Leivo, Virpi

Pentti, Matti

Pikkuvirta, Jussa

Suonketo, Jommi

Trepo - Institutional Repository of Tampere University

VOC emissions of PVC flooring - long-term analysisVirpi Leivo1,*, Jommi Suonketo1, Jussa Pikkuvirta1, Matti Pentti11 Tampere University, Faculty of Built Environment, Tampere, Finland*Corresponding email: virpi.leivo@tuni.fiSUMMARYIn this study, different screed, adhesive and PVC floor covering combinations together withdifferent floor covering conditions were used in a long-time laboratory test series.VOCemissions were then measured from material samples (Bulk-VOC) and from surfaceemission samples (FLEC-VOC). The test specimens have been measured for 3.5 to four yearsafter installing the floor covering. The test results show changes of primary and secondaryVOC emissions in both deteriorated and flawless flooring samples. In some test specimenswhere the flooring was installed directly above moist concrete the deterioration was noticedquite soon after installing the flooring. The emissions of C9- to C10-alcohols startedincreasing later than other common emissions (1-Butanol, 2-ethyl-1-hexanol). According tothe VOC analysis some peak values of the primary emissions of 2-EH and 1-Butanol werenoticed at about one year after installation the floor covering, C9-C10-alcohol emissions evenuntil two years.KEYWORDSVOC emissions, PVC flooring, IAQ1 INTRODUCTIONConcrete as alkaline (pH ~12.5) and moist material can cause deterioration of PVC floorcoverings and adhesives through alkaline hydrolysis, causing harmful volative organiccompound (VOC) emissions into indoor air. The efficiency of the reaction, the hydrolysis ofesters (Uhde and Salthammar, 2007), depends on the moisture content or relative humidity(RH), temperature and pH.  Both PVC flooring and some commonly used flooring adhesives,such as acrylate-based copolymer adhesives, consist of esters and can therefore deterioratecausing VOC emissions. The VOCs in indoor air have hazardous effects on human health andwell-being. The most typical symptoms are odour nuisance and eye and upper airwayirritation (Wolkoff et al, 2006). Attempts to prevent this phenomenon have been made byinstalling floor coverings on top of ‘dry-enough’ concrete or using a low-alkali layer (screed)between the concrete and the floor covering. The pH of low-alkali screed is typically less than11.5. Many new materials can produce primary emissions, meaning the physical release ofcompounds of a new product. Deterioration of materials cause secondary emissions, which aredefined as ‘compounds produced by chemical reactions in the product or in the indoorenvironment’.The screed, adhesive and PVC floor covering combinations have been varied together withdifferent floor covering conditions (RH of the concrete) in this study.  The measured long-time primary and secondary VOC emissions in deteriorated as well as flawless flooringsamples have been presented in this paper.2 MATERIALS/METHODSThe screed, adhesive and PVC floor covering combinations have been varied using differentfloor covering conditions (RH of the concrete) in a full-scale thickness laboratory test series.The structure of the laboratory test samples corresponds with a typical slab-on-groundstructure, with thermal insulation (EPS) beneath a 80 mm concrete slab, capacity of dryingonly upwards, and a glued PVC covering on top.  Moisture level of concrete at the installingof floor covering (RHcrit in 32 mm depth from the top) has been varied: RH80%, RH85% andRH93%. The RH85% equals the current guideline´s flooring criterion. Some samples wereprepared with a 5 mm self-levelling screed layer. The pH of the screed material or the pH ofthe flooring underlay have been varied: a gypsum-based screed (pH less than 10), a low-alkaliscreed (pH about 11.5) and a cement-based screed or no screed (pH ~12,5). Two differenttypes of adhesives were used: a common acryl copolymer dispersion or an alkali resistantadhesive. Three floor coverings have also been used: two homogenous floor coverings,intended for public spaces, one containing DINCH (diisonyl cyclohexane-1.2-dicarboxylate)plasticizer and the other DINP (diisononyl phthalate) plasticizer, and one heterogenous floorcovering, for housing rooms, containing DINCH plasticizer. The heterogenous floor coveringtypically consists foamy bottom and thin uniform PVC cover. The wear resistance