Dimensional stability of pore reduced cement (PRC)

Pore Reduced Cements (PRC) are high density, high strength materials which are made by the pressing of immature ordinary Portland cement (OPC) pastes during which there is partial removal of excess mix water. The resulting reduction in the effective water/cement (w/c) ratio and the significant reduction in porosity can increase paste densities to greater than 2 600 kg/m(3) compared with 2 000 kg/m(3) in unpressed cements. The pore characteristics of PRC and their beneficial implications on its mechanical performance and durability have already been, described.: This paper deals with the dimensional stability of PRC and addresses 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 reported and show that PRC is dimensionally more stable than OPC. This can be explained by comparing microstructures of PRC and OPC. The penetration of moisture via connected porosity is restricted in PRC and therefore the internally isolated, un;reacted cement does not present a-potential hazard for its long term dimensional stability.