Emulsion bitumen applications
Introducing some emulsion products and their uses
Surface coatings
In the implementation of surface coatings, first the adhesive agent is sprayed on the surface, and after spreading the broken sand on the water, the surface is beaten before the adhesive agent is applied. To create thicker layers, the aforementioned process is repeated. This method has been used in all types of roads to provide a temporary or permanent coating on fixed layers or the surface of automobile roads.
Surface coatings create a unique texture on the road surface, which has a very obvious role in increasing friction, resistance to water ingress and creating cracks, and because of the satisfactory results, even in deep or wet materials, the ultimate resistance can be reached faster. In comparison with return bitumen, avoiding the emission of polluting gases and fire hazards, emulsion bitumens are the best option for use as an adhesive agent in surface coatings. In order to achieve satisfactory results in relation to the use of emulsion bitumen in surface coatings, it is better to use cationic fast-breaking emulsion bitumen with a high percentage of suspended bitumen particles of about 65-08%, which is modified by polymers and hot at a temperature of about 85C0 – 50 are sprayed to be used. Of course, in North America, anionic emulsion bitumen is also used for this purpose, but in this case, adhesion boosters should be used for the emulsion bitumen used to prevent the separation of broken sand.
Liquid surface coatings (slurry)
Slurry coating refers to a mixture of fine-grained natural materials with compact granulation along with emulsion bitumen and water, which is spread on the road surface in a smooth manner to a thickness of about 3-30 mm depending on the diameter of the material. The implementation of such mixtures is mainly done by using a mixing and spreading machine. Although these mixtures can be prepared and implemented manually, the emulsions used in slurry mixtures are mainly cationic, slow-breaking or slow-breaking. be The tests related to the design of this type of coating have been presented by the International Slurry Coating Association. The choice of design method and type of experiments depends on the type of selective emulsion. In high-traffic routes, you can use fast-breaking covers, in which case the route will be ready to receive traffic after 60 minutes. On the other hand, in the manual methods that take longer, you can use more slow-breaking materials. Slurry coatings with greater thickness and using bitumen, fast-breaking polymer emulsion are called microsurfacing. In order to achieve satisfactory results in the performance of emulsion bitumen, it is better to choose the used emulsion bitumen according to the type of material. Of course, some additives can be used to improve the failure rate
Industrial mixtures
Emulsion bitumen and broken materials or shaved asphalt can be used to produce road construction materials for the same uses as hot asphalts. For such purposes, slow-breaking or slow-breaking emulsion bitumens can be used depending on the grain size of the materials. On the other hand, cold mixtures that use the combination of emulsion bitumen and cement as an adhesive agent have a much higher bearing capacity.
Cold recycling
By using some special mobile factories or even some simple machines and equipments, the surface layers or the entire structure of the road surface can be recycled in situ. In cold recycling or reuse of existing materials, emulsion bitumens are used alone or together with cement and lime. Usually, in projects like this, cationic emulsion bitumens are used.
Using cement with emulsion bitumen
The results of the tests indicate that ordinary Portland cements (type 1) leave positive effects on mixtures containing emulsion bitumen in different ways. The lump tests show that cement increases the lump rate of bitumen emulsion and results in improving the performance of the mixture. The examination of mechanical properties also indicates that cement causes the action and ultimate strength of mixtures containing emulsion bitumen to be faster and higher. This increase in strength is to the extent that the strength of a cold mixture by adding 1% of cement increases the strength of hot mixtures. Obviously, this increase in strength is not due to the role of cement as bitumen, because in warm mixtures with the addition of 1% cement, no significant resistance is observed. Studying the change in shape and flow of emulsion bitumen with cement indicates an increase in viscosity. It can be concluded that the use of cement together with bitumen emulsion both during the operation and after it causes the creation of a composite adhesive agent. which provides much more favorable properties compared to emulsion bitumen.
