The rheological properties of the bituminous components （bitumen and bituminous mastic） within asphalt mixtures contribute significantly to the major distresses of flexible pavements （i.e. rutting, fatigue and low ...The rheological properties of the bituminous components （bitumen and bituminous mastic） within asphalt mixtures contribute significantly to the major distresses of flexible pavements （i.e. rutting, fatigue and low temperature cracking）. Asphalt mixtures are usually composed of mastic-coated aggregates rather than pure bitumen-coated aggre- gates. The purpose of this study is to investigate the effects of mineral fillers on the theological behaviour of several polymer-modified bitumens （PMBs） through laboratory mixing. A neat bitumen and two types of polymers （elastomeric and plastomeric） were used to produce PMBs, and two fillers with different minerals （limestone and basalt） were selected to obtain mastics. The dynamic shear rheometer （DSR） and bending beam rheometer （BBR） were used to characterize the theological properties of PMBs and mastics. In particular, multiple stress creep recovery （MSCR） tests were performed to evaluate the rutting potential at high temperatures, whereas BBR tests were carried out to investigate the low temperature behaviour of these materials. BBR results for unmodified mastics show that the increase of stiffness is similar regardless of the filler type, whereas results for polymer-modified mastics indicate that the degree of stiffening depends on the combi- nation of filler/polymer types. MSCR results show that adding filler leads to a reduced susceptibility of permanent deformation and an enhanced elastic response, depending on the combination of filler/polymer types. Overall results suggest that a physical-chemical interaction between the filler and bitumen occurs, and that the interaction level is highly dependent on the type of polymer modification.展开更多
Granite is well known as an acid aggregate. An active mineral filler produced in the laboratory is first used as an anti-stripping filler in the granite asphalt concrete. Four aggregate gradations were chosen in this ...Granite is well known as an acid aggregate. An active mineral filler produced in the laboratory is first used as an anti-stripping filler in the granite asphalt concrete. Four aggregate gradations were chosen in this study,and the effects of the active mineral filler and aggregates on the rutting resistance performance and fatigue properties of granite asphalt concrete were investigated by means of rutting test and four-point bending fatigue test. The results indicate that the dynamic stability of granite asphalt concrete increase significantly with the addition of active mineral filler and the fatigue properties can also be improved especially at lower strain level. Meanwhile,the results demonstrate that granite asphalt concrete has better rutting resistance performance and fatigue properties than limestone asphalt concrete.展开更多
Mineral fillers are important for conserving raw fiber materials and reducing production costs in the paper industry.However,the increase in filler content will inevitably result in strength reduction,which limits the...Mineral fillers are important for conserving raw fiber materials and reducing production costs in the paper industry.However,the increase in filler content will inevitably result in strength reduction,which limits the adding amount of filler in paper production.In this study,we designed a cellulose fiber/filler co-refining approach to improve the strength and optical properties of paper;moreover,the synergistic interaction between fibers and precipitated calcium carbonate(PCC)fillers in the co-refining process was investigated.Results of fiber separation and PCC particle size analysis showed that,compared with conventional refining,the content of fines increased,whereas the PCC particle size decreased.More importantly,composites were formed between the PCC and fines,which promoted strength improvement of paper.Physical tests show that the tensile index of paper with 15%PCC content increased by 22%compared with that of the paper filled by conventional method,whereas the brightness and opacity of paper improved by fiber/filler co-refining for a specified filler content.These findings provide a basis for the further development of co-refining filling technology.展开更多
