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海排灰在道路基层及底基层中的应用研究

The Study of the Fly-Ash-Flushed-by-Seawater is Used in the Road Subbase Course

【作者】 包龙生

【导师】 陈忠达;

【作者基本信息】 长安大学 , 道路与铁道工程, 2008, 博士

【摘要】 近几年来修筑道路和制作水泥大量使用了粉煤灰,使得这种工业废渣日趋紧缺,价格一路攀升。辽宁省委、省政府实施的“五点一线”沿海经济带的道路建设需要大量的粉煤灰,仅辽宁(营口)沿海产业基地的道路建设就需要600万吨粉煤灰。当地满足规范的普通粉煤灰非常短缺,而附近的营口鲅鱼圈电厂用海水冲排的粉煤灰(亦称海排灰)就有1000万吨,至今无人使用,正污染着周围的环境。如果能把这种海排灰成功地应用于产业基地道路建设中,将变废为宝,既能节约资源,又能保护环境,真正做到可持续发展。由于至今国内外没有关于把海排灰材料应用于道路建设的任何报道,更没有相关技术规范可以参照,为了系统研究海排灰应用于道路路面基层的可行性,本研究以辽宁(营口)沿海产业基地的道路建设为依托,主要从室内试验、理论分析、试验路段验证等三个方面来进行研究。主要研究内容与成果如下:1.对海排灰的物理力学性质进行了研究。鲅鱼圈海排灰各样本中有效成分SiO2加Al2O3的含量均大于76%,烧失量最大为3.16%,满足《粉煤灰石灰类道路基层施工及验收规程》CJJ4-97规定。经过筛分试验发现海排灰粒度偏粗,不满足上述规范的规定,属于低活性粉煤灰。经化学分析,海排灰的氯盐含量一般为0.80%左右。2.对基于海排灰的水泥海排灰碎石基层及三灰碎石底基层材料配合比进行了研究。包括:确定了水泥海排灰稳定碎石基层材料的集料级配范围;从海排灰、水泥、石灰的品质入手,对水泥、石灰与海排灰最优比例的影响因素进行分析,并通过试验确定了水泥海排灰中水泥、海排灰的最佳比例和三灰中水泥、石灰、海排灰的最佳比例。根据配合比试验,采用鲅鱼圈海排灰做水泥海排灰基层,最佳配合比为水泥:海排灰:碎石=5:10:85;三灰底基层的最佳配合比为水泥:石灰:海排灰:碎石为2:10:43:45。最后通过水泥海排灰碎石和水泥石灰海排灰碎石混合料的路用性能试验,得到抗压强度、劈裂强度和回弹模量等路用性能随养生时间的变化规律。3.通过X-射线衍射分析和扫描镜法(SEM)微观分析法,研究了海排灰和普通粉煤灰按同样配比制成水泥海排灰、三灰结合料,在不同的龄期,材料的微观变化,包括孔隙变化,生成物的变化,从而在微观方面为海排灰应用于道路基层提供理论依据。本文还研究不同氯盐含量的海排灰组成的水泥海排灰、三灰结合料,在不同龄期的微观变化,得到了氯盐含量对水泥海排灰、三灰结合料微观影响规律。本文对海排灰中粉煤灰与水泥、石灰基结合料的化学反应进行分析;对粉煤灰-水泥体系对海排灰中氯离子的固化机理进行探讨。4.经研究分析,影响海排灰特性的主要因素是其中含有氯离子,其它成分对海排灰特性影响非常小。为了研究海排灰中含盐量对水泥海排灰碎石、三灰碎石路用性能的影响,本文从基层和底基层混合料的抗压强度、抗冻性能、干缩、温缩性能及冲刷性能等方面进行系统研究,得到如下重要结论:(1)氯离子对水泥海排灰混合料、三灰混合料有早强剂的作用。水泥海排灰碎石中海排灰的最佳氯离子含量在1.3%左右时,早期强度最高。三灰碎石中海排灰的最佳氯离子含量在1.8%左右时,早期强度最高。三灰碎石中水泥加石灰的含量比水泥海排灰碎石中水泥含量大,固化能力比较强。(2)根据冻融性能试验,氯盐含量变化对水泥海排灰基层材料抗冻性能影响不大;但对底基层材料的抗冻性能影响较大。通过抗冻性试验,当氯盐含量超过1.5%时,三灰碎石抗冻性能达不到规范要求。因此,要求用做底基层的海排灰氯盐含量不要大于1.5%。(3)随着粉煤灰中氯离子的增加,基层、底基层混合料试件干缩应变增长较快,干缩系数增加,因此海排灰基层。底基层施工时更要注意洒水养生。海排灰中氯盐含量对基层、底基层混合料温缩影响不大。(4)不同氯盐含量的基层和底基层材料在受到冲刷时,冲刷量不一样,氯盐含量越大,冲刷量越大。通过试验海排灰的水泥海排灰碎石抗冲刷性能比三灰碎石料差,因为水泥海排灰中结合料比较少,氯盐溶解后,水泥海排灰集料更容易被冲刷。5.通过海排灰碎石基层、底基层的多层弹性层状体系力学分析,验证基于海排灰基层、底基层的路面结构在标准荷载作用下,满足设计要求。6.通过试验路段施工和检测,对辽宁(营口)沿海产业基地海排灰基层、底基层施工的关键技术和技术指标进行研究。通过试验路段压实度、弯沉、无侧限抗压强度检测,以及对试验路段的长期使用情况(包括路面状况和弯沉)观测,路面的各项性能都满足规范要求,说明海排灰用于道路基层及底基层建设非常成功。在此基础上提出基于海排灰基层及底基层的典型路面结构。

