Abstract
The article describes a study conducted to determinecorrosion in reinforcement embedded in Portland cement(PC) mortars with different percentages of sewage sludgeash (SSA) admixtures. The polarization resistancetechnique was used to determine the steel corrosion rate(Icorr) in the test specimens. The samples were subjectedto different environmental conditions and aggressiveagents: 100% relative humidity (RH), accelerated carbonationat 70% RH and seawater immersion. Portlandcement was partially substituted for SSA in the mixes atrates of 0, 10, 20, 30 and 60% (by mass) to make thedifferent mortars. The results show that where cementwas replaced by SSA at rates of up to 10% by mass,mortar corrosion performance was comparable to thebehaviour observed in SSA-free mortars (control mortar:0% SSA). Data for higher rates are also shown. From themechanical standpoint, SSA exhibited moderate pozzolanicactivity and the best performance when SSA wasadded at a rate of 10% to mixes with a water/(binder:PC + SSA) (w/b) ratio of 0.5.
Highlights
Sewage sludge, an urban waste water treatment plant by-product, is presently used as a fertilizer to enhance the properties of farm soil
sewage sludge ash (SSA) behaviour in concrete in this regard is of particular importance, for its salt content might trigger the corrosion of reinforcing steel embedded in concrete
After 28-day curing in a moist closet (100% relative humidity (RH), 20 oC), the specimens were subjected to different environmental conditions: 100% RH, seawater immersion and accelerated carbonation
Summary
The article describes a study conducted to determine corrosion in reinforcement embedded in Portland cement (PC) mortars with different percentages of sewage sludge ash (SSA) admixtures. Portland cement was partially substituted for SSA in the mixes at rates of 0, 10, 20, 30 and 60% (by mass) to make the different mortars. The results show that where cement was replaced by SSA at rates of up to 10% by mass, mortar corrosion performance was comparable to the behaviour observed in SSA-free mortars (control mortar: 0% SSA). SSA exhibited moderate pozzolanic activity and the best performance when SSA was added at a rate of 10% to mixes with a water/(binder: PC + SSA) (w/b) ratio of 0.5. Ing. de la Construcción, Obras Públicas e Infr. Ing. de la Construcción y Proyectos de Ingeniería Civil.
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