Lightweight aggregates in Civil Engineering applications. Arnstein Watn Senior Scientist, SINTEF

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1 Lightweight aggregates in Civil Engineering applications Arnstein Watn Senior Scientist, SINTEF

2 SINTEF Independent Multiscience Research Institute About 1800 employees Closely linked to the Universities -Norwegian University of Science and Tecnology (NTNU, Trondheim) -University of Oslo Technology for a better Society SINTEF on the Web:

3 PRESENTATION CONTENT Material properties and test methods Applications and structural solutions Construction Quality control

4 R&D project Physical properties Thermal properties Mechanical properties Durability Structural performance

5 Laboratory tests-results DENSITY (kg/m 3 ) Material Loose Compacted Dry 25% water (10%) (11.8%) (10.7%)

6 Density (kg/m3) Leca Leca 0-32 water crushed rock Materials

7 Thermal properties 0.22 Thermal conductivity, W/mK Water content (volumetric) %

8 Large scale oedometer test Leca 4-20 Leca Leca Oedometermodulus, M, (MPa) Vertical stress (kpa)

9 Effect of compaction

10 Triaxial tests-friction properties Failure angle tan b = 1.02 b = 45 Characteristic friction tan k = 0.85 k = 41 Attraction/(cohesion) a (c u ) = 0 (0) kpa

11 Resistance against permanent deformations Failure zone a Failure line Rearrangement of particles Elasto-plastic zone c Pure elastic zone elastic Elastic limit line Crushing of particles

12 Cyclic triaxial tests Leca Leca 0-32 Resilient - modulus (MPa) Mean stress (kpa)

13 Mechanical properties-summary Strength and stiffness properties comparable to conventional materials (gravel/crushed rock) Provided the stress level is not resulting in crushing of the grains

14 Field investigations-existing fills

15 Field Investigations Existing fill with age up to 8 years No crushing from traffic observed Some damage/crushing of surface particles from compaction Water content, w= 15-40% (note weight %)

16 Large scale model test 150 cm 150 cm loadplate hydraulic actuator Load cell Asphalt Crushed rock geotextile Designed for AADT = , 40 and 50 kn load 5 Hz loading frequency Leca mm geotextile XPS Measured stresses and strains in the Leca layer 190 cm

17 Model testpermanent deformations Deformation, mm Top Leca layer Top asphalt 0 1,000,000 2,000,000 3,000,000 4,000,000 5,000,000 Number of load pulses

18 Numerical analyses Vertikale spenninger (kpa)

19 Field test, Sandmoen

20 Field test-lay out

21 Field test-wedge section

22 Plate load tests

23 Field test-plate load test Location E1 E2 E2/E1 Instrumented part Wedge part Strong end Wedge part Weak end 110,2 205,4 1,86 83,1 160,2 1,92 63,5 181,7 2,

24 Bearing capacity FWD Distance from asphalt edge [m] Section 3 Section [m]

25 Field test - Instrumented load test

26 Vertical stress measurements D e p t h [m] Vertical Stress [kpa] cm asphalt 30 cm crushed rock 40 cm Leca 0.8 Edge (0.15m) Inner track (3 m) (distance from asphalt edge)

27 Field test-rutting Section 1 Section 2 Section 3 Section 4 Rut depth [mm] Current distance [m] inner track outer track inner track outer track

28 Field test- Temperature 15 Measured temperatures in road with Leca. Daily mean value 10 Asphalt surface Temperature, ('C) cm below surface Between asphalt layers Bottom of asphalt Top crushed rock Top LECA Middle of LECA Bottom of LECA Top sand layer Bottom of sand layer cm depth in subsoil Air temperature 2m above ground Date

29 CONCLUSIONS Physical properties: Unit weight (compacted drained): 4-5 kn/m 3 Compaction: % Mechanical stiffness and strength: Comparable to conventional material (stress level blow crushing level)

30 Conclusions Structural performance Suitable as frost insulation layer Suitable as light weight fill material Suitable as part of lower bearing layer

31 Bearing capacity during thawing

32 Road surface cracking

33 Insulation effect

34 Structural solution 4cm Agb 6 cm Ag 20 cm Fk 30 cm LWA Existing frost susceptible road Separating geotextile

35 Bearing capacity-paradise

36 Required insulation thickness Nødvendig tykkelse av isolasjonslag Nødvendig isolasjonstykkelse (cm) Frostmengde (timegrader)

37 Bearing capacity No c ounte r fill Shear surface

38 Light weight fill road embankment

39 Road and railway extension Railway

40 Road extension

41 Settlements

42 Bridge abutment We d g e Pile s

43 Bridge abutments-visible settlements

44 Bridge abutment

45 Slope stabilisation Wa te r She ar surfac e

46 Slope stability improvement

47 Insulation of drainage ditch

48 QUALITY REQUIREMENTS Internordic working group : Nordtest Method planned implemented into a European Standard Required material properties and test methods Quality requirements on construction and field control Final version planned by April

49 Required material properties Density Grain size (variation) Amount of crushed particles Water content Thermal conductivity Water adsorption Compressive stiffness Compressive strength Dynamic compression Dynamic E-modulus Environmental acceptability

50 Installation

51 Installation by blowing

52 Installation and compaction

53 Quality control-field Detailed execution guidelines Layer thickness Compaction equipment and method Number of passages Overburden compaction

54 Quality control-field Functional requirements Degree of compaction methods proved to be suitable are not available Bearing capacity Plate bearing tests, light falling weight and Dynamic Cone Penetrometer (DCP) Integrity of aggregates Counting of damaged and crushed aggregates

55 Plate load test

56 Properties - light - high stiffness and strength LWA in Civil Engineering Applications - reduce settlements (differential and total) - increase stability (embankments, slopes) - reduce earth pressure - frost insulation Quality - required material properties - installation and compaction - field control

57 LWA for Civil Engineering Properties - application - control Leca Leca 0-32 R es ilient - m odulus (M Pa) Mean stress (kpa)