交通枢纽工程超缓凝混凝土配制与应用

PREPARATION AND APPLICATION OF SUPER-RETARDING CONCRETE IN TRANSPORTATION HUB ENGINEERING

超缓凝混凝土具有凝结时间长,可长时间保持较高工作性能的特点,适用于大体积混凝土、连续施工时间要求较长的工程,一般通过降低水泥用量、提高粉煤灰掺量或提高外加剂缓凝组分,延长混凝土凝结时间,但会导致混凝土拌合物工作性差、强度低、生产控制难等问题,并且受温度、施工环境等影响较大。通过探究水胶比、外加剂掺量、砂含泥量对超缓凝混凝土凝结时间和强度的影响规律,成功配制出初凝时间为51h左右、终凝为70 h左右的C35超缓凝混凝土,60 d抗压强度达到46.3 MPa,并成功应用于北京某交通枢纽工程。

Super-retarding concrete is characterized by long setting time and high working performance for a long time.It is suitable for projects with mass concrete construction and long continuous construction time.Generally,the setting time of concrete is extended by reducing the amount of cement,increasing the content of fly ash or improving the retarding components of admixture.However,this will lead to power workability and low strength of concrete mix,difficulty in production control and other problems.In addition,the setting time is greatly affected by the temperature and construction environment.By exploring the rules of impact of water-cement ratio,admixture content and silt content of sand on the setting time and strength of super-retarding concrete,C35 super-retarding concrete was prepared successfully,of which the initial setting time is about 51h and the final setting time is about 70h.Its 60d compressive strength is up to 46.3 MPa.It has been successfully applied to a transportation hub project in Beijing.