Early-age Shrinkage Experiment of Micro-expansive-concrete and Numerical Analysis

Abstract:

By establishing the mechanism parameter models of the early shrinkage of cement mortar and expansion effect of agent， the mesoscopic simulation analysis of micro-expansive concrete early expansion behavior was completed with mesoscopic modelling method. With parameter modification based on the measuring results of material test， the simulation accuracy was verified and the influence of material mesoscopic variability and aggregate particle types on the distribution of material shrinkage strain was discussed. The investigation results show that the mesoscopic shrinkage model of micro-expansive concrete can describe the rule of material strain time-depending distribution accurately and conveniently. The influence of aggregate random distribution on the material internal shrinkage strain distribution is remarkable. The peak tensile stress appears on in the angular position of slender aggregates and the cement mortar narrow gay between particles， and in the specified micro-expansive concrete material， the effect of expansion agent can reduce the tensile stress to about 20% of the normal concrete material， which can alleviate the potential risk of micro-scale shrinkage cracking damage and ensure the stress reserve in material for engineering structural applications. According to the discussion， it is necessary to control and optimize the aggregate types and shapes based on the detailed requirement on structural performance， and the low and uniformed initial shrinkage stress distribution in material can be realize.

Key words:concrete;micro-expansive concrete;concrete shrinkage;experiment investigation;parameter analysis