asbestos based materials: new lights for an old and ......asbestos fibres are present in insulation...

INTERNATIONAL CONFERENCE ON ENGINEERING UBI2011 - 28-30 Nov 2011 – University of Beira Interior – Covilhã, Portugal

Asbestos based materials: New lights for an old and worrisome problem F.Pacheco-Torgal University of Minho, C-TAC Research Unit, Sustainable Construction Group, Guimarães, Portugal [email protected] Yining Ding School of Engineering, Dalian University of Technology, China [email protected] Said Jalali University of Minho, C-TAC Research Unit, Sustainable Construction Group, Guimarães, Portugal [email protected]

Conference Topic – CT 14 Abstract The confirmation of the carcinogenic potential of asbestos fibres show that all the asbestos based materials present some kind of risk to human health having being considered a hazardous waste according to the European Waste List. Asbestos fibres are present in insulation materials, partition walls, corrugated roofing sheets and water pipes. Although they have been banned in 52 countries they are still being produced in more than 100 countries. The present paper reviews current knowledge about asbestos based materials, it covers asbestos toxicity, legal regulations and recycling treatments. It also discusses the possibility of rehabilitation buried asbestos cement pipes by lining them with geopolymers.

Key Words: Asbestos fibres; asbestosis; mesothelioma; threshold risk; recycling; water pipes

Introduction The word asbestos comes from the Greek work for non-combustible materials. This property combined with a low extraction cost, a high tensile strength and high woven ability lead to the rapid use of it in terms of industrial production of thermal and fire insulation products, cement based corrugated sheets and cement based water pipes, the last two represent more than 90% of world wide asbestos consumption (1). Asbestos covers several mineral fibers with 5 µm length and 3 µm in diameter such as: Chrysolite, crocidolite, amosite, anthhrophyllite, tremolite and actinolite. Although some authors (2) report the ancient use of asbestos it was not until the XIX century that asbestos fibres have been explored and processed in industrial terms (3). Although 52 countries (including the ones in the Europe area) have passed regulation to ban its exploitation due to their carcinogenic risk (4,5) asbestos is still being explored in more than 100 countries (6). In the US alone asbestos fibres have been responsible for almost 200.000 lives and the asbestos industry has already paid almost 70.000 millions dollars in compensations and litigations costs (7). Some authors (8) argue this option is economically related and that countries cease to use asbestos based materials when their income level reaches a certain point. Those authors suggest that the countries that use asbestos should ban its use to avoid future asbestos diseases. The assumption that the future health burden of asbestos based materials may not be a crucial issue may induce severe mistaken analysis like the one made by some authors (9,10) for which a life-cycle analysis of asbestos ceilings performed better than timber in the economic, social and even acidification and nutrient enrichment scores.


In the 60´s a relation between asbestos exposure and several professional diseases was established by scientific evidence. By that time only some mineral fibers (crocidolite-blue asbestos and amosite-brown asbestos) were judge as toxic and responsible for pleural mesothelioma from which most patients dies 12 moths after being diagnose (11-13). Chrysolite-white asbestos was left aside because it was thought that it had a low toxic risk and that’s why asbestos continue to be produced. Only in the 80´s with the Directive 83/477/CEE the asbestos problem started to be taken more seriously. Some years after the Directive 91/382/EEC has enforced even more strict caution about asbestos In meantime scientific evidence prove that all minerals fibers present cancer risk as asbestosis (lung damage due to acid formation in an attempt of the body to dissolve the asbestos fibers) (14) or even lung cancer or other types of cancer (15-17). Therefore the Directive 2003/18/EC finally prohibited the production of asbestos based products. The present paper analyzes the asbestos legal framework in Portugal, the recycling treatments and also the validity of using geopolymers in lining operations of asbestos cement pipes. Portugal legal framework related to asbestos In Portugal only after 6 years the Decree nº 284/89 of August 24 starts into practice the content of Directive 83/477/CEE. Four years later Portugal adopted the Directive 2003/18/EC by issuing the Decree Nº 266/2007 of July 24 which defines a threshold risk (TR) when asbestos fibre concentration is higher than 0,1fibre/cm3. Although some may think asbestos is no longer a problem let’s no forget of the vast number of fibre-cement materials asbestos based that are still installed. Portugal for instance as almost 80 square kilometers of fibre-cement asbestos roofing sheets. One may argue that cement materials containing asbestos has a low toxicity risk but it’s also true that cement will loose its binder capacity under environmental erosion and that some cracking accident could take place releasing asbestos fibres. Besides the hydration products of cement degrades with time when they are exposed to repeated wet and dry actions also the tensile stress actions wind based will contribute to the fibres release. Therefore, it is not possible to say that the persons working (or living) under those roofing sheets are not submitted to a fibre concentration higher than the TR or if persons submitted to a fiber concentration below the TR will not develop cancer problems after a long time of exposure. One must remember that according to the World Health Organization – WHO there are no such thing as safe minimum levels of asbestos exposure. In a more danger situation are the cases of buildings and plants with friable asbestos for which the Decree Nº 266/2007 of July 24 states the removal can only be done by specialized firms. However, since this legislation is very recent only some years from now Portugal can expect to have technicians with the expertise on this area. Recent studies [18] confirm that a majority of Engineers and Architects and also building managers reveal a high lack of knowledge about this subject. Besides the aforementioned legislation states that the removal of any asbestos based materials must rely on a work plan previously approved by the Portuguese Authority for Work Conditions. Since at this date there are not enough experts on this area this process can hardly proceed with enough speed. The European Waste List regulated in Portugal by the Portaria Nº209/2004 of March 3 considers asbestos based materials as hazardous wastes (Nº170601- Insulation materials with asbestos fibres; Nº 170605 – Building materials with asbestos fibres), however, the Nº 2 of the Artº14 Decree Nº46/2008 of March 12 related to construction and demolition wastes


