The Experimental Research About The Influence Of Aftershock To The Strength And Damage Of Early-age Concrete

The investigations done in this paper was one of the projects aided byScience and Technology Agency of Zhejiang(2009C16076).Wenchuan earthquake and Yushu earthquake bringed our country greatcasualties and losses.And the reconstructions after Wenchuan earthquakeand Yushu earthquake suffered ongoing aftershock.But there was fewexperimental research about the influence on the buildings underconstruction.To explore the influence of aftershock on the strength and damage ofearly-age concrete,this paper acted four types of ground acceleration(0.06g，0.15g，0.25g，0.45g)on the early-age concrete(30MPa)withdifferent ages(4.5h，7.5h，11h，1d，2d，3d for cobble concrete；5h，8h，12h，1d，2d for gravel concrete).The main test contents were thechange of compressive strength、elastic models and ultrasound speed of early-age concrete suffered vibration and the change after28days’conservation.This paper also investigated the late strength development ofearly-age concrete suffered vibration and the damage of early-agereinforced concrete suffered vibration.The results showed that:1、The maximum decreasing ratio of compression strength andultrasonic velocity were18%and15%;2、After28days’ conservation, reduction was restored.However，thedecreasing ratio of cobble concrete was14%;3、The late strength development did not stop or halt. And growthcurve of strength was similar to control set;4、The influence of aftershock to fresh concrete in one days(forgravel concrete)and two days(for cobble concrete)was little.