and watervapor resistance is lower than homogenous floor coverings. We have totally 23 different testspecimens.The RH of the concrete slab at the equivalent depth (equals the maximum RH in the area closeto the surface between the flooring and the interface of concrete or screed (Hedenblad, 1997))was measured using computer-controlled Vaisala HMP110 temperature and RH sensors andhandheld Vaisala HMP40 T and RH sensors, accuracy of the sensors being ±2 RH%.Test samples were cast into 530x325x10 mm3 steel boxes. At the bottom of the box, a 20 mmlayer of EPS (expanded polystyrene) thermal insulation layer was installed. An 80 mm layerof concrete, with a water/cement ratio of 0.5, was cast on top. The test samples were storedunder constant conditions, T = +21 °C and RH = 50%, until the RH of the concrete at theequivalent depth reached the agreed floor covering criterion. The self-levelling screed layerwas applied to some samples and dried under constant conditions before the floor coveringwas glued.VOC emissions were measured from material samples and surface emission samples. Materialsamples or Bulk-VOC samples were collected from a sample of about 40 x 40 mm2, includingfloor covering and some adhesive and screed, into a Tenax TA tube using a Micro-Chamber/Thermal Extractor (Micro-Chamber, µCTE) and then the emissions were analysedusing the TD-GC-MSD instrument (European Committee for Standardization, 2004). Themethod has been presented by Hughes et al. (2006). In Finland, the Bulk-VOC analysis usingμ-CTE analysis is the most common method in practical cases where possible deterioration ofPVC flooring structures has been investigated, because it is quicker and cheaper than FLECsampling. The surface emission samples were collected using the Field and LaboratoryEmission Cell (FLEC) method (Nordtest, 1996) and analysed using the TD-GC-MS. The mainVOC analysing method in this study was to analyse emissions from material samples (Bulk-VOC using μ-CTE analysis) because the possible deterioration could be first noticed inmaterials and their interfaces and only later in surface emissions.The pH of the concrete and the screed was defined from material samples using a methodintroduced by Björk and Eriksson (2002). A small sample was drilled from the concrete, orthe screed, and the 0.5 ± 0.01 g drill dust was mixed with 5 ± 0.2 g ion purified water and letto blend for 20 minutes, mixed together in every 5 minutes. After the solid matter settled in alaboratory tube, the pH of the liquid was measured using a pH electrode.3 RESULTSAltogether 117 Bulk-VOC analysis from the flooring material samples have been made, threeto four samples from each test specimen. The first samples have been collected about threemonths after installing the floor covering and the latest ones 3.5 or four years after.In 58% of the taken samples the floor covering was homogenous with DINCH plasticizer, in32% heterogenous with DINCH and in 10% the floor covering was homogenous with DINPplasticizer. The most common VOC emission compounds in all test samples were 2-ethyl-1-hexanol (2-EH), long-chained alcohol isomers (C9-C10) and 1-Butanol, as expected. Thedominant compound in the samples where the floor covering was homogenous with DINCHplasticizer and the adhesive being an acryl copolymer dispersion was 2-EH (43%), in thesamples of heterogenous DINCH 1-Butanol (95%) and in the samples of homogenous DINPboth 1-Butanol and 2-EH were equally common (38%). In the samples where the floorcovering was homogenous with DINCH plasticizer and the adhesive was alkali resistant, thedominant compounds were C9-C10-alcohols (71%).Homogenous floor covering with DINCH plasticizer and acryl copolymer dispersionadhesiveAmong the 10 test samples, clear deterioration was noticed in four (Figure 1, b). The VOCemission levels of material samples (Bulk) were clearly high and so were the surfaceemissions (FLEC-VOC) the maximum TVOC being 330 g/m2 h and the maximum 2-EHbeing 220 g/m2 h. The high 2-EH emissions of the material samples (Bulk) were alreadymeasured a few months after installing floor covering. In all four samples the floor coveringwas installed directly above concrete (no screed) or the used screed was cement based and themeasured pH of the flooring underlay was above 12. The RH of concrete during the floorcovering was RH85% or RH83%. Figure 1 shows the temporal changes