CN103163283A - Prediction method of cement asphalt mortar compressive strength - Google Patents

Abstract

Provided is a prediction method of cement asphalt mortar compressive strength. The method aims at shortening an ensured cement asphalt (CA) mortar proportioning cycle, and through a mechanism study and an experimental analysis, parameters which can hardly affect the strength are emitted. A mass ratio mW/mC of water use amount and cement use amount and a mass ratio mA/mC of asphalt use amount and the cement use amount are used as calculating parameters which finally can be used for quantitatively calculating the compressive strength of the CA mortar. According to the method, through utilization of the parameters provided by the CA mortar mix ratio, 28d compressive strength of the CA mortar can be conveniently and quickly predicted, and a prediction result has good reliability.

Description

A kind of Forecasting Methodology of cement asphalt mortar compressive strength

Technical field

The present invention relates to the Forecasting Methodology of cement asphalt mortar compressive strength, namely calculate the 28d compressive strength of cement asphalt mortar according to the match ratio situation of cement asphalt mortar.

Background technology

Cement asphalt mortar (CA mortar) is the key material of present high speed railway construction, plays the vital role of adjusting the track construction error and improving the train security of running at high speed and the comfortableness of taking.Compressive strength is the most basic mechanical performance index of cement asphalt mortar, is the basis of other all properties.The compressive strength of a cement asphalt mortar need to could be determined through the experimental period of 28d, if 28d compressive strength can not satisfy index request, just need to adjust match ratio, carry out again the test in next 28d cycle, and how to adjust match ratio and also be difficult for to grasp direction, therefore may need some 28d experimental period.This pattern may be incured loss through delay the progress of engineering greatly, reduces construction quality, causes significant wastage.

As everyone knows, the existing ripe compressive strength computing formula of cement concrete, reduced greatly the workload of Design of Cement Concrete Mixture Ratio, but at present the research of CA mortar strength only limited to the match ratio parameter to the qualitative analysis of intensity effect, still can not bring into play the effect of similar water cement concrete strength calculation formula.Therefore, the development of the prediction of strength method of CA mortar lags behind the development of CA mortar far away.

Summary of the invention

Purpose of the present invention is exactly long problem of solution test CA mortar compressive strength cycle, removes the worry of waiting for experimental period from, a kind of conveniently method is provided, by the match ratio parameter directly being calculated the method for cement asphalt mortar intensity, in the situation that known match ratio, can know the compressive strength of CA mortar.

By the mechanism research that the CA mortar strength is formed, find that the CA mortar remains the system that obtains intensity by hydrated cementitious, so, the mass ratio (m of water and cement _W/ m _C) still CA mortar compressive strength is played a decisive role.Mass ratio (m at coagulating cement soil water and cement _W/ m _C) determined the porosity in the Behavior of Hardened Cement Paste, thus cement strength determined.In the CA mortar, pitch is a kind of liquid phase material, does not react with other materials, and the compressive strength aspect is close to 0, so during pressurized, its mechanical property and hole approach; Pitch is a kind of lipophilicity material simultaneously, understands film forming in the CA mortar, thereby affects the aquation of cement, so the mass ratio (m of pitch and cement _A/ m _C) the intensity contribution of CA mortar not only is similar to m _W/ m _CThe effect relevant to porosity, so the also effect of influential aquation is for the intensity of CA mortar, m _A/ m _CTo compare m _W/ m _CMore significant influence factor.

The inventor has further studied various starting material consumptions and ratio to the impact of intensity by test again, by analyzing various parameters to the conspicuousness of CA mortar strength impact, got rid of wherein less to intensity effect or do not have an influential parameter, and combining with theoretical analysis, finally determined two calculating parameters of CA mortar compressive strength: the mass ratio m of pitch and cement _A/ m _CAnd the ratio m of water consumption and cement _W/ m _CNot remarkable though other parameter is influential, therefore in order to facilitate the computational short cut model, do not classify these parameters as calculating parameter.

According to above-mentioned analysis, the invention provides a kind of Forecasting Methodology of cement asphalt mortar compressive strength, do not carry out for only providing match ratio in the situation of 28d compressive strength experiment, the 28d compressive strength of cement asphalt mortar being predicted, it is characterized in that:

Mass ratio m with water consumption and cement consumption _W/ m _CAnd the mass ratio m of asphalt content and cement consumption _A/ m _CAs calculating parameter, computing formula is:

c·lnf＝y-a(m _A/m _C)-b(m _W/m _C)

In aforesaid equation, f is prediction of strength value to be asked, and coefficient y, a, b, c are constant; Wherein the value of c is relevant to cement 28d compressive strength, and cement 28d intensity test method is according to GB/T17661-1999; When if strength of cement is 57.2MPa, c=1, as benchmark, working as this cement 28d compressive strength is f _CThe time, c=4.047/lnf _CLacking 28d cement observed strength data f _CThe time, c=4.047/lnf _mf _mBe the strength of cement grade.The definition of strength grade as conch PII52.5 cement, wherein 52.5 namely represents the strength of cement grade with reference to standards such as GB175-1999, GB1344-1999, GB12958-1999.