【Abstract】 Recently, the fly ash having been built in road construction and having been made in cement largely, caused this industry waste residue to be day by day scarce, and it’s price group climbed. Liaoning (Yingkou) Coastal Industrial Base’s road construction needs 6,000,000 tons fly ash. The local fly ash which meet the standard requirement,is short.But there are 10,000,000 tons fly ash flushed by seawater (also to call fly-ash-flushed-by-seawater) in storage pool in Bayuquan power plant of Yingkou. It has never been used for road construction. If the fly-ash-flushed-by-seawater can be applied successfully in road construction, the resources will be saved and the environment will be protected.Because there is no report about appling this material for road construction in domestic and foreign until now, and no technology standard can be refered to, this paper, taking the road construction of Liaoning (Yingkou) Coastal Industrial Base as a backing, has researched the fly-ash-flushed-by -seawater how to be applied in pavement roadbase. The main research content and the achievement are as follows:1 .The study about physics mechanical properties of the fly-ash-flushed-by-seawater.The chemical composition of the fly-ash-flushed-by-seawater in Bayuquan is:SiO2+Al2O3 content is greater than 76% and the ignition loss is 3.16%, satisfing the road construction specification.It’s grain size can not satisfied the road construction specification and the fly-ash belongs to the low active fly ash. The chloride ion content of the fly-ash-flushed-by-seawater is about 0.80%2.The mixture ratio design of the Lime fly-ash-flushed-by-seawater stabilized crushed-stones includes: (1)the aggregate’s grading envelope, (2)the proportion of cement to fly-ash-flushed-by-seawater and the proportion of lime to fly-ash-flushed-by-seawater; (3)the proportion of bound materials to aggregate.This research recommends the best mixture ratio of the roadbase for Yingkou Coast Industry Base as following :the two ash stabilized roadbase,the cement: fly-ash-flushed-by-seawater: stone =5: 10:85; the three ash stabilized subbase, cement:Lime: fly-ash-flushed-by-seawater: stone is 2:10:43:45.3.The hydration reactions theory research of cement and fly-ash-flushed-by-seawater includes following two aspects: chemical reaction analysis of fly ash and cement, and of chloride ion in fly-ash-flushed-by-seawater. Through the microscopic analysis by SEM and XRD, the mix material’s strength change regular for different chlorine salt content can be disclosure.4.In order to study the salt content in fly-ash-flushed-by-seawater how to influence the road performance of the two ash stabilized roadbase and three ash stabilized roadbase, this article has done the experiments of roadbase and the subbase as follow: compressive deformation strength experiments, anti-freeze performance experiments ,dry shrinkage performance experiments, temperature shrinkage performance experiments and anti-erosion property experiments.(1) In compressive deformation strength aspect, the chloride ion content in the two ash stabilized roadbase and the three ash stabilized roadbase has an agent function to the early strength, and reject the later period intensity growth. When chlorine salt content in two ash stabilized crushed stones is not big, it is advantageous to the intensity.when the salt content in fly-ash-flushed-by-seawater is big, it is disadvantageous to two ash stabilized crushed-stones’s early strength.(2) In anti-freeze performance aspect, the salt content do not change too big to the roadbase material.If the salt content in fly-ash-flushed-by-seawater is big, the subbase material’s anti-freeze performance can be affected. Through the anti-freeze performance experiments,we found that if the chlorine salt content surpassesl.5%,.the anti-freeze performance of the three ashes stabilized crushed-stones can’t meet the standard requirement.(3) In dry shrinkage and temperature shrinkage performance aspect, it is not big influence in the salt content to the base and subbase blends.(4) In anti-erosion property experiments, the rate of mass loss grows quickly than the salt content grows. This show the anti-erosion performance of the roadbase and subbase material.is sensitive to the salt content in fly-ash-flushed-by-seawater.5.Through the mechanics analysis of fly-ash-flushed-by-seawater stabilized roadbase and subbase with multi-layered elasticity layered system,we can proved that the fly-ash-flushed-by-seawater stabilized roadbase and subbase, under the standard axial loading, can satisfy the design request.6.Through the construction and examination to the experiment road, the key technologies and the technical specification is summarized for Liaoning (Yingkou) Coastal Industrial Base fly-ash-flushed-by -seawater stabilized road construction. And through detection to the experiment road, the fly-ash-flushed-by -seawater stabilized roadbase and subbase are proved to meet the standard requirements.Lastly ,the typical pavement structure for the fly-ash-flushed-by -seawater is recommended in this paper.

  • 【网络出版投稿人】 长安大学
  • 【网络出版年期】2009年 11期
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