Using lime with bitumen emulsion
Hydrated limes have a plan similar to cement in breaking the bitumen emulsion and making the mixtures work. According to the studies, the use of lime or calcium chloride along with bitumen emulsion increases the cationic properties and in certain conditions decreases the anionic properties. In cases where the materials have a negative surface charge, it is possible to affect the reaction between the bitumen particles suspended in the emulsion and the materials by using bitumen emulsion with lime. The conducted studies show that Ca2+ plays a significant role in the performance of bitumen emulsion. Therefore, adding a small amount of calcium chloride increases the speed of action. Of course, in the use of calcium chloride, it should be noted that this material is present only as a source of Ca2+ supply in the mixture and does not cause additional adhesive force.
stabilization of soils
To stabilize the natural sandy soil, you can use bitumen cationic emulsion retarder. In many cases, soils with a sand value of more than 25 can be modified to be used as a base material for warm coating or for secondary roads that only need a bitumen protective layer against water penetration. Even materials with less sand value can be modified by using bitumen emulsion and a hydraulic binder such as lime or cement.
Surface insulation for asphalt roads
Surface insulations are cold psychoactive mixtures that can be stored and are used to insulate car tracks on parking lots and sidewalks. These mixtures can be prepared based on tar (to resist fuels) or bitumen. The bitumen emulsion used in these mixtures is stabilized by using some special clays, as well as cationic or anionic emulsifiers and additives such as latex. The use of cationic emulsifiers makes surface insulation more resistant to water penetration. The role of clay in this mixture is to stabilize the mixture in front of storage, softness (to coat the surfaces even with the use of a brush) and to achieve the necessary viscosity to keep the broken sands suspended which are used to create friction. Among the advantages of using clay, reinforcement of the resulting emulsion bitumen mixture and reducing the tendency to stick to foreign objects can be mentioned. However, if clays are used improperly, problems such as water absorption and re-suspension of bitumen particles occur.
clay emulsion bitumen
Clay emulsion bitumen are mainly used in industries. Of course, if there is a need to use bitumen with more formability in road construction or construction purposes, this type of emulsion bitumen can be used. The application of this type of bitumen emulsion is very diverse and includes tree grafting, water tank repair, and covering of buildings. Some applications of clay emulsion bitumen are as follows.
Protective covers
Preparation of adhesive materials
Bituminous mortars for floor construction
Bituminous mortars for insulation work
8-1 Theory of clay emulsion bitumen
Clay emulsion bitumen are similar to usual emulsion bitumen and are created from the combination of two immiscible phases of bitumen and water along with an emulsifying agent. In clay emulsion bitumen, the emulsifying agent is the clay emulsifier. The clay used should have a significant amount of colloidal particles. To use clay, it can be mixed with bitumen and spread in the aqueous phase. Of course, in the preparation of these emulsions, dispersing additives, coatings and PH stabilizers are also used. If necessary, active colloidal materials such as bentonite and kaolinite clay can be added to the mixture in a concentrated form through the aqueous phase. Clays such as bentonite acquire a net negative charge when soaked in water. When bitumen is added to the clay mixture that is not miscible with water, it coats the bitumen particles. (Figure 2) The aforementioned process stabilizes the bitumen-water-clay mixture and also provides the possibility of adjusting the viscosity by adding water.
One piece
Single coat is applied to a thin layer of bitumen, which is used between layers of warm asphalt to prevent the two layers from creeping on top of each other. There are many differences among the emulsion bitumen that are used as single coats all over the world. In many countries, cationic or anionic emulsion tars that may be diluted with water are used as a single coat. But in Europe, cationic emulsions are used for this purpose. It is important to note that this layer should remove dust from the surface of the bottom layer by using the water contained in it. Therefore, in order to achieve this goal, it is recommended to reduce the diameter of the suspended particles in bitumen single coat emulsion and increase the solvent percentage. The goal of new innovations in the field of tak-ket production has been to produce a very reliable adhesive agent with a high breaking and working speed and no desire to stick to passing traffic wheels and road construction machinery.
Primmest
Primmest can be used as an adhesive agent for hot mix layer on non-useful materials or base fixed with lime or cement. The primer must penetrate to a depth of 1-4 cm in the base layer. Sometimes it is possible to mix the bitumen emulsion sprayed on the surface with the base materials and pound it again to achieve this depth of penetration, which is generally true in relation to fixed bases. For priming, you can use a compound similar to single coat with a usage rate of 1.5 kilograms per square meter.
