Regarding development of a system model «defect category − composition concrete» for repair and recovery works of marine hydraulic structures open jetty type

Abstract

The actual working conditions and the engineering surveys results of seaport hydraulic structures of pile pier type are analyzed. It is shown that reinforced concrete structural elements made according to typical design solutions using «standard» concrete (ie without the use of complex chemical modifiers, mineral fillers or dispersed fiber reinforcement, etc.), because of complex multifactorial conditions of work can not guarantee the design strengths throughout the regulatory life span. The system model «defect category – composition of modified concrete» was formulated. It will allows investigating and implementing the optimal modified concrete composition for repair work of the available structural elements depending on the degrees of damage. In addition to the regulatory requirements, it is suggested to classify concrete damage by depth (up to 5cm, 5-20cm, more than 20cm). Accordingly, the concept of «Damage Modules of Concrete – Ordinary, Limited and Critical» was introduced. Practical recommendations on the selection of optimal compositions of modified concrete, depending on the «Module of concrete damage» bearing elements of the investigated structures. In this case, the use of modified concrete will provide a number of technological advantages: accelerated timing of dismantling formwork due to the acceleration of the concrete hardening term; improved workability of the concrete mix; possibility of repair work by the shotcrete method without the use of formwork, etc.