Frequently Asked Questions

Pyrite (FeS2), a naturally occurring iron sulfide, is a very common mineral that can be found in sedimentary and low grade metamorphic rocks often used as crushed stone or backfill underneath buildings’ concrete slabs.

The presence of pyrite in rock aggregates used as backfill can lead to problems if exposed to certain conditions. Aggregate particles containing certain amounts of pyrite can react with oxygen and water and are likely to expand, crack and crumble over time. This expansion can lead to cracks in the overlying concrete slab; The thrust can even lift it. In garages or other slab-on-ground-level building sections, the thrust can also be to the sides and affect the foundation walls.

Essentially, it is a series of tests to assess the quality of the crushed stone used as backfill under the concrete slab. These tests allow the determination of the Pyrite Swelling Potential Index (IPPG in French) which is a number corresponding to the swelling potential of the backfill material. This number ranges from 0 to 100. For example, if the IPPG is between 0 and 10, the swelling potential is negligible. If it is between 80 and 100, the swelling potential is extremely high.

Demand for pyrite testing is generally concentrated in the greater Montreal area since the problematic quarries are mostly located there. The Montérégie (south shore of Montreal) is where most cases are located. Certain areas of Montreal such as Rivière-des-Prairies, Pointe-aux-Trembles and the west of the Island (Pointe-Claire, Dollard-des-Ormeaux, etc.) are also known risk areas. Finally, cases are also found in Laval, in the Basses-Laurentides and Lanaudière (Repentigny, Legardeur, etc.).

No. The result obtained during the pyrite test, the Pyrite Swelling Potential Index (IPPG in French), is calculated according to the types of rock in the backfill and not according to what remains to react in the future. This therefore means that the IPPG will not vary over time. However, the age of the building is a criterion that the professionals at Sedexlab consider when writing the conclusions of the report.

Chemical analysis is another type of test that allows getting a better grasp on the progress of the chemical reaction in the backfill material. This test is complementary to the IPPG and cannot be done alone. It is often called “the 2nd stage”. This additional test will give an estimate of the progress of the pyrite oxidation reaction. Is it just at the beginning? Moderately advanced? Or finishing off? In cases where a chemical analysis is deemed necessary, professionals at Sedexlab will offer it to you as the IPPG results are put out.

Although there is no law requiring a pyrite test to be performed, it is almost always required in cities and towns deemed most at risk, often by buyers, real estate brokers, banks, notaries, or home inspectors. Cracks in the concrete floor are often a good indication of the presence of pyrite, but the absence of cracks does not necessarily mean the absence of pyrite. By performing the pyrite test, you will be informed about the future potential for damage associated with the oxidation of pyrite and you will also be protected against future claims for latent defects.

The number of tests (or samplings) will depend on the layout and size of your home. In the case of an average-sized single-family home without a garage, a single sampling will suffice. An additional sampling will be required if your house has a garage or any other added section with a ground level concrete slab. In short, a sampling is required per level of concrete floor. Also, please contact us for a quotation for larger buildings such as commercial, industrial or multi-unit condo or rental buildings.

Once the backfill sample has been taken, our technicians will fill the hole with certified crushed stone. They will then plug the top of the hole with fast-setting concrete. In the event that there is floor covering, our technicians will put the floor back in place before leaving.

Pyrrhotite, a naturally occurring iron sulfide found in rock aggregate, is the suspected cause of the failing concrete foundations problem in Connecticut and Massachusetts. These foundations are experiencing a slow crack development, resulting in the eventual loss of concrete strength. The problems, sometimes developing within the first 10 years, often begin to appear after 15 to 20 years or more. According to the Geological Society of America, rock aggregate in these failing concrete foundations was largely mined from a single quarry in Willington (CT), within a stratified metamorphic unit mapped as Ordovician Brimfield Schist.

Pyrrhotite particles in coarse aggregates are unstable in oxidizing conditions. When exposed to water and oxygen, pyrrhotite oxidizes to form acidic-, iron-, and sulfate-rich by-products. One of these products is sulfuric acid which attacks the cement paste, weakening it, and generating sulfates as a by-product. These sulfates react with portlandite and hydrated aluminate phases in the paste, resulting in an expansion in the form of secondary minerals of greater volume. With more expansion and cracking occurring, more moisture is allowed in the concrete, exposing more pyrrhotite, and consequently increasing the rate of distress. At present no measure other than foundation replacement is known to reverse or eliminate pyrrhotite-Induced concrete deterioration.

According to the Connecticut State Department of Housing, 42 towns and upwards of 35,000 homes in Connecticut could be potentially affected, primarily in the northeastern portion of the State. Single-family homes, home additions and detached garages, condominiums and other buildings are affected. Just north of the border, significant parts of south western Massachusetts could also be potentially affected although no precise numbers have been issued.

The problematic concrete allegedly originated from a single Stafford Springs (CT) concrete producer during the years 1983 – 2015. The company reportedly used reactive pyrrhotite-bearing rock aggregate from a quarry located in Willington (CT) for the fabrication of concrete for building foundations.

