1. Cement stabilization of road pavement materials

2. OBJECTIVE T o 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

3. STATUS Project completed Report completed June 2004 Stakeholders workshop 25 August 2004 Problem identification and prioritization

4. REPORT CONCLUSIONS l Limited to 2 materials and 7 cements l Setting times of cements vary widely l Time and conditioning temperature affect density and strength significantly l No dominant trends l Test each material and cement combination individually to determine workability/ construction time

5. UCS Figure 4.16: Influence of conditioning temperature on mean (of all cements) unconfined compressive strength at 7 days

6. 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

7. AUSTRALIA (Austroads) l Working time for Density and UCS based on lab determination using actual soil and cement l 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. l 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.

8. WORKING TIMES FOR THIS PROJECT l Insufficient data for full application of Australian practice –Mod at 4h –2 h and 4h conditioning only –Not triplicate tests l Means for relative rating –2 h as standard –98% of density at 2h –90 % of UCS at 2h

9. Dolerite

10. INTERPRETATION l No single cement performed best, even for one material l One cement was best or second best at all 3 temps for norite but worst or nearly worst for dolerite l 10°C – One cement performed well on both materials (WT > 2h) l 23 °C – Same cement performed well on both materials (WT > 2h) l 40 °C - none > 2h

11. PROBLEMS IDENTIFIED l Suitability of different cements/indicator l Durability l Density changes, working time, test methods, quality control and assurance l Design issues – ITS UCS ranges, transfer functions l Specification l Long-term performance l Material characteristics l Construction methods l Modification l Shoulders/ wearing courses l 18 l 34 l 65 l 22 l 17

12. WHERE TO NOW ? l Working group to identify projects l Attempt to use ongoing projects to answer some of these l Work in conjunction with Advisory Committee on Road Infrastructure Research

13. THANK YOU