Asphalt pavement exposed to the natural environment for a long time, continuously subjected to multiple effects such as vehicle load rolling, rain erosion, alternating high and low temperatures, ultraviolet aging, etc., will gradually appear subtle cracks, surface water seepage, loose aggregate, anti-skid attenuation and other hidden diseases.Without timely intervention, minor diseases will gradually evolve into serious diseases such as pits, subsidence and large-area cracks, greatly increasing overhaul costs and shortening road service life.Preventive maintenance of asphalt pavement is an active protection method before the pavement structure is in good condition and the disease has not deteriorated. The core principle is "early detection, early treatment, quick treatment of minor diseases and no treatment of serious diseases".This paper systematically combs the preventive maintenance and protection measures commonly used in asphalt pavement projects, covering five categories: surface layer sealing, thin layer repair, crack disposal, disease pretreatment and daily management and protection, which are fully adapted to the maintenance scenarios of various grades of highways and municipal roads.

Surface layer sealing measures: sealing pavement, waterproof and anti-aging

Surface layer sealing is the most widely used preventive maintenance method, mainly aimed at the road sections with overall good pavement, only surface aging, fine pores and slight water seepage, by forming a dense protective layer on the pavement, blocking pavement defects, isolating external corrosion and delaying pavement aging.

Slurry seal and micro-surface

This is the thin-layer sealing technology with the highest degree of mechanization and standardization. It relies on slurry sealing truck to mix emulsified asphalt, aggregate, mineral powder and water accurately and evenly on the pavement surface to form an ultra-thin dense sealing layer of 3- 10mm.The measure can completely block the hairline cracks and capillary pores of the road surface, block rainwater infiltration, update the wear-resistant surface layer of the road surface, restore the anti-skid performance of the road surface, and effectively solve the problems of slight peeling, pockmarks, loose surface layer and the like of the road surface.Among them, the micro-surface technology is suitable for the main road and expressway section with large traffic volume, which can repair shallow slight rutting, with higher flatness and stronger wear resistance. Traffic can be opened several hours after construction, with little impact on traffic.

fog seal curing

Fog seal layer belongs to lightweight and low-cost protective measures. Diluted emulsified asphalt and recycling agent are evenly sprayed on old asphalt pavement by special spraying equipment.Permeable liquid medicine can penetrate into the pores of pavement surface, soak aged asphalt, restore asphalt cohesion, and seal the tiny gaps of pavement to prevent rainwater and air intrusion, inhibit asphalt from further aging and aggregate shedding.The process has the advantages of high construction speed and low cost, and is suitable for preventive protection of ordinary roads and rural roads with good overall road condition, mild aging and slight water seepage. The defect is that it does not have leveling and repairing ability and cannot handle cracks and ruts.

chip seal

The asphalt binder and abrasion-resistant macadam are sprayed synchronously by synchronous macadam sealer to form asphalt macadam composite protective layer.After molding, the pavement has strong abrasion resistance and impact resistance, excellent waterproof and impervious effect, and can effectively protect the pavement base layer from vehicle load wear and rain erosion.It is often used for preventive maintenance of trunk roads, mountain roads and heavy-duty sections. It can be used as a protective layer for old roads or a waterproof adhesive layer for new roads to adapt to road scenes with relatively rough road conditions and high wear resistance requirements.

Measures for crack disposal: plugging cracks and blocking disease extension

Crack is the earliest and most common recessive disease of asphalt pavement, and it is also the core inducement to induce large-area damage of pavement.In preventive maintenance, special sealing treatment is taken for cracks of different widths, which can completely block rainwater from infiltrating into the base along the cracks and avoid secondary diseases such as crack expansion, base softening and road subsidence.

crack filling treatment

For structural cracks, regular longitudinal cracks and transverse cracks with width greater than 3 mm, professional crack filling glue shall be used for filling and plugging.During construction, dust, sundries and accumulated water in cracks shall be cleaned first to ensure cracks are dry and clean, and then elastic asphalt sealant shall be poured into cracks.Cured joint filling adhesive has good elasticity and adhesion, can follow the expansion and contraction of pavement, always maintain the crack sealing state, prevent rainwater and impurities from entering the crack, prevent the crack from widening and deepening continuously, which is the core technology of preventive maintenance of pavement cracks.

seam treatment

For irregular network fine cracks, hairline cracks and scattered shallow cracks, priority should be given to seam tape and anti-crack paste for seam protection.Without slotting and filling joints, after directly cleaning the surface layer of the road surface, the special polymer crack resistant material is pasted on the crack surface layer to form a high-strength waterproof sealing layer.This process is convenient in construction, pollution-free, and fast in forming. It is suitable for preventive protection of various fine cracks, can effectively inhibit crack reflection and spread, and prolong the recurrence cycle of crack diseases.

