CN105092451A - Method for predicting void ratio of asphalt mixture - Google Patents

Abstract

The invention discloses a method for predicting the void ratio of an asphalt mixture. The method includes the steps that scanning is carried out in the height direction of a to-be-tested asphalt mixture test piece, and corresponding section coverage scanning information is obtained after hierarchical processing is carried out; the asphalt mixture test piece single-layer calculation void ratios corresponding to all single layers and the whole calculation void ratio of the to-be-tested asphalt mixture test piece are calculated; the to-be-tested asphalt mixture test piece is sequentially divided into a plurality of sections in the height direction, and the section void ratios corresponding to all the sections are calculated; section contribution values of the section void ratios of the sections to the whole calculation void ratio of the to-be-tested asphalt mixture test piece are respectively calculated; a prediction model for the whole calculation void ratio of the to-be-tested asphalt mixture test piece is built according to the relationship between the section contribution values and the whole calculation void ratio of the to-be-tested asphalt mixture test piece. According to the method, the whole void ratio of the asphalt mixture is predicted through part of void characteristic information of the asphalt mixture, a person does not need to collect and process all the void characteristic information, the parameter calculation process is easy and convenient, and the calculation efficiency is improved.

Description

A kind of Air Voids of Asphalt Mixtures Forecasting Methodology

Technical field

The present invention relates to a kind of Air Voids of Asphalt Mixtures Forecasting Methodology, relate to a kind of Air Voids of Asphalt Mixtures Forecasting Methodology based on X-rayCT technology specifically.

Background technology

At present, the method obtaining asphalt two dimensional image has a lot, and comparatively conventional is adopt based on X-rayCT technical limit spacing asphalt two dimensional image, and analyzes accordingly as Air Voids of Asphalt Mixtures has done more work.But on the one hand because two-dimensional ct scan image cannot reduce the true form of space in asphalt inner structure, the precision of therefore voidage prediction becomes the subject matter of puzzlement researchist; On the other hand, adopt the method for carrying out layering CT scan along bitumen mixture specimen short transverse, to improve the precision of CT scan, namely the precision of CT layered shaping (number of plies of layering increases) is needed to improve, to obtain more real Air Voids of Asphalt Mixtures, as existing research adopt along the every 1mm of short transverse be 1 scanning aspect, if making 0.1mm into is 1 scanning aspect, then improve 10 times, and such successive image Treatment Analysis efficiency becomes problem.Therefore on the basis of improving CT scan precision, how to improve analytical calculation efficiency, and then realize Air Voids of Asphalt Mixtures prediction and more become a difficult problem.

Summary of the invention

In view of the defect that prior art exists, the object of the invention is to provide a kind of Air Voids of Asphalt Mixtures Forecasting Methodology based on X-rayCT technology, this Forecasting Methodology has the high and parameter of computational accuracy and calculates easy, counting yield advantages of higher.

To achieve these goals, technical scheme of the present invention:

A kind of Air Voids of Asphalt Mixtures Forecasting Methodology, is characterized in that:

Comprise the steps

1., adopt X-rayCT scanner to scan along the short transverse of bitumen mixture specimen to be measured, and acquisition scanning information is carried out layered shaping, to obtain section layer scanning information corresponding to each individual layer of bitumen mixture specimen to be measured;

2., based on the distribution of the inner each component of described bitumen mixture specimen, the section layer scanning information corresponding according to each individual layer of above-mentioned bitumen mixture specimen to be measured, calculates bitumen mixture specimen individual layer corresponding to each individual layer of bitumen mixture specimen to be measured and calculates voidage and overall calculation voidage;

3., the bitumen mixture specimen to be measured obtained through layered shaping is divided into some sections successively along the short transverse of test specimen, calculate each section of corresponding section voidage, described section of voidage calculates voidage mean value by calculating bitumen mixture specimen individual layer that in each section, each individual layer is corresponding obtains;

