Application of the latest technology and materials

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Application of new technologies and materials in slip form construction of cement concrete pavement

with the rapid development of China's economy, the traffic volume of highway increases, and the proportion of heavy transport vehicles is increasing, which puts forward higher requirements for the structural strength and service performance of highway pavement, while cement concrete pavement has the advantages of high strength, good stability, good water resistance, long service life and low maintenance cost. Therefore, in recent years, cement concrete pavement has occupied a place in high-grade highways, followed by the continuous promotion and application of new materials and new technologies in the construction of cement concrete pavement

settlement observation of subgrade

in most cases, the early broken slab failure of cement concrete pavement of expressway is caused by unstable subgrade and excessive settlement. In order to prevent this phenomenon, we should first observe the settlement of the whole line of the cement concrete pavement subgrade of the expressway, carry out the detailed reinforcement design at the construction drawing stage for the sections with large settlement, and calculate the differential settlement limit value of the permanent cement concrete pavement, so as to effectively ensure the quality and stability of the cement concrete pavement subgrade of the expressway and prolong the service life of the cement concrete pavement

According to the characteristics that cement concrete pavement is more sensitive to subgrade stability than asphalt pavement, the subgrade filling of cement concrete pavement of high-grade highway is required to improve the first-class compaction standard. For granular soil and sandy soil with particle size below loam, heavy-duty roller shall be used for forced compaction; For clayey soil with high plasticity index, the technology of using roadbed lime to improve soil stability

in the multi section expressway, the measures of improving the compaction standard and heavy roller compaction are adopted, and the technology of using roadbed lime to improve soil stability is used, which strongly ensures the quality and stability of the subgrade or base of the expressway cement concrete pavement, and greatly extends the service life of the cement concrete pavement. Subgrade improvement soil technology is a technology used for high inner diameter plastic clay, soft foundation soil or road sections with frequent subgrade filling and excavation, which cannot meet the requirements of compactness. On the one hand, it improves the strength, bearing capacity and stability of soft soil subgrade; On the other hand, the roadbed improvement soil is equivalent to adding a solid subbase, which will play a great role in improving the service life of cement concrete pavement

slip form paving technology for lean concrete base

the slip form paving technology for lean concrete base is used, and clear technical requirements are put forward for raw materials, mix proportion, paving and quality acceptance of upper base of lean concrete base, which expands the new type of base that is considered to be the most water-resistant, the highest strength and the longest service life at home and abroad, as well as its construction technology and quality acceptance control standards. Its great significance will be gradually shown in the future highway construction and maintenance in China. We hope that in the future, the base course of Expressway in China can be used for more than 50 years without renovation, but only the surface course

new technology of sliding sealing layer

the main advantage of the new technology of using asphalt surface or slurry sliding sealing layer on the surface of the upper base course is that it is conducive to preventing slab breakage; It is beneficial to prevent the semi-rigid base from long-term water erosion damage; It is conducive to grass-roots health maintenance; It is beneficial to prevent the transportation wheels from crushing or loosening the surface of the base course during construction; It is conducive to overwintering protection at the grass-roots level. However, in order to prevent the bulge of the expansion joint after using the asphalt sliding sealing layer, the width of the expansion joint plate should be increased by 5mm

high flexural tensile strength pavement slip form concrete

using the high flexural tensile strength cement concrete pavement slip form paving technology, mainly adopts the "double mixing technology" of high-performance road concrete admixture and fly ash, which is used for ultra heavy load traffic to reduce the thickness of thin plates, and enhances the resistance of the panel to fracture, improving 1 It adopts the proprietary multi-channel closed-loop harmonic loading electro-hydraulic servo control system developed independently, multi-level hydraulic loading, and smooth computer harmonic control. In the continuous force multi-level, this situation appears to everyone. The test data is automatically collected and stored, the curve is drawn, and the experimental report is automatically printed. The computer controls the experimental process in real time. According to the experimental power supply and experimental curve, the operation is simple and reliable, which is transportation, building materials, metallurgy, aviation, aerospace Colleges and universities, scientific research institutions, such as ideal experimental equipment The safety reserve of the pavement for the damage of overweight axle load. At present, the measured average flexural tensile strength of the pavement paved by slip form with high-performance road concrete technology in China is 6.5? 7.5Mpa, which is the high bending tensile strength we haven't seen in various international documents so far, ranking in the international leading level

slip form paving technology for high smoothness cement pavement

at present, the static 3M straightedge flatness of slip form paving cement concrete pavement on expressways and first-class highways in China is not greater than 3mm, which is generally more than 90%; The overall dynamic flatness is basically δ = Around 1.0, the best section of cement concrete pavement has been reached δ ≤ about 0.76, and the best 6km single pavement has been achieved δ ≤ 0.45, higher than that specified in the acceptance standard δ ≤ 1.5 is much smaller. These data show that the cement concrete pavement with high flatness in China has been equivalent to the international advanced level; At the same time, it shows that the smoothness of Slipform paved cement concrete pavement in China has the potential to be further improved; Finally, the smoothness of cement concrete pavement paved with sliding formwork in China will be equivalent to that of asphalt pavement

crack control technology of cement concrete pavement

further mastered the crack control technology of slip form paving cement concrete pavement. The first is to prevent plastic shrinkage cracks during construction; The second is to prevent temperature difference, humidity difference cracks and broken plates in the early stage of use; More importantly, the construction technology and control index of eliminating longitudinal cracks are put forward. It should be said that there is a long way to go to prevent the cracking of cement concrete pavement. At present, there are not many people who really master this technology. If they are not careful in their actual work, there are still cracks and broken plates. The main technical measures to solve the crack and broken plate are: in windy days, prevent plastic shrinkage cracking, use crack resistant concrete mix proportion, and spray curing agent in advance to strengthen the construction of curing measures; The asphalt sliding sealing layer is used to reduce the annual temperature difference, seasonal humidity difference, shrinkage cracks and broken plates of the upper base surface panel; Deepen the cutting depth (1/3.1/4) h of the joints of all plug-in rods and dowel bars, and advance the cutting time to prevent longitudinal fracture

research on frost resistance and salt frost resistance of cement concrete pavement

for the first time in China, the anti ethylene vinyl acetate copolymer (EVA) frost and salt frost resistance slip form paving technology of cement concrete pavement (Heilongjiang and Jilin in 1998) was studied and used, and the detection methods and standards of air content and bubble spacing of concrete pavement were clearly put forward, which provided effective technical measures to solve the surface freezing and salt frost delamination of cement concrete pavement in northern China, It shows that high-quality cement concrete pavement without delamination can also be built in northern China

at present, Heilongjiang and other provinces need to directly adopt the salt frost resistance test method of the European Union and formulate it as the standard test method of our country through research. In addition, it is urgent to study the salt frost resistance mechanism and prevention measures of cement concrete pavement

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