海排粉煤灰在桥涵台背回填中的应用研究

Application of Fly-ash-flushed-by-seawater in Bridge and Culvert Deck Backfill

为深入分析新型桥涵台背回填材料-海排粉煤灰的工程性质,通过海排灰中Cl-的固化机理分析以及多种室内试验方法,对水泥海排灰强度增长规律、水稳特性、干缩特性及温度收缩特性进行研究。结果表明,海排灰中的Cl-的固化作用可使水泥海排灰材料形成强度,游离态的Cl-对强度的影响是有限的;受到海排灰比表面积较小的特性制约,浆材在养生初期强度增长较慢,随着养生龄期的延长,水泥海排灰硬化浆体的强度逐渐增大;浆材的抗压强度随稠度的增加而降低;水泥掺量是影响水泥海排灰浆材干缩应变和温缩应变的主要因素。以海排粉煤灰为基材,与合理掺量的水泥可形成轻质、耐久、具有良好强度特性的优质桥涵台背回填材料。

In order to explore the engineering property of fly-ash-flushed-by-seawater which is a new material for bridge and culvert deck backfill, through the curing mechanism analysis of the Cl- in fly-ash-flushed-by- seawater and variety of indoor test methods, strength increasing regularity, water stability characteristic, dry-shrinkage and temperature shrinkage characteristics of fly-ash-flushed-by-seawater is studied. The resuhs indicate that （ 1 ） the solidification of Cl- can help cement fly-ash-flushed-by-seawater forming strength, the influence of the free C1- on the strength is limited; （2） the early strength of the paste grows slower because of the small specific surface area, the strength grows larger with the longer curing age ; （3） the compressive strength of the paste decreases as the consistency increases; （4） the cement quantity is the main cause which influence the dry shrinkage strain and temperature shrinkage strain of fly-ash-flushed-by-seawater. Fly-ash- flushed-by-seawater with reasonable cement content is lightweight, high strength and good durability for bridge and culvert deck backfill.