Page 42 - New Trends in Green Construction

Circular Economy
22 oC and humidity of 80 % up to 7 and 28 days and dried before testing.
Physical and mechanical properties after 7 and 28 days of curing were determined. Apparent density determination tests were carried out according to the standard EN 1015-10 (2000), capillary water absorption tests according to EN 1015-18 (2003). The compressive and flexural strength were determined using the Universal Testing Machine MTS 810 according to EN 1015- 11 (2007). The mortar samples and their microstructures were observed using Scanning Electron Microscopy (SEM) with JEOL SM 840
3. Results and conclusions
The results indicated that the crumb rubber content increased, while apparent density, water absorption and the compressive and flexural strength decreased. As regards of the curing time apparent density and water absorption decreased to further curing time. Compressive and flexural strength increased (except substitution of 0, 10 and 30 %) to longer curing. Finally, the influence of the additive on the properties was compared with a previous study (Puerma, 2017). The resulting values showed that, in general, properties were improved with this addition (except compressive strength). At 7 and 28 curing days, bulk density and water absorption values were lower with the additive (except to 28 days in the control mortar and 10% of rubber). The flexural resistance, at 7 and 28 days, increased (except control mortar in 28 days). However, compressive resistance decreased. The SEM images, showed that the cohesion of the rubber in the cement matrix was improved with the additive. This analysis displayed more ettringite in the union area.
4. References
Gonen T. (2018). Freezing-thawing and impact resistance of concretes containing waste crumb rubbers. Construction and Building Materials, 177, pp 436-442.
Youssf O., Mills J., Hassanli R. (2016). Assessment of the mechanical performance of crumb rubber concrete. Construction and Building Materials, 125, pp 175-183.
Topçu I.B., Demir A. (2007). Durability of rubberized mortar and concrete. Journal of Materials in Civil Engineering, 19, pp 173-178.
Puerma, Á. (2017). Neumáticos fuera de uso como aligerantes de morteros. Universidad de Jaén.
42