自密实混凝土（Self-compacting concrete, SCC）的优良流动性能使其在施工时可以无需振捣、通过自重填充模板角落，减少施工时间并提升施工质量，被广泛应用于现场浇筑与预制施工之中。但SCC的粉体用量大，其性能易受原材料变化扰动，配合比设计难度大。净浆流变阈值理论可通过净浆的流动性能预测SCC的工作性能，基于净浆流变阈值理的配合比设计方法可助于节省人力、时间与材料成本。本研究聚焦于原材料堆积特性对净浆流变阈值的影响，从流动力学模型入手，并量化研究粉体、细骨料、粗骨料堆积特性对净浆流变阈值的影响，建立通用公式。首先，考虑砂浆在粗骨料颗粒压力作用下的流动状态，基于V型漏斗试验中SCC的流动状态，建立新的SCC流动物理力学模型，基于此模型修正净浆屈服应力和塑性粘度阈值的计算公式，并通过净浆与SCC自密实性能区域的对比进行验证。为了量化评估区域对比结果，提出一种新的自密实区域预测准确度评价方法。评价结果表明，新模型的预测准确度高于原模型。其次，现有研究仅考虑粉体类型，未考虑粉体自身特定性质，尤其是堆积特性，本研究利用粉体粒径和粒径间距描述粉体的堆积特性，通过净浆与SCC对比试验，获得净浆粉体拟合系数、特性粘度与粉体参数间的关系。试验验证结果表明，修正后的净浆流变阈值预测准确度提到显著提升。再次，以三参数颗粒堆积模型为基础，提出细骨料理想最大堆积率的计算方法，取代原公式中仅考虑细骨料最大、最小粒径的最大砂率，并基于细骨料理想最大堆积率修正净浆流变阈值的计算公式，扩展净浆流变阈值理论的理论基础，量化了细骨料堆积特性对净浆流变阈值的影响，进一步完善净浆流变阈值理论。最后，基于颗粒粒径比对粗骨料堆积状态的影响，提出石子堆积孔隙率修正系数、修正剩余砂浆体积、修正剩余砂浆膜厚的计算方法，获得石子堆积特性与剩余砂浆膜厚的量化关系，通过对比自密实性能区域证明，修正后的净浆自密实性能区域整体上的预测准确度均优于原净浆自密实性能区域。

Self-compacting concrete (SCC) is a kind of high-performance concrete that has excellent flowability, making it possible to fill the corners of the formwork by its own weight without vibration. That could help to reduce construction time and improve engineering quality. SCC is widely used in on-site pouring and prefabrication construction. However, the performance of SCC is prone to be affected by the fluctuation of the materials, leading to difficult works of the mix design. The flowability of SCC can be predicted by the rheological parameters of paste based on the paste rheological threshold theory, making it more efficient to complete the mix design. This mix design method needs less manpower, construction time, and material cost. This study focuses on the influence of material characteristics (especially packing characteristics) on the paste rheological thresholds and aims at establishing general formulas to obtain high prediction accuracy. The flow mechanics models of SCC were studied first. Then, quantitative studies of the influence caused by material packing characteristics on the paste rheological thresholds were carried out. The types of materials were powder, fine aggregate, and coarse aggregate. Firstly, the flow mechanics models of flowing SCC were established, which considered the flow state of mortar under the pressure of coarse aggregate particles neglected in the previous research. Based on the flow state of SCC in the V-funnel test, the desired new flow models of SCC and the related modified threshold formulas were obtained. To verify the modification, the comparison of the self-compacting paste zone (SCP zone) and SCC zone were carried out. In order to quantitatively evaluate the results of zone comparisons, a new evaluation method for the prediction accuracy of the SCP zone was proposed. The evaluation results show that the prediction accuracy of the new models was higher than that of the original models.Secondly, in the existing studies, the powder parameters depended on the powder type, not considering the specific characteristics of a particular powder of the same type, especially the packing characteristics. In this study, the powder particle size and particle size spacing were used to describe the packing characteristics of powder particles. Through the comparison of SCP and SCC zones, the powder fitting coefficient and the intrinsic viscosity in the calculation formulas of the paste rheological threshold were modified. The modification of powder parameters was verified by the comparison test of paste and SCC. The self-compacting zone comparison results showed that the prediction accuracy of the modified paste rheological threshold was improved.Thirdly, the maximum sand ratio only considering the maximum and minimum particle size of the fine aggregate particles was modified. Based on the 3-parameter particle packing model, the calculation method of the maximum packing density of fine aggregate was proposed. Instead of the maximum sand ratio, the maximum packing density was used in the paste rheological threshold calculation. Thus, the thresholds were modified. The proposed maximum packing density expanded the theory research of the paste rheological threshold theory. The influence of the fine aggregate packing characteristics on the paste rheological thresholds was quantified. The paste rheological threshold theory was further improved.Finally, based on the influence of particle size ratio on the packing status of coarse aggregate, the following parameters were proposed: the calculation method of gravel packing properties correction coefficient, correction of excessive mortar volume, and correction of excessive mortar film thickness were proposed. The quantitative relationship between gravel packing characteristics and excessive mortar film thickness was obtained. Thus, the paste rheological threshold calculation formulas were modified. Then, the modification was proved by the comparison of the self-compacting performance zones of paste and SCC. The overall prediction accuracy of the modified SCP zone showed higher accuracy than that of the original zone.