Analysis of Factors Affecting the Compressive Strength of Cement

Stabilized Crushed Stone Materials

MiaoYu

1

, Xiangguo Chang

1

and Shasha Chen

1

1

School of Highway

，

Chang’an University

，

Xi’an 710064

，

China

Keywords: Compressive strength；prediction；model database.

Abstract: The compressive strength of the cement stabilized macadam is one of the important parameters of design

and performance evaluation. But in the present study of mud stabilized macadam pavement structure

reasonable design and behavior analysis of strength did not realize the importance of parameter selection is

relatively insufficient. This study is based on the compressive strength of cement stabilized macadam

parameter selection as the research direction, by collecting both the compressive strength of the cement

stable macadam mixture, and modulus of the test data, Establishing database of strength , obtain various

parameters represent value under different reliability, analysis of curing age, different influence factors

such as cement dosage, and the compressive strength of the cement stable macadam mixture, Using the

mathematical regression method, the establishment of different curing age, under the condition of cement

dosage prediction equation, verified the established modulus of logarithm model has higher fitting precision,

can provide for pavement structure design and performance forecast value basis.

1 INTRODUCTION

Cement stabilized macadam base material is paving

the main bearing layer under the surface in the road

surface and at the grass-roots level, take on surface

transfer driving vertical load, and the load evenly

dispersed in the roadbed. Affected by various factors

such as construction technology and construction

environment, the influence of the easy occurrence

crack in cement stabilized base construction process,

segregation, partial loose, strength, smoothness and

other defects, which affect the quality of pavement,

caused the road all kinds of diseases.

In this study, the correlation between factors

such as cement dosage, curing age and compressive

strength was studied in this study. By comparing the

compressive strength under different conditions, the

strength prediction model was studied, and the

analysis intensity was influenced by different factors.

The values of compressive strength data are selected,

which can be used as reference for experiments .

2 DATA ANALYSIS OF

COMPRESSIVE STRENGTH TEXT

The compressive strength of cement stabilized

gravel is affected by many factors, and the data

distribution is analyzed from different influencing

factors.

(a) Curing age influence diagram

3456

4

5

6

7

8

Compress ive stren gth( MPa)

Cement co ntant(%)

90%

95%

97%

对照组

(b) Cement dosage influence diagram

Fig.1 Cement stabilized gravel unconfined aging

It can be seen from figure1 (a) that, from the

perspective of the curing age, the compressive

strength of the cement stabilized gravel is at 7d, the

data volume is 400 and 28 days, the data volume is

over 600, and the time of 90 days is 400. According

to the figure1 (b) from the cement dosage, the data

of the cement stabilized gravel is mainly

concentrated in 3%, 3.5%,4%,4.5%, and 5% of the

total amount, which is over 80%.

3 THE DATA OF COMPRESSIVE

STRENGTH IS DETERMINED

BY THE VALUE

3.1 Degree of Reliability

Influenced by many factors, the pavement material

parameters have a large variability, which has a

great influence on the performance and service life

of the road surface. At present, the pavement

structure design of the reliability of the generally

accepted the range of 80% to 99%, 90%, 95% and

97% this article selects three values of high

reliability, in order to get high credible degree of

intensity values.

3.2 Selection of Representative Values

Reliability design method is actually a probability

analysis method, based on the curve of the high level

of literature, comparing the reliability condition, and

the trend of cement dose intensity values along with

age more in line with the general rules, thus choose a

reliability represent value as a representative of the

final value. To static pressure molding condition, the

skeleton dense type stable macadam mixture, cement

dosage 4.5% when change with ages and ages for 90

d change with cement dosage of compressive

strength, for example, under the assurance rate 97%,

the compressive strength of the cement stable

macadam mixture, along with the change of age

trend is more in line with the general rules, namely

with the increase of age, and in the early days (0 ~ 7

d) mixture strength is growing rapidly, medium term

(7 ~ 28 d) increase trend becomes flat, the late (28 ~

180 d) more gently. In the same way, the

compressive strength of cement stabilized crushed

stone under the guarantee rate also conforms to the

general rule, that is, the relationship between

strength and dose is roughly a linear relationship.

Therefore, under the condition of static pressure

forming, the compressive strength of the solid

cement stabilized gravel mixture is selected as the

final representative value with the value of 97%

guarantee rate. If the representative value trend of

the three guarantee rates is consistent with the

general rule, the representative value of the 95%

guarantee rate is selected as the final value.

4 THE INFLUENCE FACTORS OF

UNCONFINED COMPRESSIVE

STRENGTH

Select the compressive performance of cement

stabilized macadam mixture degree higher curing

ages, cement dosage, forming method and the

aggregate gradation type four aspects, such as

factors, through strength data contrast, analysis of

the factors under the tendency of the compressive

strength of the mixture.

