Pervious concrete made with electric furnace slag (FEA): mechanical and hydraulic properties

Volume 12, Number 3 (June 2019) p. 590 – 607 • ISSN 1983-4195 http://dx.doi.org/10.1590/S1983-41952019000300009 Pervious concrete made with electric furnace slag (FEA): mechanical and hydraulic properties Concreto permeável de escória de forno elétrico (FEA): propriedades mecânicas e hidráulicas G. F. B. SANDOVAL a https://orcid.org/0000-0002-8702-8844 I. GALOBARDES b https://orcid.org/0000-0002-3569-2241 C. DIAS a https://orcid.org/0000-0001-6604-1313 A. CAMPOS a https://orcid.org/0000-0002-0083-4481 B. M. TORALLES a https://orcid.org/0000-0001-8828-7250 Abstract The objective of this work is to make feasible the use of FEA slag instead of the conventional bulk aggregate in the pervious concrete (PC) production, reaching the minimum parameters required by NBR16416/2015 and ACI 522R-10. This substitution would minimize the use of natural aggregates, besides taking advantage of a residue that has no specific destination. In order to reach the objective, three FEAs with different grain sizes were chosen: 6-10 mm (A), 10-20 mm (B) and finally a mixture of the two previous ones (C) in the proportion 30-70 respectively. In order to evaluate its mechanical behavior, tests of compressive strength and flexural tensile tests were carried out, while the evaluation of the hydraulic behavior, porosity and constant head permeability test were performed. The compressive strength varies from 19-31MPa and 3-4MPa for flexural tensile strength was obtained. In hydraulic terms, the porosity varied from 15-20% and the permeability coefficient was 10-12mm/s. There is also a direct influence of grains of size less than 4.8 mm (small aggregate) on the compressive strength and permeability of PCs. At the end of the results, it was possible to establish a correlation between the compressive strength, the permeability and the percentage of grains inferior to 4.8mm (sand%), being this positive in relation to the studied variables, that is, the mechanical and hydraulics. Therefore, it has been concluded that the total substitution of conventional aggregates by FEA in CoPe manufacturing will comply with the minimum parameters of NBR 16416/2015. Keywords: pervious concrete, permeability, porosity, sustainability, electric furnace slag. Resumo O objetivo deste trabalho é viabilizar o uso de escória de forno elétrico (FEA) em substituição ao agregado graúdo convencional na fabricação de concreto permeável (CoPe), atingindo os parâmetros mínimos exigidos pela norma NBR16416/2015. Esta substituição minimizaria a utilização de agregados naturais, além de aproveitar um resíduo que não tem destinação específica. Para alcançar o objetivo foram escolhidos três FEA’s com diferentes distribuições granulométricas: 6-10 mm (A), 10-20 mm (B) e finalmente uma mistura das duas anteriores (C) na proporção 30-70 respectivamente. Para avaliar seu comportamento mecânico foram realizados ensaios de resistência à compressão e tração na flexão, enquanto na avaliação do comportamento hidráulico, índice de vazios e permeabilidade à carga constante foram realizados. Na compressão foram obtidas resistências variando de 19-31MPa e 3-4MPa na tração na flexão. Em termos hidráulicos, o índice de vazios variou de 15%-20% e o coeficiente de permeabilidade de 10-12mm/s. Também se verifica a influência direta dos grãos de tamanho inferior a 4.8 mm (agregado miúdo) na resistência à compressão e na permeabilidade dos CoPes. Ao final, a partir dos resultados obtidos foi possível estabelecer uma correlação entre a resistência à compressão, a permeabilidade e a porcentagem de grãos inferiores a 4.8mm (%areia), sendo esta positiva em relação às variáveis estudadas, ou seja, as propriedades mecânicas e hidráulica. Por tanto foi concluído que é viável a substituição total dos agregados convencionais por FEA na fabricação de CoPe cumprindo com os parâmetros mínimos da NBR 16416/2015. Palavras-chave: concreto permeável, permeabilidade, índice de vazios, sustentabilidade, escória de forno elétrico. a b Universidade Estadual de Londrina, Departamento de Construção Civil, Londrina, PR, Brasil; Xi’an Jiaotong-Liverpool University, Suzhou, China. Received: 02 Apr 2018 • Accepted: 16 Sep 2018 • Available Online: This is an open-access article distributed under the terms of the Creative Commons Attribution License © 2019 IBRACON G. F. B. SANDOVAL | I. GALOBARDES | C. DIAS | A. CAMPOS | B. M. TORALLES 1. Introduction The growth of the cities has taken place rapidly and sharply in the last years, bringing with it several damages to the environment, including the reduction of pervious areas. Soil waterproofing significantly reduces its natural capacity to absorb rainwater, which can result in floods that mainly affect large urban centers [1, 2]. In civil construction, a widely used material in pavements is conventional concrete, which has a low permeability coefficient (about 1x10-8 m/s) due to its low percentage of voids [3]. For this reason, its application results in soil waterproofing. In search of an alternative that does not waterproof the soil, research has been carried out in the search for materials that allow the passage of water through its structure, without changing the mechanical properties [1]. The use of permeable materials helps to reduce the impacts caused by waterproofing, which provides balance in the hydrological cycle that is altered in a radical way with the waterproof coatings of the big cities, minimizing the risk of accidents with vehicles by the phenomenon of hydroplaning and diseases derived from floods, ensuring the safety of the environment [1]. Among these materials is the pervious concrete (PC) which, because of its composition, has a high porosity due to the partial or total lack of small aggregates in the mixture. This concrete has a drainage capacity greater than the conventional one, which reduces the flow of rainwater present in the surface runoff [4]. PC is composed of Portland cement, coarse aggregate and water, with little or no small aggregate (sand), which facilitates the formation of interconnected internal voids that allow the fast and safe flow of water [1,2,5,6]. In terms of mechanical strength, this material works in the range of 3-30 MPa [7–10], and can be used on pedestrian sidewalks and light traffic pavements. In hydraulic terms, the permeability coefficient of the material varies from 1 to 20mm/s, which guarantees the rapid flow of water through its structure [4,11–14]. Currently, construction waste has been used as an aggregate in the manufacture of PC. The mechanical properties obtained with some of these aggregates vary from 6 to 14 MPa in the compressive strength and from 1 to 2 in the flexural strength[15,16], with a reduction in these properties when compared to the use of conventional aggregates [1]. However, the hydraulic properties comply with the requirements of national and international regulations, above 1 mm/s [17]. In order to improve the mechanical properties (...truncated)