Roadphalt colored epoxy asphalt

Colored asphalt has been widely used in our country, but it still has a performance gap with ordinary black asphalt, especially high-temperature performance, and generally dynamic stability of colored asphalt mixture is less than 200 times/mm. Performance of colored asphalt mixture can be modified partly by adding many polymers such as SBS, but the improvement of high-temperature performance for colored asphalt mixture is restricted significantly because colored asphalt does not contain polymers such as asphaltene, SBS, PE, EVA and SBR. Dynamic stability of modified colored asphalt mixture can reach 300-500 times/mm by adding polymer. If addition amount of polymer is more than 10% of amount of colored asphalt, the viscosity will become excessively large even though dynamic stability of colored asphalt mixture can reach 1000 times/mm, which leads to many problems during the processes of production, storage, transport, pumping, paving, rolling of mixture and so on. As high-temperature performance of colored asphalt is poor, it can not be applied in many places such as high-temperature area of south china, large traffic and permeable pavement.

Based on our research and testing of colored asphalt and referring to research results of epoxy asphalt, a special curing system of epoxy colored asphalt is selected according to characteristics of colored asphalt in our company,. High-temperature performance of colored asphalt can be improved fundamentally by adding proper amount of curing agent into colored asphalt, which makes high-temperature performance of asphalt mixture can be achieved or even more than that of black modified asphalt, and dynamic stability of epoxy colored asphalt mixture reaches 8,000 times /mm.

Epoxy Asphalt is suitable for paving not only pavement, bus lane, heavy traffic pavement, bridge and other pavement but also colored permeable pavement with high-quality requirement.

Raw materials

Colored epoxy asphalt: be composed of two materials, curing agent + colored asphalt.

Pigment: 2%-3%, red pigment; 3%-4%, green pigment.
Coarse aggregate: conventional stones with large crushed value such as basalt and diabase are suggested to be used. For example, red stone such as red granite is suggested to be used for red pavement, and here we should note that stone can not be crushed when being pressed.

Fine aggregate: limestone is suggested to be used for paving red pavement. Red stone is also suggested. For example, red granite is broken into 0-5mm stone crumb and replaces sand.

Mixing ratio design:

Gradation: Refer to grading standards and the corresponding design method of mixture in the JTJ F40-2004 construction specifications of asphalt pavement

Amount of colored asphalt: amount of asphalt is determined using the design method of mixture in the JTJ F40-2004 construction specifications of asphalt pavement. When curing agent is not added, the optimum amount of colored asphalt can be determined by porosity, and target porosity is 4%.
    After the amount of colored asphalt is determined, the amount of curing agent is 10-20% of colored asphalt amount. If dynamic stability is more than 3000 times/ mm or achieves the requirement of modified asphalt in the track experiment of colored asphalt mixture, the suggested amount of curing agent is 10-20% of colored asphalt amount; If dynamic stability in the track experiment of colored asphalt mixture achieves the requirement of ordinary black asphalt, the suggested amount of curing agent is 15-20% of colored asphalt amount. If it is used to pave colored permeable pavement, the suggested amount of curing agent is 10-13% of colored asphalt amount.

Note: the appropriate amount of curing agent can be selected and excessive pursuit of curing effect and large amount of curing agent may lead to many problems such as construction difficulty.
Mixing of mixture:

Curing agent is supplied to customer in bag, and colored asphalt is generally supplied to customer in bulk and also in drum if the project is smaller. Performances of raw materials for aggregate should be stable so that mix proportion of production target can be close to mix proportion of design.

Pre-calculate the amount of curing agent for a plate of mixture before using, and open package in advance.

As proportion of pigment with the roles of dyeing, dispersion, adsorption, stability is large; its impact on environment needs to be considered. Pre-calculate the amount of pigment for a plate of mixture according to target mix proportion of production target before production, and the pigment is packed in polyethylene plastic bag and used by artificial mixing.

Before construction, curing agent and pigment are moved to the feeding hole of mixing tank, and workers are arranged specially to be responsible for moving and feeding curing agent and pigment. Before mixing, mixing tank, transport pipeline of asphalt, truck, construction machinery and equipment in the mixing station are washed cleanly; Mixing tank in the mixing station can be washed cleanly with hot aggregate several times.

      The mixing process of mixture is as follows: the temperature of aggregate is controlled at 170 ℃-190 ℃. After aggregate is put into mixing tank, curing agent is firstly added wholly, then colored asphalt is put into mixing tank. Adequate workers are allocated to ensure the whole process smooth and quick.
    After curing agent and colored epoxy asphalt are put into mixing tank, pigment is added. Notely, pigment should be added finally. 40-60s is suggested to be mixing time, and actual mixing time is determined by a principle of both evenness of mixing and appearance of no gray material.

Temperature of mixture discharge is suggested to be at 160℃-170℃, and it can be adjusted appropriately according to temperature, wind speed and transport distance.
 

Note: mixture should be abandoned when temperature exceeds 190℃.朗读

 

Transport and paving of mixture

Vehicles and coverings used for transporting mixture, should be cleaned in advance.

 

If there is some oil on the spray, appropriate measures should be taken to ensure that black asphalt adhered to sole of worker, roller and other things that are vulnerable to pollution do not pollute pavement.
    The paving procedure of colored asphalt mixture is basically the same with that of conventional asphalt mixture. Paver should be cleaned, especially screed should be cleaned with solvent or colored asphalt mixing is paved until there are no streaks from substrate to superstratum.
     When paving begins, performances of production, transport, paving and rolling for mixture should be considered to ensure continuous paving and full-size shape for keeping color consistent, granule uniform and beautiful.

 

Compaction molding of mixture (if it is used for repair, the following information is for reference only

Water in the roller tank should be replaced, and the rust should be cleaned. Roller should be stopped on the mat so that it does not touch the substrate of black asphalt, and it rolls on directly from wooden pad to colored mixture. Any tools touched with mixture in the rolling process should be cleaned.

 

Rolling compaction combination: the same with conventional permeable asphalt mixture

 

Rolling strength: compaction should be guaranteed on the premise of no crushed stone. Over compaction should be avoided, or the colored effect will be affected if stone is crushed.

 

 After rolling starts or temperature of mixture decreases, reductions of manual work or paving and artificial feeding are suggested, or it is difficult for the substrate of mixture and artificial feeding to bond together because of water at the surface.

 

In order to avoid colored asphalt surface being contaminated, sundries and sand adhered to roller drum are washed with water before rolling, and rolling is not permitted until rolling equipment is clean. Traffic is opened after rolling is over and temperature is cooled to room temperature.

Others
Other unmentioned issues can refer to construction requirements of black asphalt pavement in the JTJ F40-2004 Specifications of Asphalt Pavement Construction.