11- Application of cement compounds
Spraying bitumen emulsion on the surface of cement concretes or foundations fixed with hydraulic bonding agents, by reducing the amount of surface evaporation, ensures reaching the maximum power of these layers.
Fog seal
Very little use of diluted emulsion bitumen on aerated surfaces will replace the bitumen in the holes and increase the lifespan with a very low cost. Fog seal is a method in which it is used to insulate and improve resistance against water penetration and keep granular materials on the road surface by increasing the adhesion of surface materials, in simple terms, fog seal improves the appearance of the road. On the other hand, improper use leads to slippery surface or surface adhesion in front of passing traffic. Fog Seal Emulsion Bitumen Producers Association is a very limited application of emulsion bitumen, which is used by spraying a very thin layer of this material in a diluted form with the primary purpose of covering and sealing the stained surface and increasing the strength of dry and weathered surfaces. It defines Other sources consider fog seal to be a factor of rejuvenation and strengthening of the road surface due to the addition of new bitumen to the old asphalt, which increases the lifespan of the road surface. Also, the use of fog seal in surface coatings is used to keep broken sand on the surface. This use of fog seal prevents damage to passing vehicles by stones that are thrown from the surface. Asphalt Institute also considers crack coating among the emulsion bitumen applications.
12-1- Fog seal performance
Fog Seal is a coating that is used to protect and rejuvenate the existing asphalt. Adding a fog seal layer increases the resistance against water penetration and reduces the effects of increasing the life or reducing the penetration of water and air. To achieve this goal, fog seal must have the ability to fill the empty spaces in the pavement. Therefore, the viscosity of the fog seal during implementation should be low enough so that there is no possibility of its failure before penetrating the empty spaces of the road surface. Achieving this goal is only possible by using tar emulsion diluted with water. Emulsion bitumens that are not sufficiently diluted with water have less penetration and after breaking or accumulation of bitumen on the road surface, it creates a very slippery surface.
During the implementation of Fog Seal, bitumen emulsion causes the materials and the surface of the existing pavement to become wet. Cationic emulsion bitumens cause displacement of the surface of existing materials or debris. Due to the loss and occurrence of some chemical reactions, the bitumen emulsion is broken and a new bitumen film appears on the existing asphalt material or surface. The failure rate of bitumen emulsion depends on several factors, including weather conditions (wind, rain, ambient temperature, etc.). In relation to emulsion bitumen, there is almost no specific internal surface gravity force with any type of granular material. This type of emulsion bitumen breaks due to water loss caused by evaporation, water absorption by materials and empty spaces.
12-2- Performance of rejuvenators
The rejuvenating emulsion bitumens have oil compounds that soften and reduce the viscosity of the existing asphalt. Also, these materials increase the formability of the existing asphalt, which also reduces the probability of failure. This application can be beneficial in cases where the texture of the existing asphalt surface is open and the probability of failure due to age increases.
Like normal emulsion bitumen, this type of emulsion bitumen also causes the road surface to become slippery if it does not penetrate the surface.
Mulch cover
Although the initial use of bitumen was mainly in road construction, this material has found wide uses today due to its diverse properties and applications. One of these uses is in agriculture, and the mulch coating is a type of bitumen emulsion that is used to reduce and delay the evaporation of water from the surface of agricultural land. The use of mulch has three very important features:
Keeping the seed in its place against the incoming forces from wind and rain
Due to the dark color of this coating, it absorbs and stores the sun’s energy well during seed germination.
By maintaining water particles in the soil, it increases the quality of the soil and the growth rate of crops. Some other results of using bitumen emulsion mulch are mentioned as follows:
Soil protection against erosion
Preventing compaction against the impact of stone rains
Maintaining water particles and avoiding frequent irrigations
Keeping the soil temperature uniform
Preventing the growth of weeds
Keeping fruits and vegetables clean
macadam penetration
The use of quick-breaking or slow-breaking cationic emulsion bitumen on the dense surface of a layer with open graining causes the emulsion bitumen to penetrate into the layer and cause the bonding of the primary materials to each other.
