CHAPTER 6 SMALL ELEMENT PAVEMENTS - TU Delft

After excavating the existing pavement structure to a depth of 1.05 m below thepavement’s surface, the following concrete block pavement structures have beenconstructed for the test pavements Rotterdam 1 to 6:- rectangular (cobble format) concrete paving blocks, thickness 0.09 m (testpavements 1 and 3) and 0.12 m (test pavements 2, 4, 5 and 6) respectively, inherringbone bond B (test pavements 1, 2, 3, 4 and 6) and herringbone bond A (testpavement 5) respectively- a bedding layer of 0.05 m crushed sand- an unbound base of 0.30 m concrete granulate (test pavements 3 and 4) or 0.30 mmix granulate (test pavements 5 and 6)- a sand sub-base, thickness varying between 0.91 m (test pavement 1) and 0.58 m(test pavements 4, 5 and 6).During some weeks in 1984 and 1985 axle load measurements were done with aweight-in-motion system. It appeared form these measurements that the testpavements Rotterdam 1 to 6 were subjected to about 1,250,000 axle loadings (> 5 kN)per lane per year. The measured axle load frequency distribution is given in table 6.4.The test pavements Rotterdam 1 to 6 actually have been in service until the middle of2000 without any significant maintenance.axle load (kN) frequency distribution (%)range average Alphen Rotterdam5 – 2020 – 4040 – 6060 – 8080 – 100100 – 120120 – 140140 – 160> 160103050709011013015017001.518.439.735.04.11.00.3060.812.7515.756.402.751.200.300.0450.01Table 6.4: Axle load frequency distributions for the test pavements Alphen andRotterdam.6.4.3 Measurements:Falling Weight Deflection measurements and rutting measurements have been doneregularly for determination of the development of the resilient deformations(deflections) and the permanent deformations (rutting) on the test pavements.6.4.3.1 Falling Weight Deflection measurements:In a Falling Weight Deflection measurement a dynamic (pulse) load of 50 kN is appliedon the pavement’s surface through a circular plate with a diameter of 300 mm (figure6.13); the contact stress thus is 0.707 N/mm 2 . The pulse loading time is about 0.025 s.The deflections (d) were measured at distances of 0, 0.3, 0.5, 1.0, 1.5 and 2.0 m fromthe load centre.199