IRF2005会议论文摘要 W21: 沥青再生 I
更新时间：2005年07月07日 来源： 作者：
第十五届国际道路联盟世界会议 ——会议论文摘要
W21: 沥青再生 I
115 粒状生胶改性沥青，一种新的路面再生方法
作者：Juan José Potti, Probisa, 西班牙
Use of grinded crumb rubber (CR) is a technology which is being used for already 40 years. However, the introduction of European Directives in Spain has generated an important awareness as far as recycling and exploitation of this residue in road construction is concerned. Probisa has a long tradition in this investigation field: studies of bituminous mixes carried out both using the dry and the humid way. Based on its experience, Probisa has developed a wide range of polymer modified bituminous binders exclusively resulting from CR. Besides the intrinsic characteristics of the binder, special attention has been paid to its viscosity to obtain bituminous mixes which can be handled under the same conditions as conventional PMB. In this way, they are coherent with the ecoefficiency objective, aimed at in all recycling processes. The paper also deals with limitations of current empirical test methods when it comes to quantifying characteristics of bituminous binders. As an alternative, a methodology based on functional behaviour tests is proposed.
116 拆建骨料在无结合料底基层和沥青无结合料基层的应用
作者：Marco Pasetto , University of Padova, 意大利
Environmental, economical and technical problems have led to increasing attention being paid to the subject of recycling marginal materials in the construction of road infrastructures. In the paper we present the results of an experimental investigation, aimed to verify the suitability of the aggregate coming from the activities of construction and demolition (C&D: bricks, concretes, etc.) in the formulation of unbound mixtures for sub-base and bituminous mixtures for road base layers of road and airport pavements.
To prepare the unbound mixtures samples, the Proctor methodology as well as the gyratory compactor (usually used for the mix-design of bituminous concrete) were utilized, in order to verify C&D aggregate suitability in road construction. The gyratory compactor has also been used for the formulation of the bituminous mixtures, together with the well-known Marshall methodology (it has given Stability values greater than 15 KN).
In both cases the compaction of the samples with the gyratory technique has allowed to obtain useful information about the shear strength of the mixtures and on the density achieved by the material during compaction, introducing so a precious element of evaluation in the mix design.
The experimentation, as it regards the unbound mixtures, has shown an optimum content of water greater for the C&D material in comparison to that necessary for the natural quarried aggregate (10% against 5%) – which has been considered as a comparative term - , while for the bituminous mixtures, it has been necessary to bring a correction in the grading, replacing the fine fraction (passing to the 4 ASTM sieve) with natural aggregate, so that to contain the dosage of binder within compatible values for the application in examination (4.5%).
The bituminous mixtures have been characterized, from a mechanical point of view, with a series of test for the determination of the dynamic modulus (from 4,100 MPa to 6,500 MPa, according to prEN 12697-26), the indirect tensile strength (up to 3.3 daN/cm2, according to the Italian Standard C.N.R. no. 134/91) and to creep (according to B.S. 598-111 and B.S. 226).
Finally, both for the unbound mixtures and for the bituminous ones, particular attention has been set to the problem of the constitutional homogeneity, that is the presence of hard grains or crashing aggregate, verifying the post-compaction grading variation: percentage differences, in comparison to the initial grading, were noticed up to 30% for the unbound mixtures and up to 13.4% for the bituminous concrete.
117 公路建设中的废物利用：废旧轮胎碎片在沥青混合料中的应用
作者：Francisco Javier Payán De Tejada González , Demarcación de Carreteras del Estado en Castilla y León Occidental, 西班牙
Spain generates over 300,000 tons of discarded tyres or NFUs per annum and it can be predicted that the recycled use of NFU dust for incorporation into asphalt mixes in their different technical variants is capable of signifying the elimination of over 50% of this volume. This paper synthesises the current situation in Spain concerning the use of NFUs in asphalt mixes to be applied in road pavements. It details the applicable Spanish legislation, the current state of NFU waste management and presents some of the regular ways of processing tyres to obtain rubber dust, describing the composition of tyres and their qualities as bitumen modifiers plus the most widespread techniques applied for them in road works. At the present time, two methodologies are being used in Spain to incorporate tyre dust into asphalt mixes, namely the wet and the dry methods. In the wet method, tyre dust is first mixed with the bitumen prior to being added to the mixer at the asphalt plant. In the dry method, the tyre dust is added directly to the mixer at the asphalt plant as if it were another agglomerate. Finally, the paper lists the works carried out in Spain where the different incorporation methods were used to add NFU rubber tyre dust to the bitumen or to the asphalt mixes and gives a detailed description of one of the works in which two wet-method techniques were used and which also involved the construction of two sections using conventional bitumen for control purposes.
