Abstract
Novel green concrete (GC) admixtures containing 50% and 100% recycled coarse aggregate (RCA) were manufactured according to the ACI 211.1 standard. The GC samples were reinforced with AISI 1080 carbon steel and AISI 304 stainless steel. Concrete samples were exposed to 3.5 wt.% Na2SO4 and control (DI-water) solutions. Electrochemical testing was assessed by corrosion potential (Ecorr) according to the ASTM C-876-15 standard and a linear polarization resistance (LPR) technique following ASTM G59-14. The compressive strength of the fully substituted GC decreased 51.5% compared to the control sample. Improved corrosion behavior was found for the specimens reinforced with AISI 304 SS; the corrosion current density (icorr) values of the fully substituted GC were found to be 0.01894 µA/cm2 after Day 364, a value associated with negligible corrosion. The 50% RCA specimen shows good corrosion behavior as well as a reduction in environmental impact. Although having lower mechanical properties, a less dense concrete matrix and high permeability, RCA green concrete presents an improved corrosion behavior thus being a promising approach to the higher pollutant conventional aggregates.
Highlights
The world’s most widely used building material is hydraulic concrete that, when combined with AISI 1018 carbon steel (CS) rebars, forms a system known as reinforced concrete.Reinforced concrete structures are known for their long-lasting service life and low-maintenance requirements
Half-cell potential monitoring (Ecorr ) and interpretation of the corrosion state were performed using the criteria presented in Table 7, which is in accordance with ASTM C876-15 [86]
It is observed that the Mixtures of Conventional Concrete (MC)-W-18 specimen presents corrosion potentials in the curing stage ranging from −260 to −160 mVCSE, moving from Days 7 to 28 from the intermediate corrosion risk to 10% risk, according to ASTM C-876-15
Summary
The world’s most widely used building material is hydraulic concrete that, when combined with AISI 1018 carbon steel (CS) rebars, forms a system known as reinforced concrete.Reinforced concrete structures are known for their long-lasting service life and low-maintenance requirements. Due to the corrosion of the steel reinforcement, billions of dollars are spent in the repair and maintenance of bridges, tunnels, roads and docks, among others, by each country [1,2,3,4,5]. Corrosion occurs due to several factors that promote passivity breakdown, primarily the carbonation or the ingress of aggressive ions [6,7]. The aggressive depassivating ions are chlorides, present in marine environments [8,9,10] and sulfates from inorganic salts normally present in both groundwater and in surface water. Laboratory simulations show that the galvanized reinforcements outperform traditional carbon steel reinforcements in aggressive environments, and in contact with contaminants found in the concrete mixture [18,19,20,21]
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