The impact toughness and compressive strength of concrete added with calcium carbonate whisker are studied.It is found that calcium carbonate whisker can significantly improve the impact energy consumption at failure ...The impact toughness and compressive strength of concrete added with calcium carbonate whisker are studied.It is found that calcium carbonate whisker can significantly improve the impact energy consumption at failure of 55℃steam cured concrete,but has limited impact on 90℃steam cured concrete.At the same time,SEM,XRD and LF-NMR were used to study the micro morphology,hydration product components and pore structure of the concrete,and the mechanism of the influence of calcium carbonate whisker on the impact toughness and compressive strength of concrete was analyzed.展开更多
C-S-H series are synthesized at different temperatures and ages by pozzolanic reaction.The change of particle size distribution,phase composition,morphology and nanostructure of C-S-H with temperatures and ages,and th...C-S-H series are synthesized at different temperatures and ages by pozzolanic reaction.The change of particle size distribution,phase composition,morphology and nanostructure of C-S-H with temperatures and ages,and the effects of C-S-H seeds and seeds parameters on the hydration behavior and mechanical properties development of cement were investigated by DLS,XRD,SEM,^(29)Si NMR,TAM-air isothermal calorimeter and mechanical properties test.The results show that the particle size,crystallinity,basal spacing and Q^(2)/Q^(1) ratio of C-S-H increases with the increase of synthesis temperature and age.The addition of synthesized C-S-H seeds to cement pastes results in the strong acceleration effect on cement hydration and significant improvement of the early strength of cement paste and mortar.The 1 day-C-S-H seeds synthesized at room temperature can increase the strength of cement paste by about 30 MPa at 12 h.The effect does not show a very regular change with the increase of the temperature and age of seeds synthesis.Considering the effect of C-S-H seeds on the hydration and mechanical properties of cement,and economy and short cycle of seeds synthesis,the C-S-H seeds synthesized at room temperature for 1 day or 55 ℃ water bath for 12 hours is recommended..展开更多
目的采用四维超声自动左房定量(4D Auto LAQ)技术探讨早期糖尿病肾病患者左心房容积和功能改变。方法选取2020年3月至2021年4月于河南省人民医院就诊的早期糖尿病肾病患者40例(早期糖尿病肾病组)、2型糖尿病患者40例(糖尿病组),收集同...目的采用四维超声自动左房定量(4D Auto LAQ)技术探讨早期糖尿病肾病患者左心房容积和功能改变。方法选取2020年3月至2021年4月于河南省人民医院就诊的早期糖尿病肾病患者40例(早期糖尿病肾病组)、2型糖尿病患者40例(糖尿病组),收集同期健康志愿者36例(对照组),测量常规超声心动图参数,四维容积探头完整留取5个心动周期左心房容积图像,采用EchoPAC工作站4D Auto LAQ软件分析,获取左心房容积和应变指标:左心房(LA)的最大容积(LAVmax)、最小容积(LAVmin)、收缩前容积(LAVpreA)、左心房最大容积指数(LAVImax)、左心房排空容积(LAEV)、左心房排空分数(LAEF)、左心房储存期、管道期及收缩期纵向及圆周应变(LASr、LASr-c;LAScd、LAScd-c;LASct、LASct-c),分析三组间以上参数的差异。结果三组间室间隔厚度(IVSd)、左室后壁厚度(LVPWd)、左室舒张期内径(LVIDd)、左室射血分数(LVEF)、二尖瓣口舒张早期血流峰值流速与舒张晚期血流峰值流速比值(E/A)差异无统计学意义(均P>0.05),三组间左心房前后径(LAD)、相对室壁厚度(RWT)、二尖瓣口舒张早期血流峰值流速与二尖瓣环水平左室侧壁舒张早期运动速度比值(E/e′)比较差异有统计学意义(均P<0.05),进一步两两比较结果显示LAD仅在早期糖尿病肾病组与对照组之间差异有统计学意义(P=0.012),RWT、E/e′在三组之间的差异有统计学意义(均P<0.05)。三组间LAEV、LAScd-c、LASct-c差异无统计学意义(均P>0.05),LAVmin、LAVmax、LAVpreA、LAVImax、LAEF、LASr、LAScd、LASct、LASr-c差异有统计学意义(均P<0.05),两两比较结果显示早期糖尿病肾病组与对照组及糖尿病组相比LAVmin、AVpreA、LAVImax增加(均P<0.05),LAEF、LAScd、LASct、LASr-c减低(均P<0.05);糖尿病组LAVmax、LAVImax、LASct较对照组增加(均P<0.05),LAEF、LAScd、LASr-c较对照组减低(均P<0.05)。结论4D Auto LAQ技术可定量评价早期糖尿病肾病左心房容量和功能的改变,早期糖尿病肾病患者出现左心房容积增加,应变值下降。展开更多
基金Funded by the National Key R&D Program of China(No.2017 YFB0310001)National Natural Science Foundation of China(Nos.51772226 and 51972249)。
文摘The impact toughness and compressive strength of concrete added with calcium carbonate whisker are studied.It is found that calcium carbonate whisker can significantly improve the impact energy consumption at failure of 55℃steam cured concrete,but has limited impact on 90℃steam cured concrete.At the same time,SEM,XRD and LF-NMR were used to study the micro morphology,hydration product components and pore structure of the concrete,and the mechanism of the influence of calcium carbonate whisker on the impact toughness and compressive strength of concrete was analyzed.
