Pyrite Testing and Analysis

Framboidal Pyrite 1

The presence of pyrite in aggregates used in the manufacture of masonry blocks and back-fill can have a devastating effect on the structural integrity of your home. When reactive pyrite combines with water and oxygen a chemical reaction results in the production of sulfuric acid which then reacts with calcium carbonate within the concrete causing expansion and can lead to cracking, degradation and destruction of structures. Testall is working with some of Ireland's leading engineers and geologists to investigate, sample and analyse suspected pyrite infected structures.

Pyrite in Ireland

The presence of pyrite is estimated to contaminate in excess of 20, 000 Irish dwellings. Pyrite concentrations have been found in numerous counties throughout Ireland such as Donegal, Mayo, Dublin, Wicklow, Louth, Offaly, Limerick and Clare; however,  the mineral can also be found at other locations throughout Ireland. The likelihood of your property being contaminated will also increase if it was built in the past 20 years; or during the construction of "Boom time" developments.

Map of Pyrite affected counties of Ireland

Defective Concrete Building Blocks

Defective concrete blocks can lead to the destruction of buildings, while pyrite can be a key cause; other factors may need to be investigated and tested for accordingly. Other possible factors leading to destruction may include: low cement content, inappropriate aggregate mix and the presence of other deleterious minerals used in the manufacturing process.

Key Signs of Pyrite Contamination or Defective Blocks

The harmful effect of reactive pyrite can have an extreme detrimental impact on the structural integrity of homes.  Defects caused by high levels of pyrite tend to be visible on internal or external walls and floors of a property; this includes multi-directional cracks/fissures, bulging and lifting. Other visible signs can be distortion of fitted structures such as cabinets and doors. To assess whether the deterioration of a building has been caused by pyrite contamination, look out for the following:

  • Multi-directional (spiderweb) cracks in the floors or walls
  • Cracking in the internal partitions or load bearing walls
  • Bulging or heave of walls/floors
  • Household doors sticking or not closing properly
  • Kitchen presses/cabinets/worktops unsettled from original placement

20210326 122242 2
20210326 122304 4

Our Pyrite Testing Services

Testall are a UKAS accredited testing provider offering a comprehensive range of laboratory and field testing services. Our team of skilled technicians and engineers perform a variety of sampling and testing procedures for masonry concrete products in compliance with the requirements of I.S. 465 : 2018 (Assessment, Testing and categorisation of damaged buildings incorporating concrete blocks containing certain deleterious materials);

  • Sampling, examining and testing cores in accordance with EN 12504 – 1 : 2019
  • Chemical Analysis (Total Sulfur Content, Acid Soluble Sulfates, Water-Soluble Sulfates, Oxidisable Sulphides) to EN 1744-1:2009+A1:2012
  • Simplified Petrographic Analysis
  • Detailed Petrographic Analysis (Thin Sections)
  • XRD Analysis
  • SEM image/EDX phase mapping
  • Cement Content 

Testing Pyrite Masonry Blocks in accordance with I.S. 465:2018

The testing required to assess the extent of pyrite contamination differs from case to case. Our professional geologist in conjunction with our engineers determine the testing requirements and will include some or all of the following :

Test Suite A : Initial Analysis 

  • Simplified Petrographic Analysis

Petrographic Analysis is performed using powerful microscopes to examine samples of masonry concrete to determine their mineralogical and chemical compositions. 

Test Suite B : Further Analysis (if Required) 

  • Chemical Analysis (Total Sulphur & Acid Soluble Sulfate)

The objective of chemical analysis is to quantify the sulfur containing compounds in a masonry concrete unit. Sulfates can be found in concrete due to Sulfate bearing aggregates used during masonry concrete unit production or from ingress into a hardened concrete from an external source. In both cases, there is a possibility of deleterious expansion which may cause cracking or disintegration of the concrete matrix leading to a reduction in the strength of the masonry concrete unit.

  • Cement Content

The cement content of concrete affects its durability, permeability and has a direct impact on the physical strength of the concrete in a building or structure. Too low a cement content may cause inadequate structural capacity.

  • Detailed Petrographic Analysis (Thin Section)

This is a more comprehensive microscopic analysis which involves the breaking down of  the masonry aggregate to manufacture thin section specimens which can be analysed in a more detailed manner.

Test Suite C : Extensive Analysis 

  • SEM image/EDX phase mapping (Scanning Electron Microscopy & Energy Dispersive X-Ray)
Scanning Electron Microscopy or SEM analysis, provides high-resolution imaging to evaluate materials
for surface fractures, flaws, contaminants, corrosion or indication of oxidation.

  • Compressive Strength
Core specimens taken from buildings under investigation are dry cored and prepared by our 
technicians in accordance with I.S.465:2018 Clause 6.2 and EN 12504–1:2019. Once prepared the                                specimens are stress tested using our calibrated compression machines; this reveals the overall

compressive strength and whether the pyrite has affected the integrity of the structure. 

Repair of Pyrite Contaminated Buildings

Unfortunately, repairing and removing pyrite from affected buildings can be a destructive and costly

job carried out by experts in the field. To clear a building from the reactive mineral the structure

(walls/floors ) or backfill must be completely removed and then reinstated in compliance with modern

building standards. Without these remedial procedures, the property is at risk of degradation or even

collapsing and consequently can drastically reduce the overall property value. While remediation may

seem like a drastic action; the result means that the structural integrity of the building is intact and

certification for the building can be provided by your engineer.