Browsing by Keyword "Aggregate"
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Item Influence of acetic acid and calcium hydroxide treatments of rubber waste on the properties of rubberized mortars(2017-02-01) Muñoz-Sánchez, Belén; Arévalo-Caballero, María José; Pacheco-Menor, María Concepción; Tecnalia Research & InnovationThe main goal of this study consisted in improving the performance of cementitious materials containing a percentage of rubber particles as a substitution for aggregates. Rubber surface was modified: new chemical and simple treatments based on calcium hydroxide or acetic acid solutions were applied. The effect of the above treatments was compared with that produced by sulphuric acid or sodium hydroxide solutions or by the use of plain rubber particles, already studied and reported in the literature. Fourier transformed infrared spectroscopy-attenuated total reflectance (FTIR-ATR) was used in order to characterize the rubber surface and chemical modifications. The rubber particles were observed by optical microscopy (OM) with the aim of detecting the possible physical changes on their surface. Then, the modified rubber particles were included in the composition of mortar specimens and their properties in the fresh (consistency) and the hardened state (porosity, flexural and compressive strength, capillarity water absorption and ultrasonic pulse velocity, UPV) were examined. Regarding the properties of rubber particles, their surface hydrophilicity, absorption and roughness increased after acid or alkaline treatments. Considering mortars including chemically treated rubber particles, calcium hydroxide gave rise to mortars with lower porosity and acetic acid to mortars with lower density. Mechanical properties of mortars were improved in comparison with these properties in mortars containing plain rubber particles. Alkaline solutions prompted the highest values of compressive strength. A delay in the hardening time for rubberized mortars may be deduced from the mechanical properties evolution. The partial substitution of natural aggregates by chemically treated rubber particles, improves the properties, in terms of flexural and compressive strength, of rubberized mortars.Item Steel slag aggregate in concrete: The effect of ageing on potentially expansive compounds(2010) Frías, M.; San-José, J. T.; Vegas, I.; GENERALGrowing numbers of plants have sprung up in recent years to treat the electric arc furnace slag generated in scrap metal melting. When this by-product is separated, crushed and screened, it yields a granular material known as steel slag aggregate, which may be profitably used in the manufacture of commercial concrete. The feasibility of this application depends essentially on the volume stability of the resulting aggregate. The present paper discusses the potentially expansive compounds (Cl-, SO3, free CaO and free MgO) present in aggregate derived from different types of black slag during aggregate ageing. The aim is to establish optimal ageing conditions to ensure volume stability in steel slag aggregate. The findings showed that the slag analyzed had low concentrations of the expansive compounds studied and that possible swelling can be reduced by 45-day ageing.Item Sustainable masonry mortars based on ladle furnace slags from the steel-making industry(University of Cantabria - Building Technology R&D Group, 2020) Santamaría, Amaia; Fiol, Francisco; García, Verónica; Setién, Jesús; González, Javier Jesús; Lombillo, Ignacio; Blanco, Haydee; Boffill, Yosbel; TRAZABILIDAD CIRCULARMasonry mortars are applied to concrete and brickwork to form structural bonds. Partial substitution of their natural raw materials by waste products from the steel industry represents a sustainable approach towards the ecological management of those materials in Spain, where iron and steelmaking is a highly developed heavy industrial sector. Additionally, a somewhat more traditional industrial sector, the building industry, also consumes large amounts of natural resources and energy, likewise resulting in high CO2 emission levels. The present research is focused on solid waste from the steelmaking industry and its addition in significant amounts to masonry mortars. Labelled as “white” slag, the waste (saturated in alumina) is commonly known as ladle furnace slag. To do so, several lab tests are presented, which investigate the partial substitution of fillers and hydraulic binders in regular masonry mortars. Firstly, the study of ladle furnace slag and its overall properties and, secondly, studying the feasibility of producing Ladle Furnace Slag mortars, yielded interesting and positive results.