Deicing Salt Resistance Of Cement Concrete Pavement

Based on the problem of increasingly serious deicing-frost scaling, the influencing factors on the frost-salt resistance of concrete was investigated in this paper according to the CDF test method using the CDF test machine which was first imported in china. The main contents and study results are as follows:In view of the sensitivity of air void system on frost-salt resistance of concrete, the influencing factors of measurement of air void system by RapidAir 457 image analyzer were investigated. The results show that the distribution and length of traverse line, threshold level, sample preparation and focus are the most critical factors on measurement of air void system. It was indicated that prolonging the length of traverse line can diminish the error introduced by traverse line distribution; the error introduced by threshold level and focus set according to the naked eye measurement can be neglected; the hardened paste at the sample surface are less damaged by using automatic grinding machine than by manual grinding; Filling void with dry barium sulfate powder produces a better image contrast than filling with zinc oxide paste.According to the CDF method effects of air void systems introduced by three different air entraining agent and surface conditions including coating face, isolation face and cutting face on frost-salt resistance of concrete were investigated. The results showed that the frost-salt resistance of concrete increases with the decreasing of spacing factor and increasing of air content. The speed of frost-salt scaling of concrete is reduced if air content beyond 6% or spacing factor less than 0.200mm. The results also showed that the frost-salt resistance of concrete of different surface exist difference. The order is coating face, isolation face and cutting face by the degree of scaling. Results indicated that it can ensure the frost-salt resistance of concrete by controlling of the spacing factor not the air content and decrease the frost-salt resistance by improperly concrete coating and vibrating.The influence of different concrete coating vehicle mobile loading and curing condition on frost-salt resistance was researched. The results show that excessive coating maybe deteriorate the air void system such as increasing the spacing factor so that diminish the frost-salt resistance; drying shrinkage, carbonization and being under traffic load too early when curing will influence the frost-salt resistance of pavement.