The main tell-tale signs of premature foundation deterioration caused by pyrrhotite-induced expansive reactions in concrete are: Map/web-like cracking patterns, horizontal cracking, spalling on surface of concrete, foundation walls bowing, rust-like discoloration on surface of concrete, white efflorescence (powder) in the vicinity of cracking surface. Cracks can rapidly evolve until the eventual loss of concrete strength.

Pyrrhotite Content

Although the undesirable nature of pyrrhotite for the manufacture of concrete is recognized and although contents as low as 0.3% pyrrhotite by mass of coarse aggregate have reportedly caused significant concrete distress (e.g., in Trois-Rivières, Canada), no precise value has been issued in any U.S. State or Federal laws, as to the maximum authorized pyrrhotite content in coarse aggregates for use in concrete. More research and case history data are needed to reveal with more accuracy the minimum level at which significant concrete deterioration will occur.

Sulfur Content

The European standard for coarse aggregate NF EN 12620 (article 6.3.2), in force since 2003, has placed a limit of 0.1% sulfur if pyrrhotite is identified in the coarse aggregate. In Canada, CSA A23.1 (R2014) states that aggregate susceptible to cause excessive expansion of the concrete due to the presence of sulfides (pyrite, pyrrhotite, marcasite) should not be used in concrete. In addition, this standard recommends not using aggregates containing pyrrhotite in new concrete if these aggregates bear sulfur content higher than 0.1%. The US Army Corps of Engineers recent recommendations state that aggregate for use in new concrete should be assumed pyrrhotite-bearing and should be accepted only if its sulfur content is below 0.1%.

Asbestos testing involves identifying, locating and sampling suspect materials present in the building in order to confirm the absence or presence of asbestos by means of laboratory analyzes. These analyzes are carried out in accordance with IRSST analytical method 244-3 for materials (ex: drywall, popcorn ceiling) and ELAP method 198.4 for floor coverings (ex: vinyl tiles).

Asbestos is found in a multitude of construction materials such as plaster and cements, drywall, joint compounds, decorative finishes (stucco, popcorn ceilings), floor and ceiling tiles, insulation, as well as fire proofing.

Asbestos testing is generally requested in residential and commercial real estate transactions or financing, as well as prior to the renovation or demolition of a building. Buildings constructed before 1990 are at greatest risk of containing asbestos. It is therefore recommended to proceed with asbestos testing in these facilities when suspect materials are identified, especially if they are damaged or friable.  Many people believe that only older buildings are likely to contain asbestos, which is not true. It is therefore important to clearly identify the materials likely to contain asbestos, especially before renovation or demolition work is carried out, regardless of the year of construction of the building, in order to avoid releasing fibers into the air, where they could be inhaled by occupants and construction workers.

Asbestos is a well-known carcinogen. When asbestos-containing materials (ACM) are damaged or “friable”, asbestos fibers can be released into the air and present a real risk to the health of building occupants and workers. The presence or absence of asbestos fibers in building materials cannot be determined solely on the basis of visual inspection. Only the sampling and laboratory analysis of suspect materials, according to current regulations, allow this. It is therefore important for a buyer or a building owner to entrust the inspection and sampling of materials likely to contain asbestos to recognized professionals who can also guide you in the safe management of these materials.

The context will often dictate the nature of the testing. In the context of renovation work, the contractor will want, for example, to target a suspect material such as a stucco/popcorn ceiling or vinyl floor tiles. While in a real estate transaction, a buyer might want to know if there is asbestos in all the materials that may contain it before buying the property. It is very important to call us in order for us to fully understand the context. This will allow us to recommend testing that suits you best.

It all depends on the type of material identified. For example, a product that would have been manufactured in a factory such as a floor tile or an acoustic ceiling tile would require only one sample, unless the area is very large or the floor is comprised of more than one type of tile. For materials mixed on site, such as plasters and decorative finishes (stucco), the asbestos concentration can vary greatly from one place to another in the work area.  In such cases, the more samples we analyze, the more our level of certainty of the absence or presence of asbestos will increase. The CNESST recommends a maximum of 9 samples per zone presenting a similarity of work (ZPSO in French). By contacting us, we will be able to fully understand the scope of the project. This will allow us to recommend the number of samples that best suits your situation.

There is no law or regulation that requires you to remove asbestos-containing materials (ACM). However, if you wish to leave it in place, we strongly suggest that you make sure that it is in good condition and that it does not release fibers into the air.  In the event that you are planning to do renovations and wish to dispose of ACMs, it is highly recommended to take certain precautions beforehand and to hire a firm specializing in the removal of ACMs to avoid contaminating your home and its occupants.

There is a test specifically designed to verify the quality of air potentially contaminated with material containing asbestos. This test consists of sampling and analyzing the air in a building to determine if the concentration of asbestos fibers meets current standards. Contact one of our professionals to find out more.

Since our technicians are experienced and use meticulous and safe sampling methods, you will have nothing to worry about when it comes to your health during sampling work.

