Keywords: composite micro-surfacing cement concrete emulsified asphalt
Classification number of China Library: U4 18.6 Document ID: A document number:1672-3791(2012) 05 (a)-0063-01.
Cement concrete pavement is used in highway, mainly to improve the stability and bearing capacity of highway. However, due to materials, design, construction technology and other reasons, the service performance of expressway is getting worse and worse, and the service life of expressway pavement is also shortening. Therefore, new methods must be developed to maintain cement concrete pavement, and composite micro-surfacing method is a newly developed method. Taking a secondary highway as an example, this paper introduces the application of composite micro-surfacing in pavement maintenance. In a certain expressway, the 24.5-meter-wide roadbed and 22.0-meter-wide cement concrete pavement were damaged due to the increase of traffic all the year round. There are some problems such as void, anti-sliding and low bearing capacity. In order to reduce pavement diseases and prolong service life, effective and reasonable maintenance measures must be taken. The composite micro-surfacing method is used to test a road section. No disease problems occurred in the experimental section within one year, and the overall effect was good.
1 predetermined
First, investigate the original road conditions. The damage of cement concrete pavement, such as joint damage and cracking degree, is measured. Then, according to the measurement results, the road test section is determined and the appropriate maintenance scheme is formulated. The investigation of pavement conditions mainly includes: the dislocation and smoothness of pavement plates, whether there are cracks in the plates and whether the expansion joints are aging, and the overall performance of each plate is recorded in detail.
Secondly, it is judged whether the cement slab is hollow. Firstly, whether there is a gap in the cement board is determined by visual inspection. If it is empty, check its weight. Then, the deflection value of cement pavement slab is judged by Kerman beam measurement method.
2 composite micro-surfacing construction technology
1. The construction process of composite micro-surfacing is: preparation before construction (pavement treatment, preparation after construction, mechanical preparation, raw material selection and mix design) → bottom paving → bottom maintenance → upper paving → upper paving → open traffic.
Secondly, it can be seen from the above construction technology that the method of composite micro-surfacing is mainly divided into three steps: pavement treatment, spreading adhesive layer oil and spreading MS-2 composite micro-surfacing.
Third, pavement treatment. The treatment of the original pavement is mainly divided into five stages: first, the pretreatment of the original pavement. According to the results of investigation and measurement, the hollowed cement pavement slab is grouted. Replace the original paving materials at the joints, adopt high-performance and high-quality joint materials, and then roughen the shiny surface of the cement board; Second, deal with cracks. According to the actual situation of cracks, the corresponding construction technology is adopted. The hollow cement slab will make the bearing capacity of cement concrete pavement poor, and heavy vehicles will break when rolling the pavement. Cracks can be slotted by grooving machine, and the cutting width can be controlled in the range of 19 cm ~ 2 1 cm, and the depth can be controlled in the range of 24 cm ~ 26 cm. In the process of slotting, the edge of cement slab is easy to peel off, so when pouring sealant, the pavement should be slightly lower than sealant. In addition, if the crack of cement board is narrow, it can be cut along the crack direction with a slit cutter, with the cutting width controlled at 4mm ~ 6mm and the depth controlled at 3cm ~ 5cm. For wide joints with large cracks, thinner sealing material can be filled; Thirdly, high-quality rubber modified materials and caulking materials should be used in asphalt pavement caulking construction. The concrete steps are as follows: cut a seam with a professional grooving machine, with a seam width of 14 mm ~ 2 1 mm and a seam depth of 19 mm ~ 2 1 mm ... Clean up the broken materials and sundries with a blower, and heat the joint materials needed for joint filling, and control the temperature at/kloc-. Then, the joint material is poured into the cracks by a joint filling machine, and each side is controlled to be 9mm ~ 1 1mm wider than the original pavement and 2mm~4mm higher. In addition, under the condition of keeping the joints dry, the hollow cement slab can be injected with mud, and its construction process is construction lofting → hole setting → drilling → hole cleaning → grouting → hole sealing → maintenance → washing → clearing the site → opening the traffic.
