A novel inorganic polymer flocculant,poly-ferric sulfate(BPFS) was prepared by oxidation of ferrous sulfate using domestic Thiobacillus ferrooxidans(T·f) under acid condition.The optimal conditions for the pr...A novel inorganic polymer flocculant,poly-ferric sulfate(BPFS) was prepared by oxidation of ferrous sulfate using domestic Thiobacillus ferrooxidans(T·f) under acid condition.The optimal conditions for the preparation were pH value of 1.5,(NH4)2SO4 dosage of 0.5 g/L,initial Fe2+ concentration of 45g/L,inoculum 10%,rotating speed of 120 r/min,reaction time of 5-6 d and reaction temperature of 30 ℃.Under the optimal conditions,the BPFS product with pH value of 1.5-2.2,basicity of 17.5%-22.7% and total iron content of 43.87-45.24 g/L was obtained.The application of the BPFS to three wastewaters was carried out,and the removal efficiencies of COD,decolorization and Zn2+ by BPFS can be reached 70%,90% and 99%,respectively.The result suggests that the BPFS is an excellent flocculant for water treatment.展开更多
The influence of magnesium and aluminum salts as impurities on the hydrolysis of titanyl sulfate was investigated.The degree of TiOSO4 conversion to hydrated titanium dioxide(HTD) and the particle size of HTD were m...The influence of magnesium and aluminum salts as impurities on the hydrolysis of titanyl sulfate was investigated.The degree of TiOSO4 conversion to hydrated titanium dioxide(HTD) and the particle size of HTD were measured as functions of the concentrations of MgSO4 and Al2(SO4)3 in the TiOSO4 solution.The Boltzmann growth model,which focuses on two main parameters,namely the concentrations of Mg2+ and Al3+(ρ(Mg2+) and ρ(Al3+),respectively),fits the data from the hydrolysis process well with R20.988.The samples were characterized by ICP,SEM,XRD,and laser particle size analyzer.It is found that the addition of Mg SO4 simultaneously improves the hydrolysis ratio and the hydrolysis rate,especially when F(the mass ratio of H2SO4 to TiO2) is high,hydrolysis ratio increases from 42.8% to 83.0%,whereas the addition of Al2(SO4)3 has negligible effect on the chemical kinetics of HTD precipitation during the hydrolysis process,hydrolysis ratio increases from 42.8% to 51.9%.An investigation on the particle size of HTD reveals that the addition of Mg SO4 and Al2(SO4)3 clearly increases the size of the crystallites and decreases the size of the aggregates.展开更多
The morphology and chemical compositions of surface and corrosion phases for two aluminum alloys(7075 and 2024 ) in the aqueous mediums containing sulfate reducing bacteria(SRB) were studied by the methods of scanning...The morphology and chemical compositions of surface and corrosion phases for two aluminum alloys(7075 and 2024 ) in the aqueous mediums containing sulfate reducing bacteria(SRB) were studied by the methods of scanning electron microscopy (SEM) and energy dispersive x ray analysis (EDXA). The results showed that serious pitting corrosion took place when aluminum alloys were exposed in the mediums containing SRB, whereas no pitting corrosion were found on the surfaces of aluminum alloys only exposed in blank mediums non containing SRB. It was demonstrated with EDXA that corrosion of aluminum alloys exposed in the solutions containing SRB, whereas the corrosion in the solution non containing microorganisms was attributed to the presence of chloride ions(Cl ).展开更多
We are reporting a rare case of acute liver injury that developed after an internal hemorrhoid treatment with the aluminum potassium sulfate and tannic acid(ALTA) regimen. A 41-year-old man developed a fever and liver...We are reporting a rare case of acute liver injury that developed after an internal hemorrhoid treatment with the aluminum potassium sulfate and tannic acid(ALTA) regimen. A 41-year-old man developed a fever and liver injury after undergoing internal hemorrhoid treatment with a submucosal injection of ALTA with lidocaine. The acute liver injury was classified clinically as hepatocellular and pathologically as cholestastic. We could not classify the mechanism of injury. High eosinophil and immunoglobulin E levels characterized the injury,and a drug lymphocyte stimulation test was negative on postoperative day 25. Fluid replacement for two weeks after hospitalization improved the liver injury. ALTA therapy involves injecting chemicals into the submucosa,from the rectum to the anus,and this is the first description of a case that developed a severe liver disorder after this treatment; hence,an analysis of future cases as they accumulate is desirable.展开更多
