The influence of superplasticizer（SP） on the early age drying shrinkage of cement paste with the same consistency was investigated. To conduct the test, which lasted for 72 hours, three paste mixtures were used for ...The influence of superplasticizer（SP） on the early age drying shrinkage of cement paste with the same consistency was investigated. To conduct the test, which lasted for 72 hours, three paste mixtures were used for comparison. The 72 hours early age drying shrinkage staring from the initial setting time was measured by a clock gauge. The pore size distribution was measured by Mercury Intrusion Method. The surface tension of capillary simulation liquid and mass loss of paste were also measured. The experimental results showed that the addition of SP increased the early drying shrinkage greatly. The ratios of water evaporation and the total free water in mixtures added with SPs showed great differences. SPs fined the capillary pores of paste, and the volume of pore with diameter within 50 nm was well consistent with shrinkage rate. The addition of SPs did not raise the capillary liquid surface tension. It showed that with the volume of pore with diameter within 50 nm and the ratio of water evaporation and the total free water a tolerable shrinkage result of paste added with SP could be predicted, and the elastic modulus could have an influence on the early shrinkage. These results have never been proposed before.展开更多
Global land cover maps are important sources of information for a wide range of studies including land change analysis and climate change research.While the global land cover maps attempt to present a consistent and h...Global land cover maps are important sources of information for a wide range of studies including land change analysis and climate change research.While the global land cover maps attempt to present a consistent and homogenous data in terms of the production process,the existing datasets offer coarse resolution data,e.g.1000 m for IGBP DISCover and 300 m for GlobeCover 2009 that is oftentimes challenging.Recently,GlobeLand30 data based on Landsat archive for two timestamps of 2000 and 2010 has been released.It presents a finer spatial resolution of 30 m,which provides numerous opportunities for a wide range of studies.The main objective of this study is to use this dataset for characterizing global land cover patterns,monitoring,and identifying extreme land change cases with their types and magnitude.The findings reveal massive land change patterns including deforestation,desertification,shrinkage of water bodies,and urbanization across the globe.The results and discussions of this research can help policy-makers,environmental planners,ecosystem services providers and climate change researchers to gain finer insights about the forms of global land change.Future research calls for further investigation of the underlying causes of the massive changes and their consequences on our ecosystems and human populations.展开更多
文摘The influence of superplasticizer（SP） on the early age drying shrinkage of cement paste with the same consistency was investigated. To conduct the test, which lasted for 72 hours, three paste mixtures were used for comparison. The 72 hours early age drying shrinkage staring from the initial setting time was measured by a clock gauge. The pore size distribution was measured by Mercury Intrusion Method. The surface tension of capillary simulation liquid and mass loss of paste were also measured. The experimental results showed that the addition of SP increased the early drying shrinkage greatly. The ratios of water evaporation and the total free water in mixtures added with SPs showed great differences. SPs fined the capillary pores of paste, and the volume of pore with diameter within 50 nm was well consistent with shrinkage rate. The addition of SPs did not raise the capillary liquid surface tension. It showed that with the volume of pore with diameter within 50 nm and the ratio of water evaporation and the total free water a tolerable shrinkage result of paste added with SP could be predicted, and the elastic modulus could have an influence on the early shrinkage. These results have never been proposed before.
文摘Global land cover maps are important sources of information for a wide range of studies including land change analysis and climate change research.While the global land cover maps attempt to present a consistent and homogenous data in terms of the production process,the existing datasets offer coarse resolution data,e.g.1000 m for IGBP DISCover and 300 m for GlobeCover 2009 that is oftentimes challenging.Recently,GlobeLand30 data based on Landsat archive for two timestamps of 2000 and 2010 has been released.It presents a finer spatial resolution of 30 m,which provides numerous opportunities for a wide range of studies.The main objective of this study is to use this dataset for characterizing global land cover patterns,monitoring,and identifying extreme land change cases with their types and magnitude.The findings reveal massive land change patterns including deforestation,desertification,shrinkage of water bodies,and urbanization across the globe.The results and discussions of this research can help policy-makers,environmental planners,ecosystem services providers and climate change researchers to gain finer insights about the forms of global land change.Future research calls for further investigation of the underlying causes of the massive changes and their consequences on our ecosystems and human populations.
