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进行了密封与沿环外侧面干燥两种条件下的自密实混凝土圆环约束收缩试验,分别研究自密实混凝土试件在自生收缩单独作用下,以及在干燥与自生收缩共同作用下钢环应变随混凝土龄期的发展规律及开裂性能,并与普通混凝土进行比较。配合比参数包括粉煤灰掺量、粉煤灰和矿渣复掺掺量、水胶比。揭示了配合比参数在两种不同条件下对钢环应变和开裂龄期的影响规律,并提出以“标准化”的钢环应变曲线作为开裂趋势曲线,以开裂系数为0.95时的龄期为“名义开裂龄期”作为圆环试验中混凝土开裂指标的建议。研究结果还表明,同一配合比参数对干燥约束收缩与自生约束收缩的作用有可能一致,也有可能完全相反,因此有必要对两种收缩分别研究;该文提出的“开裂趋势曲线”和“名义开裂龄期”能综合混凝土开裂中“作用”和“抗力”两个方面的影响,从而对混凝土的开裂性能进行动态、定量、综合的评价。
The self-compacting concrete ring constrained shrinkage test was carried out under both the sealing and the drying along the outer side of the ring. The stress-strain curves of the self-compacting concrete under the synergistic effect of autogenous shrinkage and self-shrinkage were studied respectively The development of concrete age and cracking performance, and compared with ordinary concrete. Mixing ratio parameters include the amount of fly ash, fly ash and slag complex dosage, water-cement ratio. The effects of compounding parameters on the strain and cracking age of steel rings under two different conditions were revealed. The “normalized” steel ring strain curve was proposed as the cracking tendency curve. When the cracking coefficient was 0.95, For the “nominal age of cracking ” as a ring test of concrete cracking indicators. The results also show that the same compounding ratio may or may not be the same for both dry restraint and spontaneous restraint constriction. Therefore, it is necessary to study the two kinds of constrictions separately. The “Cracking tendency curve” and “Nominal cracking age ” can be integrated in concrete cracking “effect ” and “resistance ” two aspects of the impact, so as to crack the concrete performance of a dynamic, quantitative and comprehensive evaluation.