水泥粉煤灰稳定碎石基层配合比设计和路用性能研究
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摘要
近年来水泥粉煤灰稳定碎石基层在我国的一些省份获得了应用,实践表明它具有优良的路用性能和很好的使用前景。然而,目前《公路路面基层施工技术规范》中没有这种材料的技术规定,且已有的研究结论又缺乏系统性,因此设计和施工单位在具体应用时随意性很大。为了给今后的施工生产提供科学的依据,本文深入开展了以下五项研究工作:(1)水泥粉煤灰稳定碎石基层材料配合比研究(2)水泥粉煤灰化学反应机理研究;(3)水泥粉煤灰稳定碎石材料路用性能研究;(4)水泥粉煤灰稳定碎石基层力学分析;(5)水泥粉煤灰稳定碎石混合料配合比设计方法研究。
1.水泥粉煤灰稳定碎石基层材料配合比研究共包括集料级配范围的研究,结合料与集料比例研究,水泥与粉煤灰比例研究。
(1)集料级配范围的研究中,首先开展了以最大密度曲线n幂公式为依据的连续级配范围研究;其次开展了以美国AASHTO中的25mmNMNS级配范围为基础的间断级配范围研究,并进一步指出在这种间断级配的骨架——密实类型混合料配合比设计中,应将水泥和粉煤灰计入2.36mm以下细料含量中,而且4.75mm以上粗集料的骨架间隙率VCA_(mix)必须小于捣实状态下纯粗集料骨架间隙率VCA_(DRC);在对几种骨架——密实结构配合比设计方法评价的基础上,提出了既能解决离析问题,又能保持传统骨架——密实结构特色的悬浮骨架——密实结构。
(2)在结合料与集料最优比例研究中,首先给出了最优结合料剂量的体积计算方法,其次在保持水泥粉煤灰比例不变的基础上,通过不同结合料含量的最大干密度试验,得到一张最大干密度与结合料含量的关系曲线图。此图的最大干密度峰值所对应的比例即为结合料与集料的最优比例,此时结合料剂量恰好填满集料空隙形成密实式结构,试验表明这种结构具有优良的路用性能。最后,确定出当集料级配在连续级配范围内变化时,结合料与集料的最优比例范围。
(3)水泥与粉煤灰最优比例的研究目的是在此比例下,水泥与粉煤灰的物理化学作用对路用性能的贡献均得到充分挖掘。鉴于粉煤灰火山灰反应慢,水泥水化速度快,因此可用强度后期的增幅来判断比例的优劣,增幅越大,比例越优。由于不同地区水泥与粉煤灰的品质存在一定的差异,故最优比例不是一成不变的,它受相关因素的影响。
In recent years the roadbase of cement and fly ash stabilized crushed-stones is being used in some provinces. It is testified that this material has better working properties and application perspective. But the 《Technical Specifications for Construction of Highway Roadbases》 has no technical specifications, and available research conclusions are deficient in systematization, so the department of highway design and construction has few restrictions When applying this material. In order to supply scientific method for prospective departments, this paper cam's out the following five research works in details: (1) the mix design research of cement and fly ash stabilized crushed-stones; (2)reaction theory research of cement and flyash; (3)working properties research of cement and flyash stabilized crushed-stones;(4)mechanics analysis of cement and fly ash stabilized crushed-stones; (5)mix design method research of cement and flyash stabilized crushed-stones .1. Fly ash stabilized crushed-stones mix design includes aggregate's grading envelope,the proportion of bound materials to aggregate and the proportion of cement to flyash.(1) The research of aggregate's grading envelope includes three aspects: continuous gradation envelope research based upon theory of maximum density curve; gap gradation envelope research based upon 25mmNMNS of American's AASHTO. which points out that dense framework structure's mix design method adds percentage of cement and flyash to fine-grained material below 2.36mm, and VCAmix of coarse-grained material above 4.75mm must be below VCAdrc; on the basis of appreciation of popular dense framework structure's mix design methods, thoroughly new structure named suspended frame work dense structure is put forward, which not only maintains traditional characteristics of dense framework structure, but also solve the problem of fine-grained material's separation from coarse-grained material.(2) Among the research of the best proportion of bound materials to aggregate, firstly, volume computing method of the best bound material percentage is introduced, secondly, based upon maintaining the proportion of cement to flyash, this paper gets a curve graph which shows the variation of bound material and the greatest dry density through the greatest dry density teat of different bound material percentage, the greatest dry density's climax determines the best proportion of bound material to aggregate for bound material fill up wholly the void of aggregate, then mixture makes up framework dense structure. It is proved that this structure has a series of good road properties. At last, we determine the best proportion limit of bound material to aggregate when aggregate changes.(3) when cement and flyash's physical and chemical effects which contribute to
