Light Weight Deflectometer, Principles and Versability Content: 1. - PowerPoint PPT Presentation

1 Light Weight Deflectometer, Principles and Versability Content: 1. Introduction 2. Dynatest 3031 LWD 3. Field measurements 4. Conclusions NVF/BRA Symposium Oslo Feb. 13 and 14, 2008: Helge Mork, Light weight deflectometer (LWD)

2 Light Weight Deflectometer • Introduction – Field testing equipment for determination of stiffness of pavement materials – Easy to operate, and small enough to be used at any place (especially construction sites) – Lower initial cost than an ordinary FWD (� 1/10) FV 873-01 km 3,01

3 Light Weight Deflectometer • Basic principles – Measurement of deflections induced by dropping weight (up to 20 kg – hence light weight ) using geophones.

4 Light Weight Deflectometer • LWD equipments on the market – Dynatest LWD – Prima 100, CarlBro (previously Phoenix) – Light Drop Weight (LDW), Germany – Loadman, Finland

5 Light Weight Deflectometer Dynatest 3031 LWD • It has a basic 10 kg falling mass (+5kg) • During the test, the falling mass impacts the plate, producing a load pulse up to 15 kN of 15 – 25 ms duration. • The center geophone sensor measures the deflection caused by the mass impact on the loading plate. (+2 more geophones optional) • The diameter of the loading plate can easily be varied between 150 and 300 mm • The software associated with the equipment is LWDmod, which uses the same principle as ELmod for Dynatest FWD.

6 Light Weight Deflectometer Dynatest 3031 LWD • the surface deflection modulus E 0 is calculated using Boussinesq solution as follows: � � � 2 f *(1 )* * a � 0 E 0 d 0 where: • E 0 : Surface deflection modulus • f : Factor for stress distribution (2 or �/2) � : Poisson’s ratio • P � � • � 0 : Uniformily distributed stress under plate 0 � 2 a a • : Radius of plate � � � a 3 * • d 0 : Center deflection � 0 E � � 0 2 d � � 0

7 Light Weight Deflectometer Dynatest 3031 LWD • For multi-layer systems, Odemark’s method of equivalent thickness (MET) is used in LWDmod for backcalculation of modulus values

8 LWDmod analysis • Analysis starts by filtering out unrealistic drops

9 LWDmod analysis

10 Field measurements • Objective – To compare modulus values of pavement materials determined from field measurements carried out with Light Weight Deflectometer (LWD), Falling Weight Deflectometer (FWD), Dynamic Cone Penetrometer (DCP) and Static Plate Loading Test (SPLT). – Evaluate whether LWD could be used for evaluation of low volume roads

11 Measurements in the Malvik area Pilot test locations �

12 Malvik low volume test roads 250 mm, E1 400 mm, E2 E3 Gravel road E 0 =192 MPa AC road (Bostad) E 0 =166 MPa 120 mm, E1 AC 40 mm, Stabilized gravel 750 mm, E2 500mm Bitumen stabilized 460 mm E1 gravel road (Herjuan) E 0 =126 MPa E3 E2

13 Malvik test roads • Test point arrangement at each of two sections 1 2 3 4 5 6 7 10m 10m 5m 5m Lane B C L Lane A 10m 10m 10m

14 Light Weight Deflectometer FWD LWD DCP LWD, FWD and DCP used for pilot study at Malvik

15 LWD/DCP set-up

16 LWDmod data analyses

17 LWDmod data analyses

18 LWD data analyses � � � 2 2*(1 )* * a � 0 • Comparison of surface modulus E 0 d values of the three roads 0 Road KV-12 FV 873-01 FV 873-01 km 3,0 – km 3,6 km 7,1 – km 7,7 Surfacing Gravel Asphalt Concrete Bitumen Stabilized Base/Subbase Natural Sandy gravel Silty gravel gravel Surface Modulus 192 166 126 E 0 (MPa) NB: The rating of these values agree with the visual condition evaluation

19 DCP (med mer/slag) DCP data 0 1 2 3 4 5 6 7 8 0 100 • A typical DCP plot . 200 300 DCP value [mm/blow] 0.6 2.4 6 DCP and E Dybde (mm) 400 703.6 124.4 39.6 Field CBR E (MPa) 755.1 300.6 163.5 500 E = 537.76*DCP -0.6645 Dang-Fong Lin 2006 600 700 800 900 0.0 200.0 400.0 600.0 800.0 1000.0 1200.0 1400.0 1600.0

20 Comparison of results -gravel KV-12 E1 800 y = 0.5346x + 302.88 R 2 = 0.3 1. Gravel Road KV-12 700 600 250 mm, E1 500 400 mm, E2 400 y = 0.4154x + 194.2 R 2 = 0.4951 300 E3 200 200 300 400 500 600 700 800 LWD Modulus KV-12 E1 DCP Modulus Linear (KV-12 E1) Linear (DCP Modulus) KV-12 E2 KV-12 E3 500 200 y = 2.6108x + 130.41 450 2 = 0.5112 R 180 400 160 350 140 300 250 120 200 100 150 80 y = 0.5788x + 22.367 100 R 2 = 0.4694 60 50 40 0 y = 0.0692x + 24.178 0 50 100 150 200 250 300 350 400 450 500 20 R 2 = 0.0296 LWD Modulus 0 FWD Modulus DCP Modulus 0 20 40 60 80 100 120 140 160 180 200 Linear (FWD Modulus) Linear (DCP Modulus) LWD Modulus FWD Modulus DCP Modulus Linear (FWD Modulus)