Thin layer repair measures: minimally invasive quality improvement and road performance recovery

In view of the slight flatness decline, shallow wear, local aging, slight rutting and other mild diseases of the pavement, there is no need for large-area milling and resurfacing. Through the thin-layer minimally invasive repair technology, the pavement traffic performance can be quickly restored on the basis of retaining the original pavement structure, which belongs to efficient and economical preventive maintenance measures.

Paving of ultra-thin wearing course

Paving ultra-thin asphalt wearing layer of 1.5- 3cm on the road surface with overall stable road condition and no structural damage, quickly replacing the aged and worn road surface layer.The newly-paved wearing course has high flatness, anti-sliding wear resistance and good waterproof property, which can completely solve the problems of slight rutting, bumping, peeling and insufficient anti-sliding of the road surface, greatly improve the driving comfort and safety, and has small construction thickness, less consumables and short construction period, which is suitable for preventive quality improvement maintenance of high-grade pavement such as urban expressway and expressway.

thin regenerated overlay

Aiming at the pavement with aging asphalt surface, whitening color and decreasing adhesive force, asphalt recycling technology is adopted to cooperate with thin overlay construction.By spraying regenerant to activate the performance of aged asphalt, and then supplemented with thin asphalt mixture overlay, the old pavement surface regeneration and quality improvement are realized.This measure gives consideration to disease prevention and pavement renovation, which can effectively solve the problems of loose pavement aging and slight water seepage, maximize the use of original pavement materials, be green and environmentally friendly, and have lower maintenance costs.

Local pretreatment measures: targeted elimination and prevention of disease spread

Preventive maintenance is not only aimed at the overall pavement protection, but also the early treatment of local sporadic diseases.Pretreatment of small diseases such as sporadic potholes, local looseness, corner damage and local ponding can avoid single point disease spreading to large area pavement damage, which is a low-cost and high-efficiency maintenance method.
For sporadic shallow pits and grooves, cold repair asphalt shall be used to quickly repair, and damaged points shall be closed in time to prevent rainwater intrusion and load rolling aggravation damage; for local ponding road sections, the core hidden danger of ponding soaked pavement shall be solved by fine adjusting pavement flatness, dredging road drainage gap and cleaning drainage facilities; for loose and damaged shoulders and corners of pavement, timely reinforcement and repair shall be adopted to ensure the overall integrity of pavement and avoid diseases extending to the main body of pavement.

Daily management and protection measures: long-term protection, delaying road aging

Long-term preventive maintenance cannot be separated from normal daily management and maintenance. Normal inspection and maintenance can reduce disease breeding from the source and prolong the service life of pavement.It mainly includes regular cleaning of sundries and sand on the road surface to avoid long-term rolling and abrasion of hard particles; timely cleaning of road drainage system to ensure rapid drainage of rainwater and prevent road ponding immersion; regular inspection of hidden diseases on the road surface, establishment of road condition accounts, early detection and early disposal of diseases; strict control of overloaded vehicles, reduction of long-term overload rolling of road surface, and reduction of road structural damage risk from the source.

epilogue

Asphalt pavement preventive maintenance protection measures are rich in types and have their own emphases. The core logic is "layered protection, targeted treatment and long-term management".Fog seal layer, slurry seal layer and crushed stone seal layer mainly focus on overall surface waterproof and anti-aging, joint filling and joint pasting focus on crack sealing and anti-seepage, thin layer overlay realizes minimally invasive pavement quality improvement, local pretreatment and daily management and maintenance to build up long-term protection foundation.In the actual road maintenance, it is necessary to accurately match the maintenance technology according to the road condition, disease type, road grade and climate environment. Through scientific preventive protection, the service life of asphalt pavement shall be extended to the maximum extent with the lowest maintenance cost and shortest construction period, so as to ensure the safety and stability of road traffic.