management states that the removal and disposal of asbestos based materials must be regulated by a new Portaria that is yet to be published. Therefore, in the mean time the management of asbestos based materials will remain unregulated. The aforementioned work [18] doesn’t even say nothing about the recycling of asbestos based materials which shows that this technical option needs a higher disclosure. Recycling asbestos based materials The state of the art about asbestos based wastes point out to the possibility of their inertization and several industrial processes have already been developed for that purpose: INERTAM (19), ASBESTEX (20) e ARI (21). The treatment of asbestos based wastes can be as follow: Thermal treatments; chemical or mecanochemical treatments; microwave treatments (friable asbestos). Gualtieri & Tartaglia (22) state that the use of a temperature treatment between 1000 ºC and 1250 ºC allows the inertization of friable asbestos and also cement based asbestos. The temperature is responsible for the transformations of the internal structure of asbestos into new and non-toxic crystalline phases (Fig.1).

Figure 1 –Microstructure of asbestos fibres before and after thermal treatment:a) and a1) plain

tremolite fibres; b) and b1) chrysolite fibres embedded in a cement matrix (22)

Different asbestos fibres present different performances when submitted to calcination operations. The equations 1 and 2 shows the transformations of chrysolite (1) and tremolite (2) asbestos: Mg3(OH)4Si2O5 Mg3Si2O7 + 2H2O Mg2SiO4 + MgSiO3 (1) Ca2Mg5Si8O22(OH)2 Ca2Mg5Si8O23 + 2H2O 2CaMgSi2O6 + 3MgSiO3 + SiO2 (2)

500 ºC 750 ºC

Chrysolite Metachrysolite Forsterite Enstatite

950 ºC 1050 ºC

Tremolite Metatremolite Diopside Enstatite Chrystobalite


Leonelli et al. (23) studied the inertization of friable asbestos and its incorporation as a magnesium source to produce ceramic based products. They used a thermal treatment based on microwaves of 2,45 GHz during 13 minutes. Fig.2 shows the microstructure of the asbestos fibres before and after the treatment, confirming the validity of this method.

Figure 2 – Asbestos microstructure: before and after microwave treatment (23)

