<p>To improve the applicability of red mud in subgrade construction, we studied the effects of four traditional retarders, including borax, sodium hexametaphosphate, sodium gluconate, and sucrose, on the setting time, mechanical properties and soil solidification of red mud-based subgrade engineered cementitious material (RCM). The mechanisms of the retarders on the hydration process of RCM were analyzed by hydration microcalorimeter, XRD, TG, and SEM-EDS. The experimental results show that four retarders have retarding effect on RCM, among which sodium gluconate and sucrose have significant retarding effect and do not have adverse effect on 28 d strength. Borax can slightly delay the setting time, and sodium hexametaphosphate has a better retarding effect, but they both reduce the 28 d strength. Microcosmic analysis shows that the retarders do not change the type of RCM hydration products, but mainly slow down the rate of hydration reaction through the adsorption and complexation or reaction of Ca<sup>2+</sup> in the slurry. All the results show that the retarder has no weakening effect on the unconfined compressive strength, water stability and CBR properties of the stabilized subgrade soil based on RCM.</p>

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Effect of Retarders on Hydraulic Behavior and Engineering Performance of Red Mud-based Cementitious Material

  • Zhaofeng Li,
  • Weihao Gao,
  • Xingzhang Guo,
  • Jian Zhang,
  • Xiaolin Liu

摘要

To improve the applicability of red mud in subgrade construction, we studied the effects of four traditional retarders, including borax, sodium hexametaphosphate, sodium gluconate, and sucrose, on the setting time, mechanical properties and soil solidification of red mud-based subgrade engineered cementitious material (RCM). The mechanisms of the retarders on the hydration process of RCM were analyzed by hydration microcalorimeter, XRD, TG, and SEM-EDS. The experimental results show that four retarders have retarding effect on RCM, among which sodium gluconate and sucrose have significant retarding effect and do not have adverse effect on 28 d strength. Borax can slightly delay the setting time, and sodium hexametaphosphate has a better retarding effect, but they both reduce the 28 d strength. Microcosmic analysis shows that the retarders do not change the type of RCM hydration products, but mainly slow down the rate of hydration reaction through the adsorption and complexation or reaction of Ca2+ in the slurry. All the results show that the retarder has no weakening effect on the unconfined compressive strength, water stability and CBR properties of the stabilized subgrade soil based on RCM.