4. the section voidage, calculating each section is respectively relative to the section contribution margin of bitumen mixture specimen overall calculation voidage to be measured; And using the evaluation index of the ratio of each described section of contribution margin and bitumen mixture specimen overall calculation voidage to be measured as the section voidage and bitumen mixture specimen overall calculation voidage relation to be measured of evaluating each section, wherein each described section of contribution margin refers to the product of the total number of plies number percent of test specimen shared by the number of plies that each section of corresponding section voidage is corresponding with the individual layer section layer that each section comprises, i.e. the shared total number of plies number percent=section contribution margin of the number of plies in section voidage × section;

5., according to the relation of each described section of contribution margin and bitumen mixture specimen overall calculation voidage to be measured, set up the forecast model of bitumen mixture specimen overall calculation voidage to be measured, realize the prediction to bitumen mixture specimen overall calculation voidage to be measured.

Further, described step 1. described in layered shaping refer to, based on digital image processing method, scanning information corresponding for bitumen mixture specimen to be measured be evenly divided into some layers of individual layer; And after separating the layers by scanning information corresponding for described bitumen mixture specimen to be measured from top ground floor individual layer from top to bottom and reject the individual layer of some from bottom to top respectively from bottom ground floor individual layer; The rejecting quantity of concrete individual layer carries out unrestricted choice by tester in conjunction with layering quantity, is as the criterion not affect result of calculation.

Further, 2. described step comprises following process:

Based on the distribution of the inner each component of described bitumen mixture specimen, the section layer scanning information corresponding according to each individual layer of above-mentioned bitumen mixture specimen to be measured, calculates as follows,

$\underset{k=1}{\overset{K}{\Σ}}{A}_{kki}+\underset{l=1}{\overset{L}{\Σ}}{A}_{jli}+\underset{m=1}{\overset{M}{\Σ}}{A}_{smi}=A_{ki}+A_{ji}+A_{si}=A_{ep}$

(k＝1,2,3,......,K；l＝1,2,3,......,L；m＝1,2,3,......,M)(1)

In formula (1), K is the summation of individual layer section layer internal pore quantity, and L is the summation of coarse aggregate quantity in individual layer section layer, and M is the summation of mortar quantity in individual layer section layer, A _epfor the useful area in individual layer section layer, A _kibe the void area of the i-th layer cross section layer, A _jibe the area of coarse aggregate in the i-th layer cross section layer, A _sibe the area of mortar in the i-th layer cross section layer, A _jlibe the area of l coarse aggregate in the i-th layer cross section layer, A _smibe the area of m mortar in the i-th layer cross section layer, A _kkiit is the area value in a kth space in the i-th layer cross section layer;

Simultaneously based on the section layer scanning information that each individual layer of above-mentioned bitumen mixture specimen to be measured is corresponding, digital image processing method is utilized to calculate void area corresponding to each individual layer of bitumen mixture specimen to be measured and A _ki, and utilize following formula (2) to calculate the voidage VV of bitumen mixture specimen to be measured, namely

$VV==\underset{i=1}{\overset{n}{\Σ}}{\mathrm{VV}}_i=\underset{i=1}{\overset{n}{\Σ}}\left(\frac{A_{ki}}{A_{ep}}\right)=\underset{i=1}{\overset{n}{\Σ}}\left(\frac{\underset{k=1}{\overset{K}{\Σ}}{A}_{kki}}{A_{ep}}\right)---\left(2\right)$

(i＝1,2,3,......,n；k＝1,2,3,......,K)

In formula (2), VV is the voidage of bitumen mixture specimen to be measured or is called overall calculation voidage; VV _ifor bitumen mixture specimen to be measured i-th layer cross section layer after short transverse layering voidage or be called individual layer calculate voidage; N is the total number of plies of bitumen mixture specimen to be measured along short transverse layering.

