(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%