These authors states that the cost of asbestos valorization varies between 0,05 a 0,2 euros/kg, which is almost 10 times less that the cost of asbestos landfill disposal. Other investigations (24) confirm these results, referring the possibility of using 3% to 5% of inertized asbestos in the production of porcelain products. Gualtieri et al. (25) patented a tunnel capable of achieving the inertization of asbestos cement wastes by using a temperature of 1200 ºC during 16h. This method has the advantage that it does not need the opening of the asbestos packing and does no require grinding operations. These authors use a low melting glass in order to reduce the calcination temperature. Dellisanti et al. (26) refer to a pilot installation using the Joule vitrification in which a high intensity electric power (130 A) can melt the asbestos wastes at 1500 ºC. Other authors (27) used a mechanochemical treatment to change the morphology of the asbestos fibres into a non-toxic form. For friable asbestos Takahashi et al. (28) reported a temperature treatment of 175 ºC during 24h and the use a NaOH (14M) solution. As to Anastasiadou et al. (29) they use a solution of acetic acid, a temperature range between 300 ºC to 700 ºC and a pressure between 1,75 MPa and 5,8MPa. Zaremba et al. (30) reported the detoxification of chrysotile asbestos through a low temperature heating and grinding treatment with temperatures in the range from 500 ºC to 725 °C for 3 h. Boccaccini et al. (31) also used a microwave treatment to achieve the inertization of friable asbestos, turning fibrous structures into magnesium oxide blocks. The thermal treatment of asbestos cement wastes lead to a much lower toxicity level (32). More recently Gualtieri et al. (33) presented results on the reuse of calcined asbestos cement waste and into brick, glass, plastics and pigments. Asbestos cement pipes Asbestos cement pipes were used for potable water distribution during the XX century and although they were largely discontinued in North America in the early 1980s a significant portion of the water distribution is still in service (34).


Webber & Covey (35) report a water supply contamination with samples containing between 10 million fibres per liter and 305 million fibres per liter. Constituting a health risk confirmed by some studies which show an association between ingested asbestos cancer (36). Several pipe rehabilitation techniques has been suggested by (37,38) including the lining operations with geopolymers. Although these materials are known for their excellent mechanical properties, high corrosion resistance and chemical stability (39, 40) they often present efflorescence problems (Fig.3), meaning further research is need before they could be used in water pipes lining operations.

Figure 3 – Efflorescence in metakaolin geopolymer [41]

The subject of efflorescences in geopolymers is relatively new, since very few authors have address this problem. According to Skavara et al. (41, 42) the bond between the sodium ions (Na+) and the aluminosilicate structure is weak and that explains the leaching behaviour. According to those authors in the crystalline zeolites the leaching of sodium is negligible contrary to what happens in the aluminosilicate polymers. It is the presence of water that weakens the bond of sodium in the aluminosilicate polymers, a behavior that is confirmed by the geopolymer structure model (Fig.4).

Figure 4 – Geopolymer structure model [41]


Other authors (43) also found that sodium efflorecences are higher in geopolymers based on aluminosilicate prime materials calcined at a temperature range below the dehydroxylation temperature. Temuujin et al. (44) refer that although ambient cured fly ash geopolymers exhibited efflorescences that phenomena does not occur when the same geopolymers are cured at elevated temperature which means the leachate sodium could be a sig of insufficient geopolymerisation. Conclusions Several countries have already banned the exploitation and use of asbestos based materials due to its carcinogenic potential. Portuguese legal regulations about asbestos wastes are very recent and still incomplete and do not admit the recycling of these wastes. To make things worst technicians with a high level of expertise in this field are missing. Several investigations show that is possible to achieve the inertization of asbestos wastes by thermal and mechanical methods and some countries already use such recycling procedures to avoid asbestos wastes disposal. As to the contamination of potable water by deteriorated asbestos pipes although some authors suggest rehabilitation techniques using geopolymer lining this is not yet a proven technology. References (1) Ramazzini, C.: ''Asbestos is still with us: Repeat call for a universal ban''. Archives of Environmental and Occupational Health Vol.65 (2010) pp.121-126. (2) Swamy, N.: ''Fibre reinforcement of cement and concrete. Evaluation of fibre reinforced cement based composites''. 19-FRC Committee (1977) pp.235-254. (3) Bernstein, D.: ''Asbestos''. Chapter 27 in Inhalation Toxicology, Ed. Harry Salem & Sidney Katz, CRC Press, 2006. (4) http://www.ibasecretariat.org/index.htm (5) LaDou, J.; Castleman, B.; Frank, A.; Gochfeld, M.; Greenberg, M.; Huff, J.; Joshi, T.; Landrigan, P.; Lemen, R.; Myers, J.; Soffritti, M.; Soskolne, C.; Takahashi, K.; Teitelbaum, D.; Terracini, B.; Watterson, A.: ''The case for a global ban on asbestos''. Environmental Health Perspectives Vol.118 (2010) pp.897-900. (6) Chrysotile, Institut du : ''Utilization sécuritaire du chrysotile : Exigences et realisations'', 2008. (7) The Center for Public Integrity: http://www.publicintegrity.org/ (8) Le, G.; Takahashi, K.; Karjalainen, A.; Delermaa, V.; Hoshuyama, T.; Miyamura, Y.; Furuya, S.; Higashi, T.; Pan, G.; Wagner, G.: ''National use of asbestos in relation to economic development''. Environmental Health Perspectives Vol.118 (2010) pp.116-119. (9) Abeysundara, U.; Babel, S.: ''Selecting sustainable materials for ceilings in Sri Lanka''. Proceedings of Institution of Civil Engineers: Construction Material Vol.162 (2009) pp.49-58. (10) Abeysundara, U.; Babel, S.; Gheewala, S.: ''A matrix life cycle perspective for selecting sustainable materials for buildings in Sri Lanka''. Building and Environment Vol.44 (2009) pp.997-1004. (11) Bianchi, C.; Giarelli, L.; Grandi, G.; Brollo, A.; Ramani, L.; Zuch, C.: ''Latency periods in asbestos-related mesothelioma of the pleura''. European Journal of Cancer Prevention Vol.6 (1997) pp.162-166. (12) Jarvholm, B.; Englund, A.; Albin, M.: ''Pleural mesothelioma in Sweden: an analysis of the incidence according to the use of asbestos''. Occupational and Environmental Medicine Vol.56 (1999) pp.110-113. (13) Azuma, K.; Uchiyama, I.; Chiba, Y.; Okumura, J.: ''Mesothelioma risk and environmental exposure to asbestos: past and future trends in Japan''. International Journal of Occupational and Environmental Health Vol.15 (2009) pp.166-172. (14) Akira, M.: ''Asbestosis: IPF or NSIP-like lesions in asbestos-exposed persons, and such independency''. Japanese Journal of Chest Diseases Vol.69 (2010) pp.38-44. (15) Ladou, J.: ''The asbestos cancer epidemic''. Environmental Health Perspectives Vol.112 (2004) pp.285-290.


