PROGNOSIS OF DURABILITY OF CONCRETE BY EVALUATING FREEZING AND THAWING CYCLES

Abstract

Hydraulic structures are exploited in hard environmental conditions (impact of freeze-thaw cycling, ultraviolet, humidity and drying, acidity or salinity of water, abrasion etc.), so due to the impact of environmental factors some deteriorations will occur. The repeated cycles of freezing and thawing have significant effects on durability of concrete. They reducing durability, because of cracking and scaling of concrete. Using the research results of investigated hydraulic structures concrete average compression strength f_ck, water absorption by weight W_m, by formulae (1, 2) were calculated numbers of laboratory freeze-thaw cycles n_50, freeze-thaw resistance of concrete rate F_{5 %} and from them – durability index – probable deterioration start time T_{5 %} of investigated main hydraulic structures _.( concrete strength f_ck loss in 5 % and 5 freeze-thaw cycles per year).

Relationships between shaft spillway or retaining wall freeze-thaw resistance of concrete rate F_{5 %} , durability index T_{5 %} , and average compression strength of concrete f_ck  were evaluated. These equations may be used for the durability prognosis of existing shaft spillways or retaining walls exploited in hydraulic structures.