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唐 山 学 院毕 业 设 计外文资料翻译 系 别: 土木工程系 班 级: 07级土木工程(2)班 姓 名: 赵 菲 指 导 教 师: 贾开武 2006年6月13 日唐 山 学 院 毕 业 设 计一.英文原文A STUDY ON THE EFFECT OF GLASS FIBRE ON THE STABILITY OF BITUMINOUS MIXESS. JAYALEKSHMI1 and N. ANJANEYULUABSTRACT: Surface cracking of pavements decreases its fatigue response. The inclusion of glass fibre in bituminous mixes increases the fatigue life of pavements. In the current investigation E glass fibre is mixed with the bituminous mixes and Marshall Stability test was conducted. The optimum bitumen content and flow value were evaluated. The influence of this glass fibre on durability and the engineering properties of semi dense bituminous concrete such as stability, flow, air voids in the mix, voids in mineral aggregates and voids filled with bitumen are presented in this paper. The stability values increased by as much as 32%.KEYWORDS: Fibre Glass, Bituminous Mixes, Marshall Stability Test, Stability, Flow Value1. INTRODUCTION The low tensile strength of bituminous mixes causes the pavement subjected to repeated loading to crack. The propagated cracks develop distress symptoms like raveling, undulations, rutting, cracking, bleeding, shoving and potholing of bituminous surfacing. The high traffic intensity of commercial vehicles also compounds this problem. Hence, to improve the performance of the pavements, reinforcements and additives are added to the bituminous mixes. Therefore, there arises a necessity to evaluate the optimum fibre content and the type of fibre. The fibres placed in the bituminous mix are homogeneously dispersed and act as stress absorbing layers. In the recent past, cotton, metal wire and asbestos were used. Cotton is degradable and cannot be used as long term reinforcement; metal wire rusts when water penetrates. Asbestos poses health hazard. This automatically leads to the choice of glass fibre. Transportation is the lifeline of any nations economy and hence improving the performance of the pavements indirectly boosts the economy.2. REVIEW OF LITERATURE Freeman (1978) found that the incorporation of polyester fibre as a reinforcement in the surface course, reduces reflective cracking. The effect was studied by varying the diameter, length and percentage of the polyester fibre. Gokhale (1987) carried out studies on reinforced bituminous surfaces with fibre glass sheet and Teflon sheets and with five types of gradations of mineral aggregates. Kim (1999) evaluated the performance of polymer - modified (polypropylene film and a grid) bituminous mixtures and specially designed reinforcing technique against reflective cracking for typical bituminous pavement over layers. The wheel tracking test was used to investigate durability aspects such as the plastic flow resistance and crack resistance of the geogrid reinforced bituminous mixtures by Komatsu(1998). The material used was a high strength, high modulus polyoxymethylene fibre. As per Lytton (1989), the use of geotextiles in bituminous overlays enhances reinforcing, strain relief and under sealing. The reflection cracking caused by the loads and thermal contraction was arrested by the use of geotextile reinforcement. Maurer (1989) determined the effectiveness of various geotextiles and fibres in retarding the reflective crack formation