青藏铁路桥隧结构用高性能混凝土的耐久性研究

Durability of HPC for Bridge and Tunnel Structure on Qinghai-Tibet Railway

针对青藏高原多年冻土区恶劣的自然环境条件特点,分析了青藏铁路桥隧结构混凝土的力学性能和长期耐久性能的具体指标,提出了提高混凝土耐久性的技术措施,介绍了青藏铁路专用DZ型高性能混凝土外加剂的品质指标及其混凝土的物理力学性能和长期耐久性能。DZ型系列高性能耐久混凝土的主要性能达到如下要求:最低极限灌注气温为-20℃;抗冻融循环能力达F300;耐硫酸盐腐蚀极限浓度达到15000mg·L-1;抗渗等级大于P12,氯离子渗透值小于1000库仑;耐风蚀磨耗率小于0 5kg·m-2;碱—骨料反应膨胀率小于0 04%。

In consideration of the severe natural environment conditions along the Qinghai-Tibet Railway, several indexes on concretes durability are introduced to evaluate the physical performance and durability of HPC (High Performance Concrete) for the Bridge and Tunnel Structure of QingTibet Railway. The DZ type series high performance and durable concrete has such performance that can meet the following requirements: concrete can be cast under the temperature of -20℃, freezing and thawing resistance of the HPC is about F300, antisulphate abrasion ability is 15 000 mg·L-1 (according to SO2-4 consistency), antiseepage class is greater than P12; Chloride ion penetration value is less than 1 000 coulomb, resistance to wind abrasion is 05 kg·m-2, and expansion rate of alkaliaggregate reaction is less than 004%.