AIM: To show that aluminum potassium sulfate and tannic acid(ALTA) sclerotherapy has a high success rate for Grade Ⅱ and Ⅲ hemorrhoids.METHODS: This study was based on the clinical data of 604 patients with hemorrho...AIM: To show that aluminum potassium sulfate and tannic acid(ALTA) sclerotherapy has a high success rate for Grade Ⅱ and Ⅲ hemorrhoids.METHODS: This study was based on the clinical data of 604 patients with hemorrhoids who underwent ALTA sclerotherapy between January 2009 and February 2015. The objective of this study was to assess the efficacy of this treatment for Grades Ⅱ and Ⅲ hemorrhoids. Preoperative and postoperative symptoms, complications and success rate were all assessed retrospectively. Follow-up consisted of a simple questionnaire, physical examination and an anoscopy. Patients were followed-up at one day, one week, two weeks, one month, one year, two years, three years, four years and five years after the ALTA sclerotherapy.RESULTS: One hundred and sixty-nine patients were diagnosed with Grade Ⅱ hemorrhoids and 435 patients were diagnosed with Grade Ⅲ hemorrhoids. The one year, three year and five year cumulative success rates of ALTA sclerotherapy for Grades Ⅱ and Ⅲ hemo-rrhoids were 95.9% and 93.1%; 89.3% and 83.7%; and 89.3% and 78.2%, respectively. No significant differences were observed in the cumulative success rates after ALTA sclerotherapy between Grades Ⅱ and Ⅲ hemorrhoids(P = 0.09). There were forty-seven post-operative complications(low grade fever; anal pain; urinary retention; rectal ulcer; and others). No serious or life-threatening complications occurred and all cases improved through conservative treatment. At univariate analysis there were no predictive factors of failure.CONCLUSION: ALTA sclerotherapy has had a high success rate for Grade Ⅱ and Ⅲ hemorrhoids during five years of post-operative treatment. However, additional studies are needed to evaluate the efficacy of this ALTA sclerotherapy in the management of hemorrhoidal disease.展开更多
Due to the environmental policies and economic reasons,the water used in some flotation operations of complex sulfide ores is recirculated,causing the ion concentration of some species to increase over time,affecting ...Due to the environmental policies and economic reasons,the water used in some flotation operations of complex sulfide ores is recirculated,causing the ion concentration of some species to increase over time,affecting the flotation of the minerals of interest.In this work,an experimental and thermodynamic analysis of the synthetic solutions was presented with a high content of calcium and sulfate ions.The study focused on evaluating the use of two aluminum compounds for the precipitation of Ca^(2+)and SO_(4)^(2−)in the form of ettringite.The amorphous aluminum hydroxide was found to be more efficient than the crystalline one,giving rise to 83%calcium and 91%sulfate removal.The XRD analysis of the solids showed the main reaction product of ettringite,accompanied by small amounts of calcite,due to the absorption of atmospheric carbon dioxide.The final solution after the chemical treatment showed residual calcium and sulfate concentrations below 200 mg/L.Finally,the kinetics of calcium removal appeared to correspond to a second order reaction with respect to calcium concentration,with an apparent activation energy of 53.48 kJ/mol,which may suggest that the ettringite precipitation process is governed by the chemical reaction.展开更多
This study contains comparative research of sulfate resistance of ordinary Portland cement pastes with addition of basic aluminum sulfate (hydroxosulfate, Al(OH)1.78(SO4)0.61) and amorphous Al(OH)3. Over 3 months of s...This study contains comparative research of sulfate resistance of ordinary Portland cement pastes with addition of basic aluminum sulfate (hydroxosulfate, Al(OH)1.78(SO4)0.61) and amorphous Al(OH)3. Over 3 months of storing in sodium sulfate solution, the most significant expansion and deterioration occur in case of samples with aluminum hydroxide. During sulfate resistance test, the ratio between aluminum nuclei in AFt (ettringite) and AFm phases was studied by 27Al-MAS NMR, and the impact of aluminum-containing admixtures on this ratio was specified. In accordance with NMR data, in samples with Al(OH)3, the rate of secondary ettringite formation becomes noticeable after one month of storing in sulfate solution. For samples with Al(OH)1.78(SO4)0.61, the rate of elongation and temper of changes in molar ratio between sulfoaluminate phases were comparable with reference samples without admixtures.展开更多