of 2-EH and C9-C10-alcohol concentrations. Typically, the highest 2-EH emissions were measured about one yearafter the floor covering. There were also some 2-EH emissions in the “flawless” flooringFigure 1, a), partly due primary emissions. The C9-C10 alcohol emissions reached the “peak”values about two years after installing the floor coverings.a)b)Figure 1. Temporal changes of 2-EH and C9-C10-alcohols, Bulk-VOC. a) deterioratedflooring, b) flawless flooring. Homogenous floor covering with DINCH plasticizer(HomDINCH) and acryl copolymer dispersion adhesive (Adh1) and a gypsum-based screed(Gyp), a low-alkali screed (Low-alk), a cement-based (Cem) or no screed (No). Note:different scaling in each diagram!Heterogenous floor covering with DINCH plasticizer and acryl copolymer dispersionadhesiveThe VOC emission levels of material samples (Bulk) from the 8 test specimens were usuallylower than the samples from specimens with a homogenous floor covering. The water-vaporresistance of heterogenous flooring, used in housing is relatively low and therefore theemissions penetrate the floor covering quite easily compared to specimens with a homogenouscovering. There was no clear difference in the VOC emissions of material samples betweendeteriorated and flawless specimen because the emissions penetrate through the permeablefloor covering. Though, the measured FLEC-emissions were quite high in some samples(maximum TVOC 240 g/m2 h and maximum C9-C10-alcohols 200 g/m2 h), which indicatedeterioration. Those samples were installed directly above concrete (no screed), or the usedscreed was cement based, with a high pH. Figure 2 shows the temporal changes of theconcentrations of 2-EH, C9-C10-alcohols and 1-Butanol.Figure 2. Temporal changes of 2-EH, C9-C10-alcohols and 1-Butanol, Bulk-VOC.Heterogenous floor covering with DINCH plasticizer (HetDINCH) and acryl copolymerdispersion adhesive (Adh1) and a gypsum-based screed (Gyp), a low-alkali screed (Low-alk),a cement-based (Cem) or no screed (No). Note: different scaling in each diagram!Homogenous floor covering with DINCH plasticizer and alkali resistant adhesiveFigure 3 shows the temporal changes of the concentrations of 2-EH, C9-C10-alcohols and 1-Butanol of three test samples of material samples (Bulk). The moisture of concrete wasRH93% (exceeding the guideline´s floor covering criterion) when the floor coverings wereinstalled in all three samples. The 2-EH emissions were very low, since there is no materialwhich has 2-EH as a reaction product. The smallest C9-C10-alcohol and 1-Butanol emissionsare from the specimen with the floor covering on a gypsum-based screed layer (pH lower than9). The C9-C10-alcohol emissions of one sample, where floor covering was installed directlyabove concrete (no screed) are still growing. The FLEC-emissions are still quite low(maximum TVOC less than 20 g/m2 h and maximum 1-Butanol 16 g/m2 h).Figure 3. Temporal changes of 2-EH, C9-C10-alcohols and 1-Butanol, Bulk-VOC.Homogenous floor covering with DINCH plasticizer (HomDINCH) and alkali resistanceadhesive (Adh2) and a gypsum-based screed (Gyp), a cement-based (Cem) or no screed (No).Note: different scaling in each diagram!4 DISCUSSIONOne clear finding from the research, based on both FLEC- and Bulk-VOC analysis, is that a 5mm layer of low-alkali screed (pH less than 11,5) will effectively protect PVC flooringagainst alkaline hydrolysis. The previous studies considering low-alkali layer, mainlyperformed in Sweden in 1990’s and 2000’s (Björk et al, 2003) had the same conclusion.  Thispreviously discovered finding is also valid for new PVC flooring materials with new type ofplasticizers.According to the VOC analysis from material samples (Bulk) up to 3.5 or four years after thefloor covering the highest emission peak of 2-EH and 1-Butanol was noticed about one yearafter installing the floor covering, for C9-C10-alcohol emissions about two years after.  