低掺量水泥固化高含水率黏土的强度特性及超早期预测方法

Use of "High Water content clay stabilized by Low amount of Cement" (referred to as HW-LC-clay from hereon) as land reclamation fill is able to solve the sand scarcity issue encountered by conventional land reclamation techniques. Thus, it is increasingly important to popularize the use of HW-LC-clay for land reclamation purpose. However, the strength characteristics of this new kind of filling material still remain unclear due to its low cement dosage and extremely high water content. As a result, the relevant design procedures are fairly unsound. In this project, a great quantity of Unconfined Compression Tests (UCT) will be conducted first to obtain the strength database for a target curing age. By statistically analyzing the strength database, the relations between the strength and relative proportions of the three constituents (i.e., re-moulded water content and cement dosage etc.) will be identified quantitatively, and an appropriate empirical formula for strength prediction of HW-LC-clay will be refined subsequently. This empirical formula is fairly helpful in determining the design proportion of a given actual HW-LC-clay reclamation project in a simple and rapid way. On the other hand, a large number of Vane Shear Tests (VST) covering different cement types and different clay types will be carried out to continuously measure the strength development curves for different curing temperatures, and a theoretical model will be put forward to describe the effect of curing temperature on the strength development of HW-LC-clay. Based on this theoretical model and VST data, an appropriate "accelerated" curing / testing procedure will be proposed for HW-LC-clay, and a very early-age prediction approach will be developed to predict the strength of a mix cured under normal condition for a target curing age from the very early-age strength development curve of the same mix cured under "accelerated" curing / testing condition. The proposed "accelerated" curing / testing procedure and the very early-age prediction approach can directly guide the optimization of the mixing proportion during the actual construction.

以"低掺量水泥固化高含水率黏土"（简称HW-LC-clay）作为垦地填料能有效解决传统填海工艺中砂料资源短缺的问题，值得大力推广。但由于其低水泥剂量和高含水率，HW-LC-clay填料的强度特性尚不明确，设计理论也很不成熟。本项目将首先基于单轴压缩试验和统计分析方法，建立HW-LC-clay目标龄期强度与配合比参数之间的定量关系，提炼出强度指标的经验估算公式。该经验公式有助于在实践中快速确定设计配合比。同时，本项目还将通过十字板剪切试验获取不同养护温度下HW-LC-clay的强度增长规律，建立养护温度对HW-LC-clay强度发展影响的分析模型，提炼出适用于HW-LC-clay的强度加速测试技术，进而开发出一套由加速测试条件下超早期（1~3d）强度预测正常养护条件下目标龄期强度的方法。所建立的加速测试技术和目标龄期强度超早期预测方法可以直接指导施工过程中配合比参数的优化。

以"低掺量水泥固化高含水率黏土"（简称HW-LC-clay）作为垦地填料能有效解决传统填海工艺中砂料资源短缺的问题，值得大力推广。但由于其低水泥剂量和高含水率，HW-LC-clay填料的强度特性尚不明确，设计理论也很不成熟。本项目首先基于单轴压缩试验和统计分析方法，建立了HW-LC-clay目标龄期强度与配合比参数之间的定量关系，提炼出HW-LC-clay目标龄期强度的经验估算公式。然后考察了不同类别不同配比HW-LC-clay 全过程（从超早期到晚期）强度增长规律，凝练了表征不同类别不同配比HW-LC-clay 全过程强度增长的统一模型。随后通过系列试验研究揭示了养护温度对HW-LC-clay 强度发展的影响规律，构建了综合表征HW-LC-clay 配合比参数和养护温度耦合影响的全过程强度增长模型，提出了适用于HW-LC-clay 的强度加速测试流程和标准养护条件下目标龄期强度超早期预测方法。所建立的加速测试技术和目标龄期强度超早期预测方法可以直接指导施工过程中配合比参数的实时调整和优化。此外，本项目还深入研究了养护压力和养护温度对HW-LC-clay 填料配合比参数设计的显著影响，提出了如何在HW-LC-clay 填料配合比设计中考虑养护温度效应和养护压力效应的方法和流程，这对HW-LC-clay围海垦地工程确定合理的水泥掺量、控制工程总成本意义重大。