Research and application of non-shrinkage concrete technology based on CaO and MgO composite expansion agent
Ensuring the compactness of the in-tube concrete without de-bonding and separation caused by shrinkage is of importance guaranteeing the construction quality of concrete-filled steel tube(CFST)arch bridge and promoting the further improvement of its span.This study investigated the deformation and mechanical properties of in-tube concrete containing CaO and MgO-based expansion agents with different mix ratio under both the constant temperature and varying temperature.The results showed that when the total mixing proportion was unchanged,the expansion of in-tube concrete was significantly increased with the increase of CaO dosage under the constant temperature of 20 ℃.Under the varying temperature condition consistent with the actual engineering,when the MgO dosage in composite expansion agents was 50％,the final residual expansion of in-tube concrete was about 22 μe.It can be seen that a suitable expansion component mix ratio can achieve no shrinkage in CFST structures.The external constraint of the steel tube can improve the compressive strength of in-tube concrete prepared with expansion agents by 4.5％to 7.7％at different ages.
CFST arch bridgede-bonding and separationexpansion agentmechanical propertyultrasonic velocity
万方数据
维普
