Description of road construction
Description of road construction operation of single-layer surface coating: Road construction operation is to prepare a path on the ground with a specified width that users and users can cross from one point to another. Many two items of excavation and excavation in the operation They confuse civil engineering with each other. In fact, excavation is the low and high ground harvest and the excavation depth is about 60 cm. This means that in excavation, only low elevations and surface heights are removed from the ground. In contrast, excavation has another meaning. Excavation means removing the low and high ground with a depth of more than 60 cm. Description of single-layer surface coating road construction operations Road construction operations consist of three main steps: • Asphalt bitumen base • Primekt foundation • Final pavement of surface coated asphalt - single coat (Tack Coat) to impregnate any asphalt or concrete surfaces with bitumen and Bringing adhesion with a new asphalt layer A variety of liquid bitumens are used as a thin layer. This layer is called surface coating (single coat) and creates a connection between the pavement surfaces with each other. Obviously, the use of surface coating is necessary to create adhesion between the two layers of existing and new asphalt. The use of emulsion bitumens is recommended to apply a single coat layer and the use of soluble bitumens should be avoided. CRS-1 and CRS-2 emulsion bitumens are recommended for applying single coat top layer. Due to the rapid breaking of the emulsion and the rapid readiness of the new asphalt layer, these two types of emulsions are more suitable. The amount of emulsion bitumen required for surface coating is about 250 to 500 grams per square meter. Although the exact amount of consumption is determined by the monitoring device, the amount of emulsion bitumen used on old and worn asphalt surfaces varies according to the amount of damage compared to new asphalts. The best conditions for performing a single coat at a temperature of 15-10 degrees Celsius and in such conditions should not be less than 5 degrees Celsius. Although it is possible to apply a single coat with emulsion bitumen in wet road conditions, but in rainy weather conditions or when it is likely to rain, it should be avoided. The important point is to apply the top coat on the same day that the top coat was applied. Obviously, during this period, traffic should be prevented from passing over the single coat layer, and before spraying bitumen, the road surface should be thoroughly cleaned of any contamination, soil and possible debris. To do this, you can use a mechanical vacuum cleaner and air compressor, and you must ensure that the single coat layer is uniform and the same size for all surfaces. It is important to control the bitumen nozzles and the angle and height of the spray nozzle from the road surface. The bitumen spraying machine must be equipped with the necessary tools and without defects, and it must have a speedometer and, if necessary, and according to the ambient temperature and the bitumen must be equipped with a heater. The bitumen spraying machine should be designed in such a way that the operator can activate or stop the spraying at any time and can control the volume of spraying and the machine and bitumen sprayer can circulate and heat the bitumen and can spray by means of a pump. . Also, the bitumen tank should be double-walled in order to maintain a constant temperature inside the tank. Characteristics of a good bitumen sprayer: • The quality and type of all nozzles of a bitumen sprayer should be the same. • The speed of the vehicle carrying the bitumen should be constant and uniform. • The height of the bitumen distribution pipe from the road surface is constant when the tank is full or empty. • The installation angle of the nozzles should be the same along the distribution pipe. • Bitumen sprayer must be able to change the width. • Bitumen sprayer should have internal plates to prevent bitumen turbulence in bitumen.
