FLEXIBLE PAVEMENTS - AUSTRALIA

THE USE MADE OF THE STABILIZATION OF NATURAL GRAVELS WITH CEMENT IN THE CONSTRUCTION OF AIRFIELD PAVEMENT IN AUSTRALIA IS REVIEWED. THE BENEFICIAL EFFECTS THAT HAVE BEEN FOUND FROM THE ADDITION OF SMALL QUANTITIES OF CEMENT ARE: (1) TENDS TO REDUCE THE ADVERSE EFFECTS OF HIGH PLASTICITY AND CLAY CONTACT IN A MATERIAL, (2) IMPROVES THE OVERALL STABILITY OF A MATERIAL, (3) REDUCES THE MATERIAL'S SENSITIVITY TO A SOFTENING AND LOSS OF STABILITY IN THE PRESENCE OF WATER, (4) SUBSTANTIALLY REDUCES THE COMPACTIBILITY OF THE MATERIAL AND THE SUBSEQUENT LOSS OF SHAPE DUE TO DENSIFICATION UNDER TRAFFIC, AND (5) INCREASES THE LOAD DISTRIBUTING PROPERTIES OF A MATERIAL. TO STRENGTHEN THE RUNWAY FOR JET SERVICES, THE PAVEMENT WAS ROLLED WITH A HEAVY PNEUMATIC TIRED ROLLER (WEIGHING 300,000 LBS.) AND THE TOP SIX INCH OF GRAVEL WAS MODIFIED WITH 2-3 PERCENT OF CEMENT TO REDUCE ITS WATER SENSITIVITY AND INCREASE ITS OVERALL STRENGTH. IT WAS THEN SURFACED WITH ONE AND ONE HALF INCH OF BITUMINOUS CONCRETE. A CEMENT CONTENT OF 8 PERCENT WAS ADOPTED AND THIS PROVED SATISFACTORY FOR THE MAJORITY OF THE AREA BUT SOME AREAS HAD TO BE PATCHED DURING CONSTRUCTION. VERY BAD SHRINKAGE AND CRACKING HAS OCCURRED FOLLOWING THE ADDITION OF ONLY 2 PERCENT OF CEMENT TO GRAVEL SUBSEQUENTLY SURFACED WITH BITUMINOUS SEAL TREATMENTS OR WITH 2-INCH THICKNESS OF BITUMINOUS CONCRETE. RICH BITUMINOUS SURFACE TREATMENTS BEHAVE MUCH BETTER IN COUNTERACTING REFLECTION CRACKING AS THEY TEND TO BE MORE TOLERANT TO STRETCHING AND THEY CAN BE REASONABLY MAINTAINED IN THAT CONDITION BY PERIODICAL RESEALS. OTHER EXPERIENCE INDICATES THAT ABOUT 4 INCH THICKNESS OF BITUMINOUS CONCRETE IS NECESSARY TO PREVENT REFLECTION CRACKING. TO ACHIEVE THE MAXIMUM DENSITY IT IS NECESSARY THAT THE CEMENT MODIFIED MATERIAL BE COMPACTED AT OPTIMUM MOISTURE CONTENT FOR THE COMPACTION EQUIPMENT AND THAT THE WHOLE PROCESS OF COMPACTION AND FINISHING TO FINAL LEVEL BE COMPLETED WITHIN ABOUT 2 HOURS. WHEN PROPERLY CONTROLLED, HAND SPREADING OF CEMENT IS PROBABLY THE MOST COMMONLY USED METHOD. GENERALLY, HOWEVER, A MECHANICAL SPREADING IS PREFFERED, PROVIDED THE SPREADER IS CAPABLE OF UNIFORM AND RELIABLE APPLICATION. A FAIRLY RAPID METHOD HAS BEEN DEVELOPED OF DETERMINING THE UNIFORMITY OF CEMENT CONTENT FROM SAMPLES OF STABILIZED GRAVEL REMOVED FROM THE PAVEMENT. SURFACE FINISHING AND BITUMINOUS SURFACING ARE ALSO DISCUSSED.

• Supplemental Notes:
  • No Iii-2, pP 2-11
• Authors:
  • Williams, H C
  • Purdam, R K
• Publication Date: 1967

Media Info

• Serial:
  • Perm Intl Assoc Road Congresses Proc
  • Publisher: Xiiith Congress, Tokyo

Subject/Index Terms

• TRT Terms: Airport runways; Asphalt concrete; Base course (Pavements); Bituminous materials; Cement content; Cement treated soils; Compactibility; Compaction; Densification; Flexible pavements; Gravel; Load transfer; Moisture content; Pavement design; Paving; Plasticity; Pneumatic equipment; Reflection cracking; Rollers; Seal coats; Spreaders; Stabilized materials; Surface treating; Thickness
• Uncontrolled Terms: Cement treated bases
• Old TRIS Terms: Bituminous surface treatments; Bituminous surfacing; Optimum moisture content; Pneumatic rollers; Thickness design
• Subject Areas: Construction; Geotechnology; Highways; Pavements;

Filing Info

• Accession Number: 00205531
• Record Type: Publication
• Files: TRIS
• Created Date: Jun 18 1994 12:00AM