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Rheological properties of laponite and chemically modified laponite suspenisons.

机译：皂石和化学改性的皂石悬浊液的流变性质。

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摘要

This research investigates the rheological properties of concentrated laponite RD suspensions modified through the addition of laponite RDS and sodium pyrophosphate (SPP). The work is aimed at establishing the possible suitability of these materials for treating liquefaction susceptible sands. This application requires that a laponite suspension initially exhibits liquid like behavior and low viscosity that allow its delivery into the pore space of a sand, but that over time the suspension develop a gel structure with solid like behavior that can serve to restrict sand particle mobility during earthquake shaking.;The experimental program made use of a Physica MCR 301 Rheometer, a fully automated, air bearing apparatus controlled stress apparatus. Controlled shear rate tests (CSR) and amplitude sweep tests (AS) were performed to determine the flow and the viscoelastic behavior of 30 different clay suspensions as a function of time (from immediately after mixing to after 4 months). The concentration of laponite RD was varied between 3% and 9% by mass of water, while the dosages of the modifiers ranged between 1.5% and 6% by mass of water in the case of laponite RDS, and between 1.5% and 8.0% by mass of laponite RD, in the case of the SPP.;The test results demonstrate that the addition of RDS and SPP impacts the rheology of the laponite RD suspensions, and that the effects are more marked when the concentration of RDS and SPP increases. For suspensions with the same RD %, at early aging times the addition of RDS or SPP causes a reduction in viscosity, yield stress and storage modulus. For sufficiently high dosages of RDS or SPP a Newtonian response is observed immediately after mixing.;Both CSR and AS tests show a significant evolution in the rheological behavior of all RDS and SPP modified suspensions. Over time all suspensions display an increase in viscosity, yield stress and storage modulus, and a reduction in the phase angle measured in the LVE region. These effects reflect the transition of all suspensions from sols to gels. This transition is delayed for increasing concentration of RDS or SPP.;After 2 weeks of aging all the suspensions examined in its research display phase angle less than 10°, indicating the formation of a gel-like structure with solid like behavior. While the viscosity measured at a reference shear rate of 1000/s is found to reach a "steady state" after ∼ 1 week of aging, the storage modulus of all suspensions continues to increase with time 3-4 months after mixing. Beyond 20-50 hours, the storage modulus increases with the total laponite concentration (RD plus RDS) and decreases with increasing SPP%.;Based on the tests conducted, two suspensions (5% RD suspension modified with 4% RDS and 9% RD suspension modified with 7% SPP) are identified as potentially suitable permeation materials to treat sands susceptible to liquefaction.
机译：这项研究研究了通过添加锂皂石RDS和焦磷酸钠（SPP）改性的浓缩锂皂石RD悬浮液的流变特性。这项工作旨在确定这些材料在处理易液化的沙子方面的适用性。该应用要求锂皂石悬浮液最初表现出类似液体的行为和低粘度，从而使其能够输送到沙子的孔隙中，但是随着时间的流逝，悬浮液会形成具有类似固体行为的凝胶结构，这种行为可以限制沙粒在流动过程中的流动性。实验程序使用了Physica MCR 301流变仪，这是一种全自动的，空气轴承设备控制的应力设备。进行了受控的剪切速率测试（CSR）和振幅扫描测试（AS），以确定30种不同粘土悬浮液的流动性和粘弹性行为随时间的变化（从混合后立即到4个月后）。皂石RD的浓度在3质量％至9质量％的水之间变化，而改性剂的用量在皂石RDS的情况下在1.5质量％至6％的水质量之间，而在1.5质量％至8.0％之间。测试结果表明，RDS和SPP的添加会影响Laponite RD悬浮液的流变性，并且当RDS和SPP的浓度增加时，效果会更加明显。对于具有相同RD％的悬浮液，在早期老化时间添加RDS或SPP会导致粘度，屈服应力和储能模量降低。对于足够高剂量的RDS或SPP，在混合后立即观察到牛顿响应。CSR和AS测试均显示，所有RDS和SPP修饰的悬浮液的流变行为均发生了显着变化。随着时间的流逝，所有悬浮液的粘度，屈服应力和储能模量都会增加，并且在LVE区域测得的相角会减小。这些效果反映了所有悬浮液从溶胶到凝胶的转变。该转变被延迟以增加RDS或SPP的浓度。老化2周后，在其研究中检查的所有悬浮液均显示小于10°的相角，表明形成具有类似固体行为的凝胶状结构。尽管在约1周的老化后发现以参考剪切速率1000 / s测量的粘度达到“稳定状态”，但所有悬浮液的储能模量在混合后3-4个月随时间持续增加。在20-50小时后，储能模量随总皂石浓度（RD加RDS）的增加而增加，而随SPP％的增加而降低。;基于所进行的测试，两种悬浮液（5％RD悬浮液经4％RDS和9％RD改性）经7％SPP改性的悬浮液被认为是潜在的渗透材料，可用于处理易液化的沙子。

著录项

  • 作者

    Shen, Meng.;

  • 作者单位

    Purdue University.;

  • 授予单位 Purdue University.;
  • 学科 Engineering Civil.;Geotechnology.
  • 学位 M.S.C.E.
  • 年度 2014
  • 页码 135 p.
  • 总页数 135
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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