Study of sulfate resistance of mortars with aluminum- and iron-bearing admixtures (Al(OH)3, Al2(SO4)3, FeSO4, Fe2(SO4)3) in conditions close to those established in ASTM C 1012, and the study of the mitigation effect ...Study of sulfate resistance of mortars with aluminum- and iron-bearing admixtures (Al(OH)3, Al2(SO4)3, FeSO4, Fe2(SO4)3) in conditions close to those established in ASTM C 1012, and the study of the mitigation effect of these admixtures on alkali-silica reaction in accordance with accelerated “mortar bar” test ( GOST 8269.0, ASTM C 1260) were performed. Iron (II) and (III) sulfates show ability for mitigation alkali-silica reaction, while also, in contrast with Al-bearing substances, do not induce the drastic reducing of the initial setting time and do not promote the progress of sulfate corrosion. Compared with FeSO4, iron (III) sulfate has moderate deleterious impact on the early strength of cement paste and can be of interest alone as an inhibitor of ASR. Iron (II) sulfate may be used together with aluminum sulfate to offset the accelerating effect of the latter on the setting of cement paste and to reduce a risk of sulfate corrosion. During prolonged water storage, the mortar elongation and secondary ettringite formation do not occur, even when Al2(SO4)3 is available. Therefore, the investigated admixtures cannot act as agents of internal sulfate attack, however, Al2(SO4)3 can enhance the outer sulfate attack.展开更多
The effect of benzene-1,2-diol (pyrocatechol) and benzene-1,3-diol (resorcinol) on the development of sulfate attack in Portland cement mortars containing alkali-free setting accelerator (aluminum sulfate) was studied...The effect of benzene-1,2-diol (pyrocatechol) and benzene-1,3-diol (resorcinol) on the development of sulfate attack in Portland cement mortars containing alkali-free setting accelerator (aluminum sulfate) was studied. It has been found that these compounds (especially pyrocatechol—due to its ability to form chelate complexes with aluminum ions) restrain destructive deformations of Portland cement mortars with aluminum sulfate admixture when under test conditions a constant supply of sulfate ions from external source is provided. According to 27Al-MAS NMR data, pyrocatechol does not influence the amount of ettringite formed in Portland cement paste during its store in sodium sulfate solution. Presumably, in presence of benzenediols, in cement mortars with aluminum sulfate admixture the formation of ettringite crystals with a less pronounced destructive effect takes place.展开更多
In this study, a novel flocculant was prepared by an inorganic polymetric flocculant (IPF) - polysilicate ferro- aluminum sulfate (PSFA) and rectorite (REC). The structure of the PSFA-REC composite was characterized b...In this study, a novel flocculant was prepared by an inorganic polymetric flocculant (IPF) - polysilicate ferro- aluminum sulfate (PSFA) and rectorite (REC). The structure of the PSFA-REC composite was characterized by Fourier transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD), in order to determine the optimal temperature. The flocculation test was made at 25℃, 45℃ and 65℃, the results indicated that when the temperature was 65℃, the removal efficiency of the oil and COD was the best, which was 87.2% and 92.6% respectively. Then by comparisons among rectorite (REC), PSFA and the composite PSFA-REC at the temperature of 65℃ and the optimal dosage of 11 mg/L, the composite PSFA-REC showed better flocculation performance than flocculant REC and PSFA alone.展开更多
Unilateral sulfate attack of cementitious materials containing 40% slag with different water to binder ratios was investigated. The results showed that the degradation of slag blended cement pastes was nearly from the...Unilateral sulfate attack of cementitious materials containing 40% slag with different water to binder ratios was investigated. The results showed that the degradation of slag blended cement pastes was nearly from the corners of paste surface with cracking and spallings, water-to-binder(w/b) ratio made a significant sense to the damage that low w/b ratio led to little weight loss, less cracking and spalling damage and vice versa. Microstructural experimental results demonstrated that in the three different stages of sulfate attack, degradation of pastes was primarily associated with the migration behavior and bonding configuration of aluminum, in the early ages Al was mostly present in C-(A)-S-H, and thus, the damage of pastes hardly appeared while at later ones Al had been largely transferred from C-(A)-S-H into AFt, leading to expansive damage.展开更多
