The feasibility of flue gas desulphurization （FGD） as concrete admixture was studied. A combined concrete admixture of the thermally-treated FGD gypsum and slag powder was explored. The FGD gypsum was roasted at 200...The feasibility of flue gas desulphurization （FGD） as concrete admixture was studied. A combined concrete admixture of the thermally-treated FGD gypsum and slag powder was explored. The FGD gypsum was roasted at 200℃ for 60 min and then mixed with the slag powder to form FGD gypsum-slag powder combined admixture in which the SO3 content was 3.5wt%. Cement was partially and equivalently replaced by slag powder alone or FGD gypsum-slag powder, at concentration of 25wt%, 40wt%, and 50wt%, respectively. The setting times, hydration products, total porosity and pore size distributions of the paste were determined. The compressive strength and drying shrinkage of cement mortar and concrete were also tested. The experimental results show that, in the presence of FGD gypsum, the setting times are much slower than those of pastes in the absence of FGD gypsum. The combination of FGD gypsum and slag powder provides synergistic benefits above that of slag powder alone. The addition of FGD gypsum provides benefit by promoting ettringite formation and forms a compact microstructure, increasing the compressive strength and reduces the drying shrinkage of cement mortar and concrete.展开更多
The objective of this study was to assess the feasibility of using the plant-source polymer of the matcha powder as a composite admixture for hemihydrate gypsum. Hemihydrate gypsum was mixed with different contents of...The objective of this study was to assess the feasibility of using the plant-source polymer of the matcha powder as a composite admixture for hemihydrate gypsum. Hemihydrate gypsum was mixed with different contents of matcha powder, and then the water requirement for the normal consistency, setting times, density, strength, hydration and microstructure of the hardened mixture were evaluated. The experimental results showed that it increased the water requirement for the normal consistency, and it regulated the setting times and reduced the density. Hemihydrate gypsum with more matcha powder had the higher water requirement, longer setting times and lower density. Less than 1% matcha powder had slight impact on the strength of hardened paste, but more than 1% matcha powder had a remarkable one. Matcha powder changed the hydration process and prolonged the induction and acceleration period. Small needlelike crystals were transformed into longer, larger and thicker ones as more matcha powder was mixed. This case is closely related to the prolongation of the induction and acceleration period. Besides, more and larger pores were observed in the hardened paste with more matcha powder. It is attributed to the appearances of the tea polyphenol in matcha powder and the larger and longer crystal morphology in hardened paste as well as the high water requirement for the normal consistency. These results are important to the application of matcha powder as a composite admixture for the hemihydrate gypsum as well as the prosperity and development of the tea industry.展开更多
用离子色谱法测定了脱硫石膏粉中硫酸根的含量,并以此换算成硫酸钙的质量分数。样品(0.050 0g)溶于盐酸(1+1)溶液0.5mL中,于容量瓶中定容为100mL,静置24h后定量移取部分上清液稀释25倍。分取20μL进样作离子色谱分析。样液经过Metrosep ...用离子色谱法测定了脱硫石膏粉中硫酸根的含量,并以此换算成硫酸钙的质量分数。样品(0.050 0g)溶于盐酸(1+1)溶液0.5mL中,于容量瓶中定容为100mL,静置24h后定量移取部分上清液稀释25倍。分取20μL进样作离子色谱分析。样液经过Metrosep A SUPP1柱净化,流出液通过Metrosep A SUPP5阴离子交换柱,以含1.8 mmol·L-1碳酸钠溶液和1.7mmol·L-1碳酸氢钠溶液的混合溶液为流动相进行淋洗,采用抑制电导检测。以实际样品为基体在2个浓度水平上加入硫酸根标准溶液进行回收试验,测得回收率大于95%。对同一样品作8次测定,测定值的相对标准偏差小于1%。展开更多
基金Funded by the National Natural Science Foundation of China(Nos.51208370,51172164)the Doctoral Program of Higher Education of China(No.20110072120046)+1 种基金the Fundamental Research Funds for the Central Universities(No.0500219170)the Opening Measuring Fund of LargeApparatus of Tongji University(No.0002012011)
文摘The feasibility of flue gas desulphurization （FGD） as concrete admixture was studied. A combined concrete admixture of the thermally-treated FGD gypsum and slag powder was explored. The FGD gypsum was roasted at 200℃ for 60 min and then mixed with the slag powder to form FGD gypsum-slag powder combined admixture in which the SO3 content was 3.5wt%. Cement was partially and equivalently replaced by slag powder alone or FGD gypsum-slag powder, at concentration of 25wt%, 40wt%, and 50wt%, respectively. The setting times, hydration products, total porosity and pore size distributions of the paste were determined. The compressive strength and drying shrinkage of cement mortar and concrete were also tested. The experimental results show that, in the presence of FGD gypsum, the setting times are much slower than those of pastes in the absence of FGD gypsum. The combination of FGD gypsum and slag powder provides synergistic benefits above that of slag powder alone. The addition of FGD gypsum provides benefit by promoting ettringite formation and forms a compact microstructure, increasing the compressive strength and reduces the drying shrinkage of cement mortar and concrete.
基金Funded by the National Natural Science Foundation of China(Nos.51678442,51578412,51478348,51508404,51878480,and 51878479)the National High-speed Train Union Fund(U1534207)+1 种基金Key Project of the Shanghai Committee of Science and Technology(No.15DZ1205003)the Fundamental Research Funds for the Central Universities
文摘The objective of this study was to assess the feasibility of using the plant-source polymer of the matcha powder as a composite admixture for hemihydrate gypsum. Hemihydrate gypsum was mixed with different contents of matcha powder, and then the water requirement for the normal consistency, setting times, density, strength, hydration and microstructure of the hardened mixture were evaluated. The experimental results showed that it increased the water requirement for the normal consistency, and it regulated the setting times and reduced the density. Hemihydrate gypsum with more matcha powder had the higher water requirement, longer setting times and lower density. Less than 1% matcha powder had slight impact on the strength of hardened paste, but more than 1% matcha powder had a remarkable one. Matcha powder changed the hydration process and prolonged the induction and acceleration period. Small needlelike crystals were transformed into longer, larger and thicker ones as more matcha powder was mixed. This case is closely related to the prolongation of the induction and acceleration period. Besides, more and larger pores were observed in the hardened paste with more matcha powder. It is attributed to the appearances of the tea polyphenol in matcha powder and the larger and longer crystal morphology in hardened paste as well as the high water requirement for the normal consistency. These results are important to the application of matcha powder as a composite admixture for the hemihydrate gypsum as well as the prosperity and development of the tea industry.
文摘用离子色谱法测定了脱硫石膏粉中硫酸根的含量,并以此换算成硫酸钙的质量分数。样品(0.050 0g)溶于盐酸(1+1)溶液0.5mL中,于容量瓶中定容为100mL,静置24h后定量移取部分上清液稀释25倍。分取20μL进样作离子色谱分析。样液经过Metrosep A SUPP1柱净化,流出液通过Metrosep A SUPP5阴离子交换柱,以含1.8 mmol·L-1碳酸钠溶液和1.7mmol·L-1碳酸氢钠溶液的混合溶液为流动相进行淋洗,采用抑制电导检测。以实际样品为基体在2个浓度水平上加入硫酸根标准溶液进行回收试验,测得回收率大于95%。对同一样品作8次测定,测定值的相对标准偏差小于1%。