The value of y, a, these three constants of b is only relevant to concrete curing temperature, loading velocity.

Again because all there is certain scope in standard to the requirement of various test conditions, be not absolute, be 50～500N/S as loading velocity, time to rupture is 30～90S, curing temperature also allows ± error of 2 ℃, also may there be certain difference in material quality, especially has specific (special) requirements, needs to carry out special experiment system.Therefore, the numerical value of y, a, b is determined by least square method according to the match ratio data of cement asphalt mortar more than three groups and the result of intensity test experiment; And increase tested number and can increase the correction degree of accuracy; Described cement asphalt mortar intensity test experimental technique comprises that its blanks and moulding and conserving system is according to not limiting a certain specific criteria, but must meet the following conditions: in accordance with same standard, and parallel experiment amount on the same group and data processing should be satisfied the requirement of GB/T17661-1999 for the final actual intensity test method of carrying out of match ratio institute of revising strength test that constant carries out and predicted intensity; After c, y, a, b determine, can use equation that compressive strength is predicted.

When curing temperature be 20 ℃, when loading velocity is 400N/S, the numerical value of y, a, b, c is 4.538,4.679,1.271 and 4.047/lnf _C

When curing temperature is that 20 ℃, loading velocity are 400N/S, and lacking 28d cement observed strength data f _CThe time, the numerical value of y, a, b, c is 4.538,4.679,1.271 and 4.047/lnf _m, f _mBe the strength of cement grade.The definition of strength grade as conch PII52.5 cement, wherein 52.5 namely represents the strength of cement grade with reference to standards such as GB175-1999, GB1344-1999, GB12958-1999.

Whether need to carry out the actual conditions that this aligning step depends on the selected starting material of testing department and test system.

The present invention has realized the Accurate Prediction to CA mortar compressive strength, has higher reliability.

Embodiment

Below in conjunction with instructions, invention is further illustrated, but protection domain of the presently claimed invention is not limited to the scope that embodiment describes.

The cement type that uses in each embodiment and strength grade, for the preparation of the asphalt variety of emulsified asphalt, and various amounts of components is as shown in table 1.

Table 1 experiment starting material and match ratio

Annotate: m _sQuality for sand.

In the embodiment specific implementation process, will according to the match ratio that provides in table 1, converse two calculating parameter m hereinafter _W/ m _C, m _A/ m _CList in corresponding form.

Take embodiment 1～13 as example, little wild field PII52.5 cement 28d compressive strength measured value is 57.2MPa, conch PII52.5 cement 28d compressive strength measured value is 55.2MPa, conch PO42.5 cement 28d compressive strength measured value is 48.3MPa, during to this three kinds of cement, the value of c is respectively 1,1.009,1.0438.The method of testing (comprising the blanks and moulding and conserving system) of cement asphalt mortar 28d compressive strength intensity is carried out according to " No. [2008] 74, the provisional technical conditions science and technology of passenger dedicated railway line CRTS II plate-type non-fragment orbit cement asphalt mortar base ", and actual conditions is 20 ℃ of curing temperatures, loading velocity 400N/S.

First use little wild field PII52.5 cement, SK70# pitch to carry out following L ₉(3 ⁴) orthogonal test, the value of y, a, b is determined, because little wild field PII52.5 cement 28d actual measurement compressive strength is 57.2Mpa, this moment c=1.Orthogonal array is as shown in table 2.

Table 2 orthogonal array

As shown in table 3 according to match ratio and cement asphalt mortar 28d compressive strength result that orthogonal array arranges.

Table 3 orthogonal test calendar and test findings

Annotate: m _sQuality for sand.

According to least square method and theoretical equation cln/=y-a (m _A/ m _C)-b (m _W/ m _C) to quadrature

Experimental data returns, and regression process is as follows:

$\left\{\begin{array}{c}{l}_{11}a+l_{12}b+l_{10}=0\\ l_{21}a+l_{22}b+l_{20}=0\end{array}\right.$

Wherein:

$l_{11}=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{(m_{A_i}/m_{C_i}-\stackrel{\‾}{m_A/m_C})}^2;$

$l_{22}=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{(m_{W_i}/m_{C_i}-\stackrel{\‾}{m_W/m_C})}^2;$

$l_{12}=l_{21}=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}(m_{A_i}/m_{C_i}-\stackrel{\‾}{m_A/m_C})(m_{W_i}/m_{C_i}-\stackrel{\‾}{m_W/m_C});$

