THE RESEARCH ON THE DETERIORATION OF REINFORCED CONCRETE STRUCTURES FUNCTIONING IN THE VARYING WATER LEVEL AREAS OF HYDRAULIC STRUCTURES

Abstract

There are a few hydraulic structures in Lithuania where reinforced concrete structures are used. The technical state of reinforced concrete structures is varying. Several structures have almost no damage in reinforced concrete structures, but there are those whose structures are quite severely damaged.

The research aims to determine the compressive strength of reinforced concrete structures of hydraulic structures functioning in varying water level areas and the relationship between the depth of damage and the service life of the structure.

Research objects were selected in Alytus, Anykšciai, Kaunas, Kėdainiai, Marijampolė, Pakruojis, Raseiniai, and Šiauliai districts. The age of the structures ranges from 65 years to 31 years.

The research found that reinforced concrete structures made from stronger concrete have shallower gullies. The highest compressive strength of concrete was determined in the Angiriai hydro scheme – 27.6 MPa, the lowest – in Antanavas and Savičiūnai – 5.8 MPa.

More affected are those reinforced concrete structures whose compressive strength is between 5.7 and 6.1 MPa, i.e., Antanavas, Savičiūnai, and Panevėžiukas hydro schemes. On average the gullies in the reinforced concrete structures deepened 5.4 mm per year in the Antanavas hydro scheme, 4.3 mm in Savičiūnai and 3.1 mm in Panevėžiukas. Gullies in the reinforced concrete structures developed the slowest in the Angiriai hydro scheme. The research found that the average compressive strength of concrete of this hydro scheme is 27.6 MPa, and the gully deepens an average of 0.2 mm per year.

According to the research data, the gully deepening rate and time dependencies on the average compressive strength of the concrete structure were determined. Knowing the thickness of the protective concrete layer of the reinforcement, it is possible to predict the time during which the reinforcement of the functioning reinforced concrete structure will become exposed. Based on the presented relationship, we can select concrete of such strength when designing reinforced concrete structures that will function in the varying water level areas, so that the reinforcement of these structures does not become exposed during the planned time.