set accelerator is introduced into the slurry at a distance 'D' from the nozzle spray-orifice. The level of accelerator is monitored using a sensor located in the slurry path at a point after the set accelerator is injected. A preferred sensor comprises two pairs of conductivity sensors each having an annular body with a bore corresponding to the diameter of the hose or nozzle bore. Voltage of the slurry can be correlated to yields obtained when a salt-based accelerator fluid is injected into the slurry, such that levels of accelerator can be finely adjusted, and consistently high yields of spray coatings can be achieved.

High yield spray application

Disclosed are formulations adapted to form a foamed cementitious composition, the foamed cementitious composition itself, a method of forming a hydraulic binder foam, and a method of conveying and applying the resulting foam to a substrate. A pumpable cementitious slurry is formed, the slurry is mixed with a gas such as air, and is subjected to mechanically created turbulence to generate gas bubbles and create a foam, which preferably is stabilized by a foam stabilizing agent such as polyvinyl alcohol present in the slurry. The foam is then conveyed to a nozzle or other suitable dispense point from which it is applied, for example sprayed, preferably uniformly, onto a substrate to be coated. Prior to dispensing, a set accelerator is preferably injected, which causes the foam to gel, which in turn improves the hangability of the product on a substrate. The spray material adheres to the substrate and hardens to form an insulative coating on the substrate. Also disclosed are dry compositions comprising a hydratable cementitious binder, a mechanical foam stabilizing agent, and optionally a fibrous component, set retarder and air entraining agent, said composition providing, on the addition of water, gas and mechanical turbulence, a settable foam which is capable of spray application to a steel structural member and which, after spray application, is adherent to the member in the foamed state and after setting. The foam after setting, forms a fire and heat protective adherent coating on the member.

Foamed fireproofing composition and method

An apparatus for producing shredded aggregate from, e.g., boards of expanded polystyrene, is described. The apparatus includes a shredding box defining a shredding chamber; a rotor housed in the shredding box; means for driving the rotor; a plurality of saw blades coupled to the rotor in linear succession, each saw blade having a plurality of spaced apart teeth, each successive saw blade being coupled to the rotor such that its teeth lie about halfway between the teeth of an adjacent saw blade; receiving means in the shredder box for receiving material to be shredded; and take-away means coupled to the shredder box for removing shredded material from the shredding chamber. Low density (e.g., 0.4-0.5 pcf loose bulk density) material having a uniform particle size distribution over time can be economically produced.

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Boxboro, MA, United States of America

Karl D Taub