Further, 3. the bitumen mixture specimen to be measured obtained through layered shaping is divided into 3 sections along short transverse by described step successively, is followed successively by tip portion, center section and bottom part and calculates the section voidage D that namely section voidage corresponding to various piece calculate tip portion respectively _top, center section section voidage D _middlewith the section voidage D of bottom part _bottom;

Describedly the step of 3 sections is divided into comprise successively along short transverse the bitumen mixture specimen to be measured obtained through layered shaping

(1) from the 1st layer of figure layer cross section, successively contrast individual layer corresponding to every one deck layer cross section of bitumen mixture specimen to be measured from top to bottom and calculate voidage and overall calculation voidage, when the individual layer calculating voidage of a layer figure layer cross section is equal to or less than overall calculation voidage, the individual layer of record (a-1) layer figure layer cross section calculates voidage P;

(2) from last one deck layer cross section, successively contrast individual layer corresponding to every one deck layer cross section of bitumen mixture specimen to be measured from bottom to top and calculate voidage and overall calculation voidage, when the individual layer calculating voidage of b layer figure layer cross section is equal to or less than overall calculation voidage, the individual layer of record (b-1) layer cross section calculates voidage Q;

(3) utilize statistic law to calculate and calculate voidage maximal value R from a layer figure layer cross section to the individual layer within the scope of b layer figure layer cross section;

(4) initial layers that tip portion, center section and bottom part are corresponding and stop layer is judged namely

If a P > is R, then think that tip portion initial layers is the 1st layer of figure layer cross section, stop layer is (a-1) layer figure layer cross section; If P < is R, then need again from the 1st layer of figure layer cross section, successively contrast individual layer corresponding to every one deck layer cross section of bitumen mixture specimen to be measured from top to bottom and calculate voidage and R value, when the individual layer calculating voidage of generation a1 layer figure layer cross section is equal to or less than R value, then think that the initial layers of tip portion is the 1st layer, stop layer is (a1-1) layer;

If b Q > is R, then think that the initial layers of bottom part is (b-1) layer figure layer cross section, stop layer is last one deck layer cross section; If Q < is R, then need from last one deck layer cross section, successively contrast individual layer corresponding to every one deck layer cross section of bitumen mixture specimen to be measured from bottom to top and calculate voidage and R value, when the individual layer calculating voidage of b1 layer figure layer cross section is equal to or less than R value, can think that the initial layers of bottom part is (b1-1) layer figure layer cross section, stop layer is last one deck layer cross section;

The initial layers of c, center section is that the termination number of plies of the tip portion that step a judges adds 1, and stop layer is that the initial number of plies of the bottom part that step b judges subtracts 1.

Further, calculate the section contribution margin that each section of tip portion, center section and bottom part is corresponding respectively, i.e. top contribution margin, middle-end contribution margin and bottom contribution margin, by the ratio D of each described section of contribution margin and bitumen mixture specimen overall calculation voidage to be measured _gjevaluation index as the section voidage and bitumen mixture specimen overall calculation voidage relation to be measured of evaluating each section is

D _gj=section contribution margin/overall calculation voidage=(in section voidage × section the shared total number of plies number percent of the number of plies)/overall calculation voidage

As from the foregoing, D _gjthe size of value represents that each section of contribution margin is to the influence degree of overall calculation voidage value, and the larger influence degree of numerical value is larger.

Further, experimentally analyze known, middle part contribution margin is maximum to overall calculation voidage influence degree, therefore study the number of plies percentage of center section and the space distribution of center section voidage most important to the change controlling overall calculation voidage, therefore 5. select middle-end contribution margin to carry out modeling to improve computational analysis efficiency and described forecast model is

Predicted entire calculates voidage=(in center section voidage × center section the shared total number of plies number percent of the number of plies)/center section D _gjpredicted value

Wherein, described center section D _gjpredicted value is have center section D corresponding to the bitumen mixture specimen of the same type of more than three and three of identical starting condition _gjthe mean value of value, the predicted entire voidage of the bitumen mixture specimen of the same type under all identical starting condition can adopt above-mentioned formulae discovery, namely only need to calculate the shared total number of plies number percent of the number of plies in center section voidage × center section, without the need to whole characteristic informations in acquisition and processing space.

Compared with prior art, beneficial effect of the present invention:

Adopt the present invention of said method can utilize asphalt portion void characteristic information Prediction of Asphalt Mixture overall clearance rate, without the need to whole characteristic informations in acquisition and processing space, test period and testing expenses are saved with this, and parameter is few in Forecasting Methodology, the computation process of parameter is easy, effectively improves counting yield.

