On the capillary water absorption of cement-lime mortars containing phase change materials: Experiments and simulations

GUARDIA, CYNTHIA; BARLUENGA, GONZALO; CAGGIANO, ANTONIO; SCHICCHI, DIEGO SAID; KOENDERS, EDDIE

Building Simulation

Springer Nature

Año: 2019

1996-3599

Nowadays, the use of phase change materials (PCMs) represents a novel technique employed forretrofitting facades in existing buildings, mainly to fulfil temperature comfort and building energyefficiency requirements. The present study summarizes the results of a wide series of permeabilitytests carried out for understanding the moisture transport phenomena by capillary action inmicroencapsulated-PCM (MPCM) porous cementitious composites. Particularly, twelve MPCMcement-lime mortars are analyzed, which were cast with white cement, air lime, siliceous andlightweight aggregates (LWAs), short cellulose fibers and microencapsulated paraffin waxes. A totalamount of 10% and 20% of MPCM by volume was added to the plain mixtures, and physical,mechanical and thermal properties of the composites were characterized. The experimentalresults are employed in an inverse identification procedure aimed at unveiling the key features ofthe capillary action in these partly saturated MPCM porous systems. A nonlinear FEM-based modelfor moisture transport phenomena is used with this purpose by adopting an extended Darcy?s law.The capillary pressure is considered to control the overall diffusion-driven mechanism. The outcomeof the inverse calibration allows to better understand the influence of each material component (andspecially focusing on the MPCM volume fraction) on the resulting diffusion parameters, capillarypressure and the Raleigh-Ritz pore size distribution of the analyzed porous cementitious composites.The inverse calibration procedure showed that MPCM mortars with high values of the Raleigh-Ritz(B) parameter exhibit a low capillary permeability performance. Particularly, it was observedthat when MPCMs are added into the analyzed mortars, an increment of the B value is numericallyobtained and a subsequent reduction of the permeability performance of the composites isobtained.