Patent ID: 7419544

Claim:
A cementitious slurry comprising: cement; water; a plasticiser; a dewatering additive including a component selected from the group consisting of: (i) a fly ash having particles with a predominant size up to about 10 microns forming about 30 wt % to 100 wt % based on the weight of said cement in the slurry; (ii) aluminous material having particles with a predominant size less than about 150 microns forming about 5-30 wt % based on the weight of said cement in the slurry, wherein the aluminous material is selected from the group consisting of hydrated alumina, partially hydrated alumina and unhydrated alumina; and (iii) both the fly ash of (i) and the aluminous material of (ii); wherein the components (i), (ii), or (iii) of said dewatering additive are added to provide water reduction, and the amount of said fly ash having said particle sizes is greater than the amount of said cement by weight percentage.