Based on experiments results brittle duralumin samples, effect on stresses concrete (mortar) strength caused by non-uniform cross-section shrinkage (when dried) or expanding (when moistened) was inevitable. Various authors’ experiments results diversity on concrete (mortar) tensile strength of moistening and drying effect were analyzed. Reasons for increasing air-dry concrete (mortar) strength storage at beginning of humidification were explained. Wetting sample duration (intensity) effect on concrete strength was analyzed in detail and opposite results causes on concrete strength moistening (drying) effects were obtained and justified.

It has been established that repair of quarry excavators should be carried out directly on site. In this case, the use of jacks for weighing the rotary platform of excavators Bucyrus RH340 and Terex RH200 models for repair of running equipment is impossible because of their design features. This type of repair is suggested to be performed as an excavator based on the design developed by the authors. The installation of the excavator on the support structure is carried out by its working equipment. The supporting structure is suggested to be made in the form of two identical fragments for its unification regarding the base of excavators and the convenience of transporting to the site of work. The suugested method of fixing the excavator to the support structure prevents it from being displaced from the impact of seismic loads during blasting operations. The investigation of the stress-strain state of the supporting structure was carried out using the complex of finite-element analysis.