TM
5-818-6/AFM
88-32
Resorcinol-formaldehyde. This resin-type grout is formed by con-
(2)
densation polymerization of dihydroxybenzene (resorcinol) with formaldehyde
when the pH of the solution is changed. The reaction takes place at ambient
temperatures.
The final product is a nontoxic gel possessing elastic-plastic
properties and high strengths when tested in a mortar form. The grout has
excellent set-time control, instantaneous polymerization, and a low viscosity
prior to polymerization.
( 3 ) Calcium acrylate. Calcium acrylate is a water-soluble monomer that
polymerizes in an aqueous solution. The polymerization reaction utilizes am-
monium persulfate as a catalyst and sodium thiosulfate as the activator. The
rate of polymerization is controlled by the concentration of catalyst and
a c t i v a t o r . The solution has a low viscosity immediately after mixing that
increases with time.
( 4 ) Epoxy resin. Many different compounding of epoxy resins are avail-
a b l e commercially. Some experiments have been conducted using epoxy res -
ins as grout, and as a result of these experiments, one such epoxy was used
with moderate success to grout fractured granite. The epoxy developed very
good bond with the moist granite , was not too brittle, and the effective vol -
ume shrinkage during curing was very low. The details of these experiments
and the field grouting operations are contained in reference 8. A summary
of the physical properties of several commercially available chemical grouts
is given in table 1. The values shown were obtained from various
publications.
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