Common base asphalt is greatly affected by temperature, load and climate environment, and has defects such as easy softening at high temperature, easy cracking at low temperature, poor water stability and weak anti-aging ability, which makes it difficult to meet the requirements of high-grade highway, municipal trunk road, bridge deck pavement and special working condition road. Modified asphalt additive is a functional material used to improve the performance of base asphalt. It optimizes the mechanical properties, weather resistance and construction performance of asphalt by physical blending and chemical reaction, greatly improves the traffic quality and service life of asphalt pavement, and is the core raw material of modern asphalt pavement maintenance and new construction projects. This article systematically expounds the core uses and mainstream classifications of modified asphalt additives, and clearly combs the characteristics and application scenarios of various additives.
The core use of modified asphalt additives
The core function of modified asphalt additive is to make up for the performance shortcomings of ordinary asphalt, adapt to the use requirements of different regional climates, different road grades and different load conditions, and comprehensively improve the comprehensive performance of asphalt and asphalt mixtures. The specific uses are mainly divided into five categories.
Improve high temperature rutting resistance
Under the high temperature environment in summer, ordinary asphalt pavement is easy to soften, and it is easy to appear rutting, wrapping and pushing under the repeated rolling action of vehicles, which seriously affects the ride comfort and road service life. The high temperature modifier additive can effectively improve the softening point, viscosity and structural stability of asphalt, enhance the high temperature stiffness and deformation resistance of asphalt mixture, effectively inhibit the occurrence of high temperature rutting, and adapt to the main roads and high speed sections with high temperature, large traffic flow and heavy vehicles in the south.
Enhanced low temperature cracking resistance
In the environment of low temperature in winter and large temperature difference between day and night, the brittleness of ordinary asphalt increases and the flexibility decreases. Horizontal cracks and network cracks are prone to occur on the road surface. Rainwater will penetrate into the subgrade along the cracks, causing subsequent water damage diseases. The low-temperature modifier additive can improve the low-temperature ductility and flexibility of asphalt, reduce the low-temperature hardening brittleness of asphalt, effectively resist the low-temperature shrinkage stress, reduce the cracking problem of pavement, and adapt to the road engineering in the northern cold area and high altitude area.
Improve water stability and spalling resistance
When the adhesion between asphalt and aggregate is insufficient, the pavement is easy to appear water damage diseases such as aggregate falling off, loosening, pit and peeling under the action of accumulated water immersion and vehicle dynamic water pressure in rainy season. All kinds of anti-spalling and hydrophilic modification additives can strengthen the bonding strength between asphalt and stone, improve the waterproof, anti-seepage and anti-scour ability of asphalt mixture, eliminate the problem of asphalt film spalling, greatly improve the water damage resistance of pavement in rainy season, and perfectly adapt to road maintenance in rainy season and construction of water-side sections.
Strengthen anti-aging and weather resistance
Asphalt exposed to natural environment for a long time, affected by ultraviolet ray, oxygen, rainwater and alternating high and low temperature cycles, will undergo oxidation aging, hardening and embrittlement, resulting in rapid damage to pavement. Anti-aging modifier additive can effectively inhibit asphalt oxidation reaction, delay aging and deterioration of asphalt components, improve pavement ultraviolet resistance, wind and rain erosion resistance, high and low temperature fatigue resistance, effectively prolong road service life, and reduce long-term maintenance cost.
Optimize construction and adaptation performance
Some functional modification additives can improve the workability of asphalt, reduce the viscosity of asphalt at high temperature, improve the mixing, paving and compaction effects of mixture, and reduce the problems of construction segregation and insufficient compaction. At the same time, it can adapt to special construction techniques such as waste asphalt regeneration, cold repair asphalt and slurry sealing layer, broaden the application scenarios of asphalt materials, and improve the construction efficiency and resource utilization rate of the project.
