Method for detecting void of coarse aggregate

Abstract

The invention discloses a method for detecting a void of coarse aggregate. The technical problem solved by the method is to compare the detection result of the void of the coarse aggregate with the detection result of the void of the coarse aggregate in an asphalt mixture. The method comprises the following steps of: adopting the dry tamping method to detect the void of the coarse aggregate; adding mineral powder and asphalt into the coarse aggregate and mixing the coarse aggregate, the mineral powder and the asphalt; forming a test piece; detecting the relative density of bulk volume, the mass percentage of the coarse aggregate accounting for the total mass and the relative density of synthesis bulk volume of the coarse aggregate accounting for water volume; and calculating the void of the coarse aggregate in the test piece. Compared with the prior art, the mineral powder and the asphalt are added into the coarse aggregate, the detection method is the same as that of the void of the coarse aggregate in the asphalt mixture, and the detection result is comparable, so that the skeleton-compact standard of the coarse aggregate formed by the detection method more scientifically evaluates the skeleton-compact degree of the coarse aggregate in the asphalt mixture.

Description

technical field [0001] The invention relates to a method for measuring the volume index of road engineering materials, in particular to a method for measuring the interstitial ratio of coarse aggregate used to configure asphalt mixture. Background technique [0002] The coarse aggregate gap ratio was proposed by American road engineers in order to emphasize the importance of the coarse aggregate skeleton in the process of introducing asphalt horseshoe grease mixture (SMA for short). According to AASHTO T19 method or ASTM C29 method in the United States, the void ratio VCA of coarse aggregate under dry compaction is determined DRC ,%. my country's current "Technical Specifications for Highway Asphalt Pavement Construction" (JTG F40-2004) also uses the same method as the American AASHTO T19 to measure the coarse aggregate void ratio VCA DRC . However, the coarse aggregate void ratio measured by the dry compaction method has the following differences compared with the measur...

AI Technical Summary

Problems solved by technology

However, the coarse aggregate void ratio measured by the dry compaction method has the following differences compared with the measurement method of the coarse aggregate void ratio in the asphalt mixture: (1) The specimen forming method is different, the former is compacted by inserting an iron rod , the latter is hammer impact compaction, and the compaction work of the two is incomparable; (2) The volume of the sample is different, the volume of the former sample is 10L, and the volume of the latter is about 0.5148L, resulting in the measurement of the sample volume (3) When measuring the volume of the sample, the calculation method of the surface void of the sample is different. The former includes all the voids on the surface of the sample when measuring; while the measurement of the coarse aggregate void ratio VCA in the mixture mix When the surface dry method is used to measure the bulk density of the sample, only part of the void on the surface of the sample is included.

In addition, the dry tamping method cannot make the spatial arrangement of the coarse aggregate particles reach the most compact state, so that the result of the coarse aggregate interstitial ratio measured by this method is too large. Therefore, the coarse aggregate formed under the condition of dry tamping There is still a large variability in the skeleton structure of the aggregate, and there is still a large displacement space for the coarse aggregate particles.

If the asphalt mixture composition is designed based on the coarse aggregate gap rate measured by the dry compaction method, the high temperature stability of the asphalt pavement will inevitably be insufficient, leading to the occurrence of rutting and seriously affecting the performance of the pavement.

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