Improving rebound properties of sprayed concrete

摘要

A process for improving the reboundproperties. of sprayed concrete. This is done by the inclusion, in the concrete, of micro-silica powder which has been eated with 2-25 wt.% of a liq. selected from water, alkanolamine, apolyol and an aq. material selected from a material(s) selected from a concrete additive, an alkanolamine, a polyol and a water soluble cellulosic cpd. Also claimed is a dry spraying process for applying the concrete. by mixing the dry components of the concrete, introducing this mixt. to a nozzle where it is mixed with water and spraying it from the nozzle on to a substrate. The powdery admixt. comprising the pretreated micro-silica is also claimed. The liq. is selected from water and an aq. soln. of concrete additives, or from glycerol and aq. solns. of glycerol, triethanolamine, methyl cellulose and hydroxyethyl cellulose. The liq. is pref. an aq. soln. of hardening accelerators, such that present in the sprayed concrete compsn. is 3-20(5-15)% by wt. of cement of micro-silica and 3-8 (4-6)% by wt. of cement of hardening accelerator. The micro-silica is premixed with potash in dry form, and this mixt. is then coated with an aq. soln. of sodium or potassium aluminate. The admixt. comprises 50-70 pts. of micro-silica, 8-12 pts potash and 22-38 pts sodium or potassium aluminate per 100 pts. admixt. solids.