Accompanying drawing explanation

Fig. 1 is flow chart of steps corresponding to Air Voids of Asphalt Mixtures Forecasting Methodology of the present invention;

Fig. 2 a is the bitumen mixture specimen individual layer layer scanning information schematic diagram after the layering of inventing described specific embodiment-correspondence;

Fig. 2 b is the bitumen mixture specimen entire scan information schematic diagram after the layering of inventing described specific embodiment-correspondence;

Fig. 3 is the distribution schematic diagram of the inner each component of the described bitumen mixture specimen of invention;

Fig. 4 divides tripartite effect schematic diagram for inventing described bitumen mixture specimen to be measured along short transverse.

In figure: G, height of specimen direction, G _{cross section}, cross section, height of specimen direction, X, space, Y, coarse aggregate, Z, mortar.

Embodiment

In order to make object of the present invention, technical scheme and advantage clearly understand, below in conjunction with accompanying drawing, the present invention is further elaborated.

Below in conjunction with specific embodiment and Fig. 1, technical scheme of the present invention is described further:

One, X-rayCT scanner is adopted to scan all types bitumen mixture specimen in this test, obtain bitumen mixture specimen scanning information, and bitumen mixture specimen scanning information is divided into 690 layer cross sections along short transverse by Applied Digital image procossing (DIP) technology, the actual (real) thickness of every layer cross section is 0.09mm, namely 11 layer cross sections are comprised along the every 1mm in height of specimen direction, as shown in Fig. 2 a and Fig. 2 b, the object of this step is that the numerical information contained by CT image obtained due to CT scan does not possess study condition, therefore need to utilize digital image processing techniques to process the CT image obtained, and then identify and extract the asphalt inner structural features information comprised in image.

In Digital Image Processing process, reject each 5 incomplete layer of information at bitumen mixture specimen top and two ends, bottom simultaneously, less owing to rejecting layer count, reject in this example that layer count accounts for amount of images 1.4%, therefore reject layer process to have an impact to the result of test, and improve the integrality of data.

The distribution of the inner each component of the described bitumen mixture specimen two, according to Fig. 3, the section layer scanning information corresponding according to each individual layer of above-mentioned bitumen mixture specimen to be measured, calculates bitumen mixture specimen individual layer corresponding to each individual layer of bitumen mixture specimen to be measured and calculates voidage and overall calculation voidage;

Comprise and calculating first as follows, specifically such as formula shown in (1):

$\underset{k=1}{\overset{K}{\&Sigma;}}{A}_{kki}+\underset{l=1}{\overset{L}{\&Sigma;}}{A}_{jli}+\underset{m=1}{\overset{M}{\&Sigma;}}{A}_{smi}=A_{ki}+A_{ji}+A_{si}=A_{ep}$

(k＝1,2,3,......,K；l＝1,2,3,......,L；m＝1,2,3,......,M)(1)

In formula (1), K is the summation of individual layer section layer internal pore quantity, and L is the summation of coarse aggregate quantity in individual layer section layer, and M is the summation of mortar quantity in individual layer section layer, A _epfor the useful area in individual layer section layer, A _kibe the void area of the i-th layer cross section layer, A _jibe the area of coarse aggregate in the i-th layer cross section layer, A _sibe the area of mortar in the i-th layer cross section layer, A _jlibe the area of l coarse aggregate in the i-th layer cross section layer, A _smibe the area of m mortar in the i-th layer cross section layer, A _kkiit is the area value in a kth space in the i-th layer cross section layer;

Simultaneously based on the section layer scanning information that each individual layer of above-mentioned bitumen mixture specimen to be measured is corresponding, utilize digital image processing method-void area local calculation method as A _kicomputing method namely calculate void area A corresponding to each individual layer of bitumen mixture specimen to be measured _ki, and utilize following formula (2) to calculate the voidage VV of bitumen mixture specimen to be measured, namely

