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Circular Economy
kg / m3 with the replacement of 100 wt% of MK by OPBA. The increase in bulk density with greater OPBA incorporations could be due to the higher relative density of the ash (2699 kg / m3) compared to the MK (2569 kg / m3).
Compressive strength is a key factor in structural construction materials. Compared to the reference sample (with 0 wt % OPBA) (17.5 MPa), the compressive strength of the samples with 25 and 50 wt% of OPBA was higher than that of all other geopolymers (22.7 MPa). As the substitution of MK by OPBA increased up to 75 wt % a gradual decrease in compressive strength was observed (16.7 MPa), however the addition of 100 wt % of waste produced a significant decline in compressive strength. Geopolymers 100 wt % OPBA reached values of 4.6 MPa.
Thermal conductivity is an important property in construction materials that affects its insulation capacity. The control geopolymers (100 wt % MK) presented a thermal conductivity of 0.292 W/mK. Only the incorporation of 25 wt % of MK gave rise to geopolymers with lower thermal conductivity (0.253 W/mK). The incorporation of 50 and 75 wt % of waste produced a slight increase in this properties (0.307 and 0.321 W/mK, respectively). However the geopolymers 100 OPFA wt % had a thermal conductivity higher (0.402 W/mK).
It can be concluded, therefore, that the substitution of a 25 wt % of MK for the OPBA waste produced geopolymers with better mechanical and thermal properties than the control geopolymers, also present economic and environmental advantages.
4. Acknologedments
This work has been funded by the project Development and characterization of new geopolitical composites based on waste from the olive industry. Towards a sustainable construction (MAT2017-88097-R), FEDER/Ministry of Science, Innovation and Universities, State Research Agency.
5. References
Deja J., Uliasz-Bochenczyk A., Mokrzycki E. (2010), CO2 emissions from Polish cement industry, Int. J. Greenh. Gas Con. 4, pp 583-588.
Duxson P., Fernández-Jiménez A, Provis J.L., Lukey G.C., Palomo A., van Deventer J.S.J.(2007), Geopolymer Technology: The Current State of the Art. J Mater Sci. 42, pp 2917-2933.
UNE-EN 772-1, (2011). Methods of test for masonry units - Part 1: Determination of compressive strength.
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