Abstract
This paper reports a study on 8 unconventional hydraulic lime-based mortars able to improve indoor air quality by acting as passive systems. Mortars have been prepared with commercial sand or highly adsorbent materials as aggregates with/without TiO2 as photocatalytic agent, to test also the decomposition of airborne pollutants. Mechanical properties, hygrometric behavior, inhibition of growth of molds and depollution properties have been tested. Despite using porous materials (zeolite and activated carbon), in mortars with unconventional aggregates, compressive strength is higher than in sand-based ones, with a more than double higher water vapor permeability. Zeolite-based mortars have the highest moisture buffering capacity followed by silica gel- and activated carbon-based mortars (1.5–2 times higher than reference, respectively, because of the high porosity of unconventional aggregates). Sand-based mortars show optimum inhibitory capacity against fungal growth. Concerning unconventional aggregates, silica gel mortars have good inhibitory capacity, whereas zeolite and activated carbon give to mortars an optimum substrate for molds. Mortars with unconventional aggregates as silica gel remove more than 80% of tracer pollutant after 2 h of test, whereas zeolite-based mortars remove the 65% of it after 120 min. TiO2 enhances depollution properties as photocatalytic oxidation agent when the mortar is close to saturation.
Highlights
Buildings materials are strictly related to indoor air quality (IAQ) of the environments where they are placed
This paper explores the possibility of improving IAQ using building materials able to positively interact with the indoor environment due to their adsorption capacity and/ or to their photocatalytic oxidation (PCO) activity:
Adsorbent materials are used as aggregates to prepare unconventional mortars able to improve IAQ
Summary
Buildings materials are strictly related to indoor air quality (IAQ) of the environments where they are placed. People are spending up to 90% of their time indoor, where concentration of airborne pollutants, due to insulating necessity, could be higher than outdoor [1,2]. This paper explores the possibility of improving IAQ using building materials able to positively interact with the indoor environment due to their adsorption capacity and/ or to their photocatalytic oxidation (PCO) activity: Highly adsorbent materials are used as aggregates (substituted to conventional calcareous sand) to prepare unconventional mortars able to improve IAQ. In literature it has been found that by using adsorbent materials (zeolite, silica gel and activated carbon), the adsorption process of the aggregate predominates on the photocatalytic action of TiO2 [3] Low quantity of activated carbon/zeolite in a photocatalytic cementitious matrix or superadsorbent materials are used in cementitious matrix to guarantee the decomposition of NOx or Volatile Organic Compounds (VOCs) [6,7,8,9].
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