OBJECTIVEOBJECTIVE
• To investigate the impact of the new range of cements manufactured under the SABS EN-197-1 specification on the design and construction of pavement layers stabilized with cement
STATUSSTATUS
• Project completed• Report completed June 2004• Stakeholders workshop 25 August 2004• Problem identification and prioritization
REPORT CONCLUSIONSREPORT CONCLUSIONS
Limited to 2 materials and 7 cements Setting times of cements vary widely Time and conditioning temperature affect
density and strength significantly No dominant trends Test each material and cement combination
individually to determine workability/ construction time
UCSUCS
4D
2D
4N
2N
4D
2D
4N
2N
2D4D
4N
2N
0
500
1000
1500
2000
2500
3000
3500
4000
4500
0 5 10 15 20 25 30 35 40 45
Temp (degreeC)
UC
S (
kP
a)
Figure 4.16: Influence of conditioning temperature on mean (of all cements) unconfined compressive strength at 7 days
Figure 4.24: Influence of cement type on indirect tensile strength and density of test specimen of norite (at 23°C and 4 h conditioning) after 7 days curing
Norite
2300
2320
2340
2360
2380
2400
2420
2440
2460
0 1 2 3 4 5 6 7 8
Cement number
Den
sity
(kg
/m3)
0
50
100
150
200
250
300
350
400
ITS
(kP
a)
DENSITY
ITS
AUSTRALIA (Austroads)AUSTRALIA (Austroads) Working time for Density and UCS based on lab
determination using actual soil and cement
Density– Time from addition of stabilizer to compaction, which
corresponds to 97% of mean of 3 MDD for samples composed 1 h after incorporation of stabilizer.
UCS– Time from addition of stabilizer to compaction, which
corresponds to 80% of mean of 3 UCS tests for samples composed 1 h after incorporation of stabilizer.
WORKING TIMES FOR THIS WORKING TIMES FOR THIS PROJECTPROJECT
Insufficient data for full application of Australian practice– Mod at 4h– 2 h and 4h conditioning only– Not triplicate tests
Means for relative rating– 2 h as standard– 98% of density at 2h– 90 % of UCS at 2h
DoleriteCEMENT A B
C
D E
F G
10°C
Density @ 4h/2h (%) Time to 98.0% (h) UCS @ 4h/2h (%) Time to 90% (h) Working time (h) Rating at 10°C
100.5 > 2 95 >2 > 2 1
98.6 >2 94 >2 > 2 2
98.1 2
117 > 2 2 3
97.6 < 2 70 « 2 « 2 7
97.3 < 2 92 > 2 < 2 6
99.3 >2 87 < 2 < 2 5
98.1 2
104 > 2 2 4
23°C Density @ 4h/2h (%) Time to 98.0% (h) UCS @ 4h/2h (%) Time to 90% (h) Working time (h) Rating at 23°C
100.1 > 2 87 < 2 < 2 2
99.8 > 2 80 < 2 < 2 5
99.2 >2 85 < 2 < 2 3
99.0 >2 57 « 2 « 2 7
100.7 > 2 73 « 2 « 2 6
100.2 > 2 103 > 2 > 2 1
100.3 > 2 80 < 2 < 2 4
40°C Density @ 4h/2h (%) Time to 98.0% (h) UCS @ 4h/2h (%) Time to 90% (h) Working time (h) Rating at 40°C
97.8 2
69 « 2 « 2 6
99.1 > 2 95 > 2 > 2 1
98.7 > 2 83 < 2 < 2 4
99.0 > 2 80 < 2 < 2 5
100.0 > 2 81 < 2 < 2 3
99.0 > 2 89 2 2 2
97.8 2
59 « 2 « 2 7
MDD/density at 23°C and 4h (%)
101.0 100.0 101.3 101.4 100.0 99.7 99.3
INTERPRETATIONINTERPRETATION No single cement performed best, even for one
material One cement was best or second best at all 3 temps
for norite but worst or nearly worst for dolerite 10°C – One cement performed well on both
materials (WT > 2h) 23 °C – Same cement performed well on both
materials (WT > 2h) 40 °C - none > 2h
PROBLEMS IDENTIFIEDPROBLEMS IDENTIFIED Suitability of different cements/indicator Durability Density changes, working time, test methods,
quality control and assurance Design issues – ITS UCS ranges, transfer
functions Specification Long-term performance Material characteristics Construction methods Modification Shoulders/ wearing courses
18 34 65
22
17
WHERE TO NOW ?WHERE TO NOW ?
Working group to identify projects Attempt to use ongoing projects to answer
some of these Work in conjunction with Advisory
Committee on Road Infrastructure Research
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