road properties is fully excavated, the proportion of cement to flyash is the best. For velocity of flyash's pozzolanic Reaction is slow, but velocity of cement-water system hydration reaction is fast, the degree of later strength development can judge the value of proportion, higher the degree is , better the proportion is. Because cement and flyash's properties vary from one region to another, the proportion of cement to flyash isn't identical which is influenced by relative considerations.2. The hydration reactions theory research of cement and flyash includes following five aspects: (1) particular hydration reaction development of cement and flyash's system; (2) reciprocal influence of cement and flyash's reaction; (3) special intersection between aggregate and bound material which is composed of cement and flyash; (4) research of pozzolanic reaction thermodynamics and dynamic.3. Tests show that the strength of 90d age's cement stabilized crushed-stones has reached 80 percent of its 180d age's, the strength of 120d age's cement and flyash stabilized crushed-stones has also reached 80 percent of its 180d age's, for the design age of cement stabilized crushed-stones is 90d age, it is scientific to take 120d as design age of cement and flyash stabilized crushed-stones. After that, through varying aggregate gradation and cement percent, we determine material's 7 day age's compressive strength standard, design age's cleavage strength limit and resilience modulus limit.4. In research of mechnics analysis of cement and flyash stabilized crushed-stones,the road surface deflect,every layer's tensile stress and temperature stress of three semi-rigid roadbase have bee computed. The results indicate that anti-fatigue of cement and flyash stabilized crushed-stones is the best, and its temperature stress is lower than cement stabilized crushed-stones,but higher than lime and fly ash stabilized crushed-stones.5. Based upon system engineering's relative theory, cement and flyash stabilized crushed-stones'mix design method is introduced which has four characteristics: (1) good crack resistance property, (2) good erosion resistance property; (3) covering 7 day age's compressive strength standard; (4) low investment
1.水泥粉煤灰稳定碎石基层材料配合比研究共包括集料级配范围的研究,结合料与集料比例研究,水泥与粉煤灰比例研究。
(1)集料级配范围的研究中,首先开展了以最大密度曲线n幂公式为依据的连续级配范围研究;其次开展了以美国AASHTO中的25mmNMNS级配范围为基础的间断级配范围研究,并进一步指出在这种间断级配的骨架——密实类型混合料配合比设计中,应将水泥和粉煤灰计入2.36mm以下细料含量中,而且4.75mm以上粗集料的骨架间隙率VCA_(mix)必须小于捣实状态下纯粗集料骨架间隙率VCA_(DRC);在对几种骨架——密实结构配合比设计方法评价的基础上,提出了既能解决离析问题,又能保持传统骨架——密实结构特色的悬浮骨架——密实结构。
(2)在结合料与集料最优比例研究中,首先给出了最优结合料剂量的体积计算方法,其次在保持水泥粉煤灰比例不变的基础上,通过不同结合料含量的最大干密度试验,得到一张最大干密度与结合料含量的关系曲线图。此图的最大干密度峰值所对应的比例即为结合料与集料的最优比例,此时结合料剂量恰好填满集料空隙形成密实式结构,试验表明这种结构具有优良的路用性能。最后,确定出当集料级配在连续级配范围内变化时,结合料与集料的最优比例范围。
(3)水泥与粉煤灰最优比例的研究目的是在此比例下,水泥与粉煤灰的物理化学作用对路用性能的贡献均得到充分挖掘。鉴于粉煤灰火山灰反应慢,水泥水化速度快,因此可用强度后期的增幅来判断比例的优劣,增幅越大,比例越优。由于不同地区水泥与粉煤灰的品质存在一定的差异,故最优比例不是一成不变的,它受相关因素的影响。
In recent years the roadbase of cement and fly ash stabilized crushed-stones is being used in some provinces. It is testified that this material has better working properties and application perspective. But the 《Technical Specifications for Construction of Highway Roadbases》 has no technical specifications, and available research conclusions are deficient in systematization, so the department of highway design and construction has few restrictions When applying this material. In order to supply scientific method for prospective departments, this paper cam's out the following five research works in details: (1) the mix design research of cement and fly ash stabilized crushed-stones; (2)reaction theory research of cement and flyash; (3)working properties research of cement and flyash stabilized crushed-stones;(4)mechanics analysis of cement and fly ash stabilized crushed-stones; (5)mix design method research of cement and flyash stabilized crushed-stones .1. Fly ash stabilized crushed-stones mix design includes aggregate's grading envelope,the proportion of bound materials to aggregate and the proportion of cement to flyash.(1) The research of aggregate's grading envelope includes three aspects: continuous gradation envelope research based upon theory of maximum density curve; gap gradation envelope research based upon 25mmNMNS of American's AASHTO. which points out that dense framework structure's mix design method adds percentage of cement and flyash to fine-grained material below 2.36mm, and VCAmix of coarse-grained material above 4.75mm must be below VCAdrc; on the basis of appreciation of popular dense framework structure's mix design methods, thoroughly new structure named suspended frame work dense structure is put forward, which not only maintains traditional characteristics of dense framework structure, but also solve the problem of fine-grained material's separation from coarse-grained material.