Asbestos-Free Fiber Cement Board: Fibers and Formulation

Asbestos-free fiber cement board replaces asbestos with cellulose pulp, usually refined softwood kraft, and in air-cured products adds synthetic fibers such as polyvinyl alcohol (PVA) or polypropylene (PP). Cellulose does two jobs: it reinforces the board and, on the sheet machine, it holds back the cement fines. The fiber package is tied to the curing route, because most synthetic fibers lose strength under autoclave conditions.

For a plant owner, “asbestos-free” is not a label added at the end. It decides the fiber supply, the refining equipment, how fast the sheet machine can run, the curing route and how you prove to customs and customers that the board is clean. This article covers those decisions, and the bans that make them unavoidable.

Why Asbestos Left Fiber Cement Board

Fiber cement was invented around asbestos. Ludwig Hatschek’s sheet process of 1900–1901 was designed to bind asbestos fibers with Portland cement, and the history of the machine is covered in The Hatschek Process for Fiber Cement Sheets. Asbestos did two jobs at once: its fibers reinforced the sheet, and on the machine they held the fine cement particles while the water drained away. Any replacement has to do both.

The health case against it is settled. The International Agency for Research on Cancer classifies all forms of asbestos, including chrysotile, as carcinogenic to humans (Group 1), and the World Health Organization considers stopping the use of all types of asbestos the most effective approach (Australian Asbestos Safety and Eradication Agency, chrysotile fact sheet). The European Commission’s 1999 directive on chrysotile states that “no threshold level of exposure has yet been identified below which chrysotile asbestos does not pose carcinogenic risks” and that substitutes were available for most remaining uses (Directive 1999/77/EC, recitals 6 and 7).

The industry moved early in some markets. Sweden banned asbestos cement in 1976, and in Australia James Hardie had asbestos-free boards reinforced with refined kraft wood fiber in commercial production by May 1981 (Ni, 1995). Today the North American product specification for flat fiber-cement sheets, ASTM C1186, is written for non-asbestos sheets, as explained in ASTM C1186 Explained for Fiber Cement Producers.

Asbestos Bans: Where They Apply

The most widely quoted count comes from the International Ban Asbestos Secretariat (IBAS), a campaign network that tracks national legislation: its list, revised on 23 June 2026, shows 74 countries with national asbestos bans. That figure is IBAS’s own compilation, not an official registry. A selection, with the primary source where we could open one:

Not every market is on the list, and chrysotile is still mined. The US Geological Survey estimates 2025 world mine production at about 960,000 tonnes, led by Russia (310,000 t), China and Kazakhstan (about 250,000 t each) and Brazil (150,000 t). It expects demand to continue, “particularly for cement pipe, roofing sheets, and other construction materials in Asia” (USGS Mineral Commodity Summaries 2026). Brazil is also on the IBAS list: in 2023 its Supreme Federal Court upheld a ruling that asbestos extraction, sale and use were unconstitutional, and a 2024 law in the State of Goiás sets a five-year countdown to suspend mining, starting once a mine closure plan is agreed (USGS).

What this means for a new plant:

1. Build asbestos-free even where asbestos is still legal. A board made in a country without a ban will meet one as soon as it is exported to most Gulf states, the EU, Australia, Japan or South Korea. All the lines we supply produce asbestos-free board.
2. Expect your board to be tested at the border. Between July 2020 and March 2021, the Australian Border Force detected asbestos in imported goods including “cement fibreboards and panels” (ASEA). The ABF warns importers not to assume that goods labelled “asbestos free” are free of asbestos, because some countries allow that label below a threshold (ABF, Ensuring the goods do not contain asbestos).

The Fibers That Replace Asbestos

The US Geological Survey lists calcium silicate, carbon fibers, cellulose fibers, glass and several organic fibers among the materials that substitute for asbestos across all its uses (USGS). In flat fiber cement sheets made on a sheet machine, the practical choice is narrower.

Why do synthetic fibers stay out of the autoclave? Most synthetic fibers lose strength under autoclave conditions, which is why autoclaved boards rely on cellulose. Ni’s review states the rule in general terms: “the combination of high alkalinity and high temperature eliminates most fibres apart from natural plant fibres (mainly wood pulp fibre), steel, carbon and aramid fibres” (Ni, 1995). It does not test PVA, PP or glass one by one, so if a supplier proposes a synthetic fiber for an autoclaved product, ask for its temperature and alkali data. In practice, autoclaved fiber cement uses cellulose, while air-cured products in Europe have long used PVA blended with plant fibers (Ni, 1995). Fiorelli and colleagues describe PVA and PP as the “alkali-resistant synthetic fibres” of air-cured hybrid roofing sheets made on the Hatschek machine.

