Abstract

Cement treatment is a promising and effective method to enhance strength of calcareous sand in regions where offshore foundations and coastal facilities are localized. In treatment, the added cement content and curing period influence the strength of cemented calcareous sand. In order to regulate the loading resistance of cemented calcareous sand, effects of cement content and curing period on strength enhancement are investigated experimentally. First, cemented specimens with 5%, 7.5%, and 10% cement contents and 1–28 days curing period are prepared. Then, unconfined compression test is conducted to measure strength. Nuclear magnetic resonance test is also performed to analyze microstructure change during hydration reaction. An empirical equation of strength is derived, considering the effects of cement content and curing period. This equation shows higher accuracy than existing empirical models. In addition, the microstructure change in hydration process is quantified by pore volume evolution. Void ratio is used to characterize the pore volume evolution. Hence, the dependence of strength on cement content and curing period is quantitatively explained by the change in void ratio. This sheds light on hydration reaction in cement treatment by cement content and curing period and the regulation of strength enhancement in cemented calcareous sand.

• Highlights

• Empirical equation on strength with effects of cement content and curing period

• Pore volume evolution by hydration reaction in cement treatment

• Characterization of microstructure change by void ratio

• Microscopic mechanism of strength enhancement for cemented calcareous sand

摘要

水泥处理是提高近海地基和沿海设施局部地区钙质砂强度的一种有前途和有效的方法。在处理中，水泥的添加量和养护期会影响胶结钙质砂的强度。为了调节胶结钙质砂的承载力，实验研究了水泥掺量和养护时间对强度增强的影响。首先，制备水泥含量为 5%、7.5% 和 10% 且养护期为 1-28 天的水泥试样。然后，进行无侧限压缩试验以测量强度。还进行核磁共振测试以分析水化反应过程中的微观结构变化。考虑水泥含量和养护期的影响，推导出强度的经验方程。该方程显示出比现有经验模型更高的准确度。此外，水化过程中的微观结构变化通过孔体积演化来量化。空隙率用于表征孔体积演化。因此，强度对水泥含量和养护时间的依赖性可以通过孔隙比的变化来定量解释。揭示了水泥掺量和养护期对水泥处理过程中水化反应的影响以及对胶结钙质砂强度增强的调控作用。强度对水泥含量和养护时间的依赖性可以通过孔隙比的变化来定量解释。揭示了水泥掺量和养护期对水泥处理过程中水化反应的影响以及对胶结钙质砂强度增强的调控作用。强度对水泥含量和养护时间的依赖性可以通过孔隙比的变化来定量解释。揭示了水泥掺量和养护期对水泥处理过程中水化反应的影响以及对胶结钙质砂强度增强的调控作用。

• 强调

• 水泥掺量和养护期影响强度的经验方程

• 水泥处理中水化反应引起的孔隙体积演变

• 通过空隙率表征微观结构变化

• 胶结钙质砂强度增强的微观机理