Research On The Application Of Dry Concrete Curbs

Transportation infrastructure is developing rapidly in China in recent years, levels of highway construction in full swing. Curbs as an important part of road structure, demand is also increasing. Curb setting not only play the role of guide, connectivity and ease of drainage, but also maintaining road shoulder stability and is good for road construction. Thus the durability of curbs plays important role in the smooth and safe operation of the road. Curbs are divided to rock curbs and concrete curbs. The rock curbs have better mechanical properties, corrosion resistance while the cost is high, so it could not be applied on the road widely. And the precast concrete curb could not against the damage caused by continuous freeze-thaw and corrosion, which lead to the short service life and high cost of maintenance.The water cement ratio of dry concrete was low while the early strength was high and molding velocity was fast in comparision with ordinary concrete. Thus, the form removal could be performed as soon as the samples compacted, which improved the template turnover rate and production efficiency. Dry concrete was widely used in civil engineering for its high efficiency and economy. However, it is not yet ripe in the research of curbs application. In order to promote the application of dry concrete curbs and improve its durability, this paper systematical investigated the performance of dry concrete curbs. The results of the research are as follows:The mix design of dry concrete was firstly studied. Through to the comparison and selection of concrete mix design theory, the Bailey method was selected to calculate and analyze the gradation of mix. As the dry concrete has lower water cement ratio and different molding method in comparison with ordinary concrete, the mix design of which should be modified based on the ordinary design method. With reference to the “Mix Design Manual of Modern Concrete” and experimental tested, the mix gradation of dry concrete curbs with the best mechanical properties was ensured.Dry concrete is formed by means of vibration compaction molding, which ensures that they can immediately demold after release. And it is steam curing, ensuring the rapid formation of the early strength. Thus, the compaction process parameters and curing process are significantly affecting the quality of dry concrete curbs. The concrete block molding machine manufactured by JILIN JIUSHENG ECOLOGICAL ENVIRONMENTAL TECHNOLOGIES CO.,LTD was selected to produce the dry concrete curbs. The compaction process and curing process parameters are studied in order to maximize the production efficiency and production quality.The durability of primary two group dry concrete curbs were tested. The resistance to freeze-thaw and chloride ion permeability were evaluated, and eventually chosen the better dry concrete mix. Test results showed that both the two groups can meet the application requirements, and water/cement ratio was 0.37 mix specimen performed better.Finally, the test section of dry concrete curbs was layed combined with Anlongquan interchange bridge construction to verify its performance. Through the method of tracking survey found that dry concrete curbs applied well. The resistance of dry concrete curbs to freeze-thaw durability is better than ordinary concrete, which indicates that the performance of dry concrete curbs was stable. The dry concrete curbs were suitable for seasonal frozen soil region such as Northeast China.