• Dense-graded cold-mix asphalt with emulsion bitumen is usually durable against water during implementation. However, during rain and before condensation and
the manufacture of these mixtures, vehicle traffic must be controlled until achieving the suitable condensation.
• The amount of water that is mixed has to be as much as the bitumen emulsion needs to spread uniformly and reach the suitable efficiency. Severe use of water can cause a delay in implementation and rolling process.
• The mixing time has to be as much as allows the bitumen emulsion to spread uniformly in the mixtures. Long-term mixing can make the stone materials get rid of bitumen emulsion or it can cause breakage in bitumen emulsion.
• To get the implementation of cold-mix asphalt as soon as possible, the bitumen emulsion is manufactured in several thin layers.
• The surfaces of cold-mix asphalt shouldn’t be waterproofed too soon because it shuts the water in it can cause problems.
• If pavement stripping happens due to vehicle traffic, the removed materials should be cleared from the path in order to prevent any more pavement damages. If the amount of stripped sand increases, a thin cover of %15 bitumen emulsion and %85 water should be used to help the pavement heal better.
Specifying the type and the class of emulsion bitumen that has to be used and the manufacture of stone materials are done in a laboratory. The type of the used emulsion bitumen depends on the characteristics of stone materials, climate, pavement type, and the used machinery. MS-2, MS-2h, HFMS-2, HFMS-2h, CMS-2, CMS-2h are usually used for open-graded cold-mix asphalts in place. The temperature level of spreading bitumen emulsions in manufacturing cold-mix asphalts is from 20 to 70 degrees Celsius.
C: In-situ cold-mix asphalt with emulsion bitumen
Before overlaying in-situ cold-mix asphalt, the road surface should be cleared from any dirt and loose or removed grains and its roughnesses have to get fixed. Then the surface has to get condensed. If in-situ cold-mix asphalt is overlaid on a sandy surface, the road surface should be prepared by a prime coat and if the in-situ cold-mix asphalt is overlaid on the asphalt surface, the road surface should get tack coated before the in-situ cold-mix asphalt overspreads. In this method, stone materials of cold asphalt are usually the same materials that are used on the road surface or the materials that are carried to the place and windrowed or piled on the prepared road surface as much as needed. The size of the windrow and the distance between the piles should be in a way that lets you determine the amount of emulsion bitumen that overspreads on it in order to calculate the required thickness on the way and after combining with bitumen emulsion and in-situ cold-mix asphalt overspread. In such cases that we use the stone materials that exist on the road surface for manufacturing in-situ cold-mix asphalt, first, we have to plow the road surface to the maximum depth of %25 more than the thickness of the asphalt. Its width should be 6 meters more than the width of both sides of the road. Then the plowed materials are combined as well to gives us some uniform materials. The coarse particles of stone materials with a size of more than 3.6 centimeters (5.2 inches) should get removed from the road surface. Whenever the amount of stone material is not enough to make in-situ cold-mix asphalt, the lacking amount of material should be added to it and get mixed with each other well to match the grading of the mixed stone materials with the intended grading of stone materials of the in-situ cold-mix asphalt. The required emulsion bitumen is distributed on the stone materials using a bitumen distributor machine. To determine the needed amount of emulsion bitumen first we have to determine the volume of piled or windrowed stone materials per meter of the road length. Then based on the volume of windrowed stone materials, the percentage of bitumen emulsion should be measured per meter of the road and the speed of the spreader. This method is just like the method mentioned in paragraph “B”. But the difference is there is no factory here and the stone materials are windrowed on the road or piled near the road and then, the emulsion bitumen is poured on it and mixed by path constructing machinery such as loader and grader. This method is very useful for the roads that have low vehicle traffic or rural routes. It is worth mentioning that like the above methods the stone materials should have appropriate technical specifications.