The poor fatigue properties and high rigidity of cement asphalt emulsion treated mis(CETM) have for a long time been problems restricting its further development making it impossible for C-ETMto be used as surface lay...The poor fatigue properties and high rigidity of cement asphalt emulsion treated mis(CETM) have for a long time been problems restricting its further development making it impossible for C-ETMto be used as surface layer materials. In this paper, a new kind of cement asphalt emulsion composite-rubberized asphalt emulsion modified Portland cement concrete (RACC) was proposed, which was formed by dispersing rubberized aSPhalt emulsion coated coarse aggregates into cement mortar matrix. In order to evaluate systematically the performance of RACC, laboratory tests with nearly one thousand SPecimen were conducted for resilient modulus, fatigue properties, ultimate ban and length,abrasion, temperature contraction, and dry shrinkage. The experimental results show that the problems existed in C-ETM have to a great extends been solved by RACc. To verify the field performance and inquire into paving technology, teSt road appearsatlsfactory it is concluded that when thed ape surface laycr of semi-rigid base course, RACC is more for surface layer material than both Portland cement concrete(PCC) and asphalt concrete(AC)展开更多
Nanofibrillated wood fiber was used as fillers in the partial cement matrix replacing the cement to a content of up to 2%by weight of cement.The nanofibrillated effect of wood fibers on porosity,thermal properties and...Nanofibrillated wood fiber was used as fillers in the partial cement matrix replacing the cement to a content of up to 2%by weight of cement.The nanofibrillated effect of wood fibers on porosity,thermal properties and compressive strength was studied.The results obtained showed an improvement in compressive strength of more than 40%with 1%by weight of wood fiber nanofibrillate.The addition of nanofibrillated wood fiber shows a good pore reduction,and the best result was obtained with emulsion of a mixture incorporating 1%by weight of wood fiber nanofibrillate in the presence of an anionic surfactant(SDBS).Thermal conductivity measurements and thermal expansion coefficient,compared to nanofibrillated wood fiber reinforced cement pastes,showed the reinforcing efficiency of cellulose fiber nanofibrillate.The degree of hydration of the cement increased with nanofibrillated wood fibers.This property has been confirmed by Fourier transform infrared spectroscopy.These analyzes revealed that the presence of nanofibrillated wood fibers generates and promotes the hydration of the cement,producing more portlandite and calcium silicate gel,which influences the compressive strength which gives a strong improvement.展开更多
Wood nanofibers from industrial waste have been used as polymeric material to reinforce the cement paste to a content of up to 2%by weight of cement.The effect of the wood nanofibre content on the porosity,the compres...Wood nanofibers from industrial waste have been used as polymeric material to reinforce the cement paste to a content of up to 2%by weight of cement.The effect of the wood nanofibre content on the porosity,the compressive strength and the degree of hydration of the cement was studied.The results showed an improvement in compressive strength of over 50%with 1%of added fiberwood.Chemical modification of nanofiber wood by grafting alkyl chains to their surface can reduce the amount of water absorbed by the sample.Addition of an anionic additive(SDBS)to the mixing water improves the surface of the samples more and more by minimizing the pore size by emulsion effect,hence the water absorption decreases.The degree of hydration of the cement increased with the cellulose content containing nanofibrils.The analysis revealed that the presence of nanofibers favored the hydration of the cement by producing more calcium silicate gel and portlandite,probably the main reason for this improvement in compressive strength.展开更多
Good compatibility between waterborne epoxy resin(WER)modifier and styrene-butadiene rubber(SBR)latex modified asphalt emulsion(SBRE)is an essential premise for good pavement performance of WER and SBR latex composite...Good compatibility between waterborne epoxy resin(WER)modifier and styrene-butadiene rubber(SBR)latex modified asphalt emulsion(SBRE)is an essential premise for good pavement performance of WER and SBR latex compositely modified asphalt emulsion(WSAE).This study aims to explore the compatibility between WER modifier and SBRE.To achieve the goal,several WER modifiers produced by two methods were first selected to modify SBRE,thus the WSAEs were prepared.Next,storage stability and workability of the WSAEs themselves,and high-temperature performance,rheological behavior and temperature sensitivity of their evaporated residues were compared and evaluated via performing a series of experiments,respectively,thus the WER modifier possessing an optimal modification effect was recommended.Results show that the storage stability of WSAEs is sensitive to the amount of WERs.The incorporation of 1%WERs by the mass of SBRE improves the storage stability of SBRE,while WERs that exceed 1%weaken its storage stability.When the WERs reach 3%and 4%,the 5 d storage stability of prepared WSAEs will be beyond the limitation of specification.Incorporating WERs into SBRE negatively affects the workability of SBRE,and the workability of WSAEs is adversely influenced by the WERs content and the storage time.To ensure the construction,the WSAEs with 3%and 4%WERs should not be stored for more than 36 h and 48 h,respectively.The WERs effectively improve the high-temperature performance of SBRE residue,especially the 3%WERs.Besides,the WERs notably enhance the rheological property and thermal stability of SBRE residue.In contrast,the WER modifier produced by chemically modified method has a smaller adverse impact on the storage stability and workability of WSAE,and a larger enhancement on the high-temperature performance,rheological property and thermal stability of SBRE residue,which is thus recommended to modify SBRE.展开更多
