Abstract
Concrete systems exposed to deicers are damaged in physical and chemical ways. In mitigating the damage from CaCl2 deicers, the usage of ground slag cement and MgO are investigated. Ordinary Portland cement (OPC) and slag cement are used in different proportions as the binding material, and MgO in doses of 0%, 5%, 7%, and 10% are added to the systems. After 28 days of water-curing, the specimens are immersed in 30% CaCl2 solution by mass for 180 days. Compressive strength test, carbonation test, chloride penetration test, chloride content test, XRD analysis, and SEM-EDAX analysis are conducted to evaluate the damage effects of the deicing solution. Up to 28 days, plain specimens with increasing MgO show a decrease in compressive strength, an increase in carbonation resistance, and a decrease in chloride penetration resistance, whereas the S30- and S50- specimens show a slight increase in compressive strength, an increase in carbonation resistance, and a slight increase in chloride penetration resistance. After 180 days of immersion in deicing solution, specimens with MgO retain their compressive strength longer and show improved durability. Furthermore, the addition of MgO to concrete systems with slag cement induces the formation of magnesium silicate hydrate (M-S-H) phases.
Highlights
Concrete used in road structures are often exposed to harmful external factors, one of which is the deicing products widely used to remove ice and snow in cold regions
The EDAX results show presence of Mg at approximately 22% by atomic weight, with traces of Ca and Si at approximately 9% and Building on past researches that have shown the mechanisms of calcium chloride damages, extensive tests on the mechanical properties and durability of concrete systems with MgO and slag cement showed the following conclusions
As can be seen from the compressive strength results at 28 days after water-curing, MgO hydrates at a slower rate compared to Ordinary Portland cement (OPC); in systems with slag cement, MgO manifests as magnesium silicate hydrate (M-S-H)
Summary
Concrete used in road structures are often exposed to harmful external factors, one of which is the deicing products widely used to remove ice and snow in cold regions. These deicing chemicals usually consist of chloride-based salts such as sodium chloride (NaCl), calcium chloride (CaCl2 ), and/or magnesium chloride (MgCl2 ). The physical damage from deicers are manifested in the form of cracking and salt scaling, which may not cause severe damage by itself, but will make the concrete structures more susceptible to frost action or chemical attack. Other forms of chemical damage come from the formation of Friedel’s salt (3CaO·Al2 O3 ·CaCl2 ·10H2 O), Kuzel’s salt (3CaO·Al2 O3 ·1/2CaSO4 ·1/2CaCl2 ·11H2 O), and/or calcium oxychloride (common type known as the 3:1:12 form—3Ca(OH)2 ·CaCl2 ·12H2 O) which could undergo even without freezing and melting
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