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Study on High-performance Porous Cement Concrete Pavement for Highway Tunnel

Author: ChenZuo
Tutor: ZhangQiSen
School: Central South University
Course: Road and Railway Engineering
Keywords: tunnel pavement porous cement concrete target porosity skid resistance texture sound absorption index
CLC: U416.216
Type: PhD thesis
Year: 2007
Downloads: 1076
Quote: 7
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Abstract


Focused on the crucial problems, quite rapid attenuation of skid resistance texture and high-noise traffic on common cement concrete pavement at the special service environments within highway tunnel, a conception of high-performance pavement is proposed, then the advantages and feasibilities of porous cement concrete as a new skid-resistant and noise-absorptive pavement pattern & material is clarified in this paper. It is aimed to evacuate the superiorities of porous concrete, to analyze the existing difficulties applied in pavement engineering at present and their overcoming ways, to study the all-round technical measures of manufacturing high-strength, durable, skid-resistant and noise-absorptive porous concrete, as well as to inquire into a series of related problems when actually used. To develop the functional pavement technology is an original and hot topic, and to study on the manufacturing technologies and pavement performances of porous concrete is the precondition and also the key for high-performance porous pavement technology, which is of much realistic significance for eliminating tunnel pavement disasters and improving pavement qualities.In this paper, the following research conclusions and suggestions are made:1. Study on the friction mechanism between tire and pavement surface, and a view, that a skid-resistant pavement must be of harmonious micro-textures and reasonable texture depth, of rapid water drainage as well as of strong capacities of impact and wear resistance. Analyze the tire-pavement traffic noise reasons, and the noise absorption phenomenon of porous concrete are ascribed to sound-absorptive and energy consumptive porous structure, shock absorption and energy exhaustion of flexible damping material, diffuse reflection of stochastic uneven surface textures, optimization of surface texture parameters and so on.2. Wear is a function of both working conditions and time. Explain the wear process of cement concrete pavement as under the tire-pavement system and effected by the surrounding environments such as wear particles, temperature and humidity cycles, water and other factors, a gradually lost of the materials of the pavement surface, which directly contact with moving tires. The wear mechanism, wear grade and its classifying principles are also introduced.3. Self-develop and manufacture the accelerated wear instrument and the related wear test methods for cement concrete pavement to successfully stimulated test investigate the respective wear process and the attenuation law of skid resistance texture on different pavements, and as the result, the mathematic modes for pavement wear are established individually. Moreover, it is concluded that the wear processes of ordinary groove pavement and exposed aggregate pavement are both changed with the alteration of their skid-resistant textures and the actually weared materials by stages, and that the theoretic service life of these two types of concrete pavements is 4~5 years and 7~8 years respectively. However, the wear process of porous pavement is trivial and stable with no obvious stages.4. Based on analysis of the theoretic structural mode, damage pattern and constitution conditions of porous cement concrete, the main technical parameters of porous concrete applied in highway pavement are designed as: target porosity 18~22%, compressive strength grade no less than C35, bending strength>4.5~5.0MPa, skid-resistant texture depth>1.10mm, penetration coefficient>4.0mm, sound absorption index>0.30 and comprehensive noise reduction>6dB(A).5. Linear fractal interpolation is utilized to simulate the transect contour line of porous concrete on the purpose of digging into the relativity along skid resistance & sound absorption capacity of uneven pavement surface, fractal dimension D as well as surface texture parameters. According to the principle that gives full play to strong points of porous material, and proceeding from different mathematic modes, all pavement surface texture parameters are successfully optimized as a single index D. Therefore, it is pointed out for the first time that the problem of optimizing pavement surface texture parameters is in essence to seek the maximum D, which is referred for designing and producing porous concrete.6. Analyze the technical indexes and required properties of raw materials, especially coarse aggregate for porous concrete, and recommend 5~10mm crushed hard stone as coarse aggregate. It is advocated to add ultra-pulverized active mineral powders such as fly ash and silica fume or organic macromolecule polymer to produce high-performance porous cement concrete (HPPC) and polymer porous cement concrete (PPCC). Study the functions and effects of these reinforced materials when added in porous concrete, and as result, the optimum matches, cement (90%)—silica fume (10%) or cement (80%)—UFA (12%)—silica fume (8%) for inorganic binding materials and the ratio of polymer to cement 0.10~0.15, are advised.7. Introduce the conceptions of different porosities of porous concrete and their relativities. Illustrate the methods for testing, evaluating as well as adjusting fresh porous concrete workability. Based on dissection of the effects of porosity on pavement performances and of the relativity among mix parameters and pavement performances, a quite ripe mix design method and specific procedures of pavement porous concrete are brought forth for the first time in the paper, moreover the rational value ranges of all mix parameters are also given. It is validated in practice that the proposed method is of very prominent characteristics, of high efficiency and of real feasibility. Research the indoor manufacturing technologies of porous concrete, and recommend the vibration-pressure compaction method to ensure target porosity and normal pore status within porous concrete.8. Systemic and intensive research on pavement performances of different porous cement concretes, of which the mechanical performances and the porosity control technology reach domestic advanced or leading levels. The following conclusions can be made:(1) Excellent workability of fresh HPPC and PPCC with rather high viscosity and good consistency, suitable for quite thin surface layer construction.(2) Slow attenuation of skid resistance texture with by far longer theoretic service life than common concrete pavement PPCC has the strongest wear resistance; HPPC takes the second place and ordinary porous concrete lists the last by contrast.(3) High bending strength,>5.0MPa with other mechanic properties meeting the requirements.(4) Strong water capacity and rapid water drainage for porous structure and penetration coefficient>4.0mm/s, uneasy to form harmful water film between tire and pavement surface, and excellent skid resistance of wet porous concrete pavement. (5) Strong noise absorption capacity for sound absorption index>0.30, and the sequences in noise reduction order as porous concrete pavement>exposed aggregate concrete pavement>ordinary groove concrete pavement.(6) Low drying shrinkage material with drying shrinkage value<200×10-6mm/mm, generally no severe drying shrinkage cracks under highway tunnel environments.(7) Rapid carbonation and high depth of carbonation, but no apparently harmful effects on the mechanic properties of porous concrete.(8) Strong corrosion resistance, but very poor freezing-thawing resistance.9. Porous concrete is applied as the surface layer of combinative double-layer cement concrete pavement, and the thickness of porous layer 5~8cm is suggested. Depended on the pavement performance characteristics and advantages of different porous concretes, the rational utilization advices of porous concrete according to various traffic grades, traffic features and service environments on highway pavement are also made.10. Initially inquire into the construction technology of the surface layer of porous concrete pavement, and the key is considered as the realization of both effective thickness of porous layer and its target porosity. The specific construction procedures and matters for attention are also treated. In addition, a series of related problems such as the maintenance & restoration of skid resistance and noise absorption capacity of porous concrete pavement are preliminarily discussed.

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CLC: > Transportation > Road transport > Road works > Roadbed, pavement engineering > Pavement Engineering > Road : use of the material points > Cement concrete pavement
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