$l_{10}=\underset{i=0}{\overset{n}{\mathrm{\Σ}}}(m_{A_i}/m_{C_i}-\stackrel{\‾}{m_A/m_C})(\ln f_i-\stackrel{\‾}{\ln f});$

$l_{20}=\underset{i=0}{\overset{n}{\mathrm{\Σ}}}(m_{W_i}/m_{C_i}-\stackrel{\‾}{m_W/m_C})(\ln f_i-\stackrel{\‾}{\ln f});$

$\stackrel{\‾}{m_A/m_C}=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{m}_{A_i}/m_{C_i};\stackrel{\‾}{m_W/m_C}=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{m}_{W_i}/m_{C_i};\stackrel{\‾}{\ln f}=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\ln f_i.$

Constant term y is:

$y=\stackrel{\‾}{\ln f}+a\left(\stackrel{\‾}{m_A/m_C}\right)+b\left(\stackrel{\‾}{m_W/m_C}\right)$

Order $m_i=m_{A_i}/m_C-\stackrel{\‾}{m_A/m_C},$ $n_i=m_{W_i}/m_C-\stackrel{\‾}{m_W/m_C},$ $z_i=\ln f_i-\stackrel{\‾}{\ln f},$ Obtain the binary regression reckoner according to orthogonal experiments as shown in the table.

Table 4 binary regression reckoner

As seen from the above table, l ₀₀=∑ z _i ²=0.1673, l ₁₁=∑ m _i ²=0.0054, l ₂₂=∑ n _i ²=0.0216, l ₁₂=l ₂₁=∑ m _in _i=0, l ₁₀=∑ m _iz _i=-0.0252, l ₂₀=∑ n _iz _i=-0.0275.Therefore, the regression coefficient system of equations that should satisfy is:

$\left\{\begin{array}{c}0.0054\×a+0\×b-0.0252=0\\ 0\×a+0.0216\×b-0.0275=0\end{array}\right.$

Separating above system of equations gets:

a＝4.675，b＝1.271

Basis again $y=\stackrel{\‾}{\ln f}+a\left(\stackrel{\‾}{m_A/m_C}\right)+b\left(\stackrel{\‾}{m_W/m_C}\right),$ Can get: y=4.538

Under above-mentioned loading system, when strength of cement is f _CThe time, the numerical value of y, a, b, four constants of c is respectively 4.538,4.675,1.271 and (4.047/lnf _C), f wherein _CRepresent the actual measurement 28d intensity of cement.

Therefore, theoretical equation can be converted into following equation form:

lnf·(4.047/lnf _C)＝4.538-4.675(m _A/m _C)-1.271(m _W/m _C)

At this moment, according to match ratio substitution m _A/ m _C, m _W/ m _C, and the contemporary observed strength f that enters cement _C, can dope the intensity of specifying match ratio, predict the outcome and the observed strength data as shown in table 5.

Table 5 calculating parameter and predicted intensity and observed strength contrast

Embodiment	m W/m C	m A/m C	Predicted intensity/MPa	Observed strength/MPa
					1	0.7	0.9	0.5	2.0
2	0.5	0	47.7	51.1
					3	0.5	0	49.5	52.7
4	0.5	0	42.1	43.2

5	0.42	0.222	19.42	19.74
					6	0.42	0.252	16.88	18.20
7	0.42	0.282	14.67	17.25
					8	0.48	0.222	18.00	15.89
9	0.48	0.252	15.64	15.31
					10	0.48	0.282	13.59	13.96
11	0.54	0.222	16.67	14.84
					12	0.54	0.252	14.49	14.72
13	0.54	0.282	12.60	12.23

In table 5, the listed calculating parameter of embodiment 1 is m _A/ m _C, m _W/ m _CThe extreme case that ratio is very high; M in embodiment 2～embodiment 4 _A/ m _CBe 0 extreme case, and changed cement type, can see from the contrast of extreme case predicted intensity and observed strength, both relatively approach.In table 1, embodiment 5～embodiment 13 has contrasted by one group of orthogonal test and has predicted the outcome and measured result, and by the statistical study to above data, both related coefficients are up to 0.956, so prediction effect is more satisfactory.

As lack f _CThis experimental data, also available its strength grade f _mSubstitute.The definition of strength grade as conch PII52.5 cement, wherein 52.5 namely represents the strength of cement grade with reference to standards such as GB175-1999, GB1344-1999, GB12958-1999.

Embodiment 14～17 is that cement 28d compressive strength is unknown, and the identical situation of experiment system and execution example 1～13.In this situation, y, a, b value are constant, and the c value need be used cement strength grade f _mPlace of cement observed strength data are calculated, and when cement was respectively conch PII52.5 and PO42.5, the value of c was respectively 1.021,1.079.Predict the outcome thus as shown in table 6 below with the contrast of measured result.