$VV==\underset{i=1}{\overset{n}{\&Sigma;}}{\mathrm{VV}}_i=\underset{i=1}{\overset{n}{\&Sigma;}}\left(\frac{A_{ki}}{A_{ep}}\right)=\underset{i=1}{\overset{n}{\&Sigma;}}\left(\frac{\underset{k=1}{\overset{K}{\&Sigma;}}{A}_{kki}}{A_{ep}}\right)---\left(2\right)$

(i＝1,2,3,......,n；k＝1,2,3,......,K)

In formula (2), VV is the voidage of bitumen mixture specimen to be measured or is called overall calculation voidage; VV _ifor bitumen mixture specimen to be measured i-th layer cross section layer after short transverse layering voidage or be called individual layer calculate voidage; N is the total number of plies of bitumen mixture specimen to be measured along short transverse layering.

It should be noted that: in the process of digital image processing method, usually adopt the number of pixel to represent A _epcalculated value, its value is relevant to surveying the diameter of bitumen mixture specimen, in view of the equal diameters of survey bitumen mixture specimen adopting forming method of the same race, the therefore A of forming method test specimen of the same race _epbe worth identical.

Three, preferably segmented version is that the bitumen mixture specimen to be measured obtained through layered shaping is divided into three parts successively along short transverse: tip portion, center section and bottom part.In order to state division methods more clearly, following noun is defined: the section voidage D of (1) tip portion _top: all individual layers of bitumen mixture specimen tip portion to be measured calculate the mean value of voidage; (2) the section voidage D of center section _middle: all individual layers of bitumen mixture specimen center section to be measured calculate the mean value of voidage; (3) the section voidage D of bottom part _bottom: all individual layers of bitumen mixture specimen bottom part to be measured calculate the mean value of voidage;

The segmentation method of described tip portion, center section and bottom part is with reference to figure 4, concrete steps are: (1) is from the 1st layer of figure layer cross section, namely successively contrast individual layer corresponding to every one deck layer cross section of bitumen mixture specimen to be measured from top to bottom by ascending order and calculate voidage and overall calculation voidage, when the individual layer calculating voidage of discovery a layer figure layer cross section is equal to or less than overall calculation voidage, the individual layer of record (a-1) layer figure layer cross section calculates voidage P;

(2) from last one deck layer cross section-680 layer cross section, namely successively contrast individual layer corresponding to every one deck layer cross section of bitumen mixture specimen to be measured from bottom to top by descending and calculate voidage and overall calculation voidage, when the individual layer calculating voidage of discovery b layer figure layer cross section is equal to or less than overall calculation voidage, the individual layer of record (b-1) layer cross section calculates voidage Q;

(3) utilize statistic law to calculate and calculate voidage maximal value R from a layer figure layer cross section to the individual layer within the scope of b layer figure layer cross section;

(4) initial layers that tip portion, center section and bottom part are corresponding and stop layer is judged namely

If a P > is R, then think that tip portion initial layers is the 1st layer of figure layer cross section, stop layer is (a-1) layer figure layer cross section; If P < is R, then need again from the 1st layer of figure layer cross section, successively contrast individual layer corresponding to every one deck layer cross section of bitumen mixture specimen to be measured from top to bottom and calculate voidage and R value, when the individual layer calculating voidage of generation a1 layer figure layer cross section is equal to or less than R value, then think that the initial layers of tip portion is the 1st layer, stop layer is (a1-1) layer;

If b Q > is R, then think that the initial layers of bottom part is (b-1) layer figure layer cross section, stop layer is last one deck layer cross section-680 layer cross section; If Q < is R, then need from the 680th layer cross section, successively contrast individual layer corresponding to every one deck layer cross section of bitumen mixture specimen to be measured from bottom to top and calculate voidage and R value, when the individual layer calculating voidage of b1 layer figure layer cross section is equal to or less than R value, can think that the initial layers of bottom part is (b1-1) layer figure layer cross section, stop layer is the 680th layer cross section;

The initial layers of c, center section is that the termination number of plies of the tip portion that step a judges adds 1, and stop layer is that the initial number of plies of the bottom part that step b judges subtracts 1.

