The total utilization amount of red mud is limited due to its high content of alkali,heavy metals and naturally occurring radioactive element.In order to rationalize the use of red mud,a typical field road cement usin...The total utilization amount of red mud is limited due to its high content of alkali,heavy metals and naturally occurring radioactive element.In order to rationalize the use of red mud,a typical field road cement using dealkalized red mud（content of alkali lower than 1%） as raw material was firstly prepared in this paper.Then,a preliminary research on the radioactivity of the red mud based field road cement has been carried out.For that reason,two samples of raw materials were prepared.One was with ordinary raw materials,as the control group（CG）,the other was with 23 w % red mud,as the experimental group（EG）.The clinkers were acquired by sintering the above two raw materials at 1 400 ℃.Subsequently,the two types of cement prepared by the above two kinds of clinkers were tested by measuring the normal consistency,setting time,mechanical strength and drying shrinkage.Meanwhile,the hydration products of the two types of cement were examined by XRD analysis at the curing age of 6 hours,1,3,7,and 28 days,respectively.The radioactivity of the two kinds of cement clinkers was then measured by gamma-ray spectrometry.The experimental results indicate that the main mineralogical phases components in the EG field road cement clinkers are C3S,C2S,and C4AF,the 28 days flexural and compressive strength of the EG field road cement mortars could be up to 8.45 and 53.2 MPa,respectively.The radioactive measuring results of the EG field road cement show that the value of radium equivalent activity index（Raeq） is 254.8 Bq/Kg-1,which is lower than the upper limit.展开更多
In order to reduce shrinkage and improve the mechanical properties of dental composite resins, we designed a hybrid resin formulation containing a novel matrix resin, Bis S-GMA [bisphenol-Sbis（3-methacrylato-2-hydrox...In order to reduce shrinkage and improve the mechanical properties of dental composite resins, we designed a hybrid resin formulation containing a novel matrix resin, Bis S-GMA [bisphenol-Sbis（3-methacrylato-2-hydroxypropyl）ether], and epoxy modifi ed by a spiro-orthocarbonate（SOC） expanding monomer. Then, we tested the effects of an iodonium salt, diphenyliodonium hexafl uorphosphate（DPIHFP）, on the properties of the hybrid resin with seven different concentrations. The hybrid resin was polymerized by a ternary photo-initiator system. The volumetric shrinkage（VS）, degree of conversion（DC） and compressive strength（CS） were assessed using Acu Vol^TM, FTIR and a universal testing machine, respectively. The VS, DC and CS were improved with increasing DPIHFP concentration, but a high concentration of DPIHFP had a negative infl uence on the mechanical properties of the hybrid resin and offered no added improvement in the VS and DC. The best performance of a composite resin containing Bis S-GMA and SOC-modifi ed epoxy was achieved with 2wt% DPIHFP. The results also indicated that the resin containing Bis S-GMA was superior to that containing Bis-GMA in terms of VS, DC and CS.展开更多
基金Funded by the National Natural Science Foundation of China(No.51172155)
文摘The total utilization amount of red mud is limited due to its high content of alkali,heavy metals and naturally occurring radioactive element.In order to rationalize the use of red mud,a typical field road cement using dealkalized red mud（content of alkali lower than 1%） as raw material was firstly prepared in this paper.Then,a preliminary research on the radioactivity of the red mud based field road cement has been carried out.For that reason,two samples of raw materials were prepared.One was with ordinary raw materials,as the control group（CG）,the other was with 23 w % red mud,as the experimental group（EG）.The clinkers were acquired by sintering the above two raw materials at 1 400 ℃.Subsequently,the two types of cement prepared by the above two kinds of clinkers were tested by measuring the normal consistency,setting time,mechanical strength and drying shrinkage.Meanwhile,the hydration products of the two types of cement were examined by XRD analysis at the curing age of 6 hours,1,3,7,and 28 days,respectively.The radioactivity of the two kinds of cement clinkers was then measured by gamma-ray spectrometry.The experimental results indicate that the main mineralogical phases components in the EG field road cement clinkers are C3S,C2S,and C4AF,the 28 days flexural and compressive strength of the EG field road cement mortars could be up to 8.45 and 53.2 MPa,respectively.The radioactive measuring results of the EG field road cement show that the value of radium equivalent activity index（Raeq） is 254.8 Bq/Kg-1,which is lower than the upper limit.
基金Funded by the National Natural Science Foundation of China(No.50673065)
文摘In order to reduce shrinkage and improve the mechanical properties of dental composite resins, we designed a hybrid resin formulation containing a novel matrix resin, Bis S-GMA [bisphenol-Sbis（3-methacrylato-2-hydroxypropyl）ether], and epoxy modifi ed by a spiro-orthocarbonate（SOC） expanding monomer. Then, we tested the effects of an iodonium salt, diphenyliodonium hexafl uorphosphate（DPIHFP）, on the properties of the hybrid resin with seven different concentrations. The hybrid resin was polymerized by a ternary photo-initiator system. The volumetric shrinkage（VS）, degree of conversion（DC） and compressive strength（CS） were assessed using Acu Vol^TM, FTIR and a universal testing machine, respectively. The VS, DC and CS were improved with increasing DPIHFP concentration, but a high concentration of DPIHFP had a negative infl uence on the mechanical properties of the hybrid resin and offered no added improvement in the VS and DC. The best performance of a composite resin containing Bis S-GMA and SOC-modifi ed epoxy was achieved with 2wt% DPIHFP. The results also indicated that the resin containing Bis S-GMA was superior to that containing Bis-GMA in terms of VS, DC and CS.
