The properties of road base course materials of granular soils stabilized by AGS granular soil stabilizing cement were studied.The AGS cement has an expansibility to a certain degree,so the dry shrinkage of AGS cemen...The properties of road base course materials of granular soils stabilized by AGS granular soil stabilizing cement were studied.The AGS cement has an expansibility to a certain degree,so the dry shrinkage of AGS cement paste and AGS stabilized granular is much lower than that of Portland slag cement.AGS has a good suitability to granular soils.Granular soils stabilized by AGS have a much higher strength than that of soils stabilized by P S cement.The same strength can be reached with 20% reduction of cement dosage for AGS cement.And their elastic and resilient modulus are similar,but the former has a much higher tensile splitting strength,so the AGS stabilized granular has a much better anti-cracking performance than that of the P S stabilized granular.The reduced value of the strength and the density with the retard time for the granular soils stabilized by AGS is lower than that for P S cement.展开更多
To enhance the performance of mix granulate road base courses by cement treatment. The mechanical properties of cement treated mix granulate (CTMG) were studied, which was designed with 65% crushed masonry and 35% c...To enhance the performance of mix granulate road base courses by cement treatment. The mechanical properties of cement treated mix granulate (CTMG) were studied, which was designed with 65% crushed masonry and 35% crushed concrete by mass. The central composite design was employed to prepare specimens with different levels of cement content and degree of compaction. All specimens were cured in a fog room at 20 ℃ for a specific number of days. The compressive strength and the indirect tensile strength were determined through the monotonic compression and indirect tension tests. Effective prediction models for the mechanical properties of CTMG, in relation to the cement content, the degree of compaction and the curing time, were successfully established for a mix containing 65% crushed masonry and 35% crushed concrete by mass.展开更多
The effects of the proportion of fine aggregate, the maximum size of the aggregate and the proportion of the 9.5 mm to 4.75 mm particle in the coarse aggregate on the properties of the porous concrete are investigated...The effects of the proportion of fine aggregate, the maximum size of the aggregate and the proportion of the 9.5 mm to 4.75 mm particle in the coarse aggregate on the properties of the porous concrete are investigated. Results indicate that the porous concrete with a cement dosage only 150 kg/m^3 has high strength and satisfying permeability when the aggregate has a passing percentage of 4.75 mm around 10% to 15%, with the increase of the maximum size of the aggregate, the strength of the porous concrete decreases and the permeability increases. When the proportion of the 9.5 mm to 4.75 mm particle in the coarse aggregate is about 20%, there are no interference among the particles by Weymouth theory, the strength of the pervious porous concrete reaches the peak value. The optimum continues gradation limit of the aggregate for porous concrete pervious road base material is recommended according to the theoretical calculation and experimental results.展开更多
The modulus deviation of base material calculated from the data of falling weight deflectometer (FWD) was used to evaluate the uniformity of road base so as to reflect the construction quality. Four parameters,the r...The modulus deviation of base material calculated from the data of falling weight deflectometer (FWD) was used to evaluate the uniformity of road base so as to reflect the construction quality. Four parameters,the repeatability standard deviation of the data in the same driveway, the reproducibility standard deviation of the data in the different driveway, the consistency statistics value of the data in the different driveway, and the consistency statistics value of the data in the same driveway, were introduced for the construction uniformity analysis. The experimental result shows that the materials modulus calculated from FWD has a highly correlative relationship with the uniformity of road base.展开更多