To solve the problems of high rebound rate and strength reversion of shotcrete,a non-fluorine and non-alkaline liquid flash setting admixture(FSN)with low rebound and high early strength was synthesized under 60-65℃w...To solve the problems of high rebound rate and strength reversion of shotcrete,a non-fluorine and non-alkaline liquid flash setting admixture(FSN)with low rebound and high early strength was synthesized under 60-65℃water bath environment through orthogonal test design and taking setting time and compressive strength as indicators.The experimental results show that the optimum mass ratio of FSN is aluminum sulfate:diethanolamine:triethanolamine:pseudo-boehmite:lithium carbonate:water=57%:8%:0.05%:2%:2%:31%.When FSN is added with 7%of the mass of portland cement,the cement paste can be initially set in 3 min and finally set in 5 min.The compressive strength of mortar is 1.2 MPa at 6 h,18.0 MPa at 1 d,and more than 100%at 28 days;The microscopic analysis shows that the rapid release of Li^(+),NH^(4+),and CO_(3)^(2-)ions by FSN in the paste solution effectively shortens the induction period of high C_(3)S content in Portland cement,directly forms early coagulation AFt crystals in FSN and CH dominated by Al_(2)(SO_(4))_(3),and forms a large number of C-S-H gels in the later stage,so that the cement can quickly coagulate and harden,and the strength in the later stage is not retracted.展开更多
基金Project (2009ZX07212-001-01) supported by the Major Science and Technology Program for Water Pollution Control and Treatment,ChinaProject (50925417) supported by the National Natural Science Foundation for Distinguished Young Scholars of ChinaProjects (50830301,51074191) supported by the National Natural Science Foundation of China
文摘A novel inorganic polymer flocculant,poly-ferric sulfate(BPFS) was prepared by oxidation of ferrous sulfate using domestic Thiobacillus ferrooxidans(T·f) under acid condition.The optimal conditions for the preparation were pH value of 1.5,(NH4)2SO4 dosage of 0.5 g/L,initial Fe2+ concentration of 45g/L,inoculum 10%,rotating speed of 120 r/min,reaction time of 5-6 d and reaction temperature of 30 ℃.Under the optimal conditions,the BPFS product with pH value of 1.5-2.2,basicity of 17.5%-22.7% and total iron content of 43.87-45.24 g/L was obtained.The application of the BPFS to three wastewaters was carried out,and the removal efficiencies of COD,decolorization and Zn2+ by BPFS can be reached 70%,90% and 99%,respectively.The result suggests that the BPFS is an excellent flocculant for water treatment.
基金Project(51090380)supported by the National Natural Science Foundation of ChinaProjects(2013CB632601,2013CB632604)supported by the National Basic Research Program of China
文摘The influence of magnesium and aluminum salts as impurities on the hydrolysis of titanyl sulfate was investigated.The degree of TiOSO4 conversion to hydrated titanium dioxide(HTD) and the particle size of HTD were measured as functions of the concentrations of MgSO4 and Al2(SO4)3 in the TiOSO4 solution.The Boltzmann growth model,which focuses on two main parameters,namely the concentrations of Mg2+ and Al3+(ρ(Mg2+) and ρ(Al3+),respectively),fits the data from the hydrolysis process well with R20.988.The samples were characterized by ICP,SEM,XRD,and laser particle size analyzer.It is found that the addition of Mg SO4 simultaneously improves the hydrolysis ratio and the hydrolysis rate,especially when F(the mass ratio of H2SO4 to TiO2) is high,hydrolysis ratio increases from 42.8% to 83.0%,whereas the addition of Al2(SO4)3 has negligible effect on the chemical kinetics of HTD precipitation during the hydrolysis process,hydrolysis ratio increases from 42.8% to 51.9%.An investigation on the particle size of HTD reveals that the addition of Mg SO4 and Al2(SO4)3 clearly increases the size of the crystallites and decreases the size of the aggregates.
文摘The morphology and chemical compositions of surface and corrosion phases for two aluminum alloys(7075 and 2024 ) in the aqueous mediums containing sulfate reducing bacteria(SRB) were studied by the methods of scanning electron microscopy (SEM) and energy dispersive x ray analysis (EDXA). The results showed that serious pitting corrosion took place when aluminum alloys were exposed in the mediums containing SRB, whereas no pitting corrosion were found on the surfaces of aluminum alloys only exposed in blank mediums non containing SRB. It was demonstrated with EDXA that corrosion of aluminum alloys exposed in the solutions containing SRB, whereas the corrosion in the solution non containing microorganisms was attributed to the presence of chloride ions(Cl ).