(16) Silverstein, M.;Welch, L.; Lemen, R.: ''Developments in asbestos cancer risk assessment''. American Journal of Industrial Medicine Vol.52 (2009) pp.850-858 (17) Antonescu-Turcu,A.; Schapira, R.: ''Parenchymal and airway diseases caused by asbestos''. Current Opinion in Pulmonary Medicine Vol.16 (2010) pp.155-161. (18) Pereira, L.: ''Asbestos: Measures for the implementation of a building control plan''. Master Thesis, FCT/UNL, 2008. (19) Borderes, A.: ''Vitrification of the incineration residues''. Revue Verre Vol. 6 (2000) pp.1-2. (20) European Patent EP 069 655 3A1. (21) Downey, A.; Timmons, D.: ''Study into the applicability of thermochemical conversion technology to legacy asbestos wastes in the UK''. WM´05 Conference, Tucson, USA, 2005. (22) Gualtieri, A.; Tartaglia, A.: ''Thermal decomposition of asbestos and recycling in traditional ceramics''. Journal of the European Ceramic Society Vol.20 (2000) pp.1409-1418. (23) Leonelli, C.; Veronesi, P.; Boccaccini, D.; Rivasi, M.; Barbieri, L.; Andreola, F.; Lancellotti, I.; Rabitti, D.; Pellacani, G.: ''Microwave thermal inertisation of asbestos containing waste and its recycling in traditional ceramics''. Journal of Hazardous Materials Vol.135 (2006) pp.149-155. (24) Gualtieri, A.; Cavenati, C.; Zanatto, I.; Meloni, M.; Elmi, G.; Gualtieri, M.: ''The transformation sequence of cement-asbestos slates up to 1200 ºC and safe recycling of the reaction product in stoneware tile mixtures''. Journal of Hazardous Materials Vol.152 (2008) pp.563-570. (25) Gualtieri, A.; Gualtieri, M.; Tonelli, M.: ''In situ ESEM study of the thermal decomposition of chrysotile asbestos in view of safe recycling of the transformation product''. Journal of Hazardous Materials Vol.156 (2008) pp.260-266. (26) Dellisanti, F.; Rossi, P.; Valdré, G.: ''Remediation of asbestos containing materials by Joule heating vitrification performed in a pre-pilot apparatus''. International Journal of Mineral Processing Vol.91 (2009) pp.61-67. (27) Plescia, P.; Gizzi, D.; Benedetti, S.; Camilucci, L.; Fanizza, C.; De Simone, P.; Paglietti, F.: ''Mechanochemical treatment to recycling asbestos-containing waste''. Waste Management Vol.23 (2003) pp.209-218. (28) Takahashi, S.; Ito, H.; Asai, M.: ''Transformation of asbestos into harmless waste and recycle to zeolite by hydrothermal technique''. Journal of Society Materials Science, Japan Vol.58 (2009) pp.499-504. (29) Anastasiadou, K.; Axiotis, D.; Gidarakos, E.: ''Hydrothermal conversion of chrysotile asbestos using near supercritical conditions''. Journal of Hazardous Materials Vol.179 (2011) pp.926-932. (30) Zaremba, T.; Krzakala, A.; Piotrowski, J.; Garczorz, D.: ''Study on the thermal decomposition of chrysotile asbestos''. Journal of Thermal Analysis and Calorimetry Vol.101 (2010) pp.479-485. (31) Boccaccini, D.; Leonelli, C.; Rivasi, M.; Romagnoli, M.; Veronesi, P. ; Pellacani, G. ; Boccaccini, A.: ''Recycling of microwave inertised asbestos containing waste in refractory materials''. Journal of the European Ceramic Society Vol.27 (2007) pp.1855-1858. (32) Giantomassi, F.; Gualtieri, A.; Santarelli, L.; Tomasetti, M.; Lusvardi, G.; Lucarini, G.; Governa, M.; Pugnaloni, A.: ''Biological effects and comparative cytotoxicity of thermal transformed asbestos-containing materials in a human alveolar epithelial cell line''. Toxicology in Vitro Vol.24 (2010) pp.1521-1531. (33) Gualtieri, F.; Giacobbe, C.; Sardisco, L.; Saraceno, M.; Gualtieri, M.; Lusvardi, G.; Cavenati, C.; Zanatto, I.: ''Recycling of the product of thermal inertization of cement–asbestos for various industrial applications''. Waste Management Vol.31 (2011) pp.91-100. (34) Hu, Y.; Wang, D.; Baker, S.; Cossitt, K.: ''AC pipe in North America: Rehabilitation/replacement methods and current practices''. Pipelines 2009: Infrastructure's Hidden Assets - Proceedings of the Pipelines 2009 Conference Vol.360 (2009) pp.282-291. (35) Webber, J.; Covey, J.: ''Asbestos in water''. Crit. Rev. Environ. Control Vol.21 (1991) pp.331-371.


