Around the year of 1963, AC roof sheets (also called chrysotile-cement sheets) were manufactured in our country. With superior characteristics such as good quality, high durability, resistance to typical hot and humid climate and large temperature difference, especially in coastal areas and mountainous areas, AC roof sheets are preferred by people.
AC roof sheets are used at Montreux station of Switzerland.
Since the early 20th century, production technology of AC roof sheets was studied from paper production. The main difference is that paper fibers are replaced with natural mineral fibers of chrysotile which own many advanced features. Meanwhile, kaolin is converted into cement. In the first test production, Czech engineer – Liudvik Gatchek produced thin cement sheets of 400 x 400 with 4mm thickness. They are called fiber cement sheets. By the late 1920s, these sheets run into mass production with a composition of about 10 percent of chrysotile fiber, bending strength of more than 160 kgc/cm2. This is because every 7 – 9 layers of the product have highly adherent chrysotile fibers penetrating.
In the Russian Federation, the first fiber-cement sheets were produced more than 80 years ago in the village of Branshin. In 1908, according to the behest of Emperor Nhikolai II, the first AC roof sheet factory was built. Since then, cement fiber sheet has become a specialized material for roofs and shingles in Russia.
In addition to the Russia, there are many countries which allow using fiber cement products such as the US, Brazil, China, India etc., all countries in Southeast Asia such as Singapore, Thailand, Philippines etc., In France and Switzerland, AC roof sheets have existed for hundreds of years without the replacement of other roofing materials.
Fiber cement industry in Vietnam
Around 1963, fiber cement roofing sheets (also called chrysotile-cement sheets) were manufactured in our country. With advantages such as good quality, high durability, resistance to typical hot and humid climate and large temperature difference, especially in coastal areas and mountainous areas, AC roof sheets are preferred by people. Today, in the provinces of the Central Coast, the mountainous provinces of the North and South and the Central Highlands, there have been many households using this material to roof, expand farms and warehouses.
Residing in 1A Hamlet, Long Son Commune, Can Duoc District, Long An Province, Mr. Nguyen Minh Hung shared: “My family has been using AC roof sheets for more than 30 years because of thermal insulation, soundproofing and cheap price. People can save their money. Many families here also use AC roof sheet.”
From the real experience, Mr. Nguyen Hong Thai, residing in Thon Village, Hoa Hop Town, Tam Duong, Vinh Phuc, said: “Our house built from AC roof sheets during 1997-1998 has been more than 20 years. It’s fine until now, even under the hail. However, the areas of barn and kitchen were built by galvanized plain steel sheet which light and beautiful. When summer comes, it is so hot that so we have to flush the water for cool. It has been only 2 or 3 years; however, there are cracks and holes due to animal feces and kitchen smoke.”
AC roof sheets are used extensively in remote, mountainous and hilly areas.
Together with programs of hunger eradication and poverty alleviation of the Government, AC roof sheets have been mobilized in campaigns to support people during natural disasters and floods. For many years, Vietnam Roofsheet Association has cooperated with provincial People’s Committees and factories to provide AC roof sheet for people affected by the consequences of natural disasters.
Injustice which leads to boycott
In recent years, the market of AC roof sheets has been increasingly declining. Previously, the whole industry had 40 factories with 53 lines of a total designed capacity of 105 million sqm per year to meet the large demand of consumers. Until the end of 2018, the whole industry decreased to only 25 establishments with 36 lines of a total designed capacity of 80.4 million sqm per year.
Over the years, although scientific studies of the Ministry of Health and the Ministry of Construction have confirmed that no case of cancer has been found due to exposure to chrysotile in AC roof sheets in Vietnam. Rumors have created the fear in the public. Especially, many people believe that drinking water from AC roof sheet is harmful.
According to Assoc. Prof. Dr. Luong Duc Long – Former Director of Vietnam Institute for Building Materials, Ministry of Construction, the amount of chrysotile in roofing sheets accounts for a very small proportion of mixing. Chrysotile fiber has hollow structures like hairs so they will be filled with fine particles of cement, which create a strong, stable cohesion that is difficult to destroy and disperse into the environment.
Russia is still using water pipes and many other fiber cement materials.
Many studies have been conducted to determine the risk of chrysotile-containing drinking water to human health by scientists around the world. However, no evidence that chrysotile in drinking water causes cancer.
Assuring objective information before the final conclusion
On August 2, 2019, the Committee on Science, Technology and Environment of the National Assembly issued Official Dispatch No. 1441 to the Chairman of the National Assembly, requesting the Ministry of Science and Technology, the Ministry of Health, the Ministry of Construction and the Ministry of Industry and Trade continue researching on the dangers of chrysotile for workers and users; clarify why most countries still use chrysotile, including populous countries such as China, India etc., high-tech countries of the world such as the USA, the Russia etc.; countries in ASEAN region etc.,
The Committee also asked specialized ministries and agencies to direct the media to propagate the case objectively so that people can understand the nature, avoid excessive propaganda that cause confusion in the public, and affect the economy and social situation while the country is in need of stability to develop.