摘要
在本文中作者回顾了我国高性能混凝土的技术进展,同时也分析讨论了最近几年混凝土技术出现的几个新问题:裂纹、按服务年限设计混凝土的理念以及现代水泥的品质问题。作者从混凝土最早期的弹性模量及极限拉应变的急剧变化分析了早期裂纹的成因;并提出了混凝土24h抗压强度应小于10MPa以防止裂缝的建议。作者认为基于国内外的实际工程经验和教训以及耐久性研究成果,辅以服务寿命预估模型,目前我们已能按服务寿命设计混凝土。降低混凝土的水渗透系数固然能提高耐久性,但是过度追求低水渗透性,也即过高的强度对实际结构物的耐久性可能是不利的,因为易于开裂。现状水泥工艺生产的高C3S、高C3A、高早强和高比表面的水泥对混凝土的抗裂性和耐久性都有不利影响。因此,高性能混凝土应该同时具有高耐久性、不易开裂性、适当的高强度和良好的工作性。
In the present paper,the development of HPC was reviewed and also nearly appearing problems in concrete technology in recent years in China were analysed and discussed.They are:cracking,the concept of concrete durability design and characters of modern cements.The reasons for cracking were analysed by the very sharp changes of concrete elastic modulus and ultimate tensile strain at very early ages;and the suggestion that the 24h strength of concrete should be less than10MPa was made for preventing cracking.The author pointed that we have been able to design concrete according to required service life of concrete structures based on abundant experience of both success and failure,research results on durablity and with the help of mathematical models of prediction of service life as well.Lower water permeability naturely result in higher durability,but excessive pursuit of low permeability t.e.high strength might not be beneficial to durability due to easy cracking.Cements produced by modern factories with over high C3A and C3S,high early strength and surface area might be apt to crack and consequently be harmful to durability.In conclusion,HPC should possess high durability,high resistance to cracking,appropriate high strength and good workability.
出处
《混凝土》
CAS
CSCD
2003年第7期3-9,共7页
Concrete
