On Experimental Study of Mortar Specimens under Repeated Impact Bending Load

Abstract

The purpose of this investigation was to examine the S-N diagram and fatigue process of mortar specimens under repeated impact bending load.
The results obtained were summarized as follows.
(1) The S-N diagram of mortar specimens under repeated impact bending load consists of two straight lines. When the ratio of impact level S is larger than that of singular impact level S₀, impact fracture behavior is the main behavior on the S-N diagram. When S is smaller than S₀, fatigue fracture behavior is the main. Here, S₀ is about 55 percent of impact level.
(2) As the number of impact cycles increases, the impact flexural strain increases. Therefore, the fatigue process under repeated impact bending load can be estimated by the measurement of impact flexural strain.
(3) The flexural strength of mortar specimens unbroken by repeated impact bending load of four hundred cycles is larger than the unloading flexural strength in spite of large residual strain.