Mainstream classification and characteristics of modified asphalt additives
At present, according to the modification mechanism, material properties and functional uses, the modified asphalt additives are divided into four categories: polymers, functional additives, regenerative modifications and inorganic minerals. The performance characteristics and application scenarios of various materials are significantly different.
Polymer modification additives (mainstream core category)
Polymer additives are the most widely used modified materials for high-grade roads. They form stable network structure by physical blending with asphalt, improve the comprehensive performance of asphalt in all directions, and have the best modification effect.
1. SBS modifier: styrene-butadiene-styrene block copolymer, is the current road engineering general modified materials. The modified asphalt has good elasticity, strong stability and excellent fatigue resistance. It is widely used in high-standard projects such as expressways, urban trunk roads and bridge deck pavement, and adapts to the climate environment of most parts of the country.
2. SBR modifier: styrene butadiene rubber modifier, to improve asphalt low temperature performance and adhesion performance as the core, low temperature ductility to improve the effect is significant, the price is economical. It is mainly used for ordinary roads, municipal branches and pavement preventive maintenance projects in low temperature areas in the north. The high temperature performance improvement effect is weaker than SBS.
3. PE/PP polyethylene, polypropylene modifier: polyolefin modifier, mainly high temperature modification performance, can greatly improve the asphalt softening point, high temperature deformation resistance, low cost. It is mainly used in low-grade highway, parking lot and slow lane engineering in southern high temperature area, and its low temperature crack resistance is relatively general.
Functional special additives such as this
Additives are targeted to solve asphalt single performance short board, belonging to special modified materials, mostly used for local performance optimization and maintenance engineering.
1. Anti-stripping agent: divided into amines, silicones, etc., the core use is to improve the adhesion of asphalt and acid stone, to solve the problem of road water damage, aggregate shedding, rainy season pavement maintenance, construction of water-side sections commonly used additives.
2. Anti-aging agent: by inhibiting asphalt oxidation, absorbing ultraviolet rays, delaying asphalt aging and deterioration, suitable for pavement modification maintenance in open roads and areas with strong light, effectively extending the service life of pavement.
3. Warm mixing agent: new energy-saving and environment-friendly additive, which can reduce asphalt mixing and paving temperature, reduce energy consumption and exhaust gas emission, improve construction workability, adapt to low-temperature construction, urban Urban area construction and green construction site construction scenarios.
Regeneration modification additives
It is mainly used for waste asphalt pavement recycling project, aiming at the imbalance of aging asphalt components and performance attenuation, accurately supplementing asphalt light components, softening aging asphalt, restoring asphalt adhesion and flexibility. At the same time, it can fine-tune the high and low temperature performance of recycled asphalt, so that the waste asphalt mixture can meet the construction standard again. It has the dual functions of modification and regeneration, and is widely used in old road milling regeneration and pavement renovation maintenance projects. It is energy-saving, environment-friendly and cost-effective.
Inorganic mineral modification additives
With mineral powder, fiber, diatomite, bentonite and other inorganic materials as the main materials, through filling asphalt pores, improve the compactness of the mixture to achieve the modification effect. It can enhance the abrasion resistance, high temperature resistance and water stability of asphalt mixture, and improve the overall strength and scouring resistance of pavement. This kind of material has low cost and good stability, and is mostly used in ordinary highway, rural road and pavement surface protection engineering. It is often used with polymer modifier to achieve composite modification effect.
SUMMARY
Modified asphalt additive is the key material to optimize asphalt pavement performance, adapt to complex working conditions and reduce maintenance cost. Different types of additives have different modification emphases. Polymer additives mainly improve comprehensive performance and are the first choice for high-grade roads; functional additives are targeted to solve special problems such as water loss, aging and construction difficulties; regeneration modification is suitable for old road renovation projects; inorganic minerals are mostly used for economic pavement reconstruction. In practical engineering application, it is necessary to combine local climatic conditions, road grades, traffic loads and construction scenarios to reasonably select single modification or composite modification schemes to maximize the stability, durability and traffic safety of asphalt pavement.
