Biological deterioration of concrete in subsea tunnels

Prof. Britt-Marie Wilén (WET), Chalmers

Associate Prof. Frank Persson (WET), Chalmers

Senior Engineer Per Hagelia at NPRA

Sabina Karačić

Degradation of subsea sprayed concrete

Rock mass condition

Spray tickness

The annual cost of repair work on concrete:

$5 billion in Western Europe alone!Knudsen A, Jensen FM, Klinghoffer O, Skovsgaard T: Cost-effective enhancement of durability of concrete structures by intelligent use of stainless steel reinforcement. In: Proceedings, conference oncorrosion and rehabilitation of reinforced concrete structures, Florida, 15

Biotic FactorsAbiotic Factors

Humidity

Fibers

BacteriaAlgae Fungi

Oslofjörd subsea tunnelResearch in the Oslofjord subsea tunnel has shownsignificant degradation of the sprayed concrete matrix,acidification and destructive corrosion of steel fibers inassociation with biofilms. Observation: from 2004 until now

Degradation was characterized by crumbling and material loss, locally up to 40 mm after 4-5 years!

Aims

Does the method work?

Who is there?

Where are they located?

What is the local environment?

Abiotic attack Oslofjördsubsea tunnel

Infiltration of:

MagnesiumChlorideSulfateBicarbonate

Leaching of Ca Popcorn calcite deposition Mg-substitution into C-S-H Brucite deposition Thaumasite attack

Oslofjördsubsea tunnel

Biofilm: A structured community of bacterial, algal,fungi or other types of cells enclosed in a self-producedmatrix and adherent to an inert or living surface

SEM images Oslofjörd tunnel biofilm

The biotic attack

Microbial attack

two different types of biofilm:

1) reddish-brown rich in Fe-microbes,

2) dark/black rich in Mn-microbes

A uniform reddish-brown biofilm

Mixed reddish-brown and dark/black biofilms

The biotic attack

BIOMINERALS:

• Na-buserite

• Todorokite

• Ferrihydrite (Fe(OH)3)

Calcite stalactites covered by Mn-Fe biofilm were mainly very friable in contrast to stalactites without biofilm

Lack of knowledge regarding the microbialcommunities and the impact of theirmetabolism, and lack of answers on importantquestions such as “who is doing what?” information of these biodeteriorating biofilms.

Sampling

Sampling procedures to capture the biofilm. From left to right: Sampling of thin biofilm with a scalpel; Core sampling of thick biofilm; and hole after core sampling showing the concrete beneath.

• 10 times• 90 samples

Localities Age of concrete Exposure Class(NS EN 206)

Concrete mix(NS EN 206)

Test site 5.5 years XC2-XC3, XS3 M45, B45 M40, B45(steel + PP fiber)

Main tunnel 16 years XC2-XC3, XS3 M40, B45Pump station 16 years XC2-XC3, XS3 M40, B45

From left to right: Test site; Main tunnel; and Pump station

Localities

DNA extraction

Who is there?

PCR amplification: 16S rDNA V4 region using the primers 515′F-806Rto cover both bacteria and archaea with dual-index labeling

Sequencing: Illumina MiSeq using the MiSeq Reagent Kit v2

Amplify

16S rRNA genes

Sequencing Identification

High throughput sequencing (MiSeq) result in >5000000 sequences in one run

DNA

Microsensor measurments of pH and oxygen

What is the local environment?

Results

Water chemical characteristicsParameter Unit Groundwater Water

interacting with concrete and

biofilmpH 7.60-7.93 5.5-7.7

Alkalinity (HCO3-) mmol/l 2.3-2.5 2.0-2.6

DOC mg/l 0.38-0.92 0.4-1

Cl- g/l 15.0-19.0 17.8-19.3

SO42- g/l 2.20-2.70 2.41-2.72

Ca2+ mg/l 421-460 473-1360

Mg2+ g/l 1.10-1.24 1.21-1.34

Mn2+ mg/l 1.2-1.6 0.77-1.69

Fe2+ µg/l 3-38 3-38

NH4+ µg/l 1.0-1.1 0.006-2210

NO3- µg/l <0.1-6 450-1535

Effects of DNA extraction comparing two methods

Ordination by PCA of microbial community data obtained by the two DNA extraction kits

tested, FastDNA spin kit for soil (FastDNA) and Zymo ZR-Duet (Zymo). Three different

samples of biofilm (SA1, SA2 and SA3) were split and separately extracted by the two

extraction methods, followed by PCR and high throughput amplicon sequencing

Does the method work?

Microbial community composition

Heat map showing the top 20 major genus in the biofilms. Numbers

show median percentage abundances.

Who is there?

Major roles of the microorganisms

Biofilm community composition showing the 25 most abundant OTUs at genus level. The thick middle markers show median, the upper and lower bounds of boxes designate the 25th and 75th

percentiles, the lines designate the maximum and minimum values, the dots show outliers. Numbers show median percentage abundances. Colors of the boxplot: Blue: Nitrogen

converting bacteria, Red: Iron oxidizing bacteria, Yellow: Proposed Sulfur converting bacteria, Grey: Proposed Heterotrophs converting bacteria.

NMDS plotHow are they distributed?

Microsensor profiling

Conclusion

Does the method work?

Yes ( both Fast and Zymo DNA extraction kits)

Who is there?

High abundance of Fe-oxidizing bacteria, nitrogen converting bacteria, sulfate oxidizing and reducing bacteria

How are they distributed?

Difference between tunnel sites.

What is the local environment?

Microsensor measurments showed aerobic gradientwith relatively stable pH around 7-8.

• Conference (oral presentation + poster session):

Microorganisms-Cementitious Materials Interactions, TU Delft, 23/24.06.2016

The 17th International Biodeterioration & Biodegradation Symposium, 6th – 8th September 2017, Manchester Metropolitan University, UK

• Paper published in proceedings:Microbial attack on subsea sprayed concrete. Sabina Karačić, Per Hagelia, Frank Persson, Britt-Marie Wilén.RILEM Conference on Microorganisms-Cementitious Materials Interactions p. 63-75. (2016) , RILEM Publications SARL.[Conference paper - peer reviewed]

Member of TC 253 RILEM Microorganisms-cementitious materials interactions

Member of IBBS International Biodeterioration & Biodegradation Society

Chalmers Fouling/Antifouling Group

Further research questions in my PhD

Analyse microbial metabolism and their impact on concrete

Analyse microbial distribution in depth

Establish links between microbial community structure and biomineralisation

Biofilm time course development

Thank you for your attention!