Forming mold for asphalt test pieces of bent beam rheometer

Abstract

The invention discloses a forming mold for asphalt test pieces of a bent beam rheometer. The forming mold comprises a bottom plate, inner molds and side molds, wherein a semi-closed cavity formed among the bottom plate, each two adjacent inner molds and the side molds is a forming region of the asphalt test pieces. The inner molds and the side molds of the forming mold are convenient to assemble and disassemble, and cooled molded asphalt is easy to release from the mold. By the adoption of the mold, a mixture of glycerol and talcum powder as an isolating agent in specification is avoided, resources and time are saved, a plurality of test pieces can be formed at one time, the labor intensity is low, and the forming efficiency is greatly improved; moreover, after the test pieces are formed through the mold, the situation of attachment of asphalt to the mold is avoided, the mold does not need to be cleaned and is unlikely to be damaged, the dimension accuracy of the test pieces is ensured, and the service life of the mold is greatly prolonged.

Description

technical field [0001] The invention belongs to the field of highway engineering asphalt test, and relates to a molding die for asphalt test piece of bending beam rheometer. [0002] Background technique [0003] The low-temperature cracking of asphalt pavement is related to the low-temperature performance of asphalt. The US Highway Strategic Research Program SHRP (strategic highway research program) has proved that the direct contribution rate of asphalt performance to low-temperature cracking is 80%. Based on rheological properties, the SHRP research plan proposes to use bending beam rheometer (BBR) to measure the creep stiffness (S) and rate of change of bitumen stiffness (m) at low temperature. The low-temperature performance of asphalt can be determined by measuring the stiffness of asphalt girder specimens under creep loads. "Test Regulations for Asphalt and Mixtures in Highway Engineering" JTG E20-2011 adds the flexural creep stiffness test of asphalt (bending beam ...

AI Technical Summary

Problems solved by technology

[0010] (1) Every time the test piece is formed, it is necessary to apply a release agent on the inner surface of the mold, which is a waste of material and time;

[0011] (2) Bundle the modules with O-shaped rubber rings. Long-term use will cause the rubber rings to deform or decrease in elasticity, which will lead to unstable placement of the molds or loosening between the bottom plate, side molds, and end molds, thereby deforming the formed asphalt specimens. Insufficient dimensional accuracy affects test results;

The accuracy of this step is difficult to control, and it is easy to cause residual air bubbles

Moreover, the plastic sheet is easily deformed after long-term high-temperature asphalt pouring

[0013] (4) Affected by the cleanliness of the mold surface or / and due to the non-standard operation of the test operator, the release agent cannot adhere to the mold surface very uniformly, which will cause the asphalt specimen to stick to the mold and cannot be demoulded. The method of crowbar or heating and cleaning to demould the asphalt is very easy to damage the mold or / and scratch the inner surface of the mold, especially after the inner surface of the mold is scratched, the bonding strength between the molded asphalt and the scratched part of the mold will increase, resulting in demoulding. Molding is more difficult, thus forming a vicious circle, premature damage to the mold

[0014] (5) Only one asphalt girder specimen can be formed each time, and the mold needs to be cleaned, which is cumbersome and inefficient

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