Cement
(and derivatives thereof) is one of the materials most commonly used in
construction, given its good performance at low cost. Over recent
years, one part of scientific and technological research is aimed at
incorporating additional functions into these materials.
Specifically,
Doctor Idurre Kaltzakorta studied the possibility of adding capacities
to the cement such as self-repair of cracks as well as storing latent
heat energy. Her PhD thesis, undertaken at Tecnalia’s Construction Unit,
was presented at the Univ. of the Basque Country (UPV/EHU) and
entitled: Synthesis of silica microcapsules encapsulating different
organic compounds for addition in the cement paste.
As
the title of her research suggests, Dr Kaltzakorta created silica (it
is, for instance, the base of glass) microcapsules with organic material
inside, the idea being to provide the cement with new functions. She
opted for two types of organic materials, each corresponding to one of
the two added features mentioned above. Thus, on the one hand, the
microcapsules were filled with various epoxy resins (used in the
manufacture of adhesives), to provide the cement with the capacity for
the self-repair of cracks. On the other, phase change materials were
encapsulated. These are materials which absorb or free a great quantity
of heat on the phase of the material changing (from solid to liquid or
liquid to gas and viceversa), and enable the storage of latent heat
energy in the cement material.
Sol-gel and emulsion
Ms
Kaltzakorta studied the synthesis of the encapsulated material, opting
for synthesising microcapsules by combining sol-gel chemistry with
emulsion technology. This route enabled the encapsulation of organic
material, difficult with other routes, under mild temperature and
pressure conditions.
Once
the microcapsules were obtained, the thesis analysed the effect of the
addition of these to the cement matrix, to verify the viability of the
technique. With this in mind, Ms Kaltzakorta used a number of techniques
with which the features of the new cement material could be studied,
techniques such as X-ray tomography, scanning electron microscopy,
mechanical testing, and differential scanning calorimetry.
In
conclusion, the thesis shows the viability of the development of a new
generation of cements capable of the self-repair of cracks as well as
storing latent heat energy, based on the application of silica
microcapsules with various organic materials. In fact, the research for
developing the new cement with the capacity for self-sealing of cracks
has given rise to a patent. Moreover, according to Ms Kaltzakorta, the
proposal presented in this thesis is a commitment to sustainability. On
the one hand, getting the cement material to self-repair increases the
useful life of the structures. On the other, using a material capable of
regulating the temperature within the buildings will enhance their
energy efficiency.
About the author
Ms
Idurre Kaltzakorta Arantzamendi (Ondarroa, 1978) is a doctor in
Chemical Sciences. She defended her PhD thesis in the Department of
Chemistry-Physics at the Science and Technology Faculty of the UPV/EHU
and undertook it under the direction of Ms Edurne Erkizia Jauregi (PhD),
in the Nanomaterials in Construction Team (NANOC) of the Construction
Unit at Tecnalia. She also had the help of university teacher Mr Luis
León Isidro and his team at the Department of Chemistry-Physics of the
UPV/EHU. She has also collaborated with the Univ. of Hokkaido in
Sapporo, Japan.