Cement concrete pavement has the advantages of high rigidity, strong integrity, high flexural strength, elastic modulus and lower deformation and stability of water and temperature are superior stability of asphalt concrete pavement, not easy to appear some insufficient stability of asphalt pavement damage ( such as rutting ) etc.. Therefore, Lujiang County in the nineteen ninties since the middle of transit road, S316, S319 line highway cement concrete pavement of 40 km. The county government to establish command organization construction. A few years after completion using a variety of different degrees of pavement disease.
1 disease reasons analysis
1.1 joint type
Cement concrete pavement joints is divided into longitudinal and transverse joints. Cross stitch is divided again for expansion joint ( true joint ) and contraction joint ( tack ) two. Expansion joint in use with temperature changes, temperature rise when the filling material is extruded; when the temperature drops filler cannot recover the seam formation of voids, mud, sand, stone chips and other debris become invasive, again expanding extension barrier, and the rain also can along the gap into the damaged base and subbase,, caused by pavement joint deformation and breakage, crack changes little, but after a certain number of contractions, can come true seam basting break, caulking their aging, can also cause as expansion joint the same troubles, initial construction maintenance is not standardized, cutting, trimming is not timely or failed to reach the required depth, is also the result of joint damage is one of the reasons.
1.2 crack
( 1) the longitudinal, transverse, inclined crack, refers to the bottom ( concrete slab crack fracture ), the plate segmentation into two or three pieces. The main cause of the cracks is: subgrade instability, based on wet and soft, uneven strength; due to the change in humidity, causing stretching stress exceeds the tensile strength; traffic flow is large, overweight vehicle load stress intensity, warping stress and shrinkage stress of fatigue cracking. Rainwater intrusion and large vertical displacement of the repetitive action, the erosion of void. Poor foundation stability of excessive plastic deformation of the slab void lose support. Joint after, loss of load transfer ability, in the plate produced around the excessive load stress. Cement aggregate quality difference. Construction of improper operation, the initial regimen is not good. Fracture, disruption of the board structure, the concrete face the loss of some or most of bearing capacity.
( 2) cross cracks and broken board. Cross crack crack cross each other, the plate is divided into more than three pieces ( also known as broken board ). Highway transportation overloading, thickness of concrete slab is insufficient, low strength, base loose leads to insufficient strength of soil, the uneven settlement will produce pavement cross cracks or crushing plate causes.
( 3) the board angle fracture is a vertical bottom and side seams intersect angle of plate crack, from the angle of plate to crack the distance between two points respectively is equal to or less than half of the length of the plate endpoint, reasons for the failure is usually due to expansion, contraction joint construction joint filler choice is undeserved, cause road surface water along the slit infiltration, especially when the plate under the base of poor drainage or of the base materials, fine material is overmuch, base material erosion resistance is poor, plate corner by auto repeat load, vacuum suction can make plate angle generating mud plate by scouring, causing the slab corner stress concentration, base support strength is insufficient, make the road panel generates plate angle fracture.
1.3 deformation type
( 1) mud. The joint emergence of mud, making void underneath slab. The pumping means carried by the vehicle base fine material and water from the plate seams extruding, gradually making the foundation lost support ability, the load repetition function, will eventually produce plate fracture phenomenon. The main reason is the filling material damage, rainwater infiltration and pavement drainage bad.
( 2) arch. During the hot season, the joint plate there is a sudden upward. The arch is a transverse joints on both sides of the plate body has significant elevation of the phenomenon. The reason is mainly the seam is hard blockage, or expansion joint set up properly, so that the plate is heated can not be freely extended. Mild arch the pavement evenness variation, and may lead to serious arch before and after plate fracture.
2 preventive maintenance
Cement concrete pavement is characterized in curing under good conditions, with good quality, service life than other road long. Maintenance is not timely, once destroyed, damaged will develop rapidly. Therefore, must complete the preventive maintenance, regular, through regular observing, early detection of defects, find out the reason, seize the opportune moment to treating diseases, in order to maintain the road conditions of the intact [1 ~ 3]. Concrete pavement preventive maintenance: the main content of the work is the road, seams, cracks and maintenance, filling material.
2.1 cement concrete pavement maintenance
( 1) must adhere to the weekly 2 ~ 3 removal of pavement on sand, stone, mud and dirt. If the individual small stones should be thrown in, so as to avoid the vehicle rolled and destroy the road surface. In comparison with other different types of road junction or crossing, more easy to sand, stone, soil to the road up, should set up special bonus sweep.
( 2) must hold a monthly check pavement, timely repair of damaged.
( 3) during the rainy season and frozen before the arrival, on pavement by examination, timely and general damage repair. Winter snow removal notice, especially during snowmelt, attention should be paid to clear snow and ice, water points into the base, should pay attention to the shoulder of the road maintenance and reinforcement, keeping the pavement and shoulder articulation smoothly, maintain proper transverse slope. Cleaning and dredging ditches in pavement drainage.
The 2.2 joint maintenance
Cement concrete pavement maintenance of key in the joints, often should fill or remove excess sealant joints, keep intact, smooth surface, traffic will not bounce. When the temperature drops seam expanding gap, we should choose the local temperature minimum time slot filling interstitial, when temperatures rise seam material extrusion seam, should be squeezed protruding filler eradication, and to prevent mud, sand is extruded into the joint, the effect of plate normal expansion.