Field surveys indicate lateral variation in peat humification levels （von Post） in dominantly occurring fibric,fibric to hemic,sapric and hemie to sapric peats across a gradient from the margin towards the centre of...Field surveys indicate lateral variation in peat humification levels （von Post） in dominantly occurring fibric,fibric to hemic,sapric and hemie to sapric peats across a gradient from the margin towards the centre of tropical lowland peat domes.Cement-peat stabilisation can be enhanced by adding mineral soil fillers （silt,clays and fine sands） obtained from Quaternary floodplain deposits and residual soil （weathered schist）.The unconfined compressive strength （UCS） of the stabilised cement-mineral soil fifler-peat mix increases with the increased addition of selected mineral soil filler.Lateral variation in the stabilised peat strength （UCS） in the top 0 to 0.5 m layer was found from the margin towards the centre of the tropical lowland peat dome.The variations in the UCS of stabilised tropical lowland peats along a gradient from the periphery towards the centre of the peat dome are most likely caused by a combination of factors due to variations in the mineral soil or ash content of the peat and horizontal zonation or lateral variation in the dominant species of the plant assemblages （due to successive vegetation zonation of the peat swamp forest from the periphery towards the centre of the tropical lowland peat dome）.展开更多
Interaction of unmodified starch with guest molecules or ligands(e.g.,fatty acids)as a basis for the formation of starch-encapsulated mineral filler particles is an effective process for mitigating the negative impact...Interaction of unmodified starch with guest molecules or ligands(e.g.,fatty acids)as a basis for the formation of starch-encapsulated mineral filler particles is an effective process for mitigating the negative impact of filler addition on the strength properties of cellulosic networks.As unmodified starch is essentially nonionic,the interaction of starch-engineered fillers with negatively charged cellulosic fibers is somehow limited.Here,the concept of substituting unmodified starch with a minor amount of cationic starch in filler engineering with starch inclusion complexes was proposed.It was hypothesized that filler-fiber interaction would be enhanced by cationic-anionic attraction.Encouragingly,the effectiveness of this concept was demonstrated to be very pronounced.For instance,at a cationic starch percentage of 3%(relevant to the weight of total starch),filler retention and filler bondability with cellulosic fibers were significantly improved,leading to further mitigated negative impact of filler addition on tensile strength.Basically,this easily scalable concept may shed light on greener,more efficient use of filler technologies on the basis of starch inclusion complex formation,opening up new possibilities for real commercial applications.展开更多
基金supported by the Ministry of EducationUniversities and Research project"Damage and healing of innovative nano-structured and polymer-modified bituminous materials"(Grant RBFR10JOWO)under the"FIRB-Futuro in Ricerca 2010"funding program
文摘The rheological properties of the bituminous components （bitumen and bituminous mastic） within asphalt mixtures contribute significantly to the major distresses of flexible pavements （i.e. rutting, fatigue and low temperature cracking）. Asphalt mixtures are usually composed of mastic-coated aggregates rather than pure bitumen-coated aggre- gates. The purpose of this study is to investigate the effects of mineral fillers on the theological behaviour of several polymer-modified bitumens （PMBs） through laboratory mixing. A neat bitumen and two types of polymers （elastomeric and plastomeric） were used to produce PMBs, and two fillers with different minerals （limestone and basalt） were selected to obtain mastics. The dynamic shear rheometer （DSR） and bending beam rheometer （BBR） were used to characterize the theological properties of PMBs and mastics. In particular, multiple stress creep recovery （MSCR） tests were performed to evaluate the rutting potential at high temperatures, whereas BBR tests were carried out to investigate the low temperature behaviour of these materials. BBR results for unmodified mastics show that the increase of stiffness is similar regardless of the filler type, whereas results for polymer-modified mastics indicate that the degree of stiffening depends on the combi- nation of filler/polymer types. MSCR results show that adding filler leads to a reduced susceptibility of permanent deformation and an enhanced elastic response, depending on the combination of filler/polymer types. Overall results suggest that a physical-chemical interaction between the filler and bitumen occurs, and that the interaction level is highly dependent on the type of polymer modification.
基金Department of Transportation in Hubei Province,China and Headguarters of Ma-Wu Expressway in Hubei Province for its financial support of this work.
