AASHTO T 409-2023
Determination of the Voids of Dry Compacted Filler
- Standard No.
- AASHTO T 409-2023
- Release Date
- 2023
- Published By
- American Association of State Highway and Transportation Officials US / AASHTO
- Latest
- AASHTO T 409-2023
- Introduction
AASHTO T 409-231 Technical Analysis
Published in 2023 by the American Association of State Highway and Transportation Officials (AASHTO), T 409-231 specifically specifies the method for determining the void content of dry-compacted fillers. This standard utilizes the Rigden instrument as the core testing equipment, providing a scientific basis for evaluating the performance of mineral fillers in asphalt mixtures.
Scope of Application and Technical Background
This standard applies to natural and artificial mineral fillers that pass a 0.075mm sieve. By measuring the void content of fillers in the compacted state, the volume percentage of free asphalt that can be carried by the filler can be indirectly assessed, which is of great significance to the mix design and quality control of asphalt mixtures.
Core Test Principles and Methods
The test is based on the impact compaction principle of the Rigden instrument. Through standardized impact times and heights, the packing material is brought to a stable compaction state under specific conditions. The height and mass of the compacted packing material are then measured, and the void fraction is calculated based on the packing density.
Test parameters Technical requirements Allow deviation Test significance Impact height 102mm ±1mm Ensure the consistency of impact energy Number of impacts 100 times Fixed value Establish standard compaction state Filling mass 10g ±1g Control the test sample size Temperature control 110°C ±3°C Ensure the filler is completely dry
Technical requirements of instrument and equipment
Rigden instrument The system consists of multiple precision components, and the size and quality of each component have strict requirements:
Specifications of main components
Drop block: inner diameter 25.0±1mm, inner height 65±5mm, mass 525±5g; Plunger: length 10mm, mass 350±1g; The gap between the plunger and the inner diameter of the drop block is strictly controlled within the range of 0.4±0.1mm. This precise fit ensures that the filler will not be over-extruded during the test.
Auxiliary Equipment Requirements
The depth caliper or micrometer must have a resolution of 0.01mm; the balance must have a minimum weighing capacity of 100g, an accuracy of ±0.2g, and a readability of 0.01g; and the forced-air oven must be able to maintain a constant temperature of 110±3°C.
Detailed Test Procedure
The standard test procedure includes four main stages: sample preparation, instrument calibration, compaction, and measurement calculations.
Sample Preparation Stage
The filler sample must be dried to constant weight in an oven at 110±3°C and allowed to cool to room temperature before testing. The mass change must be monitored during the drying process; constant weight is considered achieved only when two consecutive weighings, separated by at least one hour, show no change in mass.
Instrument Calibration and Testing
First, determine the zero height h0, which is the height from the top of the drop block to the bottom filter paper in the unloaded state. This is done by taking the average of three measurements taken at approximately 90-degree intervals. Next, weigh the unloaded mass m0 and add 10±1g of filler for the compaction test.
Compacting Procedures
The filler must be evenly distributed within the drop block cylinder. When inserting the filter paper and plunger, ensure that the filler does not migrate along the cylinder wall. The device is fixed to a solid, inelastic base and subjected to 100 free drops from a height of 102mm, with an interval of approximately 1 second between impacts.
Result Calculation and Precision Analysis
The void fraction calculation formula is based on the relationship between geometric volume and measured mass:
Void fraction (%) = [1 - m/(π×(D/2)²×h×ρ)] × 100
Where m is the mass of the compacted packing, D is the inner diameter of the drop block, h is the height of the compacted packing, and ρ is the packing density.
Precision Indicators
According to EN 1097-4, the repeatability of this test is 4.5% and the reproducibility is 5%. This means that repeated tests by the same operator under the same conditions should yield results that differ by no more than 4.5%, and that test results between different laboratories should differ by no more than 5%.
Standard Implementation Recommendations and Quality Control
To ensure the reliability of test results, laboratories should establish a comprehensive quality management system that complies with the requirements of AASHTO R18. Operators must undergo professional training and be familiar with instrument operation details and potential sources of error.
Common Problems and Solutions
Filler migration along the cylinder wall is a common problem during testing. Ensure that the gap between the plunger and the drop block meets the standard, and insert the plunger slowly and evenly. The stability of the test environment temperature significantly affects the results, so testing in a temperature-controlled laboratory is recommended.
Engineering Application Value
The void ratio of the filler directly affects the volumetric properties and durability of the asphalt mixture. An appropriate void ratio ensures that the filler can effectively absorb asphalt, forming a stable mortar system and avoiding mixture performance issues caused by excessive or insufficient asphalt.
Standard Technology Evolution and Comparative Analysis
The AASHTO T 409-231 standard originated from the interim standard TP 117 and will be officially released as a full standard in 2023. It shares the same core principles with the European standard EN 1097-4, but there are minor differences in instrument details and operational procedures.
Standard comparison dimensions AASHTO T 409-231 EN 1097-4 Technical consistency Impact height 102±1mm 100±1mm Basically consistent Number of impacts 100 times 100 times Completely consistent Filling mass 10±1g 10±0.1g More stringent quality requirements Precision indicators Reference to EN standards Original standard setter Consistent data source The technical innovation of this standard lies in the precise specification of instrument components and the refinement of operating procedures, which improves the repeatability of tests and the comparability between laboratories. In particular, the tolerance control of key dimensions of the Rigden instrument ensures the reliability of test results.
AASHTO T 409-2023 Referenced Document
- AASHTO M 339M/M 339 Standard Specification for Thermometers Used in the Testing of Construction Materials*， 2024-05-19 Update
- AASHTO R 18 Establishing and Implementing a Quality Management System for Construction Materials Testing Laboratories
- IEC 60584-1 Thermocouples - Part 1: Ed. 3.0: EMF specifications and tolerances
AASHTO T 409-2023 history
- 2023 AASHTO T 409-2023 Determination of the Voids of Dry Compacted Filler
