Strength and Corrosion Studies of Mortars Added with Pozzolan in Sulphate Ions Environment
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pISSN 1226-7988, eISSN 1976-3808 www.springer.com/12205
DOI 10.1007/s12205-020-0183-2
Structural Engineering
Strength and Corrosion Studies of Mortars Added with Pozzolan in Sulphate Ions Environment Roxana I. Martínez-Rosales a, Juana María Miranda-Vidales and Juan Manuel Lozano de Poo b
b
, Lilia Narváez-Hernández
b
,
a
Instituto de Metalurgia, Universidad Autónoma de San Luis Potosí, San Luis Potosí 78210, México Facultad del Hábitat, Universidad Autónoma de San Luis Potosí, San Luis Potosí 78290, México
b
ARTICLE HISTORY
ABSTRACT
Received 18 February 2020 Revised 12 June 2020 Accepted 12 July 2020 Published Online 24 September 2020
The pozzolanic materials have the capacity to modify the performance of Portland cement (PC) mortars. When they are used as supplementary materials, the physical-chemical properties such as compressive-strength and resistance to aggressive environments (chloride, sulphate, acids) are improved. In this article, a study was carried out to evaluate the effects of the addition of two natural pozzolans: volcanic pumice and zeolite. Both used as substitutes for PC in mortars based on cement, considering mechanical strength and the aggressive effect of sulphate ions. Furthermore, the electrochemical behavior of the steel rebar embedded in these mortars was studied during 730 days of exposition to aggressive conditions. The results revealed that the development of the compressive strength of mortars with pozzolans added reached similar values to the reference mortar. It was possible to observe that the addition of the pozzolan suppresses the ettringite formation proportionally to the pozzolan content. The corrosion resistance of the steel improves with the addition of pozzolans after 730 days of exposition at sulphate environment. The results of this study revealed the feasibility to use natural pozzolan as an additive during the preparation of cement up to 25% without significant changes of the physical-chemical properties of the mortars.
KEYWORDS Volcanic pumice Zeolite Sulphate ions Compressive strength Corrosion resistance Rietveld method
1. Introduction Cement is the most employed material in the construction industry, because when it is combined with the aggregates (gravel and sand) it acquires high compressive strength and great durability in diverse environments, natural and industrial. Nevertheless, the cement industry contributes with 7 − 8% of the annual CO2 production (Hamidi et al., 2013), promoting global warming. Being this a worldwide problem of great importance, it is necessary to reduce cement consumption in order to preserve the environment. Several researchers have studied the use of pozzolanic materials such as fly ashes, slag furnace, pozzolans, etc., to replace or replace cement. Most of these pozzolanic materials have cementitious properties when they are mixed with cement, providing good mechanical properties similar to the ones cement possesses. The use of natural pozzolans as an additive, decreases the consumption of Portland clinker, and consequent
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