Styrene-acrylate latex with high glass transition temperature （T）, low minimum film forming temperature（MFT） and good stability was prepared via core-shell emulsion polymerization. With semicontinuous process, hig...Styrene-acrylate latex with high glass transition temperature （T）, low minimum film forming temperature（MFT） and good stability was prepared via core-shell emulsion polymerization. With semicontinuous process, high conversion rate of monomer and low gel rate were achieved. The weight ratio of core monomer to shell monomer was approximately 1.35. It is found that many factors such as emulsifiers, initiators, reaction temperature, pH value and polymerization technology have influences on the permormance of styrene-acrylate latex. The prepared latex was characterized by TEM and FTIR. The obtained latex with T of 20.57 ℃, MFT or5.0 ℃, and good stability, had good stability of film forming.展开更多
A new kind of inelastomer impact modifier with a coreshell structure was synthesized by employing a multistep composite emulsion polymerization technique, the size and morphology structure of the coreshell particles c...A new kind of inelastomer impact modifier with a coreshell structure was synthesized by employing a multistep composite emulsion polymerization technique, the size and morphology structure of the coreshell particles could be controlled by the multistep composite emulsion polymerization technique. The study of the impact strength and the elongation at break of the PVC/CPE blend with different contents of coreshell particles(CS) indicated that the mechanical properties of PVC/CPE/CS composite were the best when the concentration of the particle was 25%(mass fraction) which showed the different regularities and characteristics of elastomer toughening plastic.展开更多
The emulsion copolymerization of acrylates(methylmethacrylate,bulylacrylate acry lic acid,hydroxyethylmethacrylate) and vinyltriethoxysilane(VTS) using a reactive emulsifier DNS-86 has been studied as function of emul...The emulsion copolymerization of acrylates(methylmethacrylate,bulylacrylate acry lic acid,hydroxyethylmethacrylate) and vinyltriethoxysilane(VTS) using a reactive emulsifier DNS-86 has been studied as function of emulsifier a mount, initiator amount, VTS amount, HEMA amount and polymerization temperature. The results showed that the monomer conversion i ncreased with increase in emulsifier amount, initiator amount , amount of HEMA monomer and reaction temperature, but decreased w ith increase in the amount of VTS monomer.展开更多
文摘The poor fatigue properties and high rigidity of cement asphalt emulsion treated mis(CETM) have for a long time been problems restricting its further development making it impossible for C-ETMto be used as surface layer materials. In this paper, a new kind of cement asphalt emulsion composite-rubberized asphalt emulsion modified Portland cement concrete (RACC) was proposed, which was formed by dispersing rubberized aSPhalt emulsion coated coarse aggregates into cement mortar matrix. In order to evaluate systematically the performance of RACC, laboratory tests with nearly one thousand SPecimen were conducted for resilient modulus, fatigue properties, ultimate ban and length,abrasion, temperature contraction, and dry shrinkage. The experimental results show that the problems existed in C-ETM have to a great extends been solved by RACc. To verify the field performance and inquire into paving technology, teSt road appearsatlsfactory it is concluded that when thed ape surface laycr of semi-rigid base course, RACC is more for surface layer material than both Portland cement concrete(PCC) and asphalt concrete(AC)
文摘Nanofibrillated wood fiber was used as fillers in the partial cement matrix replacing the cement to a content of up to 2%by weight of cement.The nanofibrillated effect of wood fibers on porosity,thermal properties and compressive strength was studied.The results obtained showed an improvement in compressive strength of more than 40%with 1%by weight of wood fiber nanofibrillate.The addition of nanofibrillated wood fiber shows a good pore reduction,and the best result was obtained with emulsion of a mixture incorporating 1%by weight of wood fiber nanofibrillate in the presence of an anionic surfactant(SDBS).Thermal conductivity measurements and thermal expansion coefficient,compared to nanofibrillated wood fiber reinforced cement pastes,showed the reinforcing efficiency of cellulose fiber nanofibrillate.The degree of hydration of the cement increased with nanofibrillated wood fibers.This property has been confirmed by Fourier transform infrared spectroscopy.These analyzes revealed that the presence of nanofibrillated wood fibers generates and promotes the hydration of the cement,producing more portlandite and calcium silicate gel,which influences the compressive strength which gives a strong improvement.
