Gross volume density test

Asphalt mixture gross volume density refers to the dryness of the compacted asphalt mixture unit volume (including the total mineral volume of the mixture and the closed pores that do not absorb moisture, the open pores that can absorb moisture, and the total gross volume surrounded by the particle surface contour) quality. The gross bulk density is an important indicator of the mix design of asphalt mixture and the quality control of asphalt pavement. It directly determines the oil-stone ratio of the mixture design and the compactness of the pavement.

Domestic gross bulk density test method

There are four kinds of density test methods specified in "JTG E20-2011 Highway Engineering Asphalt and Asphalt Mixture Test Regulations":

1

Water weight method (T0706-2011)

The water weight method is used to determine the apparent relative density or apparent density of densely graded asphalt mixture specimens that hardly absorb water. The basic principle is that the volume of an object is equal to its missing weight in water.

Applicable conditions

Specimen water absorption rate <0.5%

European and American Land Analysis

1. Generally speaking, it is difficult for the asphalt mixture to achieve a water absorption rate of less than 0.5%;

2. The water density method measures the apparent density, not the gross bulk density, and the concepts do not match. Try to use it as little as possible.

2

Surface dry method (T0705-2011)

The surface dry method determines the relative density or gross volume density of the compacted asphalt mixture specimen, and uses this as a basis to calculate various volume indicators such as the porosity, saturation and mineral void ratio of the asphalt mixture specimen .

Applicable conditions

Specimen water absorption rate <2%

European and American Land Analysis

For large-pore mixtures, such as SMA, OGFC, etc., the open void is connected to the closed void, and water enters the closed void in the test piece. The measured volume is too small, resulting in a large gross bulk density.

3

Wax seal method (T0707-2011)

The wax seal method is used to determine the relative bulk density or gross bulk density of asphalt concrete or asphalt mixture specimens.

Applicable conditions

Specimen water absorption rate> 2%

European and American Land Analysis

The wax sealing method is time-consuming and wastes test pieces. It is difficult to operate, and there are too many human-induced factors, which leads to inaccurate data.

4

Volume method (T0708-2011)

Applicable conditions

Macroporous mixtures not suitable for surface drying and wax sealing

European and American Land Analysis

The volume measurement is not accurate and is generally not used.

summary

The water weight method, wax seal method and surface dry method all use the water replacement method to measure the gross volume of the test piece, but due to the water absorption of the test piece, the gap connection and human factors, etc., resulting in different test methods and different test personnel, the test results vary greatly .

When the volume method is used to measure the gross volume of a rough surface test piece, the measurement result is not accurate, so the frequency of use is not high.

So how to accurately measure the bulk density of the test piece?

And see the breakdown below

CoreLok test method

CoreLok in the US

1998

Instrotek's CoreLok Vacuum Density Tester test method was first used to measure the bulk density of open grade anti-slip wear layer (OGFC)

year 2002

Become ASTM / AASHTO prescribed test method

2000, 2001

Instrotek has upgraded more test functions of the CoreLok vacuum density tester, including:

Maximum theoretical density measurement

Aggregate density measurement

Porosity measurement

In the United States, CoreLok vacuum density tester has become a multi-purpose asphalt mixture measuring equipment.

CoreLok US usage map

Comparison with other gross volume testing methods

Comparison of four test method models

From the above comparison, it can be seen that the surface of the dry sample is too large, and water can penetrate into the real sample. The measured sample volume is low, resulting in a high bulk density of the compacted asphalt sample and a low porosity. ; The wax seal method closes the open gap, forming a dry state of the saturated surface, but when the paraffin melts and enters the event, the internal void leads to a small sample volume and a large calculation result of the gross volume density; the volume measurement method has a volume error; The sealing machine forms a state similar to the wax sealing method to prevent the penetration of moisture, which is a more convenient and accurate test method.

CoreLok VS traditional method

Through the establishment of regression equation analysis of porosity and permeability coefficient, the accuracy of Corelok's test density value is better than traditional test methods.

CoreLok porosity comparison

From the above comparison, it can be seen that the porosity is> 8%. Due to the penetration of water into the test piece, the SSD method cannot accurately measure the porosity; the porosity is less than 8%, and the porosity measured by the CoreLok method and the SSD method is within 3%.

CoreLok reproducibility comparison (average coefficient of variation of three test pieces)

From the above comparison, it can be seen that the test reproducibility of the CoreLok method is better than the other two methods. Among them, CoreLok method has the best reproducibility for testing open-graded asphalt mixture specimens. The volume method has the worst reproducibility.

summary

Corelok density testing meets the requirements of ASTM D6752 \ D6867 and has a high market share. The equipment is easy to operate, has a high degree of automation, fast testing, and accurate repeatability. It is an automatic vacuum packaging equipment specially designed for asphalt companies, scientific research units, universities and other relevant units for measuring the density of asphalt mixtures and gravel materials.

At present, the CoreLok test method has become the recommended test method in the new version of "JTG E20-2011 Highway Engineering Asphalt and Asphalt Mixture Test Regulations".

Introduction to CoreLok Vacuum Density Meter

The CoreLok Vacuum Density Tester from InstroTek Company of America can not only measure the relative gross density and maximum theoretical relative density of asphalt mixture, but also measure the apparent relative density, absorption rate and gross bulk density of coarse and fine aggregates.

It has the following advantages:

● High measurement efficiency. 5-10 minutes to complete the measurement of the bulk density of the test piece.

● The data repeatability and accuracy are good. Compared with the current surface dry method, wax seal measurement method, volume measurement method, the test results are closer to the true value.

● Simple operation. No need for calibration, special software calculation, test data operation is less affected by personnel.

● Multi-purpose measurement. The bulk density and porosity of the test piece, the maximum theoretical density of the mixture, and the aggregate density can all be measured.

Test steps:

American InstroTek company was founded in 1997, has 20 years of research and development experience and many high-tech talents, invented the world's first portable nuclear meter calibration device, the world's first automatic asphalt sealing equipment and can accurately measure its total density, etc., scientist He engineer has many national patents. The products developed by InstroTek are all over the world, and technological innovation is in the leading position in the industry, which is worthy of customers' choice.

Apron Tubs

Cast iron apron tubs need to be placed against the wall. This kind of tubs are beautiful and have good heat preservation. Cast iron bathtubs are also solid and easy to clean.

Apron Tubs,Bathtub Apron,Two Sided Apron Bathtub,Integral Apron Bathtub

Anping Sunshine Sanitary Ware Co., Ltd. , https://www.sunshinebathtubs.com