Furthermore,the suitability of each repairing method was analyzed.

Based upon introduction of the classification of the cracks of concrete the reasons caused those concrete cracks are analyzed,at the same time corresponding prevention measures and repairing methods are proposed in order to promote the application of measures in practice.

Based on the practice of the treatment of the quality defects occurring on the Precast reinforced concrete members used in some engineering of the Fenghuangshan Coalmine, this paper analyzes on the causes why the fractures occur on the Precast reinforced concrete members, and puts forward some repairing methods, which obtain good results.

This article analyzes the causes and the features of defects on the appearance quality in the process of precasting cement concrete members,and put forwards to patching methods,in combination with working practice,for eliminating the defects and improving the appearance quality of concrete precast members.

As a result,the repair method by installing liner , and than building-up welding was proposed.

The paper discussed nine shapes of broken slab cracks for cement concrete pavement,and proposed several repair methods.

In this method,associated with each node of the branch-decision tree,a parametric solution of the relaxed assignment problem and a feasible solution obtained by patching algorithm are used to tighten the lower and upper bound.