In the process of construction, cement slab grouting is generally carried out according to this process. Fourth, the surface brush. Because the cement concrete pavement is dense and flat. Therefore, it is difficult to bond the micro-surfacing to the road surface. The milling machine can be used to roughen the surface of cement concrete, thus effectively increasing the smoothness and friction coefficient of pavement. Fifth, in order to enhance the adhesion between the pavement and the micro-surface, after the damaged pavement is repaired, the impurities such as dust and debris on the pavement are cleaned manually, and then cleaned by a blower.
Fourth, sticky blankets. In order to strengthen the bonding force between cement concrete pavement and micro-surfacing, after the pavement is cleaned, a layer of modified emulsified asphalt waterproof bonding layer can be covered, which can effectively prevent the pavement from seeping and washing away fine substances on the pavement surface. In addition, it can absorb the stress between asphalt pavement and cement concrete pavement and coordinate the stress between micro-surfacing and cement concrete pavement.
Fifth, micro-surfacing paving. The conventional micro-surfacing method is to spread polymer modified materials on the road surface with a paver according to the mix design and the selection of raw materials to form a thin-layer structure with a thickness of about 0.5 cm ~ 1.5 cm, and then open the traffic after paving1.5 h ~ 2.5 h. The composite micro-surfacing method is to pave the bottom layer and the upper layer respectively according to the preliminary pavement treatment, construction site preparation, machinery preparation, raw material selection and mixture ratio design preparation. The bottom pavement is mainly made of fine aggregate, which can enhance the cohesiveness and effective waterproof function. Laying materials with good wear resistance on the upper layer can effectively increase the wear resistance of the surface layer.
3 the effect of using composite micro-surfacing
After being treated by composite micro-surfacing, it can be opened to traffic. The structural depth, friction, water seepage system and pavement detection one year after the test section was opened to traffic 1 month and 7 months respectively.
The results of one month's measurement show that the friction coefficient of cement concrete pavement without composite micro-surfacing is 42BPN, while the friction coefficient of cement concrete pavement with composite micro-surfacing is 63VPN, the structural depth is 1.32mm and the water seepage coefficient is 0 after one month's opening. It can be seen from the measurement results that the anti-skid performance of pavement has been greatly improved after the composite construction of micro-surfacing. The waterproof ability of pavement is improved, and the probability of danger caused by water seepage on pavement is greatly reduced. In addition, the composite micro-surfacing construction in the experimental section makes the exterior of the pavement smooth, dense and uniform.
The measured results after 7 months show that the friction coefficient of the micro-surfacing pavement is 59BPN and the structural depth is 0.94 mm Compared with the measured results after 1, the pavement performance is lower, but it can still be seen from the data that the pavement performance is higher. And there is continuous rainfall and high temperature weather in July, and the micro-surfacing pavement can maintain good anti-sliding ability and waterproof effect.
Results of pavement measurement after one year: The pavement detection after one year is mainly to detect pavement damage and structural depth. The test results show that the overall condition of the pavement in the test section is still good, and there are no obvious pavement functional diseases. In terms of structural depth, the structural depth of wheel track pavement is in the range of 0.649 mm ~ 0.8759 mm, and the shoulder is in the range of 0.743 mm ~1.135 mm. ..
From the above data, it can be seen that using composite micro-surfacing to maintain cement concrete pavement can prolong the service life of pavement, increase the safety of driving and improve the performance of pavement.
4 conclusion
In a word, although the cement concrete pavement passes through the composite micro-surfacing, the anti-sliding ability is reduced under the action of continuous rainfall, high temperature and vehicle stress, and the pavement at the micro-surfacing can still maintain good anti-sliding ability and waterproof effect, reducing the probability of pavement diseases. Therefore, in the maintenance of cement concrete pavement, the method of composite micro-surfacing should be popularized.
refer to
[1] Jiang Fufa. Application of Composite Micro-surfacing Filling Technology in the Treatment of Rutting Disease in expressway, Nanyou [J]. Guangxi Quality Supervision Herald, 2008 (7): 164 ~ 166, 168.