Cellulose stays in both routes because nothing else does its process job as cheaply. Synthetic fibers lack a surface that bonds well to the cement and can cause drainage problems on the machine (Ni, 1995), so even a PVA or PP board still carries refined pulp. The pulp itself, from kraft grades to recycled paper, refining and freeness, is the subject of Cellulose Fiber in Fiber Cement Board.

Asbestos-Free Formulation: Air-Cured and Autoclaved

There are two families of asbestos-free formulation, and they differ in more than the fiber.

Two numbers explain why cellulose contents sit where they do. Flexural strength rises with fiber content up to about 8% and does not improve beyond it, while fracture toughness keeps rising until about 8–10% fiber by mass and then levels off (Ni, 1995). A 2015 study in BioResources also cites about 8–10 wt% as the practical maximum for cellulosic fibers (Claramunt et al., 2015). More fiber than that adds water absorption without adding strength.

The patent and EPD figures above are published examples, not recipes. Your cement, sand or limestone and the pulp grade you can buy reliably decide the final mix, which is why raw material tests come before the line is configured.

What Changes on the Sheet Machine

Taking asbestos out changed how the sheet machine works, and the changes still shape a new line.

• Retention. Asbestos held cement fines on its own. Cellulose only does so after refining, which exposes fibrils that catch the fines. Ni reports that the “main value” of refining on the Hatschek machine is in “improving the drainage rate and solids retention”; unrefined fiber drained too fast and lost matrix, giving weak board.
• Drainage and speed. More refining holds more fines but drains more slowly, so the machine runs slower. Every asbestos-free plant is tuned between these two limits.
• Synthetic fiber dispersion. PVA and PP are dosed and dispersed separately from the pulp, and because they do not form a filter mat themselves, they depend on the cellulose to stay in the sheet.
• Water circuit. Fines that pass the felt or sieve end up in the process water. Settling and returning them to the mix is part of an asbestos-free line, not an extra.

Both forming machines work with asbestos-free slurries. We supply both flow-on and Hatschek board machines; on the board lines we supply, flow-on forming is the more common choice. On our reference designs, presses of 5,000, 7,000, 10,000 and 14,000 tonnes are matched to board density and output, and fiber cement board is made at 1.4–1.8 g/cm³. For the full flow from pulping to packing, see Fiber Cement Board Manufacturing Process.

Durability of Asbestos-Free Fiber Cement Board

Asbestos-free boards are not weaker by default, but they behave differently over time, because cellulose responds to water and alkali.

• Wet strength. In laboratory samples, flexural strength of wood-fiber cement can fall to “as low as 50% of dry strength values,” although commercial products show smaller losses (Ni, 1995). Ask which moisture condition a strength figure refers to, and check the conditioning rules in the current edition of your product standard.
• Ageing route. In the research Ni reviews, air-cured products lost fracture toughness markedly with ageing, while ageing of autoclaved materials “did not result in mineralisation of the fibres.”
• Synthetic fibers. PVA is alkali-resistant but not inert: the 19% strength loss in the Fiorelli test came before it stabilized. Field exposure in the same study recorded edge cracking that varied widely with the fiber combination (Fiorelli et al.).

The mechanisms, and what a plant can do about them, are covered in the cellulose article linked above.

Proving the Board Is Asbestos-Free

Customers and customs authorities increasingly want evidence, not a statement. A practical program for a new plant:

1. Control the raw materials. The ABF advises importers to ask suppliers about any use of asbestos, or raw materials containing naturally occurring asbestos, at the point of manufacture. Ask the same of your own mineral suppliers, especially fillers and any recycled material.
2. Never repulp old asbestos-cement scrap. Only your own trimmings and rejects should go back into the slurry.
3. Test with an accredited laboratory. The ABF recommends sampling and accredited testing before goods ship, and contracts that require nil asbestos content.
4. Keep the records. A documented supply-chain assurance program can help avoid clearance delays (ABF).
5. Declare to the right standard. Exterior sheets for the US market are specified to ASTM C1186, a non-asbestos specification. European sheets follow EN 12467; see EN 12467 Fiber Cement Sheet Standard Explained.

FAQ

What fibers are used in asbestos-free fiber cement board?

Refined cellulose pulp, usually softwood kraft, is used in almost every asbestos-free board because it reinforces the board and holds cement fines on the sheet machine. Air-cured boards add synthetic fibers such as PVA or polypropylene for strength and toughness. Autoclaved boards rely on cellulose, because most synthetic fibers lose strength under the combined heat and alkalinity of the autoclave.

