Determination of Critical Relative Humidity of Construction Materials for Mold Growth by Experimental Study

Öz

Resistance of materials to mold fungi is directly related to the material properties and the environmental temperature and relative humidity level. Critical relative humidity occurs when the relative humidity reaches to the point where mold fungi can grow on the substrate. A strategy should be developed to address the conditions of mold fungi growth and use more suitable materials depending on the humidity conditions in the building. The purpose of this research was to establish the essential relative humidity of various construction materials based on their substrate category in order to get a better understanding of mold resistance and to reduce the danger of mold development. The critical relative humidity for six building materials was determined in this research to assess each substrate category’s resistance to mold growth. Inoculation of construction materials with six mold spores (Penicillium, Cladosporium, Chaetomium, Scopulariopsis, Aspergillus, and Acremonium) and incubation in a desiccator at 22° C (%75-95 ). For 3 months, samples were analyzed once a week. Mold growth was most sensitive to substrate category I (gypsum board) in this laboratory experiments. There was no evidence of growth in any of the glass or composite samples. The essential moisture level varied according to substrate category. For example, the essential humidity level for drywall (category I) was 80%, whereas for rock wool it was 85% (category II). At various relative humidity levels, the time needed for critical mold development varied. Critical mold development times for gypsum board are 12 weeks at 75% relative humidity and 1 week at 95% relative humidity. The greater the environment relative humidity, the less time essential mold development requires on the substrate.

Anahtar Kelimeler

• Mould
• Relative humidity
• Critical relative humidity level
• Building material
• Mould resistance

Deneysel Çalışma ile Küf Büyümesi için Yapı Malzemelerinin Kritik Bağıl Neminin Belirlenmesi

Öz

Yapı malzemelerin küf mantarlara karşı direnci, malzeme özellikleri, ortam sıcaklığı ve bağıl nem seviyesi ile doğrudan ilişkilidir. Kritik bağıl nem, bağıl nem, substrat üzerinde küf mantarlarının gelişebileceği noktaya ulaştığında meydana gelir. Küf mantarlarının üreme koşullarını ele almak ve binadaki nem koşullarına bağlı olarak daha uygun malzemeler kullanmak için bir strateji geliştirilmelidir. Çalışmada yapı malzemelerinin küf direncini daha iyi anlamak ve küf oluşumu riskini en aza indirmek için substrat kategorisine bağlı olarak kritik bağıl nemini belirlenmesi amaçlanmıştır. Bu çalışmada, her substrat kategorisinin küf oluşumuna karşı direncini değerlendirmek için altı yapı malzemenin kritik bağıl nemi belirlendi. Yapı malzemeleri altı küf sporu (Penicillium, Cladosporium, Chaetomium, Scopulariopsis, Aspergillus ve Acremonium) ile aşılandı ve 22°C’de (%75-95) bir desikatörde inkübe edildi. Üç ay boyunca numuneler haftada bir kez analiz edildi. Laboratuvar testlerinde, küf oluşumuna en duyarlı, substrat kategori I (alçı levha) olmuştur. Cam ve kompozit numunelerinin hiçbirinde üreme tespit edilmedi. Kritik nem seviyesi farklı substrat kategorileri için farklıydı. Örneğin, alçıpan (kategori I) için kritik nem seviyesi %80, taş yünü için (kategori II) ise %85 idi. Farklı bağıl nem seviyelerinde kritik küf gelişimi için gereken süre değişiklik göstermiştir. Bu kapsamda alçı levha için kritik küf gelişimi %75 bağıl nemde 12 hafta, %95 bağıl nemde ise bir haftadır. Ortamın bağıl nemi ne kadar yüksek olursa, substrat üzerinde kritik küf oluşumu için gereken sürenin o kadar kısa olduğunu göstermektedir.

Anahtar Kelimeler

• Küf
• Bağıl nem
• Kritik bağıl nem seviyesi
• Yapı malzemesi
• Küf direnci

Teşekkür

İTÜ Mimarlık Fakültesi yapı malzemeleri laboratuvarında her zaman malzeme kullanımımızda bize yardımcı olan teknisyen İbrahim Öztürk'e teşekkürlerimizi sunarız.

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