Deleterious internal sulfate attack on concrete caused by an aggregate with low iron sulfide content

Andreas Leemann; Beat  Münch; Paul Dunlop

Deleterious internal sulfate attack on concrete caused by an aggregate with low iron sulfide content

Andreas Leemann
, Beat Münch
, Paul Dunlop

Research output: Contribution to conference › Paper › peer-review

9 Downloads (Pure)

Abstract

A considerably damaged Irish home in County Donegal built with concrete blocks of low total sulfur content was investigated to identify the cause of deterioration. Despite the low total sulfur content the concentration of SO3 present in cement hydrates is in the same range as the one of homes heavily affected by internal sulfate attack. Moreover, the analysis of the cement hydrates indicate secondary ettringite formation. Residual pyrrhotite and pyrite are identified in the shells of the sea dredged sand used as aggregates in the blocks in combination with micaceous meta-quartzite and greywacke. The results indicate that ISA can be caused by an aggregate with a relatively low iron sulfide content, if oxidation has progressed close to completion.

Original language	English
Pages	1-6
Number of pages	6
Publication status	Published (in print/issue) - 14 May 2026
Event	2nd International Conference on Iron-Sulfide Reactions in Concrete – 2026: ICISR 2026 - Hilton, Mystic, Connecticut, United States Duration: 12 May 2026 → 14 May 2026 https://crumblingconcrete.engr.uconn.edu/icisr-2026/

Conference

Conference	2nd International Conference on Iron-Sulfide Reactions in Concrete – 2026
Country/Territory	United States
City	Connecticut
Period	12/05/26 → 14/05/26
Internet address	https://crumblingconcrete.engr.uconn.edu/icisr-2026/

Bibliographical note

For the purpose of open access, the authors have applied a Creative Commons
Attribution (CC BY) licence to any Author Accepted Manuscript version arising
from this submission.

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

SDG 11 Sustainable Cities and Communities

Keywords

concrete blocks
cracking
ettringite formation
internal sulfate attack,
microstructure

Access to Document

Leemann et al_ICISR_2026Author Accepted Manuscript, 1.46 MB

Cite this

@conference{812b7ee3c1d94f6cb0ed474a27ef9336,

title = "Deleterious internal sulfate attack on concrete caused by an aggregate with low iron sulfide content",

abstract = "A considerably damaged Irish home in County Donegal built with concrete blocks of low total sulfur content was investigated to identify the cause of deterioration. Despite the low total sulfur content the concentration of SO3 present in cement hydrates is in the same range as the one of homes heavily affected by internal sulfate attack. Moreover, the analysis of the cement hydrates indicate secondary ettringite formation. Residual pyrrhotite and pyrite are identified in the shells of the sea dredged sand used as aggregates in the blocks in combination with micaceous meta-quartzite and greywacke. The results indicate that ISA can be caused by an aggregate with a relatively low iron sulfide content, if oxidation has progressed close to completion.",

keywords = "concrete blocks, cracking, ettringite formation, internal sulfate attack,, microstructure",

author = "Andreas Leemann and Beat M{\"u}nch and Paul Dunlop",

note = "For the purpose of open access, the authors have applied a Creative Commons Attribution (CC BY) licence to any Author Accepted Manuscript version arising from this submission. ; 2nd International Conference on Iron-Sulfide Reactions in Concrete – 2026 : ICISR 2026 ; Conference date: 12-05-2026 Through 14-05-2026",

year = "2026",

month = may,

day = "14",

language = "English",

pages = "1--6",

url = "https://crumblingconcrete.engr.uconn.edu/icisr-2026/",

}

TY - CONF

T1 - Deleterious internal sulfate attack on concrete caused by an aggregate with low iron sulfide content

AU - Leemann, Andreas

AU - Münch, Beat

AU - Dunlop, Paul

N1 - For the purpose of open access, the authors have applied a Creative Commons Attribution (CC BY) licence to any Author Accepted Manuscript version arising from this submission.

PY - 2026/5/14

Y1 - 2026/5/14

N2 - A considerably damaged Irish home in County Donegal built with concrete blocks of low total sulfur content was investigated to identify the cause of deterioration. Despite the low total sulfur content the concentration of SO3 present in cement hydrates is in the same range as the one of homes heavily affected by internal sulfate attack. Moreover, the analysis of the cement hydrates indicate secondary ettringite formation. Residual pyrrhotite and pyrite are identified in the shells of the sea dredged sand used as aggregates in the blocks in combination with micaceous meta-quartzite and greywacke. The results indicate that ISA can be caused by an aggregate with a relatively low iron sulfide content, if oxidation has progressed close to completion.

AB - A considerably damaged Irish home in County Donegal built with concrete blocks of low total sulfur content was investigated to identify the cause of deterioration. Despite the low total sulfur content the concentration of SO3 present in cement hydrates is in the same range as the one of homes heavily affected by internal sulfate attack. Moreover, the analysis of the cement hydrates indicate secondary ettringite formation. Residual pyrrhotite and pyrite are identified in the shells of the sea dredged sand used as aggregates in the blocks in combination with micaceous meta-quartzite and greywacke. The results indicate that ISA can be caused by an aggregate with a relatively low iron sulfide content, if oxidation has progressed close to completion.

KW - concrete blocks

KW - cracking

KW - ettringite formation

KW - internal sulfate attack,

KW - microstructure

UR - https://crumblingconcrete.engr.uconn.edu/icisr-2026/

M3 - Paper

SP - 1

EP - 6

T2 - 2nd International Conference on Iron-Sulfide Reactions in Concrete – 2026

Y2 - 12 May 2026 through 14 May 2026

ER -

Deleterious internal sulfate attack on concrete caused by an aggregate with low iron sulfide content

Abstract

Conference

Bibliographical note

UN SDGs

Keywords

Access to Document

Other files and links

Fingerprint

Living the Crisis, Leading the Science: Activism, Evidence and Changing the Narrative of the Irish Defective Concrete Crisis

Defective homes in Donegal, Ireland: effect of exposure conditions and concrete quality on pyrrhotite oxidation and internal sulfate attack

The "mica crisis" in Donegal, Ireland – a case of internal sulfate attack?

Greg Hughs Show

Cite this

Deleterious internal sulfate attack on concrete caused by an aggregate with low iron sulfide content

Abstract

Conference

Bibliographical note

UN SDGs

Keywords

Access to Document

Other files and links

Fingerprint

Activities

Living the Crisis, Leading the Science: Activism, Evidence and Changing the Narrative of the Irish Defective Concrete Crisis

Research output

Defective homes in Donegal, Ireland: effect of exposure conditions and concrete quality on pyrrhotite oxidation and internal sulfate attack

The "mica crisis" in Donegal, Ireland – a case of internal sulfate attack?

Press/Media

Greg Hughs Show

Cite this