文摘We are reporting a rare case of acute liver injury that developed after an internal hemorrhoid treatment with the aluminum potassium sulfate and tannic acid(ALTA) regimen. A 41-year-old man developed a fever and liver injury after undergoing internal hemorrhoid treatment with a submucosal injection of ALTA with lidocaine. The acute liver injury was classified clinically as hepatocellular and pathologically as cholestastic. We could not classify the mechanism of injury. High eosinophil and immunoglobulin E levels characterized the injury,and a drug lymphocyte stimulation test was negative on postoperative day 25. Fluid replacement for two weeks after hospitalization improved the liver injury. ALTA therapy involves injecting chemicals into the submucosa,from the rectum to the anus,and this is the first description of a case that developed a severe liver disorder after this treatment; hence,an analysis of future cases as they accumulate is desirable.
文摘AIM: To show that aluminum potassium sulfate and tannic acid(ALTA) sclerotherapy has a high success rate for Grade Ⅱ and Ⅲ hemorrhoids.METHODS: This study was based on the clinical data of 604 patients with hemorrhoids who underwent ALTA sclerotherapy between January 2009 and February 2015. The objective of this study was to assess the efficacy of this treatment for Grades Ⅱ and Ⅲ hemorrhoids. Preoperative and postoperative symptoms, complications and success rate were all assessed retrospectively. Follow-up consisted of a simple questionnaire, physical examination and an anoscopy. Patients were followed-up at one day, one week, two weeks, one month, one year, two years, three years, four years and five years after the ALTA sclerotherapy.RESULTS: One hundred and sixty-nine patients were diagnosed with Grade Ⅱ hemorrhoids and 435 patients were diagnosed with Grade Ⅲ hemorrhoids. The one year, three year and five year cumulative success rates of ALTA sclerotherapy for Grades Ⅱ and Ⅲ hemo-rrhoids were 95.9% and 93.1%; 89.3% and 83.7%; and 89.3% and 78.2%, respectively. No significant differences were observed in the cumulative success rates after ALTA sclerotherapy between Grades Ⅱ and Ⅲ hemorrhoids(P = 0.09). There were forty-seven post-operative complications(low grade fever; anal pain; urinary retention; rectal ulcer; and others). No serious or life-threatening complications occurred and all cases improved through conservative treatment. At univariate analysis there were no predictive factors of failure.CONCLUSION: ALTA sclerotherapy has had a high success rate for Grade Ⅱ and Ⅲ hemorrhoids during five years of post-operative treatment. However, additional studies are needed to evaluate the efficacy of this ALTA sclerotherapy in the management of hemorrhoidal disease.
文摘Due to the environmental policies and economic reasons,the water used in some flotation operations of complex sulfide ores is recirculated,causing the ion concentration of some species to increase over time,affecting the flotation of the minerals of interest.In this work,an experimental and thermodynamic analysis of the synthetic solutions was presented with a high content of calcium and sulfate ions.The study focused on evaluating the use of two aluminum compounds for the precipitation of Ca^(2+)and SO_(4)^(2−)in the form of ettringite.The amorphous aluminum hydroxide was found to be more efficient than the crystalline one,giving rise to 83%calcium and 91%sulfate removal.The XRD analysis of the solids showed the main reaction product of ettringite,accompanied by small amounts of calcite,due to the absorption of atmospheric carbon dioxide.The final solution after the chemical treatment showed residual calcium and sulfate concentrations below 200 mg/L.Finally,the kinetics of calcium removal appeared to correspond to a second order reaction with respect to calcium concentration,with an apparent activation energy of 53.48 kJ/mol,which may suggest that the ettringite precipitation process is governed by the chemical reaction.
文摘This study contains comparative research of sulfate resistance of ordinary Portland cement pastes with addition of basic aluminum sulfate (hydroxosulfate, Al(OH)1.78(SO4)0.61) and amorphous Al(OH)3. Over 3 months of storing in sodium sulfate solution, the most significant expansion and deterioration occur in case of samples with aluminum hydroxide. During sulfate resistance test, the ratio between aluminum nuclei in AFt (ettringite) and AFm phases was studied by 27Al-MAS NMR, and the impact of aluminum-containing admixtures on this ratio was specified. In accordance with NMR data, in samples with Al(OH)3, the rate of secondary ettringite formation becomes noticeable after one month of storing in sulfate solution. For samples with Al(OH)1.78(SO4)0.61, the rate of elongation and temper of changes in molar ratio between sulfoaluminate phases were comparable with reference samples without admixtures.
