6Kelham S A. A water absorption test for concrete [J], Magazine of Concrete Research, 1988, (40): 106--110.
7Atzeni L, Massidda,Sanna U. Capillary absorption of water in hardened cement pastes treated with silicic esters or alkylalkoxysitoxane [J]. Magazine of Concrete Research, 1993, 45 (162) :11--15.