Hybrid Mortars Activated with Alternative Steel-Compatible Salts: Impact on Chloride Diffusion and Durability

Eco-friendly mortars have been manufactured with hybrid binders made of blast furnace slag and a reduced amount of clinker. The objective is to explore new formulations suitable for reinforced structures. Previous studies are mainly focused on activation with sulfates, a salt that is corrosive to re...

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Main Authors: Angily Cruz-Hernández, Francisco Velasco, Manuel Torres-Carrasco, Asunción Bautista
Format: Article
Language:English
Published: MDPI AG 2025-07-01
Series:Applied Sciences
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Online Access:https://www.mdpi.com/2076-3417/15/14/8055
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author Angily Cruz-Hernández
Francisco Velasco
Manuel Torres-Carrasco
Asunción Bautista
author_facet Angily Cruz-Hernández
Francisco Velasco
Manuel Torres-Carrasco
Asunción Bautista
author_sort Angily Cruz-Hernández
collection DOAJ
description Eco-friendly mortars have been manufactured with hybrid binders made of blast furnace slag and a reduced amount of clinker. The objective is to explore new formulations suitable for reinforced structures. Previous studies are mainly focused on activation with sulfates, a salt that is corrosive to reinforcing steel. Sodium nitrate and sodium carbonate, easily implementable in construction, have been used as activators in two different concentrations that involve similar Na content. A Type II PC mortar is used as reference. The dimensional stability of the mortars during curing (at 99% RH) and subsequent drying at 40% RH, has been evaluated, as well as their porosity and mechanical properties. Böhme tests revealed that studied hybrid binders have lower wear resistance than PC mortar. Activation with Na<sub>2</sub>CO<sub>3</sub> allows the obtention of mortars with reduced porosity and good compression resistance, but generates microcracking that favors chloride diffusion. Activation with nitrates favors precipitation of AFm phases identified through differential thermal analysis. Nitrates in moderate amounts (4% <i>w</i>/<i>w</i>) allow manufacturing hybrid mortars with good resistance to chloride penetration and reasonably good mechanical properties. Hence, this binder can be a promising option for reinforced structures. Higher amounts of nitrates (8%) for activation give rise to more porous mortars.
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issn 2076-3417
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spelling doaj-art-221128d802a1432aacb3f8c1eca87b742025-08-20T03:32:24ZengMDPI AGApplied Sciences2076-34172025-07-011514805510.3390/app15148055Hybrid Mortars Activated with Alternative Steel-Compatible Salts: Impact on Chloride Diffusion and DurabilityAngily Cruz-Hernández0Francisco Velasco1Manuel Torres-Carrasco2Asunción Bautista3Materials Science and Engineering Department–IAAB, Universidad Carlos III de Madrid, Leganés, 28911 Madrid, SpainMaterials Science and Engineering Department–IAAB, Universidad Carlos III de Madrid, Leganés, 28911 Madrid, SpainMaterials Science and Engineering Department–IAAB, Universidad Carlos III de Madrid, Leganés, 28911 Madrid, SpainMaterials Science and Engineering Department–IAAB, Universidad Carlos III de Madrid, Leganés, 28911 Madrid, SpainEco-friendly mortars have been manufactured with hybrid binders made of blast furnace slag and a reduced amount of clinker. The objective is to explore new formulations suitable for reinforced structures. Previous studies are mainly focused on activation with sulfates, a salt that is corrosive to reinforcing steel. Sodium nitrate and sodium carbonate, easily implementable in construction, have been used as activators in two different concentrations that involve similar Na content. A Type II PC mortar is used as reference. The dimensional stability of the mortars during curing (at 99% RH) and subsequent drying at 40% RH, has been evaluated, as well as their porosity and mechanical properties. Böhme tests revealed that studied hybrid binders have lower wear resistance than PC mortar. Activation with Na<sub>2</sub>CO<sub>3</sub> allows the obtention of mortars with reduced porosity and good compression resistance, but generates microcracking that favors chloride diffusion. Activation with nitrates favors precipitation of AFm phases identified through differential thermal analysis. Nitrates in moderate amounts (4% <i>w</i>/<i>w</i>) allow manufacturing hybrid mortars with good resistance to chloride penetration and reasonably good mechanical properties. Hence, this binder can be a promising option for reinforced structures. Higher amounts of nitrates (8%) for activation give rise to more porous mortars.https://www.mdpi.com/2076-3417/15/14/8055hybrid binderssolid activationslagchloride diffusionshrinkagewear
spellingShingle Angily Cruz-Hernández
Francisco Velasco
Manuel Torres-Carrasco
Asunción Bautista
Hybrid Mortars Activated with Alternative Steel-Compatible Salts: Impact on Chloride Diffusion and Durability
Applied Sciences
hybrid binders
solid activation
slag
chloride diffusion
shrinkage
wear
title Hybrid Mortars Activated with Alternative Steel-Compatible Salts: Impact on Chloride Diffusion and Durability
title_full Hybrid Mortars Activated with Alternative Steel-Compatible Salts: Impact on Chloride Diffusion and Durability
title_fullStr Hybrid Mortars Activated with Alternative Steel-Compatible Salts: Impact on Chloride Diffusion and Durability
title_full_unstemmed Hybrid Mortars Activated with Alternative Steel-Compatible Salts: Impact on Chloride Diffusion and Durability
title_short Hybrid Mortars Activated with Alternative Steel-Compatible Salts: Impact on Chloride Diffusion and Durability
title_sort hybrid mortars activated with alternative steel compatible salts impact on chloride diffusion and durability
topic hybrid binders
solid activation
slag
chloride diffusion
shrinkage
wear
url https://www.mdpi.com/2076-3417/15/14/8055
work_keys_str_mv AT angilycruzhernandez hybridmortarsactivatedwithalternativesteelcompatiblesaltsimpactonchloridediffusionanddurability
AT franciscovelasco hybridmortarsactivatedwithalternativesteelcompatiblesaltsimpactonchloridediffusionanddurability
AT manueltorrescarrasco hybridmortarsactivatedwithalternativesteelcompatiblesaltsimpactonchloridediffusionanddurability
AT asuncionbautista hybridmortarsactivatedwithalternativesteelcompatiblesaltsimpactonchloridediffusionanddurability