4.1 Curing Age

In order to study the change of unconfined

compressive strength with age in different cement

doses the change curve of the value of compressive

strength was plotted with the age.

(a) The static pressure molding GM mixture

0 20 40 60 80 1 00 12 0 140 160 18 0

0

100

200

300

400

500

600

700

Data volume

Aging(d)

0 28 56 84 1 12 140 16 8 1 96

3

4

5

6

7

C omp r e ss i ve st r en gt h ( M Pa)

Aging (% )

3%

4%

4.5%

5%

6.00%

(b) The static pressure molding XM mixture

Fig.2 Cement stabilized gravel unconfined compressive

strength and the ages

The figure 2 shows that the cement stabilized

gravel unconfined compressive strength along with

the growth of the age, is nonlinear, according to the

change trend can be divided into three stages: when

age in 0 ~ 28 days, strength increase, the biggest can

reach 25%; At the age of 28~90 days, the strength

growth rate starts to decrease by about 2%; When

the age is greater than 90 days, the strength growth

curve flattens out and reaches the ultimate strength

of the cement stabilized gravel.

According to the practical engineering

experience, the cement macadam mixture when

designing age 90 d has basically completed the

intensity of the development, for comparison, this

paper enumerates the 4% dosage of cement mixture

unconfined compressive strength represents the

values, are shown in table 1

Table1 unconfined compressive strength of the

relationship with the age

compressive

strength/MPa

7d 28d 90d 180d

pressure

shaping GM

3.56 4.34 4.92 5.24

pressure

shaping XM

3.34 4.15 4.75 4.87

compressive

strength/MPa

7d/180d 28d/180d 90d/180d

pressure

shaping GM

68% 83% 95%

pressure

shaping XM

68% 85% 98%

The table 1 shows that when the 7 d of the

cement stable macadam mixture, the unconfined

compressive strength of about 60% of the nearly

180d, 28d of the unconfined compressive strength

has reached more than 80%, 90 d / 180 d unconfined

compressive strength ratio has been close to 90%,

and the general law of the experiment.

4.2 Cement Content

Cement dosage of the cement stabilized gravel

unconfined compressive strength and one of the

factors under the condition of different age, the

cement stabilized gravel unconfined compressive

strength with the change of cement dosage, as shown

in figure 2.

(a) The static pressure molding GM mixture

(b) The static pressure molding XM mixture

Fig.3 Cement stabilized gravel unconfined compressive

strength and cement dose relationship graph

Can be seen from figure 2, the same situation in

other conditions, cement stable macadam mixture

unconfined compressive strength increase with the

increase of dosage of cement, and the cement dosage

range, usually between intensity and dose of

approximate linear growth. Increase the dosage of

cement is helpful to improve the compressive

strength, the reason is that the increase of cement

dosage, can make the increase in the number of

cement hydration reaction of cement, and thus

enhanced the cohesive force of the mixture, thus

0 20 40 60 80 1 00 12 0 14 0 16 0 18 0 20 0

3

4

5

6

7

Compressi ve strength( MPa)

Aging (d)

3%

4%

4.5%

5%

6%

3.03.54.04.55.05.56.0

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

Compressive strength (MPa)

Ceme nt co nta nt ( %)

7d

28d

90d

180 d

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10

11

12

13

C o mpr ess ive s tr en gt h( MP a)

Cement contant（%）

7d

28d

90d

180d

improve the compressive strength. Consistent with

existing research results.

5. CONCLUSIONS

Based on the analysis of the influence factors of the

unconfined compressive strength of cement

stabilized gravel mixture, the following conclusions

are drawn:

(1) Combining with analysis and outlier data

screening, classification, sorting out the method of

calculating the strength of the representative values

under different reliability, and analyze the influence

of different influence factors on the representative

value degree, the analysis shows that the factors

affecting the strength of cement stabilized macadam

mixture are in line with the general law of

experiment, the influence of selecting typical

representative value.

(2) Analyze the influence of different influencing

factors on the index of cement stabilized macadam

mixture, and it can be concluded that the increase of

cement stabilized gravel (before 28d) is large; At the

same time, the strength increases with the increase

of cement dosage. According to the specification,

the representative value has certain accuracy and

representativeness.

(3) Using different models to predict the strength

of cement stabilized macadam mixture and the

strength of the mixture and cement dosage and

curing age the relationship between the change of

the fitting, determine the has higher fitting precision

of the cement stable macadam mixture strength

prediction equation, has high reliability verification,

for the strength of the cement stable macadam

mixture parameter selection for reference.

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