Inorganic cement grouts for roof bolting applications provide an alternative to resin-grouted bolts. Inorganic cement grout is nonflammable, nontoxic, and nonallergenic and offers the potential for significant savings over petroleum-based resin if it can be mixed and injected cheaply and reliably. This report describes the development and testing of a device that mixes on demand and injects cement-based grouts for roof bolting. The grout mix-inject system mixes dry cement with water to form grout, pumps it into a delivery hose, and injects it into the roof bolt hole. The mixing and pumping system is based on a twin screw extruder. The geometry of the twin screws is such that the unit is self-cleaning. The injection is performed pneumatically, and no hardware is placed up the hole. The bolter-mounted device was developed through laboratory testing during which injections were made into simulated bolt holes drilled in concrete. The underground testing and evaluation program demonstrated the ability of the system to install competent cement-grouted roof bolts.