文摘Wood nanofibers from industrial waste have been used as polymeric material to reinforce the cement paste to a content of up to 2%by weight of cement.The effect of the wood nanofibre content on the porosity,the compressive strength and the degree of hydration of the cement was studied.The results showed an improvement in compressive strength of over 50%with 1%of added fiberwood.Chemical modification of nanofiber wood by grafting alkyl chains to their surface can reduce the amount of water absorbed by the sample.Addition of an anionic additive(SDBS)to the mixing water improves the surface of the samples more and more by minimizing the pore size by emulsion effect,hence the water absorption decreases.The degree of hydration of the cement increased with the cellulose content containing nanofibrils.The analysis revealed that the presence of nanofibers favored the hydration of the cement by producing more calcium silicate gel and portlandite,probably the main reason for this improvement in compressive strength.
基金funded by the National Natural Science Foundation of China(NSFC)under Grant No.211021180360the Transportation Science and Technology in Shaanxi Province under Grant No.KY17-02.
文摘Good compatibility between waterborne epoxy resin(WER)modifier and styrene-butadiene rubber(SBR)latex modified asphalt emulsion(SBRE)is an essential premise for good pavement performance of WER and SBR latex compositely modified asphalt emulsion(WSAE).This study aims to explore the compatibility between WER modifier and SBRE.To achieve the goal,several WER modifiers produced by two methods were first selected to modify SBRE,thus the WSAEs were prepared.Next,storage stability and workability of the WSAEs themselves,and high-temperature performance,rheological behavior and temperature sensitivity of their evaporated residues were compared and evaluated via performing a series of experiments,respectively,thus the WER modifier possessing an optimal modification effect was recommended.Results show that the storage stability of WSAEs is sensitive to the amount of WERs.The incorporation of 1%WERs by the mass of SBRE improves the storage stability of SBRE,while WERs that exceed 1%weaken its storage stability.When the WERs reach 3%and 4%,the 5 d storage stability of prepared WSAEs will be beyond the limitation of specification.Incorporating WERs into SBRE negatively affects the workability of SBRE,and the workability of WSAEs is adversely influenced by the WERs content and the storage time.To ensure the construction,the WSAEs with 3%and 4%WERs should not be stored for more than 36 h and 48 h,respectively.The WERs effectively improve the high-temperature performance of SBRE residue,especially the 3%WERs.Besides,the WERs notably enhance the rheological property and thermal stability of SBRE residue.In contrast,the WER modifier produced by chemically modified method has a smaller adverse impact on the storage stability and workability of WSAE,and a larger enhancement on the high-temperature performance,rheological property and thermal stability of SBRE residue,which is thus recommended to modify SBRE.
文摘Styrene-acrylate latex with high glass transition temperature （T）, low minimum film forming temperature（MFT） and good stability was prepared via core-shell emulsion polymerization. With semicontinuous process, high conversion rate of monomer and low gel rate were achieved. The weight ratio of core monomer to shell monomer was approximately 1.35. It is found that many factors such as emulsifiers, initiators, reaction temperature, pH value and polymerization technology have influences on the permormance of styrene-acrylate latex. The prepared latex was characterized by TEM and FTIR. The obtained latex with T of 20.57 ℃, MFT or5.0 ℃, and good stability, had good stability of film forming.
文摘A new kind of inelastomer impact modifier with a coreshell structure was synthesized by employing a multistep composite emulsion polymerization technique, the size and morphology structure of the coreshell particles could be controlled by the multistep composite emulsion polymerization technique. The study of the impact strength and the elongation at break of the PVC/CPE blend with different contents of coreshell particles(CS) indicated that the mechanical properties of PVC/CPE/CS composite were the best when the concentration of the particle was 25%(mass fraction) which showed the different regularities and characteristics of elastomer toughening plastic.
文摘The emulsion copolymerization of acrylates(methylmethacrylate,bulylacrylate acry lic acid,hydroxyethylmethacrylate) and vinyltriethoxysilane(VTS) using a reactive emulsifier DNS-86 has been studied as function of emulsifier a mount, initiator amount, VTS amount, HEMA amount and polymerization temperature. The results showed that the monomer conversion i ncreased with increase in emulsifier amount, initiator amount , amount of HEMA monomer and reaction temperature, but decreased w ith increase in the amount of VTS monomer.
