National Road 753, Nord-Trøndelag NORWAY – 1997
Roads (01-017-A)
01-017-A – pag 2/4
Problem A road embankment situated almost directly next to the lake shore, with very bad subsoil, was constructed as a test to study the performance of the structure with Leca® used as a lightweight aggregate.
Composition Road bed Low thickness in order to study performance of Leca® under traffic load; 40 mm wearing course; 40 mm binder course (recycled asphalt); 60 mm upper base course; 200 mm lower base course, ballast 0-32 mm; Geotextile, type Geoknit PD 70.
Cubic Area: approx. 3,500 m3. Load: Cars: approx. 1,000 vehicles/day. HGVs: approx. 100 vehicles/day.
Performance Tests of the Leca® fill after 10.5 months. Measurements Settlement measurements, pore pressure measurements; Excavation at a various points along the carriageway + inspection of the Leca®.
Base Leca®wrapped in geotextile, thickness: up to 2.5 m; Side support structures. Subsoil Bad subsoil; Groundwater near to surface.
Construction
Test Site
Site plan of the Leca® fill.
Building method Application and compaction of the Leca® using a digger on caterpillar tracks.
Quality control No data.
construction is
01-017-A – pag 3/4
Sample points
Location
Purpose
Method
Depth intervals
A
inner wheel track
water content and damage to individual grains as a function of depth
careful excavation within a Ø 40 cm steel tube, pushed downwards in stages
0-5 cm 5-13 cm 13-23 cm
B
between wheels
as above
as above
0-5 cm 5-27 cm 27-42 cm
C
inner wheel track
dry and wet density
the Ø40 cm steel tube was carefully pushed manually to a depth of 25 cm
0-25 cm
D
between the wheels
as above
the Ø40cm steel tube was pushed to a depth of 40 cm using a vibroplate
0-40 cm
Visual examination –› apart from the top 3-5 cm (larger, looser grains) very good compression and few damaged grains
Water content, mass unit weight
Sample point
A
B
Depth interval
Water content
Total mass unit w ei gh t
γ
0-5 cm
22%
5-13 cm
24%
13-23 cm
23%
Dry mass unit weight
γd
0-5 cm
22%
5-27 cm
32%
27-42 cm
29%
C
0-25 cm
23%
6.66 kN/m3
5.42 kN/m3
D
0-39 cm
25%
5.97 kN/m3
4.78 kN/m3
Grain distribution
Sampling point
A (inner wheel track)
B (between wheels)
Depth interval
0-5 cm
5-13 cm
13-23 cm
0-5 cm
5-27 cm
27-42 cm
Proportion grains > 8 mm
62,6%
44,0%
49,6%
54,2%
45,3%
38,0%
Proportion grains 4-8 mm
24,5%
27,4%
24,9%
27,9%
29,4%
31,9%
Proportion grains 1-4 mm
6,0%
16,0%
14,2%
12,1%
19,1%
24,9%
Proportion grains < 1 mm
6,9%
12,6%
11,3%
5,8%
6,2%
5,2%
construction is
01-017-A – pag 4/4
Proportion of crushed/damaged grains.
Sampling point
A (inner wheel track)
B (between wheels)
Depth interval
0-5 cm
5-13 cm
13-23 cm
0-5 cm
5-27 cm
27-42 cm
Proportion crushed grains
12,0%
10,4%
11,9%
9,9%
4,2%
2,3%
Proportion damaged grains
36,8%
33,2%
23,6%
34,9%
25,7%
28,7%
Proportion undamaged grains
51,2%
56,4%
64,4%
55,1%
70,2%
69,0%
Extrapolation as a function of depth
damaged or crushed grains as a % of all materials
Flaws/damage Type: no data. Time: --
depth under top of fill (cm)
Maintenance work Not known.
Sample point A (under wheel track) Sample point B (between wheels)
Appraisal/Experiences The project is very interesting for future observation; For performance of the expanded clay fill (grain crushing, grain size curve, mass unit weight, grain movement,…) see above.
Compaction test using dynamic penetration test. (DCP = Dynamic Cone Penetration) –› steady, almost linear increase in blow count –› penetration depth 23-34 mm/blow
Blow count
Inner wheel track Outer wheel track test a Outer wheel track test b Between wheels test a
Depth (mm)
Between wheels test b
www.maxit-group.com maxitGroup AB, Box 415, SE-191 24 Sollentuna, Sweden Tel.: +46 (0)8 858 70 64 00, E-mail: info@maxit-group.com
construction is