To contribute to the enhancement of unconventional local materials used for road construction,this study characterizes a crushed sand 0/5,a clayey soil and the litho-stabilized material without and with hydraulic bind...To contribute to the enhancement of unconventional local materials used for road construction,this study characterizes a crushed sand 0/5,a clayey soil and the litho-stabilized material without and with hydraulic binder and determines their use in accordance with some reference specifications(CEBTP 1984).It is shown that the different components are not usable alone in pavement base.Indeed,the plasticity index obtained for the clayey soil is 21%,a value higher than the imposed standards.In addition,the grading of the 0/5 crushed sand does not fit into the range proposed by CEBTP.A combination of these two(02)components is therefore considered to obtain a suitable material usable for the sub-base.This new material does not enter any class of the CEBTP lateritic soils.In order to be used in base layer,a treatment with hydraulic binder is carried out with the intention to improve its mechanical performances.The optimal dosage of hydraulic binder to achieve the desired mechanical performance is obtained by studying the evolution of the mechanical characteristics of the mixture.After this treatment,the Bearing Ratio index of the mix increases from 37 to 223 for the optimal dosage and the dry compaction density decreases from 2.11 to 2.06 g/cm3 while the optimal water content increases from 9%to 10.1%.展开更多
Roads are the major asset of any country and to conserve them maintenance is essential. The delay of maintenance works can lead the road in the stage of expensive rehabilitation and reconstruction. In Nepal, Departmen...Roads are the major asset of any country and to conserve them maintenance is essential. The delay of maintenance works can lead the road in the stage of expensive rehabilitation and reconstruction. In Nepal, Department of Roads (DoR) is responsible for maintenance of strategic roads of country. The maintenance practice of the road under Department of Road is predominantly based on Strengthen Maintenance Division Process where several maintenance activities like Routine maintenance, Recurrent Maintenance, Periodic Maintenance and Emergency Maintenance are planned and carried out. The maintenance work is based on traditional quantity and unit price based short term maintenance contracts, where maintenance of physical works is outsourced. Client demands the contractor what work is to be done, when to be do it and the extent of the work. The contractor is paid on the basis of a defined output or quantity accomplished, and the schedule of the rates. DoR engineers required full time supervision of work. Pilot based performance based maintenance practice of road started in Nepal in 2003. The study assesses performance road maintenance practices of road maintenance in Nepal on the basis of the framework of cost efficiency, level of service effectiveness and quality of service. The study concluded that implementation of Performance Based Maintenance Contract (PBMC) was not successful in Nepal as Road Asset condition was not maintained to performance standard. One of the reasons is the weak service delivery of contractor alongside weak contract enforcement from the road agency.展开更多
作为推动构建人类命运共同体的实践载体,“一带一路”倡议从愿景走向现实,擎画了全球发展的蓝图。借助信息可视化软件CiteSpace,文章以Web of Science核心数据库收录的“一带一路”研究领域的583篇论文作为数据来源,绘制国际“一带一路...作为推动构建人类命运共同体的实践载体,“一带一路”倡议从愿景走向现实,擎画了全球发展的蓝图。借助信息可视化软件CiteSpace,文章以Web of Science核心数据库收录的“一带一路”研究领域的583篇论文作为数据来源,绘制国际“一带一路”研究的知识图谱。研究发现,该领域研究成果丰硕,研究队伍庞大,研究方法多样。“一带一路”倡议的内涵、动因和影响构成了该主题的知识基础。研究热点集中于“一带一路”与经济发展、“一带一路”与全球治理新模式、“一带一路”的文化融合与规范认同等维度,一定程度呼应了“一带一路”建设的“五通”目标。绿色“一带一路”等成为研究的前沿课题。进一步深化“一带一路”研究需要加强学术对话,阐释“一带一路”建设蕴含的中国发展理念,加强国际传播能力建设以提升我国的国际话语权。展开更多
文摘The properties of road base course materials of granular soils stabilized by AGS granular soil stabilizing cement were studied.The AGS cement has an expansibility to a certain degree,so the dry shrinkage of AGS cement paste and AGS stabilized granular is much lower than that of Portland slag cement.AGS has a good suitability to granular soils.Granular soils stabilized by AGS have a much higher strength than that of soils stabilized by P S cement.The same strength can be reached with 20% reduction of cement dosage for AGS cement.And their elastic and resilient modulus are similar,but the former has a much higher tensile splitting strength,so the AGS stabilized granular has a much better anti-cracking performance than that of the P S stabilized granular.The reduced value of the strength and the density with the retard time for the granular soils stabilized by AGS is lower than that for P S cement.
文摘To enhance the performance of mix granulate road base courses by cement treatment. The mechanical properties of cement treated mix granulate (CTMG) were studied, which was designed with 65% crushed masonry and 35% crushed concrete by mass. The central composite design was employed to prepare specimens with different levels of cement content and degree of compaction. All specimens were cured in a fog room at 20 ℃ for a specific number of days. The compressive strength and the indirect tensile strength were determined through the monotonic compression and indirect tension tests. Effective prediction models for the mechanical properties of CTMG, in relation to the cement content, the degree of compaction and the curing time, were successfully established for a mix containing 65% crushed masonry and 35% crushed concrete by mass.