基金Funded by National Key R&D Program of China(No.2017YFB0310001)the National Natural Science Foundation of China(Nos.51772226,51972249,51872216)。
文摘C-S-H series are synthesized at different temperatures and ages by pozzolanic reaction.The change of particle size distribution,phase composition,morphology and nanostructure of C-S-H with temperatures and ages,and the effects of C-S-H seeds and seeds parameters on the hydration behavior and mechanical properties development of cement were investigated by DLS,XRD,SEM,^(29)Si NMR,TAM-air isothermal calorimeter and mechanical properties test.The results show that the particle size,crystallinity,basal spacing and Q^(2)/Q^(1) ratio of C-S-H increases with the increase of synthesis temperature and age.The addition of synthesized C-S-H seeds to cement pastes results in the strong acceleration effect on cement hydration and significant improvement of the early strength of cement paste and mortar.The 1 day-C-S-H seeds synthesized at room temperature can increase the strength of cement paste by about 30 MPa at 12 h.The effect does not show a very regular change with the increase of the temperature and age of seeds synthesis.Considering the effect of C-S-H seeds on the hydration and mechanical properties of cement,and economy and short cycle of seeds synthesis,the C-S-H seeds synthesized at room temperature for 1 day or 55 ℃ water bath for 12 hours is recommended..
文摘目的采用四维超声自动左房定量(4D Auto LAQ)技术探讨早期糖尿病肾病患者左心房容积和功能改变。方法选取2020年3月至2021年4月于河南省人民医院就诊的早期糖尿病肾病患者40例(早期糖尿病肾病组)、2型糖尿病患者40例(糖尿病组),收集同期健康志愿者36例(对照组),测量常规超声心动图参数,四维容积探头完整留取5个心动周期左心房容积图像,采用EchoPAC工作站4D Auto LAQ软件分析,获取左心房容积和应变指标:左心房(LA)的最大容积(LAVmax)、最小容积(LAVmin)、收缩前容积(LAVpreA)、左心房最大容积指数(LAVImax)、左心房排空容积(LAEV)、左心房排空分数(LAEF)、左心房储存期、管道期及收缩期纵向及圆周应变(LASr、LASr-c;LAScd、LAScd-c;LASct、LASct-c),分析三组间以上参数的差异。结果三组间室间隔厚度(IVSd)、左室后壁厚度(LVPWd)、左室舒张期内径(LVIDd)、左室射血分数(LVEF)、二尖瓣口舒张早期血流峰值流速与舒张晚期血流峰值流速比值(E/A)差异无统计学意义(均P>0.05),三组间左心房前后径(LAD)、相对室壁厚度(RWT)、二尖瓣口舒张早期血流峰值流速与二尖瓣环水平左室侧壁舒张早期运动速度比值(E/e′)比较差异有统计学意义(均P<0.05),进一步两两比较结果显示LAD仅在早期糖尿病肾病组与对照组之间差异有统计学意义(P=0.012),RWT、E/e′在三组之间的差异有统计学意义(均P<0.05)。三组间LAEV、LAScd-c、LASct-c差异无统计学意义(均P>0.05),LAVmin、LAVmax、LAVpreA、LAVImax、LAEF、LASr、LAScd、LASct、LASr-c差异有统计学意义(均P<0.05),两两比较结果显示早期糖尿病肾病组与对照组及糖尿病组相比LAVmin、AVpreA、LAVImax增加(均P<0.05),LAEF、LAScd、LASct、LASr-c减低(均P<0.05);糖尿病组LAVmax、LAVImax、LASct较对照组增加(均P<0.05),LAEF、LAScd、LASr-c较对照组减低(均P<0.05)。结论4D Auto LAQ技术可定量评价早期糖尿病肾病左心房容量和功能的改变,早期糖尿病肾病患者出现左心房容积增加,应变值下降。
