Abstract
To develop new grouting materials using calcium phosphate compounds (CPC), which are one of the most fundamental of biological substances, we explored suitable conditions for CPC precipitation, conducted unconfined compression tests of Toyoura sand test pieces cemented by CPC. CPC precipitation was recognized in all reaction mixtures based on 2 kinds of phosphate stock solution (monoammonium phosphate and diammonium phosphate) and 2 kinds of calcium stock solution (calcium nitrate and calcium acetate). The volume of CPC precipitation in the reaction mixture increased with pH, rising from weakly acidic to around neutrality. One of the sand test pieces cemented by CPC showed a tendency for the UCS to increase with time, reaching a maximum of 87.6 kPa at a curing time of 84 days. The results indicate the fundamental feasibility of novel CPC rock grouts including chemical grouts using the self-setting property of CPC, and biogrouts using the pH dependence of the precipitation and crystal structure of CPC.