Four, the product of the section voidage D top of the tip portion of bitumen mixture specimen to be measured and top number of plies percentage is defined as the contribution margin of tip portion to overall calculation voidage, is called for short " top contribution margin "; In like manner, define " middle-end contribution margin " and " bottom contribution margin " voidage characteristic parameter, the computing formula of each section of contribution margin is shown below,

Section voidage D _topthe shared total number of plies number percent=top contribution margin of the number of plies in × tip portion

Section voidage D _middlethe shared total number of plies number percent=middle-end contribution margin of the number of plies in × center section

Section voidage D _bottomthe shared total number of plies number percent=bottom contribution margin of the number of plies in × bottom part

Utilize the ratio D by each described section of contribution margin and bitumen mixture specimen overall calculation voidage to be measured _gjas the evaluation section voidage of each section and the evaluation index of bitumen mixture specimen overall calculation voidage relation to be measured, from following formula

Tip portion D _gj=top contribution margin/overall calculation voidage=(section voidage D _topthe shared total number of plies number percent of the number of plies in × tip portion)/overall calculation voidage;

Center section D _gj=middle-end contribution margin/overall calculation voidage=(section voidage D _middlethe shared total number of plies number percent of the number of plies in × center section)/overall calculation voidage;

Tip portion D _gj=bottom contribution margin/overall calculation voidage=(section voidage D _bottomthe shared total number of plies number percent of the number of plies in × bottom part)/overall calculation voidage;

Can find out, each D _gjthe size of value represents that each section of contribution margin is to the influence degree of overall calculation voidage value, and the larger influence degree of numerical value is larger.Meanwhile, according to the definition of contribution margin, D _gjthe size of value also characterize the shared total number of plies number percent of each section of number of plies comprised and each section calculate voidage jointly to the influence degree of overall calculation voidage.

Five, experimentally analyze known, middle part contribution margin is maximum to overall calculation voidage influence degree, therefore study the number of plies percentage of center section and the space distribution of center section voidage most important to the change controlling overall calculation voidage, therefore 5. select middle-end contribution margin to carry out modeling to improve computational analysis efficiency and described forecast model is

Predicted entire calculates voidage=(in center section voidage × center section the shared total number of plies number percent of the number of plies)/center section D _gjpredicted value

Wherein, described center section D _gjpredicted value is the center section D that the bitumen mixture specimen of the same type with more than three and three of identical starting condition that calculated by above-mentioned steps is in advance corresponding _gjthe mean value of value, the predicted entire voidage of the bitumen mixture specimen of the same type under all identical starting condition can adopt above-mentioned formulae discovery, namely only need to calculate the shared total number of plies number percent of the number of plies in center section voidage × center section in the predicted entire voidage of carrying out bitumen mixture specimen of the same type, center section D _gjpredicted value is by center section D corresponding to precalculated some bitumen mixture specimens of the same type _gjthe mean value of value obtains, and obtains without the need to repeating whole calculation procedure again the predicted entire voidage that whole characteristic information can dope current bitumen mixture specimen.

The above; be only the present invention's preferably embodiment; but protection scope of the present invention is not limited thereto; anyly be familiar with those skilled in the art in the technical scope that the present invention discloses; be equal to according to technical scheme of the present invention and inventive concept thereof and replace or change, all should be encompassed within protection scope of the present invention.

Claims (6)

1. an Air Voids of Asphalt Mixtures Forecasting Methodology, is characterized in that:

Comprise the steps

1., adopt X-rayCT scanner to scan along the short transverse of bitumen mixture specimen to be measured, and acquisition scanning information is carried out layered shaping, to obtain section layer scanning information corresponding to each individual layer of bitumen mixture specimen to be measured;

2., based on the distribution of the inner each component of described bitumen mixture specimen, the section layer scanning information corresponding according to each individual layer of above-mentioned bitumen mixture specimen to be measured, calculates bitumen mixture specimen individual layer corresponding to each individual layer of bitumen mixture specimen to be measured and calculates voidage and overall calculation voidage;

3., the bitumen mixture specimen to be measured obtained through layered shaping is divided into some sections successively along short transverse, calculate each section of corresponding section voidage, described section of voidage calculates voidage mean value by calculating bitumen mixture specimen individual layer that in each section, each individual layer is corresponding obtains;

