Research of Concrete Durability in Compressed Elements with Different Types of Confinement Reinforcements

The paper presents experimental research of short center compressed elements with circular cross section in different types of concrete confinement reinforcements, namely by introducing glass fiber-reinforced shell, steel spiral and by using these two types together was conducted. The results of the conducted experiments show the positive influence of both outer glass fiber-reinforced shell and spiral reinforcements on the durability of such elements. The highest degree of durability was achieved when two types of confinement reinforcements were used simultaneously. The durability of the concrete core of the samples made from class C40 concrete increased by 3.25 times and equaled 135 MPa. In case of the initial class C80 concrete the effect of confinement reinforcements was considerably smaller but nevertheless it was high enough. The durability of the concrete core increased by 2 times. The introduction of two types of confinement reinforcements considerably improved the deformability of compressed elements. The maximum recorded values of contraction longitudinal strain of the samples made of high endurance concrete were about 1%, and in case of concrete class C40 they were 2.4%. Such high level of deformability in compressed elements will help to effectively use high durability longitudinal reinforcements with the compression yield strength up to 2000 MPa and higher in them. (paper)