Afterthat the emissions levels started decreasing. These emissions are partly/mainly primaryemissions. There is a risk of misleading interpretation of floor covering deterioration ifmaterial samples for Bulk-VOC analysis are taken from recently installed floor coverings. Wesuggest that another round of sampling and analysis should be performed two or even threeyears after installing the floor covering when investigating an actual case with suspicions offloor problems. Furthermore, a more reliable assessment of possible VOC emissions intoindoor air can then be obtained from a FLEC-VOC sampling.Castagnoli (2019) studied the surface (FLEC) and bulk emissions of two DEHP‐free PVCfloorings over three years. The floorings were glued on the screed layer above concrete slabwhich RH was 75%, 85%, or 95%. The highest emissions of 2-EH from Bulk-VOC analysiswere measured in first months in samples with 75% RH and about 8 months after covering insamples with 95% RH. The highest emissions of C9-alcohol from Bulk-VOC analysis weremeasured about 8 months after covering in samples with 75% RH and in samples with 85% or95% RH the C9-alcohol emission levels were more or less increasing in the last measurement36 months after covering. These results are quite congruent with our results.The research will continue until at least five years has passed from installing the floorcoverings of all the samples.5 CONCLUSIONSVOC emissions of totally 23 different test specimens where the moisture level (RH80%,RH85% and RH93%) of concrete, flooring underlay material (gypsum-based, low-alkali orcement-based screed or no screed), adhesive (acryl copolymer dispersion and alkali resistantadhesive) and floor covering (homogenous floor covering, containing DINCH or DINPplasticizer and heterogenous floor covering containing DINCH plasticizer) have been studied3.5 to four years after installing the floor coverings. The highest VOC emissions anddeterioration were measured in samples where the floor coverings were installed directlyabove concrete (no screed) or where the used screed was cement based with the measured pHof flooring underlay above 12 and the moisture level of concrete was RH85 or RH93%.According to the VOC analysis from material samples the highest emission peak of 2-EH and1-Butanol, mainly due primary emissions, was noticed about one year after installing the floorcovering, for C9-C10-alcohol emissions even two years after.ACKNOWLEDGEMENTThis research was financed by the Confederation of Finnish Construction Industries, theFinnish Concrete Industry, the Concrete Association of Finland, the Federation of Floor andWall Covering Contractors, the cities of Helsinki and Turku, South Karelia Social and HealthCare District, and several floor covering, adhesive and screed manufacturers and the largestconstruction companies. The authors thank all financiers and steering board members for theirvaluable contributions.6 REFERENCESBjörk, F. & Eriksson, C. A. 2002. Measurement of alkalinity in concrete by a simpleprocedure, to investigate transport of alkaline material from the concrete slab to a self-levelling screed. Constr. Build. Mater. 16, 535–542.Björk, F Eriksson, CA Karlsson, S Khabbaz, F. 2003. Degradation of components in flooringsystems in humid and alkaline environments. Constr. Build. Mater. 17, pp. 213–221.Castagnoli, E. et al. 2019. Emissions of DEHP-free PVC flooring. Indoor Air, Volume 29,Issue 6, pp. 903–912.European Committee for Standardization. EN ISO 16000-6. 2004. Indoor air - part 6:Determination of volatile organic compounds in indoor air and test chamber air by activesampling on Tenax TA sorbent, thermal desorption and gas chromatography usingMS/FID.Hedenblad, G. 1997. Drying of construction water in concrete - drying times and moisturemeasurement. Swedish Council for Building Research. T9:1997.Hughes, P. et al. 2006. Recent advances in materials emissions testing chamber technology.Proceedings of Healthy Buildings 2006. Lisbon. ISIAQ.Nordtest. 1996. Nordtest Method NT Build 484. Building materials: Emission of volatilecompounds - On-site measurements with Field and Laboratory Emission Cell (FLEC).Uhde, E. and Salthammer, T. 2007. Impact of reaction products from building materials andfurnishings on indoor air quality—A review of recent advances in indoor chemistry.Atmos. Environ. 41, 3111–3128.Wolkoff, P., Wilkins, C. K., Clausen, P. A. & Nielsen, G. D. 2006. Organic compounds inoffice environments - sensory irritation, odor, measurements and the role of reactivechemistry. Indoor Air 16, 7–19.

VOC emissions of PVC flooring - long-term analysis

https://trepo.tuni.fi/bitstream/10024/158883/1/IA22_1389.pdf

VOC emissions of PVC flooring - long-term analysis

Abstract

Similar works

Full text

Available Versions

Trepo - Institutional Repository of Tampere University