1. Deicing salt pathways in road structure: Using tracer test monitored by ERT during
different seasons
Authors:
Hedi Rasul - KTH & Koya University
Robert Earon - KTH
Bo Olofsson - KTH
Hello everyone! My name is Hedi Rasul, I am PhD student at KTH. I will present a part of my research.
This part/ or draft is entitled as “Deicing…………………..” the field work is completed on 2015 and research is still on going with both Robert Earon and Bo Olofsson.
Before I talk about the current work I will talk about the previous research which it was the base for the current one
Transportforum 2018 1

2. Outline
Part 1: Previous work, (Spread of water-borne pollutants at traffic accidents on roads)
Part 2: Deicing salt pathways using Tracer test and ERT
The outline of my presentation will be devided in two main parts,
First is the previous research which it was published recently, entitled (Spread……………..
Then Part 2 will focus on the current research and how we detecting salt pathways using tracer test and ERT. 2

3. Part 1: Spread of water-borne pollutants at traffic accidents on roads
Field work started 2010
9 different locations in Sweden.
2 main type of roads
In the first part, which it was Spread………
The tracer test and field works started several years ago by Bosse and Annika
9 different locations in Sweden have been investigated, 2- main type of road modern and forest roads
Sodium Chloride was used as a tracer test 3

4. Field sites
Field sites were at two main locations, Stockholm and Småland area, and the 9 test locations are shown here. 4

5. How de-icing salt transport from road to surrounding environments?
Aim
How de-icing salt transport from road to surrounding environments?
Investigation on pollution spread at traffic accidents on roads.
The aim was to investigate water borne pollutants from traffic accidents and tracer test used was used and monitored by 3D ERT of 8*8 (64 electrode) pole-dipole (selected) 5

6. Field tracer setupp and the infiltration test was as follows, some of you probably recognize Bosse!

7. Simulering av olycka, 50L vatten, 1000 mg Cl/L
The work was started by measuring the resistivity of the shoulder as a background measurement then
Adding 50L of tracer and sudden release! to simulate Road accident
Finaly analyse the resistivity differences and model simulations to understand the percolation speed and sirection
Mätningar i Småland (väg 897)
Elektrodavstånd 0.2 m

8. Data Used Soil profiles used in CoupModel
The soil stratigraphy and road material data was based on the Swedish standard, ad for the shoulder material the grain size distribution were analyzed 8

9. 1D- simulation COUP Result:
Results from 1D COUP model was ´based on the material and stratigraphy
Showing the different speed of percolation at different locations

10. 2D- simulation COMSOL results:
Results from COMSOL medel, 2D.model built for 2 type of roads and a flux added to the shoulder to simulate the percolation process
For example in the modern roads, the percolation down to 1m it can be very fast and in some cases were less than half hour, meanwhile in the old roads the percolation of 1m can take up to 3 hours.

11. 3D- simulation ERT results:
Småland - väg 897
Förändring i resistivitet efter infiltration av saltvatten
-variation med djupet
och avstånd från vägen
(m)
0.6
1.0
1.4
1.8
2.2
Further 3D results from ERT have been analyzed and discussed, but I will not talk too much about this work since if you are interested please read the article which it has been published last July, next slide
2.6
3.0
Förändring i resistivitet (%)

12. August 2017 the paper is published in the Water Air and soil pollution journal.12

13. Part 2: Deicing salt pathways using Tracer test and ERT
Part 1: Previous work, (Spread of water-borne pollutants at traffic accidents on roads)
Part 2: Deicing salt pathways using Tracer test and ERT
Aim
Analyse the pathways, using ERT
Analyse the impact of the frozen period.
This research idea for part 2 started from previous research and experience (already presented)
We were wondering why not just look at ERT patterns at different seasons check for one location?
So the new aim was to Analyse the pathways using ERT and analyse the impact of the frozen period. 13

14. Location
Most of the field works was carried out at test site E18, most of you have already seen the station 

15. Tracer test (fixed lines)
We used a fixed ERT lines for tracer test, we focused on one location at test site E18 and performed the tracer test at different seasons, mainly 4 was used , the Tracer from April, Aug, and twice at December
Test station E18

16. Infiltration test
We took infiltration tests as well, the average infiltration was 0.03 mm/sec

17. Field measurement Papers
We used other data from the station as well, for example
Temperature, Precipitation and Moisture content,
We can see here the frost (soil temperature) data for the first year.

18. Field measurement Papers
Locations of the TDR sensors are as follows, at the depth of around 20 cm under the asphalt layer

19. Tracer Test April 2015 December 2015
Only to grasp the main result, we will show the difference between two of the tracer tests from April and December

20. Resistivity changes (%) with depth for April 2015
Resistivity changes (%) with depth for December 2015
Percent of resistivity changes with depth for tracer test on 24th April 2015
For example here is one of results in 2D – Electrical resistivity differences,
As we can see during non-frozen ground the resistivity changes at different depth and distances were approximately the same
This was repeated in all cased where the ground was frozen, we could see a clustered changes in reduced resistivity and we concluded it from the preferential flow patterns.

21. Resistivity changes (%) in 2.5D for April 2015
Resistivity changes (%) in 2.5 D for December 2015
Percent of resistivity changes in 2.5D- for tracer test on 24th April 2015 and December
And here is the electrical resistivity changes in 2.5D

22. Conclusions
ERT as a non-destructive method to monitor tracer tests proved to be a good approach for analysing and monitoring flow pathways in road layers.
During the spring and summer, the flow paths were more uniformly distributed, while changes in the resistivity were both positive and negative.
Finger flow paths were observed during tests in winter time and in frozen ground, as evidenced by a sharp negative change in resistivity.
For better estimation of the chloride concentration some soil  sampling for road material at different depths is still needed.

23. Acknowledgments
For field works
Stipendiums:

24. Thanks for listening, Questions?