21 Comparison of results -gravel KV-12 E1 800 y = 0.5346x + 302.88 1. Gravel Road KV-12 R 2 = 0.3 700 250 mm, E1 600 500 400 mm, E2 400 y = 0.4154x + 194.2 R 2 = 0.4951 300 E3 200 200 300 400 500 600 700 800 LWD Modulus KV-12 E1 DCP Modulus Linear (KV-12 E1) Linear (DCP Modulus) KV-12 0.01 0.009 0.008 0.007 0.006 0.005 < 0.004 0.003 0.002 0.001 0 0.00 200.00 400.00 600.00 800.00 1000.00 1200.00 LWD E1 LWD E1 FWD E1 FWD E1

22 Comparison of results -AC Bostad E1 4000 2. AC Road: FV 873 km 3-3.6 (Bostad) 3500 3000 120 mm, E1 AC y = 1.3231x - 756.99 FWD Modulus (E1) 2500 R 2 = 0.71 2000 750 mm, E2 1500 1000 500 E3 0 0 500 1000 1500 2000 2500 3000 3500 4000 LWD M odulus (E1) Bostad E3 Bostad E2 70 200 180 60 y = 0.0277x + 45.609 y = 0.6731x + 63.577 R 2 = 0.0003 160 R 2 = 0.1978 50 140 120 40 100 30 80 y = -0.0816x + 47.982 60 R 2 = 0.1017 20 40 y = 0.134x + 13.24 10 20 R 2 = 0.1566 0 0 0 20 40 60 80 100 120 140 160 180 200 0 10 20 30 40 50 60 70 LWD Modulus (E2) LWD Modulus (E3) FWD Modulus DCP Modulus FWD Modulus DCP Modulus Linear (FWD Modulus) Linear (DCP Modulus) Linear (FWD Modulus) Linear (DCP Modulus)

23 Comparison of results -AC Bostad E1 4000 2. AC Road: FV 873 km 3-3.6 (Bostad) 3500 120 mm, E1 AC 3000 y = 1.3231x - 756.99 FWD Modulus (E1) 2500 R 2 = 0.71 750 mm, E2 2000 1500 1000 E3 500 0 0 500 1000 1500 2000 2500 3000 3500 4000 LWD M odulus (E1) FV873 3-3.6 Bostad 0.0009 0.0008 0.0007 0.0006 0.0005 0.0004 < 0.0003 0.0002 0.0001 0 0.00 1000.00 2000.00 3000.00 4000.00 5000.00 6000.00 7000.00 LWD E1 LWD E1 FWD E1 FWD E1

24 Comparison of results -stabilized Herjuan E1 700 3. Stabilized Road: FV 873 km 7.1-7.7 (Herjuan) 600 40 mm, Stabilized gravel 500 y = 0.2887x + 167.81 R 2 = 0.8801 500mm 400 460 mm E1 300 200 y = 0.1219x + 128.79 100 R 2 = 0.2898 E2 0 0 100 200 300 400 500 600 700 LWD Modulus FWD Modulus DCP Modulus Herjuan E2 Linear (FWD Modulus) Linear (DCP Modulus) 110 100 90 80 y = -0.0163x + 68.572 70 R 2 = 6E-05 60 50 40 30 y = 0.3676x + 17.593 R 2 = 0.1634 20 10 0 0 10 20 30 40 50 60 70 80 90 100 110 LWD Modulus FWD Modulus DCP Modulus Linear (FWD Modulus) Linear (DCP Modulus)

25 Comparison of results Herjuan E2 110 3. Stabilized Road: FV 873 km 7.1-7.7 (Herjuan) 100 40 mm, Stabilized gravel 90 80 500mm y = -0.0163x + 68.572 70 460 mm R 2 = 6E-05 E1 60 50 40 30 y = 0.3676x + 17.593 E2 R 2 = 0.1634 20 10 0 0 10 20 30 40 50 60 70 80 90 100 110 LWD Modulus FV873 7.1-7.6 Herjuan FWD Modulus DCP Modulus Linear (FWD Modulus) Linear (DCP Modulus) 0.05 0.045 0.04 0.035 0.03 0.025 0.02 < 0.015 0.01 0.005 0 0.00 50.00 100.00 150.00 200.00 LWD E2 LWD E2 FWD E2 FWD E2

26 SPLT, DCP and LWD at E6 Steinkjer LWD DCP SPLT

27 Comparison of results -subgrade Results of tests on clay subgrade at E6 construction site, Steinkjer, May 14 2007 160 y = 0.706x + 74.532 2 = 0.5773 R 140 0.035 120 0.03 100 0.025 80 0.02 60 y = 0.2405x + 41.464 0.015 40 R 2 = 0.6043 20 0.01 0 0.005 0 20 40 60 80 100 120 140 160 0 LWD Modulus 0.00 50.00 100.00 150.00 200.00 250.00 SPLT Modulus* DCP Modulus LWD SPLT DCP Linear (SPLT Modulus*) Linear (DCP Modulus)