Device and method for determining gross volume density of bituminous mixture through wax sealing

Abstract

Provided are a device and method for determining the gross volume density of a bituminous mixture through wax sealing. The determination device comprises a water tank with the top opened, a water-immersion balance is fixed at the top of the water tank through a support, a mesh basket used for containing a test piece is arranged in the water tank, and the mesh basket is connected with a hook of the water-immersion balance; the support comprises four supporting legs and a flat plate arranged on the top of the supporting legs, and the center of the flat plate is provided with a circular hole allowing the hook of the water-immersion to pass. The determination method comprises the following steps that 1, the mass of a dry test piece in the air is weighed; 2, standard sand is injected into the surface of the test piece, a paraffine film is formed on the surface of the test piece, and wax sealing is completed; 3, the mass of the test piece subjected to wax sealing in the air is weighed; 4, the test piece subjected to wax sealing is immersed in water, and the mass of the test piece in water is weighed; 5, the mass of the standard sand filled into the surface of the test piece is weighed; 6, the gross volume relative density of the bituminous mixture test piece is calculated according to a formula. The device is simple, implementation is convenient, and a test result error is small.

Description

technical field [0001] The invention belongs to the field of road construction, and in particular relates to a device and a method for measuring the bulk density of asphalt mixture with a wax seal. Background technique [0002] Asphalt mixture is a kind of porous and heterogeneous material, and its composition includes six parts: ① Mineral aggregates of various mineral materials (considered according to the state of being ground into powder without pores); ② Asphalt (all filled in aggregates) In the gap between the aggregates, it is only covered on the surface of the mineral aggregate, assuming that it will not be absorbed by the aggregate); ③The closed pores of the aggregate itself; ④The open pores of the aggregate itself (basically closed by asphalt in the mixture) closed pores); ⑤ the gap between the asphalt-coated mineral material and the mineral material (including open and closed); ⑥ surface depressions on the surface of the test piece due to failure of normal compacti...

AI Technical Summary

Problems solved by technology

The essential difference of each test method lies in the void composition of the asphalt mixture contained in it. Among them, the volume method measures the entire appearance size of the specimen, including all open pores, closed pores and surface depressions of the specimen; The method measures the apparent density of the test piece. When the porosity of the test piece is less than 0.5%, it can be approximately considered that the apparent density of the test piece is equal to its bulk density, but the asphalt mixture design cannot be determined by this method. density; the surface-dry method considers that it forms a saturated surface-dry state on the surface of the specimen, and in this state it is considered that the tested pores include the open pores of the specimen, that is, the pore volume of the specimen includes the open pores of the specimen It is reasonable in theory, but in actual operation, due to human or other reasons, the water in the open pores of the specimen may be absorbed into the test results, and at the same time, when the asphalt mixture specimen When the pores are large, that is, when there are many open pores, it is difficult to form the saturated surface dry state of the asphalt mixture. When the specimen is taken out of the water, the water in the open pores will flow out, which will affect the test results and affect the asphalt. The mix ratio design of the mixture; the wax sealing method is to seal the open pores with wax to form an imaginary saturated surface dry state, so it has the same meaning as the surface dry method, both of which are based on the gross volume including open pores and closed pores It is used as a volume for calculating density, but the wax sealing method also has its own defects. Its key is that the wax seal should not only seal the pores, but also prevent the wax from being absorbed into the pores, which is difficult to achieve in actual operation. , at the same time, if the wax is sucked into the specimen, it will seriously affect the test results of the specimen, especially for the surface performance test of the asphalt mixture specimen.

In addition, my country's "Highway Engineering Asphalt and Asphalt Mixture Test Regulations" stipulates that when the water absorption of the asphalt mixture specimen is less than 2%, the surface dry method is used, and when the water absorption of the asphalt mixture specimen is greater than 2%, the wax seal method is used. Moreover, it is stipulated in the test that before wax sealing, the water absorption of the test piece should be measured by surface dry method first. If the water absorption is less than 2%, wax sealing is not required, which invisibly makes the test of the bulk density of the asphalt mixture test piece change. more cumbersome

In addition, the common foreign method for testing the bulk density of asphalt mixture specimens is the sealing film sealing method. This method uses the sealing film to seal the specimens to form a saturated surface dry state. It is correct in theory, but in the process of operation In , the parafilm cannot form a true saturation state containing only open pores and closed pores, and still contains too many surface depressions, which ultimately makes the test results inaccurate

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