4. the section voidage, calculating each section is respectively relative to the section contribution margin of bitumen mixture specimen overall calculation voidage to be measured; And using the evaluation index of the ratio of each described section of contribution margin and bitumen mixture specimen overall calculation voidage to be measured as the section voidage and bitumen mixture specimen overall calculation voidage relation to be measured of evaluating each section, wherein each described section of contribution margin refers to the product of the number of plies percentage that each section of corresponding section voidage is corresponding with the individual layer section layer that each section comprises, i.e. the shared total number of plies number percent=section contribution margin of the number of plies in section voidage × section;

5., according to the relation of each described section of contribution margin and bitumen mixture specimen overall calculation voidage to be measured, set up the forecast model of bitumen mixture specimen overall calculation voidage to be measured, realize the prediction to bitumen mixture specimen overall calculation voidage to be measured.

2. Air Voids of Asphalt Mixtures Forecasting Methodology according to claim 1, is characterized in that:

Described step 1. described in layered shaping refer to, based on digital image processing method, scanning information corresponding for bitumen mixture specimen to be measured be divided into some layers of individual layer; And after separating the layers by scanning information corresponding for described bitumen mixture specimen to be measured from top ground floor individual layer from top to bottom and reject the individual layer of some from bottom to top respectively from bottom ground floor individual layer.

3. Air Voids of Asphalt Mixtures Forecasting Methodology according to claim 2, is characterized in that:

2. described step comprises following process

Based on the distribution of the inner each component of described bitumen mixture specimen, the section layer scanning information corresponding according to each individual layer of above-mentioned bitumen mixture specimen to be measured, calculates as follows,

$\underset{k=1}{\overset{K}{\&Sigma;}}{A}_{kki}+\underset{l=1}{\overset{L}{\&Sigma;}}{A}_{jli}+\underset{m=1}{\overset{M}{\&Sigma;}}{A}_{smi}=A_{ki}+A_{ji}+A_{si}=A_{ep}$

(k＝1,2,3,......,K；l＝1,2,3,......,L；m＝1,2,3,......,M)(1)

In formula (1), K is the summation of individual layer section layer internal pore quantity, and L is the summation of coarse aggregate quantity in individual layer section layer, and M is the summation of mortar quantity in individual layer section layer, A _epfor the useful area in individual layer section layer, A _kibe the void area of the i-th layer cross section layer, A _jibe the area of coarse aggregate in the i-th layer cross section layer, A _sibe the area of mortar in the i-th layer cross section layer, A _jlibe the area of l coarse aggregate in the i-th layer cross section layer, A _smibe the area of m mortar in the i-th layer cross section layer, A _kkiit is the area value in a kth space in the i-th layer cross section layer;

Simultaneously based on the section layer scanning information that each individual layer of above-mentioned bitumen mixture specimen to be measured is corresponding, digital image processing method is utilized to calculate void area corresponding to each individual layer of bitumen mixture specimen to be measured and A _ki, and utilize following formula (2) to calculate the voidage VV of bitumen mixture specimen to be measured, namely

$VV==\underset{i=1}{\overset{n}{\&Sigma;}}{\mathrm{VV}}_i=\underset{i=1}{\overset{n}{\&Sigma;}}\left(\frac{A_{ki}}{A_{ep}}\right)=\underset{i=1}{\overset{n}{\&Sigma;}}\left(\frac{\underset{k=1}{\overset{K}{\&Sigma;}}{A}_{kki}}{A_{ep}}\right)---\left(2\right)$

(i＝1,2,3,......,n；k＝1,2,3,......,K)

In formula (2), VV is the voidage of bitumen mixture specimen to be measured or is called overall calculation voidage; VV _ifor bitumen mixture specimen to be measured i-th layer cross section layer after short transverse layering voidage or be called individual layer calculate voidage; N is the total number of plies of bitumen mixture specimen to be measured along short transverse layering.