in bituminous overlay. The fatigue life and the rut resistance also improved. The cheapest type of glass fibre available commercially is the E-Glass Fibre and this material is used in the present study as reinforcement within the bituminous mix.3. LABORATORY STUDY3.1 MATERIAL PROPERTIES3.1.1 Glass FibreThe properties of the E-Glass Fibre used are as listed in Table 1.3.1.2 Aggregate The aggregate used in the study is of the gradation specified by the MORT&H (Specifications for Road and Bridge Works (2001) for 25 - 30 mm thick Semi-Dense Bituminous Concrete (Grade II). This is the most widely used surface course for highways in India. Tests conducted on the aggregate showed the material properties indicated in Table 2. Correct sampling (Representative sample) was ensured as correctness of the Marshall Stability Test largely depends on proper sampling. The required gradation was arrived at by batch mixing by carefully proportioning two or three sizes of aggregate mixtures. The nominal size of the aggregate is 10 mm. The layer thickness is 25 mm - 30 mm. The gradation is as shown in Table 3. The Semi Dense Bituminous Pavement Layers have a minimum stability of 8.2 kN at 60. The flow is 2 mm to 4 mm. Compaction is achieved by giving 75 blows on each of the two faces of the specimen. The percentage of air voids is 3 - 5. The percentage of voids filled with bitumen is 65 - 78.3.1.3 Bitumen The engineering properties of Bitumen used in the study are listed in Table 4. Both 60/70 grade bitumen and 80/100 bitumen were used in the study.4. METHODOLOGY Bitumen and aggregate form the major constituents of the surface layer of a flexible pavement. The following properties were evaluated. Bitumen: Penetration, softening point, ductility, specific gravity. Aggregate: Crushing value, impact value, abrasion value, flakiness index, elongation index, water absorption, specific gravity. Gradation of Semi Dense Bituminous Concrete usually used for surface layers of the flexible pavements in India has been selected for the present study. All the tests were performed according to the standards. Marshall Method of mix design was carried out on glass fiber reinforced and unreinforced bituminous mixes to arrive at optimum fiber content and optimum binder content. Following are the variables set for the present study: Fiber percentages of 0,0.1,0.2,0.3,0.4,0.5 Grade of bitumen:60/70 and 80/100 The dimensions of the glass fiber used are as follows; Glass fiber length: 12.5mm Diameter of glass fiber: 5-10 m It is important to characterize the various pavement materials and find the optimum conditions for testing. Glass fiber available in the local market is used as reinforcement for the experimental investigation. To eliminate any possibility of errors in sampling for preparing batch mixes, a mix has been prepared that has the gradation around the mid-value of the gradation limits given in Table 3.3. Thus, one parameter of gradation of aggregate has been fixed. Marshall Stability and flow values have been used as parameters for the assessment of the strength of the pavement. The Marshall Stability test has been carried out at various percentages of the fibre , to arrive at the optimum percentage of the glass fiber that gives maximum stability and a flow within specification limits.5. RESULTS AND