(36) Kjærheim, K.; Ulvestad, B.; Martinsen, J.; Andersen, A.: ''Cancer of the gastrointestinal tract and exposure to asbestos in drinking water among lighthouse keepers (Norway) ''. Cancer Causes and Control Vol.16 (2005) pp.593-598. (37) Hayes, C.: ''Plumbosolvency control. Best practice guide''. IWA Specialista Group on Metals and Related Substances in Drinking Water. Cost 637, 2009. (38) Allouche, E.; Montes, C.; Diaz, E.: ''A new generation of cementitious materials for mortar lining of buried pipes''. Pipelines 2007: Advances and Experiences with Trenchless Pipeline Projects - Proceedings of the ASCE International Conference on Pipeline Engineering and Construction (39) Torgal, F. Pacheco; Gomes, J. P.;Jalali, S.: ''Alkali – activated binders: a review Part 1 Historical background, terminology, reaction mechanisms and hydration products''. Construction and Building Materials Vol.22 (2008) pp.1305-1314. (40) Allahverdi, A.; Skvara, F.: ''Sulfuric acid attack on hardened paste of geopolymer cements part 1. Mechanism of corrosion at relatively high concentrations''. Ceramics - Silikaty Vol.49 (2009) pp.225-229. (41) Skvara, F.; Kopecky, L.; Smilauer, V.; Alberovska, L.; Vinsova, L.: ''Aluminosilicate polymers – Influence of elevated temperatures, efflorescence''. Ceramics - Silikaty Vol.53 (2009) pp.276-282. (42) Skvara, F.; Kopecky, L.; Smilauer, V.; Alberovska, L.; Bittner, Z.: ''Material and structural characterization of alkali activated low-calcium brown coal fly ash''. Journal of Hazardous Materials Vol.168 (2008) pp.711-720. (43) Torgal, F. Pacheco; Jalali, S.: ''Influence of sodium carbonate addition on the thermal reactivity of tungsten mine waste mud based binders''. Construction and Building Materials Vol.24 (2010) pp.56-60. (44) Temuujin, J.; Van Riessen, A.; Williams, R.: ''Influence of calcium compounds on the mechanical properties of fly ash geopolymer pastes''. Journal of Hazardous Materials Vol.167 (2009) pp.82-88.

asbestos based materials: new lights for an old and ......asbestos fibres are present in insulation...

Documents