Cyclic testing of low-strength plain concrete

Abstract

This study investigates the cyclic performance of low-strength plain concrete (LSPC) between 5 MPa and 10 MPa. In highly seismic regions, deficient reinforced concrete (RC) structures have low concrete strength and the seismic evaluation of such RC structures depends on knowledge of the stress-strain relation of confined and unconfinedconcrete. An experimental study was thus undertaken to determine the mechanical properties of LSPC. The test results indicate that the axial strain of LSPC at peak stress varied between 0 . 0025 and 0 . 0055 with respect to concrete strength and aggregate type. Furthermore, it was observed that the cyclic behaviour of LSPC cannot be simulated with a well-known model proposed in the literature. The model predicted the cyclic behaviour of LSPC in terms of residual strain and elastic modulus with a high error. In addition, the modulus of LSPC was not predicted by equations defined in the code. Finally, it was observed that the cyclic behaviours of LSPC significantly depend on the characteristics of the aggregate.

Predicting Changes of the State of a Bridge Reinforced with Concrete Superstructures in View of Operational Changes

“…A very important property of the crack is the stability of its opening; many cracks in concrete "breathe" under the impact of alternating thermal and humidity strains and changes of external load, that is to say, their opening size varies during the structure's operation. Compared with stable varieties, such cracks are more dangerous with regard to reinforcement corrosion as protective deposits degrade periodically [7,8]. Cracks of corrosive origin, regardless of their growth, are dangerous: they indicate both the aggressiveness of the environment in which concrete fails in its protective function in relation to reinforcement and a deep, continuous corrosion process.…”

“…Corrosion cracks are formed in the protective layer due to the high tensile stresses in concrete, developed due to the accumulation of rust on the surface of the rebar if conditions are favourable for corrosion. Corrosion of reinforcement at the original monolithic layer can be caused by many factors: high concrete porosity, carbonization, stray currents impact, and corrosive gases [7,9]. Due to the nature of corrosion damage, it can be either a) non-uniform; b) isolated; c) pitting; d) spot; e) penetrative; f) threadlike; g) inter-granular; h) selective.…”