DISCUSSION For various binder contents, the values of stability, flow, unit weight, percentage voids and percentage aggregate voids were examined for the reinforced and un-reinforced bitumen. For the unreinforced case, the Marshall Stability values for different bitumen contents is as shown in Figure 1 The Marshall stability value increases with the bitumen content until it reaches a peak value corresponding to 5.3% for 60/70 grade bitumen and 5.10% for 80/100 grade bitumen. The variation of bulk density and percentage air voids with the bitumen content was also examined. The bulk density vs. bitumen content variation is plotted in Figure 2. The percentage air voids vs. bitumen content variation is as shown in Figure 3. From Figure 1, Figure 2 and Figure 3, the optimum bitumen content for 60/70 grade bitumen is found to be 5.3% and that for 80/100 bitumen is found to be 5.10%. Figure 4 and Figure 5 show the variation of bulk density with fibre content for 60/70 and 80/100 grade bitumen respectively. At a fibre content of 0.3%, the optimum bitumen content for reinforced mix is 4.5%.For higher grades of bitumen, the stability decreases because of insufficient bondage between aggregates , fibre and bitumen. The flow was found to be within the limits of 2 - 4 mm as specified by MORT&H 2001 (Specifications for Road and Bridge Works)There is a negligble change in unit weight.6. CONCLUSIONS Based on the experimental investigation on glass fiber reinforced bituminous mix, the following conclusions were drawn: About 20 to 32 percent increase in stability values can be achieved by reinforcing the bituminous mix with glass fiber. Higher stability values indicate that the reinforced mixes would be less susceptible to cracking of Flexible pavements. From the Marshall Stability tests conducted, an optimum fiber content of 0.3% by the weight of total mix was found for a bitumen content of 4.5%. For the optimum fiber content, the maximum stability value was found to be 17.65 kN for a bitumen content of 4.5%. The service life of the pavement is expected to increase after reinforcing the bituminous mix with glass fiber. From the observed improvements in stability and engineering properties, it can be concluded that the reinforced bituminous mixes are suitable in heavy traffic conditions also.7. REFERENCES1. Freeman, R.B., Burati Jr., J.L., Amirkhanian, S.N., and Bridges Jr., W.C. (1989). “Polyester fibre in asphalt paving mixtures,” Proceedings, Association of Asphalt Paving Technologists, Vol. 58 pp 387-409.2. Gokhale.Y.C, Bose.S. and Singh. M.P, (1987). “Laboratory study on flexural fatiguecharacteristics of reinforced bituminous surfacings,” Highway Research Bulletin, No. 32, pp 45- 56.3. Khanna, S.K., and Justo, C.E.G. (1992). “Highway Material Testing,” Nem Chand & Bros.Roorkee, India.4. Khanna, S.K., and Justo, C.E.G. (1992). “Highway Engineering,” Nem Chand & Bros., Roorkee, India.5. Kim, K.W., Doh, Y.S., and Lim, S. (1999). “Mode I reflection cracking resistance of strengthened asphalt concretes,” Construction and Building Materials, Vol. 13, pp. 243-251.6. Komatsu, T., Kikuta, H., Tuji, Y., and Muramatsu, E. (1998). “Durability assessment of geogridreinforced asphalt concrete,” Geo-textiles and Geo-membranes, Vol. 16, pp 257-271.7. Lytton, R.L. (1989). “Use of geo-textiles for reinforcement and strain relief in asphalt concrete,” Geotextiles and Geomembranes, Vol. 8, No. 3, pp. 217-237.8. Mourer, D.A, and Malasheskie.G.J. (1989). “Field performance of fabrics and fibres to retard reflective cracking,” Journal of Geotextiles and Geomembranes, Vol. 8, pp 239-267.9. Ministry of Road Transport & Highways (2001), “Specifications For Road And Bridge Works”.