Cement stabilization of road pavement materials

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

THANK YOU THANK YOU