What is cold asphalt? Its use in road construction
Application of cold asphalt in road construction: Cold asphalt (Cold Mix) is a mixture of rock materials and bitumen or bitumen emulsion whose raw materials are mixed at room temperature. Cold asphalt is prepared by mixing aggregates with soluble bitumen or bitumen at room temperature. And at the same temperature it spreads and condenses. The mixing time with bitumen can be wet, but with soluble bitumen, it must be dried at room temperature or under heat. Cold asphalt can be transported and then spread over long distances or stored in a workshop and used later. Stay with us until the end of this article.
What is cold asphalt? Its use in road construction Cold asphalt is prepared by mixing aggregates with soluble bitumen, bitumen or tar at ambient temperature and spreading and compacting at the same temperature. Aggregates can be wet when mixed with bitumen, but for soluble bitumen, the moisture content of the material must be dried at room temperature or under heat. Cold asphalt mixtures prepared with concentrated soluble bitumens such as 3000-MC or 3000-SC are practically mixed with bitumen at a temperature of 95 ° C or higher and spread and compacted within the same temperature.
Classification of cold asphalt Cold asphalts can be classified according to the following factors:
1- Method of preparing and applying asphalt 2- Cold asphalt granulation
Classification of cold asphalt in terms of method of preparation and implementation Cold asphalt can be divided into two categories according to the method of preparation and implementation:
Factory cold asphalt Cold asphalt mixed on site Factory cold asphalt Cold asphalt is prepared in fixed and central asphalt factories and then transported to the place of consumption for distribution. In cold asphalt plants, the necessary controls are observed to regulate granulation, distribution of aggregates and mixing with bitumen similar to hot asphalt. Of course, when using emulsion bitumen, provided that the moisture content of the material is not more than 3%, the heating or drying steps of the aggregates are often removed from the mentioned operation cycle. Stone materials are heated either under the conditions of using soluble bitumens or emulsion bitumens.
Cold asphalt mixed in place Cold asphalt mixed in place is divided into two categories:
A- The type of mixture in place, where the aggregates are spun along the path and sprayed with bitumen, and then the mixing and spreading operation is done with a grader or similar equipment. Cold asphalt prepared with soluble bitumen, the prepared asphalt mixture should be turned over and over again by machines (loaders and graders) in the open air as necessary to reduce the amount of solvent in the soluble bitumen.
B- The type of mixture in the mobile workshop, where the bitumen and aggregates are mixed in mobile factories and the prepared mixture is transported to the place of consumption for distribution.
Scope of application of cold asphalt Cold asphalt has three uses, which are:
Cold asphalt in road construction Maintenance of pavements In special cases such as the floor of sports venues Application of cold asphalt in road construction Cold asphalt is used in all layers of pavement, provided that all design criteria and traffic restrictions of the route are observed. This type of asphalt can be used in surface layers, bitumen base and foundation for light and medium traffic and in bitumen base layer for heavy and very heavy traffic. Cold asphalt is used in the surface layer in light and medium traffic conditions and its implementation. For conditions Heavy traffic is possible as a base layer. If the traffic situation changes from light to medium to heavy for the route in which this type of asphalt is used as a surface layer, hot asphalt should be used as a cover to prevent damage.
Application of cold asphalt in road repair and maintenance Staining of pavement failures is one of the most important road maintenance operations. In general, the use of high quality hot asphalt mixes, although more expensive, is more convenient, but in many areas, It is not possible to produce and apply hot asphalt throughout the year, staining operations can be done using cold depot mixtures. In general, cold asphalts are used in local repairs such as staining, filling holes, filling cracks and.. In general, two types of cold asphalt mixtures are used for staining operations and pavement repairs. They are cold asphalt mixture with immediate use and cold asphalt mixture with non-immediate use. Cold asphalt mixtures with immediate use can be produced in late summer or early fall, and for later use (during the colder months of the year), Chapter 1 - Introduction of cold asphalt types and their application in remote areas. Depending on the type of bitumen used in the preparation of cold asphalt, these mixtures can be used for up to six months and can be used without the use of heat.