Study on Loading Method of Multi-Factor Durability Test about Concrete in the Atmospheric Environment

Abstract

Damage and degradation of the concrete structure is based on the combination of the mechanical and environmental factors (double or multiple), so the durability of the concrete structure is a very complicated research subject. The key of the multi-factor durability test of concrete under load is how to choose the loading device. In this paper, the adopted loading device which is suitable for the multi-factor durability test of concrete in the atmosphere environment is determined by analyzing the force principle of different loading systems and comparing the advantages and disadvantages of various loading methods. So far, inland and aboard, the valuation about durability of concrete structure and service life, and also the improving measures are basically based on the research about single environment factor. While it is not conform to reality that the actual engineering bears the damage of multiple factors, mechanics, environmental change and the interaction among them. In fact, concrete structure is not only a structure that operates under different environment factors mixed, also a supporting load structure. Therefore, it is more realistically to reflect the damage of engineering structures suffered by carrying out the study about the loads of concrete multi-factor durability. The using dosage of concrete in engineering construction in our country is ranking in the world, most of the concrete structures including bridges, dams and other important projects are directly exposed to the atmosphere environment, corroded by CO2 and acid rain. Besides, the load always exists during the using process in actual structures, it is lacking of sufficient data to prove whether the structure stress state aggravate the degradation process of materials under the environment. So it is necessary to study the durability of concrete structure under loading in general atmospheric environment. The appropriate loading devices must be had for doing the test of loading concrete which carbonized or eroded by acid-rain. Firstly, the load applied should be the most common form in the structures. The researchers used to selecting bending load, because structure bending component can apply tensile stress to one side of concrete samples and apply compression stress to another side. Secondly, due to the limited volume of test boxes such as the carbonization tank, a loading device which have small volume and can not be affected by temperature changes and corrosive solution should be selected to assure the quantity and quality of the experiments. Besides, loading devices must have enough load precision, and considering the concrete samples are ponderous, so loading devices shall be as simple as possible to use.