文摘Granite is well known as an acid aggregate. An active mineral filler produced in the laboratory is first used as an anti-stripping filler in the granite asphalt concrete. Four aggregate gradations were chosen in this study,and the effects of the active mineral filler and aggregates on the rutting resistance performance and fatigue properties of granite asphalt concrete were investigated by means of rutting test and four-point bending fatigue test. The results indicate that the dynamic stability of granite asphalt concrete increase significantly with the addition of active mineral filler and the fatigue properties can also be improved especially at lower strain level. Meanwhile,the results demonstrate that granite asphalt concrete has better rutting resistance performance and fatigue properties than limestone asphalt concrete.
基金This work was financially supported by Innovation Capability Support Program of Shaanxi(2020KJXX082)the Foundation(202005)of Tianjin Key Laboratory of Pulp&Paper(Tianjin University of Science&Technology).
文摘Mineral fillers are important for conserving raw fiber materials and reducing production costs in the paper industry.However,the increase in filler content will inevitably result in strength reduction,which limits the adding amount of filler in paper production.In this study,we designed a cellulose fiber/filler co-refining approach to improve the strength and optical properties of paper;moreover,the synergistic interaction between fibers and precipitated calcium carbonate(PCC)fillers in the co-refining process was investigated.Results of fiber separation and PCC particle size analysis showed that,compared with conventional refining,the content of fines increased,whereas the PCC particle size decreased.More importantly,composites were formed between the PCC and fines,which promoted strength improvement of paper.Physical tests show that the tensile index of paper with 15%PCC content increased by 22%compared with that of the paper filled by conventional method,whereas the brightness and opacity of paper improved by fiber/filler co-refining for a specified filler content.These findings provide a basis for the further development of co-refining filling technology.
基金the IPPP grant PV018-2011A for financial support from the University of Malaya
文摘Field surveys indicate lateral variation in peat humification levels （von Post） in dominantly occurring fibric,fibric to hemic,sapric and hemie to sapric peats across a gradient from the margin towards the centre of tropical lowland peat domes.Cement-peat stabilisation can be enhanced by adding mineral soil fillers （silt,clays and fine sands） obtained from Quaternary floodplain deposits and residual soil （weathered schist）.The unconfined compressive strength （UCS） of the stabilised cement-mineral soil fifler-peat mix increases with the increased addition of selected mineral soil filler.Lateral variation in the stabilised peat strength （UCS） in the top 0 to 0.5 m layer was found from the margin towards the centre of the tropical lowland peat dome.The variations in the UCS of stabilised tropical lowland peats along a gradient from the periphery towards the centre of the peat dome are most likely caused by a combination of factors due to variations in the mineral soil or ash content of the peat and horizontal zonation or lateral variation in the dominant species of the plant assemblages （due to successive vegetation zonation of the peat swamp forest from the periphery towards the centre of the tropical lowland peat dome）.
基金support from the Fundamental Research Funds for the Central Universities of China (2572015DB01)the Program for New Century Excellent Talents in University (NCET-12-0811)the National Natural Science Foundation of China (31100439).
文摘Interaction of unmodified starch with guest molecules or ligands(e.g.,fatty acids)as a basis for the formation of starch-encapsulated mineral filler particles is an effective process for mitigating the negative impact of filler addition on the strength properties of cellulosic networks.As unmodified starch is essentially nonionic,the interaction of starch-engineered fillers with negatively charged cellulosic fibers is somehow limited.Here,the concept of substituting unmodified starch with a minor amount of cationic starch in filler engineering with starch inclusion complexes was proposed.It was hypothesized that filler-fiber interaction would be enhanced by cationic-anionic attraction.Encouragingly,the effectiveness of this concept was demonstrated to be very pronounced.For instance,at a cationic starch percentage of 3%(relevant to the weight of total starch),filler retention and filler bondability with cellulosic fibers were significantly improved,leading to further mitigated negative impact of filler addition on tensile strength.Basically,this easily scalable concept may shed light on greener,more efficient use of filler technologies on the basis of starch inclusion complex formation,opening up new possibilities for real commercial applications.
