The effectiveness of concrete sealants as determined by the rapid chloride permeability test

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University of New Brunswick


Ten different types of concrete sealing compounds were tested for their effectiveness against water absorption and chloride ion penetration on liqhtweiqht concrete containing 25*4 fly ash. The National Cooperative Highway Research Pro.iect (NCHRP) TE77 recommends a limit of 25f/» absorption weight gain of of uncoated control cubes. All tests conducted on cast surfaces that were subsequently sand blasted showed much qreater absorption rates than the recommended limits and ranged from 30 to 83*A with an averaqe of 60%. In qeneral the si lanes/si loxanes were more effective than the acrylics or methacry1ates ( 50% vs 70% ). The rapid chloride permeability tests.were also conducted and indicated that the coatings reduced the chloride permeability from 13 to 51 % of the contro1 specimens. Aqain the si1ane/ siloxanes proved to be more effective in reducing the chloride permeability rates than the acrylics ( 3E'!A VS 5V/i ) but equalled the effectiveness of the methacry 1 ates ( 3B*A vs 30% ) . A compar i son of the resuIts wit h similar wor k done o n nor ma1 weight concrete at the Ministry of Transportation of Ontario indicated that the liqhtweiqht concrete containing E5Vi fly ash has only about one half the permeability of normal weight concrete even though the water absorption is much greater.