Recycled Aggregate(RA)has only been used as sub-grade applications,roadwork and unbound materials because it is believed that RA has lower strength and poorer quality than normal aggregate.This paper assesses RA quali...Recycled Aggregate(RA)has only been used as sub-grade applications,roadwork and unbound materials because it is believed that RA has lower strength and poorer quality than normal aggregate.This paper assesses RA quality by propos-ing a new testing procedure.The new procedure is developed by using correlation information among the standard twenty three tests commonly employed in the construction industry.Samples of RA from ten demolition sites were ob-tained with service life ranging from ten to forty years.One additional set of samples was specifically collected from the Tuen Mun Area 38 Recycling Plant,Hong Kong for testing.The characteristics of these eleven sets of samples were then compared with normal aggregate samples.A Vandermonde matrix for interpolation polynomials coefficient estimation is employed to yield detailed mathematical relationships between results of two particular tests,from that redundant tests can be identified.Different orders of interpolation polynomials are used for comparison,hence the best-fit equations with lowestfitting errors from different orders of polynomials can be found.This paper shows that four out of twenty three tests are required in the new testing procedure.展开更多
Recently,an Environmental Management System(EMS)has been used to promote effective environmental protection.Environmental Performance Assessment(EPA)is a critical tool of the EMS in checking,reviewing,monitoring and e...Recently,an Environmental Management System(EMS)has been used to promote effective environmental protection.Environmental Performance Assessment(EPA)is a critical tool of the EMS in checking,reviewing,monitoring and evaluating environmental performance of organizations.To implement EPA,the relations between Environmental Operational Indicators(EOIs)used in EPA and Environmental Performance Indicators(EPIs)are required,which,however,are lacking in the construction industry.This paper attempts to develop a series of EOIs and EPIs of individual construction projects for EPA and to measure their relations by using least-squares fitting and robust fitting methods.The results show that the defined EOIs correlate strongly with EPIs.Therefore,EPA can be used to identify areas for continuous improvement,and also can provide an early indication of the environmental performance for an organization.展开更多
Recycled concrete is a material with the potential to create a sustainable construction industry.However,recycled concrete presents heterogeneous properties,thereby reducing its applications for some structural purpos...Recycled concrete is a material with the potential to create a sustainable construction industry.However,recycled concrete presents heterogeneous properties,thereby reducing its applications for some structural purposes and enhancing its application in pavements.This paper provides an insight into a solution in the deformation control for recycled concrete by adding supplementary cementitious materials fly ash and blast furnace slag.Results of this study indicated that the 50%fly ash replacement of Portland cement increased the rupture modulus of the recycled concrete.Conversely,a mixture with over 50%cement replacement by either fly ash or slag or a combination of both exhibited detrimental effect on the compressive strength,rupture modulus,and drying shrinkage.The combined analysis of environmental impacts and mechanical properties of recycled concrete demonstrated the possibility of optimizing the selection of recycled concrete because the best scenario in this study was obtained with the concrete mixture M8(50%of fly ash+100%recycled coarse aggregate).展开更多
文摘Recycled Aggregate(RA)has only been used as sub-grade applications,roadwork and unbound materials because it is believed that RA has lower strength and poorer quality than normal aggregate.This paper assesses RA quality by propos-ing a new testing procedure.The new procedure is developed by using correlation information among the standard twenty three tests commonly employed in the construction industry.Samples of RA from ten demolition sites were ob-tained with service life ranging from ten to forty years.One additional set of samples was specifically collected from the Tuen Mun Area 38 Recycling Plant,Hong Kong for testing.The characteristics of these eleven sets of samples were then compared with normal aggregate samples.A Vandermonde matrix for interpolation polynomials coefficient estimation is employed to yield detailed mathematical relationships between results of two particular tests,from that redundant tests can be identified.Different orders of interpolation polynomials are used for comparison,hence the best-fit equations with lowestfitting errors from different orders of polynomials can be found.This paper shows that four out of twenty three tests are required in the new testing procedure.
文摘Recently,an Environmental Management System(EMS)has been used to promote effective environmental protection.Environmental Performance Assessment(EPA)is a critical tool of the EMS in checking,reviewing,monitoring and evaluating environmental performance of organizations.To implement EPA,the relations between Environmental Operational Indicators(EOIs)used in EPA and Environmental Performance Indicators(EPIs)are required,which,however,are lacking in the construction industry.This paper attempts to develop a series of EOIs and EPIs of individual construction projects for EPA and to measure their relations by using least-squares fitting and robust fitting methods.The results show that the defined EOIs correlate strongly with EPIs.Therefore,EPA can be used to identify areas for continuous improvement,and also can provide an early indication of the environmental performance for an organization.
文摘Recycled concrete is a material with the potential to create a sustainable construction industry.However,recycled concrete presents heterogeneous properties,thereby reducing its applications for some structural purposes and enhancing its application in pavements.This paper provides an insight into a solution in the deformation control for recycled concrete by adding supplementary cementitious materials fly ash and blast furnace slag.Results of this study indicated that the 50%fly ash replacement of Portland cement increased the rupture modulus of the recycled concrete.Conversely,a mixture with over 50%cement replacement by either fly ash or slag or a combination of both exhibited detrimental effect on the compressive strength,rupture modulus,and drying shrinkage.The combined analysis of environmental impacts and mechanical properties of recycled concrete demonstrated the possibility of optimizing the selection of recycled concrete because the best scenario in this study was obtained with the concrete mixture M8(50%of fly ash+100%recycled coarse aggregate).