二.中文译文玻璃纤维对于沥青稳定性影响的研究摘要:沥青路面上的裂纹会降低其疲劳反应。包含玻璃纤维的沥青混合物可以提高沥青路面的寿命。在最近的一次研究中,将无碱玻璃纤维掺在沥青混合物中并进行了马歇尔稳定度试验。测定最佳沥青含量和流值。本文从稳定性、流量、混合物空隙率、矿物聚合物空隙率以及沥青空隙率等方面介绍玻璃纤维对于半致密沥青混凝土的耐久性及其工程适用性的影响,其稳定性值会增长多达32%。关键词: 玻璃纤维 沥青混合物 马歇尔稳定度试验 稳定性 流值1.引言 沥青混合物受到低强度拉力致使沥青路面反复承受荷载而开裂。路面开展的裂纹会加重裂缝,车辙,挤出沥青铺装层甚至出现地洞。在商业化的今天,高密度的交通拥堵现象更加重了这一问题。因此,为了提高沥青道路的性能,沥青混合物中需增添额外强化物质。为此,有必要对于最佳纤维含量及纤维种类做出评估。将纤维均匀散至沥青混合物表面可以起到分解应力的作用。最近,棉花、金属丝以及石棉等是常用的纤维品种。但由于棉花易降解,并不能用于长期加筋;金属在渗水后易生锈;石棉则会对健康造成危害。因此玻璃纤维成为了最佳选择。交通是任何一个国家的经济的生命线,因此提高道路性能可以间接促进经济的发展。2.文献综述弗里曼(1978年)发现将聚酯纤维加入物质表面可以减少反射开裂。他研究了掺入不同直径、长度和百分比的聚酯纤维会产生的不同影响。格克哈莱(1987)对用玻璃纤维板材和特氟隆薄片以及五种等级的矿物骨料掺入沥青表面进行强化的效果进行了研究。金(1999) 评价了聚合物-改性(聚丙烯薄膜和网格)沥青混合物的性能,并特别设计了增强技术应对典型的沥青路面表层的反射开裂。小松(1998)发明的车轮跟踪试验方法通常会用于检验塑料流阻的耐久性,及增强沥青混合物的抗裂性能。所用原材料是一种高强度、高模量纤维甲醛。利顿 (1989)使用土工织物来加强沥青加铺层,缓解压力层并密封。但利用土工织物加固会引起由与荷载和热收缩引发的反射裂纹。莫伊尔雷(1989)之后明确了各种能够延缓反射裂缝的沥青加铺层的土工织物和纤维。道路寿命和车辙阻力也得到改善。现在市场上可买到最便宜的玻璃纤维就是无碱玻璃纤维,这一材料也同样应用于本次加固沥青混合物的研究中。3.实验室研究3.1 材料性能3.1.1 玻璃纤维表1为无碱玻璃纤维的性能。表1 玻璃纤维的性能编号性能价值及评价1比重2.5-2.62杨氏模量69-723抗拉强度1.7-3.54直径5-255使用最高温度3506尺寸稳定性良好耐热,抗寒,防腐性3.1.2 骨料研究中使用的骨料为MORT&H道路与桥梁工程规程(2001)中的分级规格中的25 - 30毫米厚的半致密性沥青混凝土(II级)。这一材料是印度高速公路中最为广泛使用的,表2显示了该材料的性能。表2 骨料性能编号性能价值及评论1比重2.722冲击值203压碎指标244洛杉矶磨损值205薄片指数176针状指数12正确的采样(代表性试样)能确保马歇尔稳定度试验的正确性,通过仔细搅拌配料使两三种不同粒径的集料混合物达到所需的层次分级,集料的公称直径为10毫米,层厚约为25毫米-30毫米,表3为分级情况。沥青路面半致密层的最低稳定性为60时加压8.2 kN,浮动值为2mm至4mm。在样本的每面的捶击数75次得到的压实值,空隙率是3%-5%,而沥青填充率为65%-78%。3.1.3沥青该研究中沥青的工程性能列在表4。研究中均使用了60/70与80/100两种型号的沥青。表3 路层混凝土半致密性沥青的成分编号筛孔直径(毫米)骨料传送重量的累积积百分比113.2010029.5090-10034.7535-5142.3624-3951.1815-3060.309-1970.0753-8表4 沥青性能编号性能60/70级沥青80/100级沥青1温度25度时的针入度65862软化点4743325度时的延性68854比重1.021.024.方法沥青和骨料是柔性路面表层的组成成分,本研究将对下列性能进行评估:沥青:针入度、软化点、延度、比重。骨料:冲击值、压碎指标、磨损值、薄片指数、针状指数、吸水率、比重。当前研究中的混凝土等级为用于印度韧性道路层半致密性沥青表面的混凝土等级。所有的试验都符合标准,运用马歇尔配合比设计方法研究玻璃纤维增强非加强沥青混合物的韧性并从中得到最佳纤维和最佳粘合剂的含量。以下是本研究中所设置的变量:纤维百分比:0,0.1,0.2,0.3,0.4,0.5沥青等级:60/70和80/100所用的玻璃纤维的尺寸如下:玻璃纤维长度:12.5毫米玻璃纤维直径:5-10微米显示各种路面材料的特征并找到最佳测试条件这一点非常重要。从当地市场上采购的玻璃纤维被用作加固实验检测的材料。为了准备批量混合而消除产生任何取样误差的可能,必须事先准备一个围绕中期层次的灰度值范围,具体情况参见表3.3。 因此,对骨料级配参数已被修正。马歇尔稳定度和流量值被用来作为对路面强度的评估参数。马歇尔稳定性试验在对不同比例的纤维进行分析后,得出最佳比例的玻璃纤维,从而保证有最强的稳定性并且是规格限制内流量。5.结果与讨论对于各种参量内容,如粘结剂含量、稳定性、流量、单位重量、空洞百分比比值和未加固的沥青材料间隙检查。对于未加固的情况,针对不同的沥青马歇尔稳定值的内容如图1所示:马歇尔稳定性随着沥青含量的增加,达到一个峰值时对应的稳定值分别为5.3的60/70级沥青和5.10%的80/100级沥青。对散装密度的变化与沥青含量的空隙百分比也会影响实验结果。大容量密度与沥青含量变化情况绘制于图2。马歇尔稳定性和沥青含量符号 沥青等级马歇尔稳定性(公斤)图1 马歇尔稳定性和沥青含量沥青含量() 流量与沥青含量沥青含量()流量(毫米)图2 流量对比沥青含量空隙率百分比和沥青含量变化如图3:散装密度与沥青含量散装密度沥青含量()图3 散装密度与沥青含量从图1、图2和图3中可看出,对60/70级沥青的最佳沥青含量是5.3,而80/100沥青是5.10。沥青含量()空隙率(%)空隙率百分比和沥青含量图4 空隙率和沥青含量的对比沥青稳定性kg纤维含量() 图5 纤维百分比(60/70)图5和图6显示的是散装密度和纤维含量变化分别为60/70和80/100级的沥青。纤维含量()稳定性(kg)沥青图6 稳定性与纤维百分比(80/100)在纤维含量为0.3,最佳的加固沥青含量为4.5。对于高级沥青,稳定性适当降低,由于骨料纤维和沥青之间的束缚不紧密。该浮动限制在2- 4毫米,这是2001年由MORT&H公司所指定的(道路与桥梁工程的规格允许有一个单位重量的变化)。6.结论在对玻璃纤维增强沥青混合料的实验研究的基础上,得出以下结论: 通过玻璃纤维加强的沥青混合物可增加约20%至32%的稳定性。稳定性值越高表明该种混合物将不易造成柔性路面开裂。 从马歇尔稳定性试验显示最佳纤维含量是总重量的0.3,是沥青含量的4.5。对于最佳纤维含量,对于含量为4.5的
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