文摘Study of sulfate resistance of mortars with aluminum- and iron-bearing admixtures (Al(OH)3, Al2(SO4)3, FeSO4, Fe2(SO4)3) in conditions close to those established in ASTM C 1012, and the study of the mitigation effect of these admixtures on alkali-silica reaction in accordance with accelerated “mortar bar” test ( GOST 8269.0, ASTM C 1260) were performed. Iron (II) and (III) sulfates show ability for mitigation alkali-silica reaction, while also, in contrast with Al-bearing substances, do not induce the drastic reducing of the initial setting time and do not promote the progress of sulfate corrosion. Compared with FeSO4, iron (III) sulfate has moderate deleterious impact on the early strength of cement paste and can be of interest alone as an inhibitor of ASR. Iron (II) sulfate may be used together with aluminum sulfate to offset the accelerating effect of the latter on the setting of cement paste and to reduce a risk of sulfate corrosion. During prolonged water storage, the mortar elongation and secondary ettringite formation do not occur, even when Al2(SO4)3 is available. Therefore, the investigated admixtures cannot act as agents of internal sulfate attack, however, Al2(SO4)3 can enhance the outer sulfate attack.
文摘The effect of benzene-1,2-diol (pyrocatechol) and benzene-1,3-diol (resorcinol) on the development of sulfate attack in Portland cement mortars containing alkali-free setting accelerator (aluminum sulfate) was studied. It has been found that these compounds (especially pyrocatechol—due to its ability to form chelate complexes with aluminum ions) restrain destructive deformations of Portland cement mortars with aluminum sulfate admixture when under test conditions a constant supply of sulfate ions from external source is provided. According to 27Al-MAS NMR data, pyrocatechol does not influence the amount of ettringite formed in Portland cement paste during its store in sodium sulfate solution. Presumably, in presence of benzenediols, in cement mortars with aluminum sulfate admixture the formation of ettringite crystals with a less pronounced destructive effect takes place.
文摘In this study, a novel flocculant was prepared by an inorganic polymetric flocculant (IPF) - polysilicate ferro- aluminum sulfate (PSFA) and rectorite (REC). The structure of the PSFA-REC composite was characterized by Fourier transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD), in order to determine the optimal temperature. The flocculation test was made at 25℃, 45℃ and 65℃, the results indicated that when the temperature was 65℃, the removal efficiency of the oil and COD was the best, which was 87.2% and 92.6% respectively. Then by comparisons among rectorite (REC), PSFA and the composite PSFA-REC at the temperature of 65℃ and the optimal dosage of 11 mg/L, the composite PSFA-REC showed better flocculation performance than flocculant REC and PSFA alone.
基金Funded by the National Key Research Program(973 Program)(No.2015CB655101)National Natural Science Foundation of China(No.51379163)
文摘Unilateral sulfate attack of cementitious materials containing 40% slag with different water to binder ratios was investigated. The results showed that the degradation of slag blended cement pastes was nearly from the corners of paste surface with cracking and spallings, water-to-binder(w/b) ratio made a significant sense to the damage that low w/b ratio led to little weight loss, less cracking and spalling damage and vice versa. Microstructural experimental results demonstrated that in the three different stages of sulfate attack, degradation of pastes was primarily associated with the migration behavior and bonding configuration of aluminum, in the early ages Al was mostly present in C-(A)-S-H, and thus, the damage of pastes hardly appeared while at later ones Al had been largely transferred from C-(A)-S-H into AFt, leading to expansive damage.
基金Funded by the National Key Research and Development Program of China(No.2021YFB2601200)the Natural Science Foundations of Hebei Province(No.E2022210103)。
文摘To solve the problems of high rebound rate and strength reversion of shotcrete,a non-fluorine and non-alkaline liquid flash setting admixture(FSN)with low rebound and high early strength was synthesized under 60-65℃water bath environment through orthogonal test design and taking setting time and compressive strength as indicators.The experimental results show that the optimum mass ratio of FSN is aluminum sulfate:diethanolamine:triethanolamine:pseudo-boehmite:lithium carbonate:water=57%:8%:0.05%:2%:2%:31%.When FSN is added with 7%of the mass of portland cement,the cement paste can be initially set in 3 min and finally set in 5 min.The compressive strength of mortar is 1.2 MPa at 6 h,18.0 MPa at 1 d,and more than 100%at 28 days;The microscopic analysis shows that the rapid release of Li^(+),NH^(4+),and CO_(3)^(2-)ions by FSN in the paste solution effectively shortens the induction period of high C_(3)S content in Portland cement,directly forms early coagulation AFt crystals in FSN and CH dominated by Al_(2)(SO_(4))_(3),and forms a large number of C-S-H gels in the later stage,so that the cement can quickly coagulate and harden,and the strength in the later stage is not retracted.