Predicting the outcome of table 6 strength of cement grade place of cement observed strength

Embodiment	m W/m C	m A/m C	Predicted intensity/MPa	Observed strength/MPa
					14	0.58	0.31	10.0	11.2
15	0.53	0.28	12.2	13.5
					16	0.48	0.25	14.9	13.6
17	0.43	0.22	18.2	19.5

Data can be found out from table 6, and the intensity results of prediction and measured result are still more approaching, therefore substitute observed strength with strength grade, predict the outcome still more satisfactory.

When the loading system in the method for testing employing GB/T17671-1999 of observed strength, be 2.4KN/S, this moment the obvious impact prediction result of variation meeting of loading velocity and the matching of measured result, therefore need to test row coefficient y, a, b revises, and the c value is only relevant with cement 28d compressive strength, can dispose with reference to embodiment before.Be the experiment that correction factor carries out, in its test findings such as table 7, embodiment 18～22.

Table 7 coefficient correction experiment

Embodiment	m W/m C	n A/m C	Observed strength/MPa
				18	0.5	0	57.2
19	0.42	0.222	23.3
				20	0.54	0.252	17.0
21	0.54	0.282	14.3
				22	0.48	0.282	16.0

Use test parameters in embodiment 18～22 and result by least square method to lnf (0.247/lnf _C)=y-a (m _A/ m _C)-b (m _W/ m _C) in coefficient find the solution, the value that can draw y, a, b is respectively 5.122,4.562,2.297, the above-mentioned constant of substitution gets final product to such an extent that the equation that makes new advances is:

lnf·(4.047/lnf _C)＝5.122-4.562(m _A/m _C)-2.297(m _W/m _C)

Embodiment 23～26 is with the CA mortar strength of revised accounting equation prediction and the contrast of observed strength.

Table 8 update equation predicted intensity and observed strength contrast

Embodiment	Cement type and grade	m W/m C	m A/m C	Predicted intensity/MPa	Observed strength/MPa
						23	Little wild field PII52.5	0.4	0.4	10.8	9.5
24	Little wild field PII52.5	0.46	0.2	23.5	24.3
						25	Little wild field PII52.5	0.48	0.25	17.9	19.7
26	Little wild field PII52.5	0.40	0.30	17.1	16.3

As can be seen from the above table, revised equation has believable predictive ability to the measured result under New Terms.

In sum, the present invention has realized the Accurate Prediction to CA mortar compressive strength, has higher reliability.

Claims (3)

1. the Forecasting Methodology of a cement asphalt mortar compressive strength, do not carry out for only providing match ratio in the situation of 28d compressive strength experiment, the 28d compressive strength of cement asphalt mortar being predicted, it is characterized in that:

Mass ratio m with water consumption and cement consumption _W/ m _CAnd the mass ratio m of asphalt content and cement consumption _A/ m _CAs calculating parameter, computing formula is:

c·lnf＝y-a(m _A/m _C)-b(m _W/m _C)

In aforesaid equation, f is prediction of strength value to be asked, and coefficient y, a, b, c are constant; Wherein the value of c is relevant to cement 28d compressive strength, and cement 28d intensity test method is according to GB/T17661-1999; When if strength of cement is 57.2MPa, c=1, as benchmark, working as strength of cement is this cement 28d compressive strength f _CThe time, c=4.047/lnf _CF when lacking 28d cement observed strength data _C, c=4.047/lnf _m, f _mBe the strength of cement grade;

The value of y, a, these three constants of b is only relevant to concrete curing temperature, loading velocity;

The numerical value of y, a, b is determined by least square method according to the result of cement asphalt mortar intensity test experiment more than three groups; Described cement asphalt mortar intensity test experimental technique comprises that its blanks and moulding and conserving system does not limit a certain specific criteria, but must meet the following conditions: in accordance with same standard, and parallel experiment amount on the same group and data processing should be satisfied the requirement of GB/T17661-1999 for the final actual intensity test method of carrying out of match ratio institute of revising strength test that constant carries out and predicted intensity; After coefficient c, y, a, b determine, can use equation that compressive strength is predicted.

2. Forecasting Methodology as claimed in claim 1 is characterized in that:

When curing temperature be 20 ℃, when loading velocity is 400N/S, the numerical value of y, a, b, c is 4.538,4.679,1.271 and 4.047/lnf _C

3. Forecasting Methodology as claimed in claim 2 is characterized in that:

When curing temperature is that 20 ℃, loading velocity are 400N/S, and lacking 28d cement observed strength data f _CThe time, the numerical value of y, a, b, c is 4.538,4.679,1.271 and 4.047/lnf _m, f _mBe the strength of cement grade.