2.3 concrete slab crack maintenance method
The width of 3 mm the following the expansion of crack, low viscous asphalt or epoxy resin and other materials such as perfusion; expansion of cracks along the crack, gouge, injected into the crack filling material; for concrete plate under the fabric or buried hard objects while the cracks, should also be cut along the cracks after perfusion caulking material.
2.4 filler update
( 1) with a small flat chisel to remove the old sealant materials, steel wire brush brush cleaning slit wall, and the dust blower blowing dust inside the net joint.
( 2) with dilute asphalt coating gap wall; low temperature operation, application of burner and blow drying, makes the asphalt uniform.
( 3 ) in the road on both sides of the slit spread a thin layer of powder ( or lime ), keep filling material contaminated pavement.
( 4) with a good filler for filling, attention should be paid to fill the side pressure side, until it filled up, the summer should be slightly higher than the road, winter can be slightly below the pavement, and then with the iron burger flat, so that seams dense.
2.5 perfusion joints and crack construction points
( 1) should be carefully cleaned, the removal of the old filler, sand, dust and other debris, as far as possible to expose clean concrete area joint.
( 2) filling materials should be original material with the same quality. If the perfusion of the material and the quality of raw materials, and the residual materials intact and concrete bonding firm, you do not need to remove all.
( 3) perfusion seams, cracks before must make joint, crack dry, wet, or filler bond fragile.
( 4) the joint plate edges missing corner, if the lack of angular size, width and depth are in the range of 30 mm the following, and was independent of the presence, the loosening of the concrete removed, dissection, poured into the pouring material.
3 disease treatment
The 3.1 joint treatment
( 1) joint cleaning : small flat do except or joint cleaning equipment removed the old joint fillers and other debris, and dust blowing device will sew in lime blowing clean.
( 2) joint. The plastic floor or building hot asphalt coating in slit wall, then the joint plate block is pressed into the seam. Butt seam plate joints and joint plate and the dowel bar between the gap, must use the asphalt or other filler is filled. With the upper sealing strip, should be timely embedded sealing strip.
3.2 crack treatment
( 1) to a small crack, timely blowing dust device with steel wire with a small hook clearance gap soil sundries, gap inside the dust cleared, in the dry state, poured into the dilute bitumen and sprinkle powder.
( 2) the wide cracks, cracks on both sides of the loose part should be removed and cleaned, and then dry conditions with liquid asphalt in seam wall walls again, then fill the asphalt mixture ( asphalt 40%, mineral mineral powder 60% ). Asphalt sand frying or fine grained asphalt concrete, iron tamping tamping iron, and ironing, and cover with a thin layer of fine sand.
( 3) on the crack width is greater than 3 mm cracks, available in epoxy resin and curing agent evenly direct perfusion.
( 4) the crack is more, should put cracks concentrated zoned for a construction surface. The cracks around all loose parts are cut into a concave, then the seams of dust brush clean and dry, then sprinkled with a thin layer of fine sand.
( 5) the crack repair work should be in the late autumn and early winter, therefore when temperature is low, wide gap, and is suitable for construction.
3.3 local boards broken treatment
( 1): corner repair of rupture surface depth according to size, determine the cutting range and lofting. II with a cutting machine cut edge seam, chiseling damaged portion, a rule in the vertical plane, reinforced, and should take care not to cut steel. Such as steel is difficult to keep all, or at least keep 20 ~ 30 cm steel head, and is staggered. The examination of the original sliding dowel bar, such as defective, will promptly repair or reset the new rod. The original pavement joint surface. As for coarctation, should be separated with plastic film, or coated with asphalt, prevention of new and old concrete bonding together, such as expansion joints, should set up a joint board. The hardening of the concrete, with cutting machinery cutting seam groove, and then poured into the sealant materials [4 ].
( 2) Pavement Transverse Crack longitudinal, local repair : 1 line lofting, cutting machinery cutting edge and chisel, in addition to the damaged part. The seam edge sides of central hole plate thickness, depth of 10 cm, diameter of 2 ~ 4 cm, 30 ~ 40 cm level spacing. The crushed material removal inside the hole and wetting, tamped cement mortar after insertion of a diameter of 18 ~ 20 cm. Approx. 20 cm long thread reinforcing steel. The cement concrete tamping tamping, smooth and spray curing agent. The reinforced net of road slab, crack location away from the seam is not more than 3 m, can according to processing corner fracture approach for local repair, when the crack location away from the seam exceeds 3 m, should be the cracks as a contraction joint processing, repair of cracks [4 ].
3.4 road hog patch
(1 ) combined with the emergency repair for inspection of joints. When the bulge of slight degree, as the tilt plate falling from the tilt of the seam plate, in 50 ~ 60 cm position, parallel to the seam into the cutter, crusher with the partial destruction of.
( 2) the old concrete plate removed, in the part of emergency into soil, gravel, crushed after forming in the surface is paved with asphalt mixture, formed after compaction of open to traffic.
(3 ) the board fully stable, then the board of revision.
The 4 ending
Highway maintenance work must be carried out " give priority to prevention, combining prevention with control". According to the accumulation of technical and economic information and local circumstances, do preventive maintenance and timely repair of damaged part and disease treatment, so as to achieve the aim to prolong service life of highway. Keep intact state highway, traffic safety, comfort, security, unimpeded.