DIMENSIONAL STABILITY OF PORE REDUCED CEMENT (PRC)

Pore Reduced Cements (PRC) are high density, high strength materials w hich are made by the pressing of immature ordinary Portland cement (OP C) pastes during which there is partial removal of excess mix water. T he resulting reduction in the effective water/cement (w/c) ratio and t he significant reduction in porosity can increase paste densities to g reater than 2 600 kg/m(3) compared with 2 000 kg/m(3) in unpressed cem ents. The pore characteristics of PRC and their beneficial implication s on its mechanical performance and durability have already been, desc ribed.: This paper deals with the dimensional stability of PRC and add resses concerns relating to the significant proportions of unhydrated clinker which remain in the matrix. Weight and dimensional changes of PRC exposed to different regimes of curing with progressing time are r eported and show that PRC is dimensionally more stable than OPC. This can be explained by comparing microstructures of PRC and OPC. The pene tration of moisture via connected porosity is restricted in PRC and th erefore the internally isolated, un;reacted cement does not present a- potential hazard for its long term dimensional stability.