It is well known that as concrete hydrates its permeability decreases. Continued hydration, however, is not the only mechanism which causes such reduction. Selfsealing, which is largely attributed to the dissolution and redeposition of hydrates, and autogenous healing of cracks, can also significantly reduce the flow. This paper reviews the relative effects of self-sealing, autogenous healing and hydration. I1 est bien connu que

A B S T R A C T R I~ S U M I~The findings of an experimental study are described, documenting and quantifying the influence of concrete porosity on its mechanical properties in saturated and dry states. Concrete porosity consists of capillary and entrained air, and described respectively as active and nonactive, depending on its influence on mechanical properties with changing moisture state. It was found that the active (capillary) porosity influence on mechanical properties is more pronounced with decreasing moisture. The influence of non-active (entrained-air) porosity on concrete mechanical properties is invariant of moisture state. Les principaux r~sultats d'une ~tude visant h quantifier l'influence de la porosit( sur les propri(t~s m~caniques du b~ton (~ l'~tat sec et saturn) sont pr~sent~s. La porosit~ du b(ton consiste en des pores capillaires et des vides el'air entrafn~ qui sont respectivement d(crits comme actifs et non-actifs selon leur influence sur les proprie~t(s mdcaniques du b(ton test( ~ cliff, rents degr~s de saturation. Les r~sultats des essais d~montrent que l'influence des pores capillaires (actifs) est inversement proportionnelle au degr~ de saturation du b~ton. Les effets des vides d'air entrafnk (non-actifs) apparaissent comme ~tant peu sensibles au degr~ de saturation du mat&iau.

No abstract

No abstract