Bitumen emulsions are successfully applied in construction of pavements with various mineral aggregates by mixing on the road and impregnation surface treatment (single or double) and also by making black top with mineral aggregate made by mixing the aggregate with emulsions.
Acidic bitumen emulsions ensure excellent adhesion of bitumen with the minerals for water resistant skid-resistant surface. Inverted highly concentrated tar emulsions can also be used for this purpose (directly or in combination with basic bitumen emulsions). Such emulsions can be used for limestone materials.
Construction of black pavement my mixing emulsion and mineral material on the road
This method involves bringing mineral materials (gravel or macadam) by dump trucks and unloading them into a container. Graders distribute the material evenly and continuously along the road and mixed with the bider, then mixed by graders and rakes. The material is unloaded onto the road, where it is evened out by graders, profiled and compacted by pneumatic rollers.
The dosage of the binder (calculated as the amount of dry bitumen) for emulsion may be considered as 2-4% of the mineral material weight for the bottom layer, while with straight bitumen the consumption is 5-6%. For the top layer, the consumption of the binder in an emulsion is 4-5.5%, while with straight bitumen it is 8-9%, i.e. different by a factor of 1.5-2. Besides, when using bitumen, a tac coat is needed, consuming additionally 1.6 kg of the binding material per m2.
The process of single layer surface treatment with an emulsion is different from the regular surface treatment. After cleaning the road from dirt and dust, half of the small stones (5-10 mm) brought from the quarry is distributed on the surface. Following that, half of the emulsion is sprayed over it, at the rate of approximately 0.35 liters/m2. This prevents the emulsion from spreading too thin over the base. The process is repeated one more time. Then the surface is compacted by a light roller. The new layer is cared for over a few shifts.
Double layer surface treatment is also performed in two stages, alternating between applying low and top stone layer and emulsion, the only difference being the application of larger stone fraction first (10-20mm).
The construction of black mineral layer with an emulsion is easier than applying cold asphalt mix, since it does not require heating of the binder and tac coating of the base. Such emulsified material can be applied without tac coating in damn cold weather. The stones, after mixing and distribution, is treated with emulsion or paste, and compacted by pneumatic or smooth rollers (motorized or towed). The resulting pavement is strong, water and skid resistant.