Betons holdbarhed omfatter betons frostbestandighed, uigennemtrængelighed, kemisk resistens, stålkorrosionsbestandighed og erosionsbestandighed. Jeg vil kun tale om dets frostbestandighed, uigennemtrængelighed og kemiske modstandsdygtighed over for beton. Den erosive effekt.
a) Frostmodstand: Når mængden afSilica pulverer lille, er frostbestandigheden af ​​silicagasbeton stort set den samme som for almindelig beton. Når mængden af ​​silicapulver overstiger 15%, er dets frostbestandighed dårlig. Gennem et stort antal tests er denne opfattelse grundlæggende blevet bekræftet. Hovedårsagen er, at når silica -dampen overstiger 15%, stiger ekspansionen af ​​betonen, det relative dynamiske elastiske modul falder, og trykstyrken falder kraftigt. Set fra betonets indre egenskaber er det specifikke overfladeareal lille, og afstandskoefficienten er stor.
b) Impermeability: Because Silica pulver particles are small, 20-100 times smaller than cement particles, they can be filled into the voids between cement particles to make concrete compact. At the same time, the secondary hydration of silica powder blocks new products. Permeation channels in concrete, so the impermeability of silica fume concrete is very strong, the permeability of concrete increases with the increase of water-binder ratio, this is because the compactness of water-cement is relatively poorer than that of concrete.
c) Chemical resistance: Mixing Silica pulver into concrete can reduce the content of Ca (OH) 2 and increase the compactness of concrete. It can effectively improve the corrosion ability of weak acid. However, it cannot be used in strong acid or high-depth weak acid. CSH decomposes in acid. In addition, it is also resistant to salt corrosion, especially to chlorides and sulfates. The reason why it is resistant to salt corrosion is that the silica fume concrete is denser and the pore structure is improved, thereby reducing The transmission speed of harmful ions is reduced and the formation of soluble Ca (OH) 2 and ettringite (3CaO·Al2O3·3CaSO4 ·32H2) is reduced, and the result of increasing hydrated calcium silicate crystals.