118 西班牙在沥青表面层拌和站再生方面的经验
作者：Adolfo Güell Cancela, Ministerio De Fomento. Unidad Carreteras Del Estado En Ourense (Spain)., 西班牙
1. Background. The recycling of existing pavements includes several constructive techniques in order to take advantage of aged pavement materials which, since the energetic crisis of the seventies, are being more and more used in the structural rehabilitation of road pavements.
Works carried out in Spain during the last ten years and the experience derived of then, and also the need of this recycling technique as an alternative, because of environmental issues and also because of road security and economic items were the main reasons which considered Spanish Roads Administration for drafting the specifications about recycling techniques which have been published in the standard document O.C. 8/2001 about “Pavement recycling” which has come into force in January 18th, 2002.
2. Report’s content.
This report develops the technique of bituminous surfacing layers recycled in plant.
This technique, which consists in the use of the materials which are the result of the demolition, the grinding or the crush of bituminous aged layers, for using them in the production of hot bituminous mixes, has been chosen in several works of pavement rehabilitation by Spanish Roads Administration in Ourense.
In this report we develop several issues about the design, production, spread an quality control of bituminous surfacing layers recycled in plant, analysing and describing the works carried out recently with this technique in Ourense (Spain).
119 介绍一种使用煤渣填充物的薄层水泥作为路面基层并用压路机压实的再生方法
作者：Alexander Mironov, The Centre of Road Testing and Researches, 俄罗斯
The main feature of road pavements with cement concrete coats is their ability to ensure during the service life the operation of a road construction, i.e. in the stage of elastic deformation.
The most promising road concrete of a new generation is a lean concrete with a low content of cement, which is compacted by rollers. A lean concrete is a heavy cement concrete of class B5; B7,5; B12,5; B15. A lean concrete is preferably used for building pavement bases of a major type.
Such a lean concrete differs from an ordinary cement concrete by a low content of cement or water, they can be compacted by ordinary road rollers, which have pneumatic or smooth metal rolls. The low content of cement results in forming a low quantity of cement stone an as a result there are a few cracks in a pavement. This pavement can be formed without cutting deformation joints.
As a mineral filler by preparing a lean concrete we have used a crushed stone of a blast furnace cinder of “Chelyabinsk metallurgical works “Mechel””, whose volume of output is about 100 thousand m3 a year and whose price is three tomes low as the price of a rock crushed stone.
According to strength a cinder crushed stone corresponds to mark “1000”. The mass loss in the test of a crushed stone fraction of 5-20 mm is from 15,1% to 23,6% (an average value is 18%), for a fraction of 20-40 mm – from 17,0% to 42,5% (an average value is 21,7%).
Show that the porosity of the cinder crushed stone is 3-4 times as much as compared with the porosity of the natural one. As a result the adhesion between cinder filler and a cement mortar is greatly improved, the water absorption is 1,5-2 times as much that leads to an improved hardening of the lean concrete and to a lesser strength (by 20-25%).
To increase the service life of the lean concrete it is necessary to use a surface-active additive and a plasticizing agent jointly.
Experimental studies have shown that the optimum dosage of additives is within (% mass of cement in the mix): -0,1 – 0,3 for a plasticizing agent; -0,003-0,02 for a surface-active additive.
As a result the recommended dosages for building bases of the lean concrete are as follows (%mass of cement): a plasticizing agent – 0,2, a surface-active additive – 0,04.
The composition of the lean concrete of class 10, recommended for building is as follows: port land cement of mark 400 – 230 kg/m3, natural sand – 830 kg/m3, cinder crushed stone – 935 kg/m3 for a fraction of 5-20 mm, water –164 l/m3, a plasticizing agent – 9 l/m3, a surface-active additive – 0,8 l/m3, water-cement ratio – 0,71, the density of the lean concrete, freshly placed, - 2169 kg/m3; the volume of air, entrained into concrete mix – 5,3%.
When building motorways there is no possibility in Russia for installation a ready mix plant near by a motorway. It is often not profitable. That is why we propose to build road bases of the lean concrete by the cold recycling method.
The advantages of this method are the mobility of the recycler, high exactness of water and cement batching, accurate mixing of all components and finally – high quality of building of such foundation.
