Analysis For Causes Of Cracking In The Concrete Structure And Strengthening Technology

Cracking is always a hot issue in the field of concrete materials research. Cracking of early ages is especially cared for. Cracking can be caused by loading or deformation. The latter one is commonly considered as the main factor, and need to be solved urgently. It has been proved that shrinkage can't be used as the indicator of crack resistance of concrete and the evaluation experiments should be carried out under restrained conditions. Till now much progress have been made on the restrained shrinkage test methods abroad. The methods are generalized and divided into Plate, Ring and Uniaxis types.Generalized tests show good correlation between the property of cementitious system and the crack-resistance of concrete. And this method also can avoid the disturb of complexity of the conctete composition. A set of ring apparatus of cement is developed to determine the cracking time. Tests results indicate that great difference lies in diverse brands of cement. Based on this system the cracking resistence of Portland Cement Paste system was tested. Also the effect of fly ash, slag, silica fume and admixtures on the cracking at early ages was studied.According to the basis relation of stress, strain and the value of limit deformation during the strengthening of concrete architecture, the derivate computing method is applied under different state of load and internal force. And it is towards difference of stress and strain of the new and old part of the strengthening structure . It is pointed out that unloading is the necessary and important method of taking advantage of effect of the strengthening structure.It is analyzed in this paper that what causes of the cracking in the concrete structure and how to compute the strengthening, and then bring forward the technical method of how to strengthen and compute the strengthening of concrete structure for the reference in engineering.