自密实补偿收缩钢纤维钢管混凝土的抗冻性研究与应用

摘要

It is mainly about that an ideal model of center concrete in the truss girder structure of steel tubing concrete and a method that used for limiting the shrinkage of the steel tubing concrete mixed with steel fiber.Through finding out the reasonable amount of highly ef-fective water and shrink reducer as well as the high-performance swelling agent ,we resolve the problem about the shrinkage in concrete. The amount of the steel fiber is limited less than 60 kg/m3,equal to 0.75%in volume measures,which can be satisfied with the demands to concrete.Also,we do a research about the rules of variable strength performance and cubic deformation property.Furthermore ,in order to meet the demand of engineering technique in cold condition,we have been discover a frost-resisting method that can be used for limiting the shrinkage of the steel tubing concrete mixed with steel fiber,and carefully verified its availability.The results of research showed that if the dosage of sodium nitrite was about 0.4%,and there was no difference between the strength of both short columns and its standard cur-ing samples under axial compression.Moreover,the frost-resisting performance of the concrete can be satisfied with the demands of con-structing quality in cold condition.%提出了钢管混凝土桁架梁式结构核心混凝土理想结构模型与自密实补偿收缩钢纤维钢管混凝土设计方法。通过确定复掺减缩型高效减水剂与高能膨胀剂合理掺量，有效补偿混凝土的收缩。钢纤维掺量不超过60 kg/m3（体积掺量0.75%）时能满足自密实混凝土技术要求。研究了钢纤维对微膨胀钢管混凝土力学性能与体积变形性能的影响规律；并根据钢管混凝土低温施工要求，研究了自密实补偿收缩钢纤维钢管混凝土的抗冻性设计方法，对其抗冻性进行了验证。试验结果表明，亚硝酸钠掺量0.4%时，现场养护核心混凝土试件与钢管混凝土短柱轴压与相应标准养护试件的轴压基本没有差异，混凝土抗冻效果良好，满足低温施工质量要求。