Is asbestos-free fiber cement board as strong as the old asbestos-cement sheets?

It can meet the same product classes, but it gets there differently. Strength comes from refined fiber, density and curing rather than from asbestos alone, and wet strength is lower than dry strength in cellulose boards. Plants control this through fiber content (typically up to about 8–10% cellulose), pressing and the curing route, and verify it against EN 12467 or ASTM C1186.

Can an existing asbestos-cement line be converted to asbestos-free?

The sheet machine itself can usually work with asbestos-free slurry, but the fiber preparation cannot stay the same. You need pulping and refining equipment, synthetic fiber dosing if you air-cure, adjusted drainage and felts, and often a new formulation. Decontamination of the old plant is a separate, regulated job that must be done before conversion.

Which countries have banned asbestos in building products?

By the count of the International Ban Asbestos Secretariat (IBAS), 74 countries had national asbestos bans in its June 2026 list, including all EU member states, the UK, Australia, Japan, South Korea, Saudi Arabia, Qatar, Oman, Kuwait, Bahrain, Egypt, Turkey and South Africa. Chrysotile is still mined in Russia, China, Kazakhstan and Brazil, and USGS expects continued demand for asbestos-cement products in Asia.

How do I prove my fiber cement board is asbestos-free?

Use contracts that require nil asbestos content, control your mineral raw materials, and have samples tested by an accredited laboratory before shipment. Australia’s Border Force warns that overseas “asbestos free” certificates do not always meet its requirements, so check the destination market’s rules and keep a documented supply-chain record.

Planning an Asbestos-Free Fiber Cement Board Plant?

Our fiber cement board production line page shows how fiber preparation, forming, pressing and curing are configured for 3, 5 or 8–10 million m² a year. The calcium silicate insulation plant setup guide covers a different product, insulation board and pipe sections, but its planning sequence from raw material tests onward applies here too.

Sources

• Australian Asbestos Safety and Eradication Agency, Chrysotile asbestos fact sheet (2025): https://www.asbestossafety.gov.au/sites/default/files/2025-12/Chrysotile_Asbestos_factsheet.pdf
• European Commission, Directive 1999/77/EC (chrysotile), full text: https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELEX:31999L0077
• International Ban Asbestos Secretariat, Current asbestos bans (revised 23 June 2026): http://www.ibasecretariat.org/alpha_ban_list.php
• US Geological Survey, Mineral Commodity Summaries 2026: Asbestos: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-asbestos.pdf
• Australian Asbestos Safety and Eradication Agency, ABF targets asbestos in imported building products: https://www.asbestossafety.gov.au/about-us/news-and-announcements/abf-targets-asbestos-imported-building-products
• Australian Border Force, Ensuring the goods do not contain asbestos: https://www.abf.gov.au/importing-exporting-and-manufacturing/prohibited-goods/asbestos/ensuring-the-goods-do-not-contain-asbestos
• Y. Ni, Natural Fibre Reinforced Cement Composites, PhD thesis, Victoria University of Technology / CSIRO, 1995: https://vu-9.eprints-hosting.org/15654/1/Ni_1995compressed.pdf
• J. Fiorelli, H. Savastano Jr., G. H. D. Tonoli, S. F. Santos, Durability of Fibre-Cement Roofing Corrugated Sheets, XIII International Conference on Durability of Building Materials and Components: https://www.irbnet.de/daten/iconda/CIB_DC33112.pdf
• Etex Services NV, US 10,611,683 B2, Polypropylene fibers… for the production of fiber cement products: https://patents.google.com/patent/US10611683B2/en
• James Hardie Research, US 6,676,745 B2, Fiber cement composite materials using sized cellulose fibers: https://patents.google.com/patent/US6676745B2/en
• J. Claramunt, M. Ardanuy, L. J. Fernandez-Carrasco, Wet/Dry Cycling Durability of Cement Mortar Composites Reinforced with Micro- and Nanoscale Cellulose Pulps, BioResources 10(2), 2015: https://bioresources.cnr.ncsu.edu/BioRes_10/BioRes_10_2_3045_Claramunt_AC_Durability_Wet_Dry_Cycling_Cement_Mortar_6876.pdf
• Swisspearl Group AG, Environmental Product Declaration, fibre cement boards (EPD-SWP-20180028-IAD1-EN): https://www.swisspearl.com/media/6093/download/Even%20boards%2C%20small%20and%20medium-size%2C%20made%20of%20fibre%20cement.pdf