Patent CA-1142556-A (CA)
Inventor: COURSEN DAVID L
IPC: F16B13/14
Filed: 1978-09-05
Granted: 1983-03-08
Abstract: ABSTRACT A grouting system for use in anchoring a rein-forcing member such as a rock bolt in a hole, e.g., in a mine roof, by the reaction of the mixed components Or an inorganic grouting composition so as to form a hardened grout around the reinforcing member includes a hardenable inorganic grouting composition containing, in a first component, a particulate inorganic cement combined with a liquid which is non-reactive therewith in the form Or a slush or sludgy mass and, in a second component, separated from the first, a liquid which is reactive with the cement, a particulate aggregate such as sand preferably being present in the cement slush and/or the reactive liquid component.  A high-early strength grouting system for anchoring a reinforcing member in a hole at a pull strength level Or at least about 175 kg/cm anchoring length within an hour, and usually within 5-10 minutes, includes a hardenable inorganic grouting composition containing an acidic component comprising an acidic oxy phosphorus compound, e.g., H3PO4 or Al(H2PO4)3; a basic component comprising a basic Group II or III metal compound, e.g., MgO; water; and aggregate, e.g., sand; the basic component preferably being in the form of a slush with a non-reactive liquid.  The weight of any aggregate present is no more than about 80 percent of the total weight of the composition. The cement or basic component in slush form and controlled aggregate content impart lubricity to the system for easy insertion and rotation of a reinforcing member, and make the cement or basic component and the combined com-ponents pumpable through small-diameter passageways, while permitting the development of an adequate pull strength Abstract Continued          1A in the hardened grout formed around the reinforcing member when the mixed components react.          A preferred aggregate, for providing a grout of higher shear strength and facilitating the use of the composition in packaged form, is a non-uniformly graded fine sand, i.e., sand having a deviation of the maximum and minimum particle sizes from the median particle size of more than about ? 20% and having no more than about 10% of its total volume consisting of particles larger than about 600 microns.  Of the cements that set by hydration, a pre-ferred cement, on the basis of higher early strength, is one which contains (by weight) about from 20 to 40 percent of 3CaO?3Al2O3?CaSO4 and about from 10 to 35 percent of chemically unbound CaSO4, the remainder being substantially .beta.-2CaO-SiO2.  When the reactive liquid component is water containing a particulate aggregate, a small amount of poly-ethylene oxide and/or polyacrylamide preferably is added to the water component as a thickener-lubricant so as to facilitate a bolt insertion into the composition while per-mitting the development of an acceptable shear strength.          The two components preferably are delivered into the hole separately, e.g., from separate feeding con-duits or, more preferably, in separate compartments of a frangible package, which is broken by the penetration of the reinforcing member.