(2) Among the research of the best proportion of bound materials to aggregate, firstly, volume computing method of the best bound material percentage is introduced, secondly, based upon maintaining the proportion of cement to flyash, this paper gets a curve graph which shows the variation of bound material and the greatest dry density through the greatest dry density teat of different bound material percentage, the greatest dry density's climax determines the best proportion of bound material to aggregate for bound material fill up wholly the void of aggregate, then mixture makes up framework dense structure. It is proved that this structure has a series of good road properties. At last, we determine the best proportion limit of bound material to aggregate when aggregate changes.(3) when cement and flyash's physical and chemical effects which contribute to
road properties is fully excavated, the proportion of cement to flyash is the best. For velocity of flyash's pozzolanic Reaction is slow, but velocity of cement-water system hydration reaction is fast, the degree of later strength development can judge the value of proportion, higher the degree is , better the proportion is. Because cement and flyash's properties vary from one region to another, the proportion of cement to flyash isn't identical which is influenced by relative considerations.2. The hydration reactions theory research of cement and flyash includes following five aspects: (1) particular hydration reaction development of cement and flyash's system; (2) reciprocal influence of cement and flyash's reaction; (3) special intersection between aggregate and bound material which is composed of cement and flyash; (4) research of pozzolanic reaction thermodynamics and dynamic.3. Tests show that the strength of 90d age's cement stabilized crushed-stones has reached 80 percent of its 180d age's, the strength of 120d age's cement and flyash stabilized crushed-stones has also reached 80 percent of its 180d age's, for the design age of cement stabilized crushed-stones is 90d age, it is scientific to take 120d as design age of cement and flyash stabilized crushed-stones. After that, through varying aggregate gradation and cement percent, we determine material's 7 day age's compressive strength standard, design age's cleavage strength limit and resilience modulus limit.4. In research of mechnics analysis of cement and flyash stabilized crushed-stones,the road surface deflect,every layer's tensile stress and temperature stress of three semi-rigid roadbase have bee computed. The results indicate that anti-fatigue of cement and flyash stabilized crushed-stones is the best, and its temperature stress is lower than cement stabilized crushed-stones,but higher than lime and fly ash stabilized crushed-stones.5. Based upon system engineering's relative theory, cement and flyash stabilized crushed-stones'mix design method is introduced which has four characteristics: (1) good crack resistance property, (2) good erosion resistance property; (3) covering 7 day age's compressive strength standard; (4) low investment
引文
[1] 杨锡武,梁富权,水泥(石灰)粉煤灰碎石混合料半刚性路面基层设计参数研究,中国公路学报,1996(3).
[2] 杨锡武,梁富权,水泥(石灰)粉煤灰混合料的最佳配合比研究,公路,1995(9).
[3] 萧赓等,水泥粉煤灰级配碎石基层混合料的路用性能研究,重庆交通学院学报,2001(11).
[4] 杨锡武,凌天清,梁富权,水泥(石灰)粉煤灰混合料路面基层研究,重庆交通学院学报,1997(2).
[5] 俞建荣,栗学铭,窦有年,粉煤灰水泥稳定粒料的路用性能研究,中国公路学报,1998(8).
[6] 萧赓等,水泥粉煤灰级配碎石基层混合料微观机理研究,重庆交通学院学报,2002(2).
[7] 杨锡武,梁富权,水泥(石灰)粉煤灰混合料路面基层成型延迟时间研究,重庆交通学院学报,1995(4).
[8] 徐江萍等,水泥——粉煤灰碎石早强特性的研究,中南公路工程,1999(2).
[2] 杨锡武,梁富权,水泥(石灰)粉煤灰混合料的最佳配合比研究,公路,1995(9).
[3] 萧赓等,水泥粉煤灰级配碎石基层混合料的路用性能研究,重庆交通学院学报,2001(11).
[4] 杨锡武,凌天清,梁富权,水泥(石灰)粉煤灰混合料路面基层研究,重庆交通学院学报,1997(2).
[5] 俞建荣,栗学铭,窦有年,粉煤灰水泥稳定粒料的路用性能研究,中国公路学报,1998(8).
[6] 萧赓等,水泥粉煤灰级配碎石基层混合料微观机理研究,重庆交通学院学报,2002(2).
[7] 杨锡武,梁富权,水泥(石灰)粉煤灰混合料路面基层成型延迟时间研究,重庆交通学院学报,1995(4).
[8] 徐江萍等,水泥——粉煤灰碎石早强特性的研究,中南公路工程,1999(2).