为推动全固废胶凝材料在自密实混凝土中的应用,对采用全固废胶凝材料制备的高性能自密实混凝土的工作性能、力学性能、耐久性及水化机理进行了全面研究。结果表明:相较于普通硅酸盐水泥自密实混凝土,全固废胶凝材料自密实混凝土的工作性能更优;其早期抗压强度低,但后期强度略高;其氢氧化钙(CH)含量更低,因此其抗硫酸盐侵蚀性能优,但抗碳化性能较差。全固废胶凝材料早期水化速率较慢,累计放热量仅为普通硅酸盐水泥的49.8%,主要水化产物为C-S-H和AFt,二者相互交织形成致密网状结构,进而获得优异的力学性能与抗硫酸盐侵蚀性能。

[Objective] In order to fill the research gap regarding self-compacting concrete with full-solid-waste cementitious materials, this study utilizes full-solid-waste cementitious materials with low heat and micro-expansion prepared from multi-source solid waste to produce self-compacting concrete (SSC). The aim is to achieve high-value utilization of industrial solid waste and mitigate the shrinkage of SSC. [Methods] In strict compliance with the stipulations in the “Technical Specification for Application of Self-compacting Concrete” (JGJ/T 283—2012) and the “Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete” (GB/T 50082—2024), a comprehensive series of tests was carried out. These tests encompassed workability assessments, compressive strength evaluations, flexural strength measurements, prolonged immersion trials in sodium sulfate solution, accelerated carbonation experiments, and microstructural analyses, all aimed at thoroughly evaluating the workability, mechanical properties, durability, and underlying micro-mechanisms of SSC formulated with full-solid-waste cementitious materials. [Results] (1) The workability of SSC with full-solid-waste cementitious materials is better than that of the ordinary Portland cement system, with a slump flow of 720~760 mm. The slurry is homogeneous and the reinforcement passing ability is good. The compressive strength of SSC with mix S1 (full-solid-waste cementitious material system) at 3 days, 28 days and 90 days is 18.3,46.3,55.5 MPa, respectively, and the flexural strength at 3 days and 28 days is 6.8 MPa and 11.6 MPa, respectively. After incorporating 30% fly ash (mix S2) or 30% fly ash plus silica fume (mix S3), the 28-day compressive strength decreases by 31.7% and 50.5%, respectively, compared with reference mix S1. After accelerated carbonation for 28 days, the carbonation depth of S1-S3 (full-solid-waste cementitious material system) ranges from 11 to 50 mm (S3 fully carbonated), while that of the ordinary Portland cement SSC system is only 0~8 mm. In 5% Na₂SO₄ solution, for the full-solid-waste cementitious material system under full immersion for 0~180 days, the mass of the specimens increases, with a maximum of 0.42%, and the maximum compressive strength reaches 67.4 MPa. Under half-immersion for 0~150 days, the mass increase reaches a maximum of 0.41%, and the maximum compressive strength reaches 59.6 MPa. In terms of hydration heat, the peak heat flow of full-solid-waste cementitious materials occurs at about 26 hours, and the cumulative heat release over three days is 56.03 J/g, which is only 49.8% of that of ordinary Portland cement (112.40 J/g). (2) Microstructural analysis (XRD) showed that no CH diffraction peak was detected for the full-solid-waste cementitious material (whereas the CH peak in cement was obvious). Because it contains no cement clinker, the small amount of CH is rapidly consumed by pozzolanic components, which is the main reason for its poor carbonation resistance but better sulfate resistance. SEM showed that the main hydration products of the full-solid-waste cementitious material system are ettringite (AFt) and C-S-H gel. At 28 days, acicular AFt is widely distributed within the C-S-H matrix, forming a dense network structure. However, the mixtures containing fly ash or silica fume exhibit more pores and a less compact structure, consistent with the decrease in macroscopic strength. In terms of environmental economics, the carbon emission factor of the full-solid-waste cementitious material is 62.57 kg CO₂/t, which is 91.48% lower than that of ordinary Portland cement (735 kg CO₂/t); the material cost is 180 RMB/t, which is 21.7% lower than that of ordinary Portland cement (230 RMB/t). [Conclusion] Compared with the ordinary Portland cement system, SSC with full-solid-waste cementitious material shows better workability, with slightly lower early strength but slightly higher later strength. The low CH content endows it with excellent sulfate resistance but weak carbonation resistance. The early hydration rate of the material is slow, and the cumulative heat release is only 49.8% of that of ordinary cement. The main hydration products are C-S-H and AFt, which interweave to form a dense network, providing good mechanical properties and sulfate resistance.