4. Air Voids of Asphalt Mixtures Forecasting Methodology according to claim 3, is characterized in that:

3. the bitumen mixture specimen to be measured obtained through layered shaping is divided into some sections along short transverse by described step successively, calculate each section of corresponding section voidage, described section of voidage calculates voidage mean value by calculating bitumen mixture specimen individual layer that in each section, each individual layer is corresponding obtains;

3. the bitumen mixture specimen to be measured obtained through layered shaping is divided into 3 sections along short transverse by wherein said step successively, is followed successively by tip portion, center section and bottom part and calculates the section voidage D that namely section voidage corresponding to various piece calculate tip portion respectively _top, center section section voidage D _middlewith the section voidage D of bottom part _bottom;

Describedly the step of 3 sections is divided into comprise successively along short transverse the bitumen mixture specimen to be measured obtained through layered shaping

(1) from the 1st layer of figure layer cross section, successively contrast individual layer corresponding to the current layer cross section of bitumen mixture specimen to be measured from top to bottom and calculate voidage and overall calculation voidage, when the individual layer calculating voidage of a layer figure layer cross section is equal to or less than overall calculation voidage, the individual layer of record (a-1) layer figure layer cross section calculates voidage P;

(2) from last one deck layer cross section, successively contrast individual layer corresponding to the current layer cross section of bitumen mixture specimen to be measured from bottom to top and calculate voidage and overall calculation voidage, when the individual layer calculating voidage of b layer figure layer cross section is equal to or less than overall calculation voidage, the individual layer of record (b-1) layer cross section calculates voidage Q;

(3) utilize statistic law to calculate and calculate voidage maximal value R from a layer figure layer cross section to the individual layer within the scope of b layer figure layer cross section;

(4) initial layers that tip portion, center section and bottom part are corresponding and stop layer is judged namely

If a P > is R, then think that tip portion initial layers is the 1st layer of figure layer cross section, stop layer is (a-1) layer figure layer cross section; If P < is R, then need again from the 1st layer of figure layer cross section, successively contrast individual layer corresponding to the current layer cross section of bitumen mixture specimen to be measured from top to bottom and calculate voidage and R value, when the individual layer calculating voidage of generation a1 layer figure layer cross section is equal to or less than R value, then think that the initial layers of tip portion is the 1st layer, stop layer is (a1-1) layer;

If b Q > is R, then think that the initial layers of bottom part is (b-1) layer figure layer cross section, stop layer is last one deck layer cross section; If Q < is R, then need from last one deck layer cross section, successively contrast individual layer corresponding to the current layer cross section of bitumen mixture specimen to be measured from bottom to top and calculate voidage and R value, when the individual layer calculating voidage of b1 layer figure layer cross section is equal to or less than R value, can think that the initial layers of bottom part is (b1-1) layer figure layer cross section, stop layer is last one deck layer cross section;

The initial layers of c, center section is that the termination number of plies of the tip portion that step a judges adds 1, and stop layer is that the initial number of plies of the bottom part that step b judges subtracts 1.

5. Air Voids of Asphalt Mixtures Forecasting Methodology according to claim 4, is characterized in that:

Calculate the section contribution margin that each section of tip portion, center section and bottom part is corresponding respectively, i.e. top contribution margin, middle part contribution margin and bottom contribution margin, by the ratio D of each described section of contribution margin and bitumen mixture specimen overall calculation voidage to be measured _gjevaluation index as the section voidage and bitumen mixture specimen overall calculation voidage relation to be measured of evaluating each section is

D _gj=section contribution margin/overall calculation voidage=(in section voidage × section the shared total number of plies number percent of the number of plies)/overall calculation voidage.

6. Air Voids of Asphalt Mixtures Forecasting Methodology according to claim 5, is characterized in that: 5. select middle part contribution margin to carry out modeling to improve computational analysis efficiency and described forecast model is

Predicted entire calculates voidage=(in center section voidage × center section the shared total number of plies number percent of the number of plies)/center section D _gjpredicted value

Wherein, described center section D _gjpredicted value is have center section D corresponding to the bitumen mixture specimen of the same type of more than three and three of identical starting condition _gjthe mean value of value.