The sustainable geotechnical approach for addressing the challenges associated with clayey soils at construction sites involves the modification of these soils’mechanical and chemical characteristics using soil enhan...The sustainable geotechnical approach for addressing the challenges associated with clayey soils at construction sites involves the modification of these soils’mechanical and chemical characteristics using soil enhancement methods.The present study investigates the coupling effect of sandstone slurry waste(SSW)and calcium carbonate nanoparticle(CCN)as potential stabilizers to enhance the characteristics of clayey soil.A comprehensive investigation was conducted using compaction tests,plasticity index(PI)tests,California bearing ratio(CBR)tests,unconfined compressive strength(UCS)tests,and microstructural analyses of clayey soil,SSW and SSW-CCN-treated clay samples containing 5%,10%,15%,20%,25%,30%,and 35%SSW and 0.3%,0.6%,0.9%,1.2%,and 1.5%CCN mixed with clayey soil in different combinations of clay,SSW,and CCN.The findings reveal that incorporating 25%SSW with 0.9%CCN into clay soil results in an increase in the UCS from 132.2 kPa for untreated clayey soil without curing to 263 kPa after a 28-d curing period.Similarly,a rising trend in CBR results is observed up to 25%SSW addition in clay soil and up to 0.9%CCN addition in SSW-clay mixture.Initially,notable enhancements in UCS were attributed to a denser soil structure,followed by the formation of calcium–silicate–hydrate(CSH)gel,which intensified with prolonged curing.Gel patches were detected by scanning electron microscopy(SEM)in addition to particle aggregation.The results obtained from thermogravimetric analysis,Fourier transform infrared spectroscopy(FTIR),and X-ray diffraction(XRD)supported the presence of hydration products such as CSH.The experimental study indicates that SSW,in combination with CCN,offers a sustainable alternative to traditional soil stabilizers.展开更多
针对坐落于意大利帕维亚大学的TRIGA Mark Ⅱ反应堆热柱结构进行优化设计,从而满足面向硼中子俘获治疗(BNCT)的单光子发射计算机断层成像(SPECT)研究要求。为提高计算效率并减小统计误差,对比分析使用SSW/SSR方法与直接使用反应堆为源...针对坐落于意大利帕维亚大学的TRIGA Mark Ⅱ反应堆热柱结构进行优化设计,从而满足面向硼中子俘获治疗(BNCT)的单光子发射计算机断层成像(SPECT)研究要求。为提高计算效率并减小统计误差,对比分析使用SSW/SSR方法与直接使用反应堆为源项时热柱内照射位置处中子能谱,其结果基本一致,从而验证了SSW/SSR方法的可靠性。为在该反应堆开展BNCT中SPECT实验,热柱中子束需准直为笔形束。对比分析四种热柱优化方案下束流口处及探测器处热中子和光子通量:40cm长石墨(射束口5cm×3cm);0.5cm厚硼包裹40cm长石墨(射束口5cm×3cm);30cm长天然锂聚乙烯(射束口直径4cm);30cm长天然锂聚乙烯(20cm长射束口直径5cm,5cm长射束口直径4cm,5cm长射束口直径2cm)。结果显示,射束口处热中子通量分别为1.05×108,2.52×107,6.08×107和5.10×107#/(cm2·s)。综合考虑中子准直效果及光子污染,方案三具有最优性能。为后续进行BNCT-SPECT理论和实验研究提供了基础,从而有效促进BNCT剂量准确评估方法的研究进程。展开更多
文摘The sustainable geotechnical approach for addressing the challenges associated with clayey soils at construction sites involves the modification of these soils’mechanical and chemical characteristics using soil enhancement methods.The present study investigates the coupling effect of sandstone slurry waste(SSW)and calcium carbonate nanoparticle(CCN)as potential stabilizers to enhance the characteristics of clayey soil.A comprehensive investigation was conducted using compaction tests,plasticity index(PI)tests,California bearing ratio(CBR)tests,unconfined compressive strength(UCS)tests,and microstructural analyses of clayey soil,SSW and SSW-CCN-treated clay samples containing 5%,10%,15%,20%,25%,30%,and 35%SSW and 0.3%,0.6%,0.9%,1.2%,and 1.5%CCN mixed with clayey soil in different combinations of clay,SSW,and CCN.The findings reveal that incorporating 25%SSW with 0.9%CCN into clay soil results in an increase in the UCS from 132.2 kPa for untreated clayey soil without curing to 263 kPa after a 28-d curing period.Similarly,a rising trend in CBR results is observed up to 25%SSW addition in clay soil and up to 0.9%CCN addition in SSW-clay mixture.Initially,notable enhancements in UCS were attributed to a denser soil structure,followed by the formation of calcium–silicate–hydrate(CSH)gel,which intensified with prolonged curing.Gel patches were detected by scanning electron microscopy(SEM)in addition to particle aggregation.The results obtained from thermogravimetric analysis,Fourier transform infrared spectroscopy(FTIR),and X-ray diffraction(XRD)supported the presence of hydration products such as CSH.The experimental study indicates that SSW,in combination with CCN,offers a sustainable alternative to traditional soil stabilizers.
文摘针对坐落于意大利帕维亚大学的TRIGA Mark Ⅱ反应堆热柱结构进行优化设计,从而满足面向硼中子俘获治疗(BNCT)的单光子发射计算机断层成像(SPECT)研究要求。为提高计算效率并减小统计误差,对比分析使用SSW/SSR方法与直接使用反应堆为源项时热柱内照射位置处中子能谱,其结果基本一致,从而验证了SSW/SSR方法的可靠性。为在该反应堆开展BNCT中SPECT实验,热柱中子束需准直为笔形束。对比分析四种热柱优化方案下束流口处及探测器处热中子和光子通量:40cm长石墨(射束口5cm×3cm);0.5cm厚硼包裹40cm长石墨(射束口5cm×3cm);30cm长天然锂聚乙烯(射束口直径4cm);30cm长天然锂聚乙烯(20cm长射束口直径5cm,5cm长射束口直径4cm,5cm长射束口直径2cm)。结果显示,射束口处热中子通量分别为1.05×108,2.52×107,6.08×107和5.10×107#/(cm2·s)。综合考虑中子准直效果及光子污染,方案三具有最优性能。为后续进行BNCT-SPECT理论和实验研究提供了基础,从而有效促进BNCT剂量准确评估方法的研究进程。
