Page 41 - New Trends in Green Construction

CHARACTERIZATION OF MORTARS CONTAINING RUBBER FROM TYRES OUT OF USE
Sofía Jurado-Contreras, M. Dolores La Rubia Dolores, D. Eliche-Quesada
Keywords: Crumb rubber, concrete, mortars 1. Introduction
Due to the increase in the number of motor vehicles, environmental pollution caused by the used tires has also increased. Vehicle tires are made of rubbers which, after completing their useful life, turn into a waste that needs to be destroyed in the environment (Gonen, 2018). Taking into account both the environmental risks presented from used tire as well as the scarcity of natural mineral aggregates, a lot of recent research has focussed on utilizing used tire in concrete as a partial replacement of its natural aggregates (Youssf, 2016). The inclusion of waste rubber in concrete has significant effects on the physical and mechanical properties of the concrete. Thus, some researchers have used the waste particles in the concrete mix and have studiedtheeffectsoftheseparticlesonthecharacteristics(Topçu,2007).Theaimofthis studyis to assess the environmental benefits of the use of waste rubber from out of use tires. For this purpose, a replacement in volume of standardized sand by crushed rubber was made in mortars. At the same time, the inclusion of an air-entrainment / plasticizing additive to mortars (to improve cohesion) was studied.
2. Materials and methods
The raw materials used in this investigation were Portland cement type CEM II/A-V 42.5 R, supplied by Holcim (Spain), crumb rubber from Renean (Jaén, Spain) as partial replacement of sand, air-entrainment/plasticizing additive, Sikamor A, from Rescatec MC (Almería, Spain) natural sand CEN DIN-EN-196-1 from Instituto Torroja (Madrid, Spain). To simulate the granulometry of the sand, a mixture of two different ranges of rubber 0-0.6 mm and 0.6-2 mm were added in 70% and 30% respectively.
The chemical composition of the raw materials was determined by X-ray fluorescence (XRF) by a spectrometer Philips Magix Pro (PW-2440). Crystalline phases were evaluated in an X-ray diffractometry with a X’Pert Pro MPD automated diffractometer (PANanalytical) equipped with Ge (111) primary monochromator, using monochromatic Cu Kα radiation (λ = 1.5406 Å) and an X’Celerator detector. The content of carbonates was determined by calcimetry Blaine method. The relative density value was obtained by the Le Chatelier`s volumetric method. The pH was determined by a solid pH-meter PCE-PH20S, (PCE Instrument).
Mortars were prepared according to EN standards with natural sand CEN DIN-EN-196-1. The mortars were made with Portland cement type CEM II/A-V 42.5 R and the water relation (W/C) was 0.5 by weight. The sand was replaced in volume by crumb rubber and nine different percentages of substitution were used: 0, 5, 10, 20, 30, 40, 50, 75 and 100 %. The air- entrainment / plasticizing additive, Sikamor A, was added into the mortars mixture by 0.05% on the weight of cement. The mixing procedure used was defined by the standard EN 1015-3 (1999). Two series of three prismatic specimens were prepared for each mortar mixture, 40 x 40 x 160 mm size, by casting them in steel forms. They were cured in environmental chamber at
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New Trends in Green Construction