Method for detecting diffusion coefficient of water vapor in bituminous mixture

Abstract

The invention discloses a method for detecting the diffusion coefficient of water vapor in a bituminous mixture. The method comprises the following steps: forming a to-be-detected cylindrical bituminous mixture sample; placing the sample in a closed chamber, and testing the mass of the sample in vacuum and at a test temperature by a magnetic levitation weight balancing system; calculating the saturated vapor pressure of the water vapor at the test temperature through the Antoine equation, obtaining the vapor pressure required in a reaction chamber under a relative humidity condition of the corresponding test through further calculation, inputting the vapor pressure value, setting the test temperature, and detecting the mass of the sample constantly; testing the change of the vapor adsorption of the sample along with time under the conditions of various specific test temperatures and relative humidity gradient conditions, and obtaining a water vapor diffusion coefficient through formula fitting. Tests of the diffusion coefficient of the water vapor in the bituminous mixture at different temperatures and multiple relative humidity gradients can be realized with the method; the test progress can be accelerated effectively and the test time can be shortened when the tests are performed at negative pressure. The method receives little interference from environmental factors and is high in test precision.

Description

technical field [0001] The invention belongs to the field of road engineering and relates to a method for detecting the water vapor diffusion coefficient of road asphalt mixture. Background technique [0002] Water damage is the main form of early disease of asphalt pavement. At present, relevant research at home and abroad mainly focuses on the influence of water on asphalt mixture when it exists in liquid form. For example, the domestic Marshall design method uses the Marshall residual stability ratio obtained before and after immersion in water and the freeze-thaw splitting strength ratio before and after immersion freeze-thaw cycles as the two main indicators for evaluating the water stability of asphalt mixtures; the Superpave design in the United States The method is also to use the tensile strength ratio of the indirect tensile strength test of the specimen before and after the vacuum saturated freeze-thaw treatment as an index to evaluate the water sensitivity of the...

AI Technical Summary

Problems solved by technology

However, the current studies are all carried out under a single humidity gradient, which is inconsistent with the multi-humidity gradient service environment in which asphalt pavement is actually located, and the existing tests are all carried out under normal pressure conditions, because water vapor diffusion itself is a slow and long-lasting process , resulting in a longer time-consuming test process

Images