The technical route of epoxy asphalt and its application

1, the chemical mechanism of epoxy asphaltepoxy asphalt as a two-component material, A component is epoxy resin, B component is a uniform and stable multi-component mixtureChemical modification of matrix asphalt, the introduction of functional groups with epoxy resin sylacross reaction on asphalt molecules, to ensure that asphalt can participate in the curing reaction of epoxy resin, and then with the preferred resin to produce epoxy asphalt B components, and A component reaction to form a three-dimensional mutual wear network structure polymer, fundamentally changed the thermoplasticity of ordinary asphalt, significantly improved the high temperature stability and the strength of the high temperatureIts curing reaction chemical equation is shown in Figure 1Figure 1 The curing reaction schematic2, the physical and mechanical properties of epoxy asphalt
epoxy asphalt is neither asphalt material nor epoxy resin material, but a new road bridge building material with both advantages of thermosolid high strength, high adhesion force and high elongationThe basic characteristics ofepoxy asphalt are:0
1epoxy asphalt A, B two components mixed, with time, the two material and chemical effects, the system's viscosity gradually increased, and the higher the temperature, the faster the viscosity increases0
2the curing of epoxy asphalt is a chemical reaction, so the curing process and temperature is very relevant, at 120oC 4h can basically complete the curing, if the temperature is reduced, then the curing time correspondingly extendedGenerally to 120oC 4h curing degree as the standard strength0
3 epoxy asphalt is cured to form insoluble, insoluble thermosolid materials The curing process is irreversible, and even if the temperature rises again (e.g., above 300oC), the material is still in solid state, thus ensuring that epoxy asphalt maintains good mechanical properties at high temperatures 0
4 the adhesion of epoxy asphalt is produced by both physical and chemical, not just the usual physical bonding force, so its adhesion is very high (up to 6 to 9MPa with steel plates) 0
5 epoxy asphalt has a special molecular structure, so it can maintain good flexibility even at -10oC, with a fracture elongation rate of 120% (SBS modified asphalt is only 20%) 3, the preparation and process requirements of epoxy asphalt 3.1 epoxy resin selection
epoxy resin is a low-polymer containing epoxy group with a lipothal, lipoly or aromatic organic compounds as a skeleton Usually at room temperature for viscous liquid, at the corresponding temperature mixed with curing agent and curing reaction can occur to form a spatial three-dimensional structure of the mesh polymer, the product has a high bonding strength, small shrinkage, heat resistance, chemical resistance and mechanical and electrical properties of good characteristics but the weakness of epoxy resin in the process of use, such as its high brittleness, poor weather resistance and low ductility, also greatly limited the scope of use of epoxy resin Usually to improve the brittleness and ductility of epoxy hardening products, mainly by selecting or table-forming the appropriate curing agent to change the molecular structure of the curing product, thereby improving the performance of the use to a certain extent epoxy resin sympathisers can be classified according to structural characteristics can be divided into shrinking glycerides, shrinking glycerides, dyskeletal glycerides, li-cyclocyclic epoxy resins and epoxide olefins Among them, bisphenol A epoxy resin in the shrinking glycerin ether is a widely used product in the epoxy family Currently used is by diphenol-based propane (bisphenol A) and epoxy chloropropane under the action of alkaline catalysts The line-type epoxy resin with the end base of the shrink product is: bisphenol A epoxy resin has a highly reactive epoxy-based structure in the molecular structure, and there are many ether bonds on the main chain is a linear polyether structure There are many hydroxyls at a certain distance from the molecular chain, which is a long chain polyol There are also phenyl sylph rings, submethyl and isopropyl sylph in the main chain These features can play the following role: epoxy and hydroxyl make the resin reactive and make the hardener have a strong cohesion and adhesion Ether bonds and hydroxyl are polar genes that help to improve leaching and adhesion The ether and C-C bonds give the macromolecules a certain degree of smoothness The benzene ring makes the curing material heat resistant and rigid The key of the key can be high, which is higher and alkaline And the dominant lethal mutation index (Ames) test proves that bps A epoxy resin is not carcinogenic, teratogenic, cell-causing mutagenic, so it can be used safely Based on the above advantages of bisphenol A epoxy resin, this experiment uses it as a conventional modified resin in epoxy modified asphalt 3.2 the choice of curing agent
because the choice of curing agent on the effect of epoxy asphalt is greater, the choice should be adapted to the following requirements: 0
1 epoxy resin and curing agent after mixing, at a certain curing temperature, the initial mixture curing time should meet the asphalt concrete mixing, transportation, paving and crushing and other required time 0
2 curing agent should not only cure epoxy resin at high temperature, but also at room temperature can also be slowly cured, because the epoxy asphalt mixture after the paving of the normal temperature conditions, still need to further curing, so that the strength of the mixture has been growing 0
3 curing agent in practical application, should have a large yield, low value, non-toxic, easy to control these prerequisites, so that the use of epoxy asphalt easy to popularize and popularize therefore, the curing agent generally chooses the acid anhydride (methyl tetrahydrobenzene or methyl hexahydro parametia, etc.) as the curing agent of epoxy asphalt Because of its low toxicity and low volatility, it not only saves costs, but also facilitates the curing of epoxy asphalt 3.3 The process of preparation of epoxy asphalt requires epoxy resin and asphalt reaction to produce an irreversible curing substance, which fundamentally changes the thermoplasticity of asphalt However, because epoxy asphalt makes thermoset substances, compared with ordinary asphalt, there are still many problems Therefore, when preparing epoxy asphalt, we need to consider the following aspects: 1 The ethylene oxide resin is poorly compatible with asphalt
epoxy resin is a polar substance, while asphalt is a non-polar substance, and the compatibility between the two is poor In order to prepare an equal and stable epoxy asphalt mixture, the dispersion of epoxy resin and asphalt should be improved and the compatibility between the two should be improved Generally add compatibility agents 2 The flexibility of epoxy asphalt prepared by ordinary epoxy resin is poor
