Properties of road concrete from mixtures of various mobility
Abstract
The article is devoted to the properties of road concretes, which are made from concrete mixtures of various workability. For the manufacture of road concrete, moderately mobile mixtures and moderately hard mixtures are used. In recent decades, highly mobile and cast concrete mixtures have been used for road surfaces. An analysis of studies that have been carried out by different scientists has shown that there are different opinions on the effect of the mobility of concrete mixtures on the properties of the concrete that is made from them. It is known that an increase in the amount of water in a concrete mix leads to a decrease of the quality of concrete. Therefore, the quality of concretes made from cast mixes is always worse than the quality of concretes made from moderately mobile mixes. Concretes made from hard mixes have the highest characteristics. In practice, concretes made from cast mixes have a strength of more than 100 MPa. The disadvantages of concretes made from moderately mobile and rigid mixtures with W/C below 0.45 are increased cement consumption, high capillary porosity and low frost resistance. Therefore, the purpose of research is to assess the effect of the mobility of the concrete mixture and, accordingly, the compaction method, on the properties of concrete.
The article presents the results of studies of the properties of concretes made of cast mixes with a slump of 20 cm, mixtures with a slump of 2...4 cm, which are compacted by vibration, as well as hard mixes, which are compacted by pressing together with vibration. The consumption of cement is determined, less than which the properties of concretes made from cast mixes are lower than concretes made from harder mixes. It is shown that in the range of cement consumption 350...450 kg/m3, the use of polycarboxylate superplasticizers makes it possible to obtain concretes with high performance regardless of their mobility. At the same time, cement is used as efficiently as possible, as evidenced by a significant increase in its utilization rate.
