The surface of carbon fibre is studiedwhich has been treated with heated sodiumhydrate solution(NaOH).It is found that thesurface of carbon fibre is not corroded duringthe treatment.But at the same time,it is alsofound that after this treatment,a certainnumber of carbonyl groups(>C=O)and(—COOH or—COONa) are produced on thetreated surface of carbon fibre.When carbonfiber is mixed with cement paste,the abovereactive groups will link with Cain the paste,which will result in an early stage hydration ofcement in inter facial areas.In addition,theexperiments show that the rheological propertiesof cement paste reinforced with alkali-treatedcarbon fibre differ greatly from that ofuntreated carbon fibre reinforced cement paste.