The human health effects of prolonged and unsafe asbestos exposure are well documented. Asbestos fibers are easily inhaled and transported to the lower part of the lungs, where they can cause pulmonary fibrosis (asbestosis) as well as changes in the lining of the chest cavity (pleura). These diseases can lead to reduced respiratory function and even death. Long-term inhalation of asbestos fibers also increases the risk of lung cancer and mesothelioma. The people who are most likely to have asbestos-related health problems are those who are exposed to high concentrations of asbestos, those who are exposed to it for prolonged periods of time and those who are exposed to asbestos more frequently.

Steel, aluminum, glass, plastic, concrete, natural stone, marble, sandstone and wood, among others, are construction materials considered to be asbestos-free.

Vermiculite is a naturally occurring mineral worldwide. When heated rapidly to high temperatures, this crystalline mineral expands into low density, accordion-like, golden brown strands. In fact, its worm-like shape is what gives vermiculite its name. The worms are broken into rectangular chunks about the size of the eraser on the end of a pencil. In addition to being light, vermiculite chunks are also absorbent and fire retardant. These characteristics make it great as an additive, for example to potting soil. It also makes a good insulating material.

Vermiculite testing involves sampling the suspect insulation material in the attic to confirm the absence or presence of asbestos in harmful amounts, by means of laboratory analyzes. These analyzes are carried out in accordance with IRSST analytical method 244-3.

Vermiculite is typically found in the attic of a residential building dating 1990 and earlier. However, it can also be found in walls and sub floors.

No. Based on our experience and case history, we estimate that about half of vermiculite-based insulation in Quebec contains asbestos, with concentrations of 1 to 5% asbestos.

There is no law or regulation that requires you to remove vermiculite from your home. However, if your vermiculite contains asbestos, it is very important not to release fibers when moving the insulation. If you wish to remove it, it is strongly recommended that you hire a firm specializing in the removal of materials containing asbestos to avoid contaminating your home and its occupants.

There is a test specifically designed to verify the quality of air potentially contaminated with material containing asbestos. This test consists of sampling and analyzing the air in a building to determine if the concentration of asbestos fibers meets current standards. Contact one of our professionals to find out more.

There is no demonstrated risk if the vermiculite is sealed in wall panels, in the floor or else insulated in the attic with other types of insulation. However, you must take all necessary precautions if you plan to undertake renovation or demolition work.

Asbestos-containing vermiculite was typically sourced from mines in Libby, Montana. It was mined and marketed from the 1920s to the very early 1990s throughout North America. Buildings insulated with vermiculite during this period are therefore presumed to contain it.

As vermiculite was marketed and sold in bags, it would be plausible that the vermiculite in your attic comes from different sources.   It is therefore recommended that a minimum of three (3) separate samples be taken from different areas of the attic to increase the degree of certainty of the test results.

Since our technicians are experienced and use meticulous and safe sampling methods, you will have nothing to worry about when it comes to your health during sampling work.

When asbestos-containing vermiculite is found, there are two options: seal all openings between the ceiling and the attic, or have it removed by a specialized company. The first option will be the least expensive, but consider that the presence of asbestos could affect the resale value of your house.

The human health effects of prolonged and unsafe asbestos exposure are well documented. Asbestos fibers are easily inhaled and transported to the lower part of the lungs, where they can cause pulmonary fibrosis (asbestosis) as well as changes in the lining of the chest cavity (pleura). These diseases can lead to reduced respiratory function and even death. Long-term inhalation of asbestos fibers also increases the risk of lung cancer and mesothelioma. The people who are most likely to have asbestos-related health problems are those who are exposed to high concentrations of asbestos, those who are exposed to it for prolonged periods of time and those who are exposed to asbestos more frequently.

The test consists of sampling and analyzing the air in the living environment of a building to determine if the asbestos fibers concentration meets current standards. The air is sampled using a pump and a membrane filter to collect the fibers. The sample will then be analyzed in the laboratory to confirm the absence or presence of asbestos and to quantify the fibers present in your environmentThe fiber count must be less than 0.01 f / cm3 according to the regulations on occupational health and safety in Quebec. The testing is carried out by phase contrast optical microscopy according to IRSST 243-1 method.

The air test is generally requested in the context of the removal of materials containing asbestos. The test can be done before the start of the work to identify any fibers in your living environment, during the work to ensure the protection of workers and after remediation to ensure that the work has been done properly.

This 4 hour test is necessary following the removal of vermiculite material or those containing asbestos. The test checks whether the decontamination work has been carried out correctly.

The exposure test consists of measuring the concentration of asbestos fibers during asbestos removal work on high risk construction sites. The test should be done at least once per shift. This procedure is designed to keep worker exposure to a minimum depending on the type of asbestos and the type of respirators used.

No. Results are only valid for the moment the test was carried out.

No, all fibers considered to be breathable are counted during the test. Further analysis can measure asbestos fibers only. However, this analysis is not necessary when the total number of fibers is below a threshold considered safe.