the brittleness of ordinary epoxy resin is poor, which results in poor ductile performance, which is difficult to meet the requirements of the steel bridge paving layer for the performance of the mixture 3 The determination of the optimal fit ratio of each component of epoxy asphalt epoxy asphalt by asphalt, epoxy resin, curing agent and other additives and other materials, first of all, it is necessary to determine their appropriate proportion of the combination, however, in many cases, the relative proportion of each component is a pair of contradictions, therefore, need a large number of tests to determine the optimal fit ratio and evaluation indicators 4, the application of epoxy asphalt in engineering
4.1 epoxy asphalt in the bridge paving application
theory and engineering practice shows that the steel bridge surface paving should mainly meet the following conditions: 1) steel bridge panel due to vehicle load caused by local deformation, the same wheel load effect on the steel plate generated by the deflection halo is about three times the effect on the general road surface Therefore, the bridge paving must have sufficient deformation adaptability 2) Steel bridge panels are susceptible to climate, so the bridge paving should be able to maintain stable performance over a large temperature range 3) Under the action of wheel load, the steel bridge surface is laid in the grid-shaped strength rib part, will form a larger bending stress repeated action, easy to lead to fatigue cracking of the paving layer, therefore, the bridge paving structure should have good anti-fatigue cracking performance 4) Steel bridge surface should have a perfect anti-draining and anti-corrosion system to ensure that the steel plate is not eroded 5) has a good combination between structural layers to ensure the synergy between paving and bridge panels 6) good flatness to reduce the impact of driving load In recent years, with the increase of traffic volume and shaft load in China, as well as the increasing of climatic conditions, the bridge pavement in China generally appeared serious early damage, greatly affecting the service life of the bridge, resulting in huge economic losses Practice shows that the maintenance cost after the bridge paving layer is often several times higher than the original investment, and the repair time is longer, which seriously affects the safety, speed and comfort of traffic bridge as a suspended structure, its upper bridge pavement layer is sensitive to changes in natural factors, and is more prone to early diseasethand than the asphalt pavement in the roadbed section In the hot summer, the temperature of the steel bridge panel is 25 degrees C to 35 degrees C higher than the temperature, the rut is more likely to occur than the ordinary road section, the bridge is more sensitive to low temperature and temperature rise and fall cycle, so it is more prone to various forms of cracks The bridge has a large deflection, is significantly affected by temperature stress, and sometimes there is a negative bending moment, and these external force conditions are more stringent than the road surface In addition, because the asphalt mixture layer and the bridge structure in the material performance is large, so it will lead to stress and deformation discontinuity under the action of external forces Due to the influence of this complex temperature stress, negative bending moment, shear stress, overload and impact force, the bridge paving is prone to deformation and crack damage the use of epoxy asphalt pavement, starting from the second bridge of the Yangtze River in Nanjing, China introduced epoxy asphalt, a bridge paving material, and thus launched a new page in the history of bridge paving in China Subsequently, the epoxy asphalt concrete bridge paving has been used in runyang Yangtze River Bridge test bridge, Jiangyin Yangtze River Bridge test section, Zhejiang Zhoushan Taotianmen Bridge and Runyang Yangtze River Bridge, Jiangyin Yangtze River Bridge bridge repair, Nanjing Yangtze River Bridge and other national key projects From the use of the bridge surface of the Second Bridge of the Yangtze River in Nanjing for more than five years and other construction quality inspection indicators of each bridge, epoxy asphalt concrete bridge paving regardless of the bridge surface waterproof, interlayer bonding, asphalt layer paving has obvious advantages, and has good road surface performance epoxy asphalt mixture is the ideal road construction material for steel bridge paving, road grinding layer, super-heavy traffic road, has a wide range of application prospects, the research and development of domestic epoxy asphalt has become an urgent task, the successful development of domestic epoxy asphalt coagulation technology will greatly reduce the engineering cost and use cost of bridge paving, while having its own epoxy asphalt technology, and also facilitate the optimization of epoxy asphalt in future production practice 4.2 Epoxy asphalt in the high-grade highway and urban main road application
traffic pressure increased caused a variety of road surface damage, asphalt itself thermoplastic nature makes its repair relatively difficult, thermoset epoxy asphalt just fill this defect The application of epoxy asphalt on the road is mainly reflected in the following aspects: 1
road, especially the parking station due to the frequent braking, starting and long-term parking effect of locomotives, the traditional asphalt pavement will appear serious rut damage phenomenon When using epoxy asphalt as a paving material, this problem can be reduced and the performance of the road surface can be improved 2
epoxy asphalt has a good bonding performance and large stiffness, so the deformation at high temperature is very small, the surface after grinding will not become a light surface because of pan-oil These features make epoxy asphalt the preferred surface paving material when laying the anti-slip and grinding layer It can be used on airport roads to improve the safety factor of aircraft landing and take-off 3
the researchers suggested laying porous, permeable asphalt surfaces to reduce splashing on rainy roads, improve visibility on road marking slots on rainy days, and glare at night However, the permeable road surface built with ordinary asphalt is easily pressed by the drive, thus reducing the gap of the permeable layer and greatly reducing its application effect, while at the brake, acceleration and bends are prone to peeling The appearance of epoxy asphalt can solve these problems very well, and achieve the optimization of structure and materialatly in addition, on some road surfaces that are susceptible to corrosion and wear severely Places such as car depots and container oil transit stations are in urgent need of epoxy asphalt as a paving layer in order to reduce damage and repair