For the resource utilization of the solid waste coking sulfur paste and the improvement of performance of the asphalt mixture,a method for preparing modified asphalt mixture with coking sulfur paste modifier(CSPM)is h...For the resource utilization of the solid waste coking sulfur paste and the improvement of performance of the asphalt mixture,a method for preparing modified asphalt mixture with coking sulfur paste modifier(CSPM)is herein proposed.Compared with the matrix asphalt mixture,the Marshall stability of the 30%CSPM modified asphalt mixture increased by 38.3%,the dynamic stability increased by nearly one time(reaching 1847.5 times/mm),the splitting strength ratio increased by 39.3%while the splitting tensile strength decreased by 11.7%.After curing,the performance of the CSPM modified asphalt mixture was further improved.The results show that CSPM improved the high temperature stability and water damage resistance of the asphalt mixture,and the low-temperature anti-cracking performance of that was slightly reduced.Chemical analysis of asphalt binders shows that a little sulfur reacted with asphalt to produce polysulfide compounds(R-Sx-R′),and a part of sulfur existed in the form of crystalline sulfur which was further increased after curing.The presence of crystalline sulfur as an inorganic filler is the key point for improving the high temperature stability and water resistance performance of modified asphalt mixture.展开更多
In order to investigate the effects of carbonation on the microstructure of cement concrete,the carbonation depth and microstructure of cement paste with 0.3,0.4 and 0.5 water/cement ratio after 7,14,21 and 28 d accel...In order to investigate the effects of carbonation on the microstructure of cement concrete,the carbonation depth and microstructure of cement paste with 0.3,0.4 and 0.5 water/cement ratio after 7,14,21 and 28 d accelerated carbonation were studied respectively.The results showed that with the increase of waterto-cement ratio and carbonation age,the carbonation depth was deepened with faster early carbonation speed and slower later carbonation rate.Carbonation densified the structure of hardened cement stone with refinement of pore structure and reduced porosity.Then,during the carbonation process from the surface to the inside of carbonation area,it was prone to form micro-cracks extending to the interior specimen,resulting in cement paste carbonation depth uneven.It is further illustrated that the color reaction method using phenolphthalein solution combined with X-CT and X-ray diffraction analysis is much more reasonable to evaluate the cement concrete carbonation degree.Moreover,during carbonation process sulfur element in cement paste migrated to the area un-carbonated and the concentrated shape of sulfur element is consistent with the coloring region in carbonation interface.Finally it was identified that carbonation not only reduced the p H value in cement concrete but also made prone to crack in carbonation zone,which increased the probability of reinforcement corrosion.展开更多
基金Project(201703D321006)supported by the Shanxi Provincial Key Research and Development Project(Social Development),China。
文摘For the resource utilization of the solid waste coking sulfur paste and the improvement of performance of the asphalt mixture,a method for preparing modified asphalt mixture with coking sulfur paste modifier(CSPM)is herein proposed.Compared with the matrix asphalt mixture,the Marshall stability of the 30%CSPM modified asphalt mixture increased by 38.3%,the dynamic stability increased by nearly one time(reaching 1847.5 times/mm),the splitting strength ratio increased by 39.3%while the splitting tensile strength decreased by 11.7%.After curing,the performance of the CSPM modified asphalt mixture was further improved.The results show that CSPM improved the high temperature stability and water damage resistance of the asphalt mixture,and the low-temperature anti-cracking performance of that was slightly reduced.Chemical analysis of asphalt binders shows that a little sulfur reacted with asphalt to produce polysulfide compounds(R-Sx-R′),and a part of sulfur existed in the form of crystalline sulfur which was further increased after curing.The presence of crystalline sulfur as an inorganic filler is the key point for improving the high temperature stability and water resistance performance of modified asphalt mixture.
基金Funded by K.C.Wong Magna Fund in Ningbo Universitythe National Natural Science Foundation of China(Nos.51278255,51478227)Ningbo Municipal Science and Technology Project(Nos.2013C51006,2015A610300)
文摘In order to investigate the effects of carbonation on the microstructure of cement concrete,the carbonation depth and microstructure of cement paste with 0.3,0.4 and 0.5 water/cement ratio after 7,14,21 and 28 d accelerated carbonation were studied respectively.The results showed that with the increase of waterto-cement ratio and carbonation age,the carbonation depth was deepened with faster early carbonation speed and slower later carbonation rate.Carbonation densified the structure of hardened cement stone with refinement of pore structure and reduced porosity.Then,during the carbonation process from the surface to the inside of carbonation area,it was prone to form micro-cracks extending to the interior specimen,resulting in cement paste carbonation depth uneven.It is further illustrated that the color reaction method using phenolphthalein solution combined with X-CT and X-ray diffraction analysis is much more reasonable to evaluate the cement concrete carbonation degree.Moreover,during carbonation process sulfur element in cement paste migrated to the area un-carbonated and the concentrated shape of sulfur element is consistent with the coloring region in carbonation interface.Finally it was identified that carbonation not only reduced the p H value in cement concrete but also made prone to crack in carbonation zone,which increased the probability of reinforcement corrosion.