基金Funded by the Opening Fund of the Key Laboratory of Silicate Material Science and Engineering,Ministry of Education(No.YSJJ2004-13)
文摘The effects of the proportion of fine aggregate, the maximum size of the aggregate and the proportion of the 9.5 mm to 4.75 mm particle in the coarse aggregate on the properties of the porous concrete are investigated. Results indicate that the porous concrete with a cement dosage only 150 kg/m^3 has high strength and satisfying permeability when the aggregate has a passing percentage of 4.75 mm around 10% to 15%, with the increase of the maximum size of the aggregate, the strength of the porous concrete decreases and the permeability increases. When the proportion of the 9.5 mm to 4.75 mm particle in the coarse aggregate is about 20%, there are no interference among the particles by Weymouth theory, the strength of the pervious porous concrete reaches the peak value. The optimum continues gradation limit of the aggregate for porous concrete pervious road base material is recommended according to the theoretical calculation and experimental results.
文摘The modulus deviation of base material calculated from the data of falling weight deflectometer (FWD) was used to evaluate the uniformity of road base so as to reflect the construction quality. Four parameters,the repeatability standard deviation of the data in the same driveway, the reproducibility standard deviation of the data in the different driveway, the consistency statistics value of the data in the different driveway, and the consistency statistics value of the data in the same driveway, were introduced for the construction uniformity analysis. The experimental result shows that the materials modulus calculated from FWD has a highly correlative relationship with the uniformity of road base.
文摘To contribute to the enhancement of unconventional local materials used for road construction,this study characterizes a crushed sand 0/5,a clayey soil and the litho-stabilized material without and with hydraulic binder and determines their use in accordance with some reference specifications(CEBTP 1984).It is shown that the different components are not usable alone in pavement base.Indeed,the plasticity index obtained for the clayey soil is 21%,a value higher than the imposed standards.In addition,the grading of the 0/5 crushed sand does not fit into the range proposed by CEBTP.A combination of these two(02)components is therefore considered to obtain a suitable material usable for the sub-base.This new material does not enter any class of the CEBTP lateritic soils.In order to be used in base layer,a treatment with hydraulic binder is carried out with the intention to improve its mechanical performances.The optimal dosage of hydraulic binder to achieve the desired mechanical performance is obtained by studying the evolution of the mechanical characteristics of the mixture.After this treatment,the Bearing Ratio index of the mix increases from 37 to 223 for the optimal dosage and the dry compaction density decreases from 2.11 to 2.06 g/cm3 while the optimal water content increases from 9%to 10.1%.
文摘Roads are the major asset of any country and to conserve them maintenance is essential. The delay of maintenance works can lead the road in the stage of expensive rehabilitation and reconstruction. In Nepal, Department of Roads (DoR) is responsible for maintenance of strategic roads of country. The maintenance practice of the road under Department of Road is predominantly based on Strengthen Maintenance Division Process where several maintenance activities like Routine maintenance, Recurrent Maintenance, Periodic Maintenance and Emergency Maintenance are planned and carried out. The maintenance work is based on traditional quantity and unit price based short term maintenance contracts, where maintenance of physical works is outsourced. Client demands the contractor what work is to be done, when to be do it and the extent of the work. The contractor is paid on the basis of a defined output or quantity accomplished, and the schedule of the rates. DoR engineers required full time supervision of work. Pilot based performance based maintenance practice of road started in Nepal in 2003. The study assesses performance road maintenance practices of road maintenance in Nepal on the basis of the framework of cost efficiency, level of service effectiveness and quality of service. The study concluded that implementation of Performance Based Maintenance Contract (PBMC) was not successful in Nepal as Road Asset condition was not maintained to performance standard. One of the reasons is the weak service delivery of contractor alongside weak contract enforcement from the road agency.
文摘作为推动构建人类命运共同体的实践载体,“一带一路”倡议从愿景走向现实,擎画了全球发展的蓝图。借助信息可视化软件CiteSpace,文章以Web of Science核心数据库收录的“一带一路”研究领域的583篇论文作为数据来源,绘制国际“一带一路”研究的知识图谱。研究发现,该领域研究成果丰硕,研究队伍庞大,研究方法多样。“一带一路”倡议的内涵、动因和影响构成了该主题的知识基础。研究热点集中于“一带一路”与经济发展、“一带一路”与全球治理新模式、“一带一路”的文化融合与规范认同等维度,一定程度呼应了“一带一路”建设的“五通”目标。绿色“一带一路”等成为研究的前沿课题。进一步深化“一带一路”研究需要加强学术对话,阐释“一带一路”建设蕴含的中国发展理念,加强国际传播能力建设以提升我国的国际话语权。