文档介绍：混凝土早期收缩、开裂对结构耐久性的影响 XXX 1 XXX 1 XXX 2 摘要由于早强水泥和高效减水剂广泛应用, 混凝土凝固和硬化强度发展迅速, 初期收缩变形受约束产生很大的弹性拉应力得不到松弛则产生开裂,严重地影响处于侵蚀性环境混凝土结构的耐久性和安全性,迫切需要提高对这一问题的认识,并落实到设计、施工、材料各方面,使混凝土结构基础设施建设在新世纪能够可持续地发展。关键词早期混凝土自收缩开裂性能耐久性 Shrinkage and C racking ofC oncrete and I tsE ffect on D urability ofS tructures Qu Tao 1 LuoJian Feng 2 ( 1. Wuhan university of technology Wuhan 430070 university Shanghai 200092 ) Abstract Concrete has been set and hardened fast and its strength developed quickly because of application of high early strength cement and superplasticizer, so may be cracked since drastic elastic stress developed and almost no relaxation effect occurred when shrinks was restricted at early age. It affects seriously durability and safety of concrete structures in aggressive environment. It is on edge to improve the knowledge in this field, to put into effect of design, construction and material. They would play an important rule to sustainable development of infrastructure construction in this new century. Keywords high early-strength concrete, autogenous shrinkage, crack performance, durability 1. 概述人们很早就已经认识到温度对混凝土开裂的影响, 提出了掺入火山灰、采用低热水泥、利用大粗骨料粒径、预冷拌和物原材料、限制浇注层高和冷却水管等措施,来可降低水化温峰,抑制温度裂缝。但是,许多混凝土结构,包括桥梁、道路、隧道、港口、大坝、建筑物等,在建期间或建成后不长时间后出现可见裂缝,影响结构耐久性的现象还是十分严重。特别是近些年来随着早强混凝土的广泛应用,混凝土结构劣化迅速的情况越来越多。为什么会造成这种现象呢?因为很多人都忽视了混凝土自身收缩的影响。自身收缩还会与混凝土温度收缩相叠加使很多断面并不大的构件产生裂缝。在混凝土硬化初期, 其温度变形和自生变形是产生内应力,造成混凝