Wspólnotowy Serwis Informacyjny Badan i Rozwoju - CORDIS

Performance of HPC in the field

This result details how HPC performed in field tests with regards to various degradation attacks. 22 mixtures from each of the 3 regions (Nordic, Central Europe, Southern Europe) were placed in various field conditions for a period of 2 ½ years to assess how they perform when subjected to various environmental conditions. Field stations were established in various countries to account for the varying environments.

The field stations were:

- Mulheim Ruhr (N. Rhine), Germany; Moderate exposure, 130 m elevation; testing Freeze-thaw, with and without deicing salt

- Kruft, Germany; Moderate exposure; testing Freeze-thaw, with and without deicing salt

- Northern Italy; Moderate exposure; testing Freeze-thaw with deicing salt (scaling)

- Southern Italy; Mild exposure; testing Seawater, chloride penetration
- Kopavogur, Iceland; HAKOP floating seawater station; testing freeze-thaw with salt (scaling), seawater attack, chloride penetration

- Reykjavik, Iceland; KORPA station; testing freeze-thaw without deicing salt

- Boras, Sweden; Severe exposure; along Highway Rv40; testing freeze-thaw with deicing salt

- Traslovslage Harbour, Sweden; Seawater station; testing seawater attack, chloride penetration

- Sodankyla, Finland; Harsh exposure; testing freeze-thaw without deicing salt

It was intended that the results from the field exposure would be used to improve upon the scientific understanding of HPC durability. The results would hopefully indicate which types of concrete could better withstand environmental attacks, such as frost or salt.

Many of the samples at these field stations will continue to be monitored in the future, beyond the duration of this project. The main conclusions drawn after the field exposure testing are:

- Nearly all of the 22 concretes in each region performed extremely well and did not show much damage.

- Samples exposed to real-time field-testing did not have as severe of damage as accelerated laboratory tested samples.

- The two-year (three winters) test period was not long enough to provide enough winter exposure for extensive correlations to laboratory tests or for service-life estimates.
- The only location where a significant difference in freeze-thaw performance between the 22 concretes could be detected was at Field Station 9 (Finland). In this climate two mixtures showed severe damage after just 1 winter of freeze-thaw cycles.

- In the case where there was damage (Field Station 9), there was a good correlation between the field and laboratory tests.

- Chloride testing showed the field results (Field Station 8) were comparable with the results of chloride diffusivity measured in the laboratory using an accelerated method.

- In the German region (Field Station 1), additional lab testing after field exposure showed that good correlation could be found by measuring the chloride content in different depths compared to the values found by accelerated lab testing. Compressive strength results showed on the other side high variations and could therefore not help to detect the start of deterioration. Additional frost and de-icing salt testing showed comparable results as found by testing of specimens at later ages. Here, the influence of ageing altered the frost resistances in some cases to a great extend.

The exposure time and environment of these real-time tests was taken into account when modelling the life expectancy of the concretes. A wider range of concrete behaviour was expected from the 22 different mixtures in each of the 3 regions to provide more insights for modelling of HPC deterioration. The data obtained from the field stations was used in combination with field-cored structures (see Deliverable D2) and laboratory tests (see Deliverable D6) for modelling within Workpackage 4 (Deliverables D8 through D10).

The findings from the field station results will be shared with the engineering community, to provide them with information for improved decision in future design of buildings and structures. Designers and engineers will have better tools for specifying concrete for high performance in the various environments across Europe and worldwide.

Reported by

Technical Research Centre of Finland
Lampomiehenkuja 2, PO Box 1800
02044 VTT
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