Hybrid Mortars Activated with Alternative Steel-Compatible Salts: Impact on Chloride Diffusion and Durability
Source abstract
Abstract
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 Na2CO3 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% w/w) 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.
Source: crossref · Quality: baseline
Research context
OpenAlex topics: Concrete and Cement Materials Research · Innovations in Concrete and Construction Materials · Magnesium Oxide Properties and Applications
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
Affiliations
Materials Science and Engineering Department–IAAB, Universidad Carlos III de Madrid, Leganés, 28911 Madrid, Spain
Funding
FEDER “Una manera de hacer Europa”
References (74)
Show source-provided references
1. Recent progress in environmentally friendly geopolymers: A review10.1016/j.scitotenv.2020.143166 ↗
2. Global strategies and potentials to curb CO2 emissions in cement industry10.1016/j.jclepro.2012.10.049 ↗
3. Carbon dioxide emissions from the global cement industry10.1146/annurev.energy.26.1.303 ↗
4. Promoting the use of Fe-rich slag in construction: Development of a hybrid binder for 3D printing10.1016/j.cemconcomp.2023.104959 ↗
5. Characterisation of pre-industrial hybrid cement and effect of pre-curing temperature10.1016/j.cemconcomp.2016.07.019 ↗
6. Fundamental properties of industrial hybrid cement: Utilization in ready-mixed concretes and shrinkage-reducing applications10.3989/mc.2016.04615 ↗
7. Hybrid binders: A journey from the past to a sustainable future (opus caementicium futurum)10.1016/j.cemconres.2019.105829 ↗
8. Controlling the hydration rate of alkali-activated slag by the slow release of NaOH10.1016/j.geoen.2023.211960 ↗
9. Influence of the early-age length change of alkali-activated slag mortars on the corrosion of embedded steel
10. Shrinkage behavior and mechanical properties of alkali activated mortar incorporating nanomaterials and polypropylene fiber10.1016/j.ceramint.2022.04.297 ↗
11. Internal curing and its application to alkali-activated materials: A literature review10.1016/j.cemconcomp.2023.105360 ↗
12. Study on the effect and mechanism of cement-based material retarder on red mud-based hybrid alkali activated cement10.1016/j.jobe.2023.106353 ↗
13. Sulphate-based activation of a binary and ternary hybrid cement with portland cement and different pozzolans10.1016/j.conbuildmat.2024.135683 ↗
14. Exploring diatomite as a novel natural resource for ecofriendly-sustainable hybrid cements10.1016/j.resconrec.2023.107402 ↗
15. Chemical activation of hybrid binders based on siliceous fly ash and Portland cement10.1016/j.cemconcomp.2015.11.003 ↗
16. Effect of sodium sulfate activation on the early age behaviour and microstructure development of hybrid cementitious systems containing Portland cement, and blast furnace slag10.1016/j.cemconcomp.2023.105101 ↗
17. Effect of cement clinker type, curing regime and activator dosage on the performance of one-part alkali-activated hybrid slag/clinker composites10.1016/j.jobe.2023.106164 ↗
18. Influence of processed tea waste ash on the hydration products and mechanical property of hybrid cement as an eco-friendly solution10.1016/j.wasman.2024.11.016 ↗
19. One-part hybrid cements from fly ash and electric arc furnace slag activated by sodium sulphate or sodium chloride10.1016/j.jobe.2021.103298 ↗
20. Corrosion of hybrid alkaline cements in saline solution simulating evaporite rock–Effect of the Portland clinker content10.1016/j.cemconres.2023.107215 ↗
21. Study on the cementation and engineering properties of ternary eco-binder mortar containing pulverized coal fly ash mixed with circulating fluidized bed co-fired fly ash10.1016/j.jcou.2024.102787 ↗
22. Barboza-Chávez, A.C., Gómez-Zamorano, L.Y., and Acevedo-Dávila, J.L. (2020). Synthesis and characterization of a hybrid cement based on fly ash, metakaolin and Portland cement clinker. Materials, 13.10.3390/ma13051084 ↗
23. Chloride-induced corrosion of steel reinforcement in mortars manufactured with alternative environmentally-friendly binders10.1016/j.cemconcomp.2022.104557 ↗
24. Strength and microstructural characteristics of chemically activated fly ash–cement systems10.1016/S0008-8846(02)00973-0 ↗
25. Hybrid alkali activated cements (HAACs) system: A state-of-the-art review on fresh, mechanical, and durability behaviour10.1016/j.conbuildmat.2022.129636 ↗
26. Hydration kinetics in hybrid binders: Early reaction stages10.1016/j.cemconcomp.2013.03.025 ↗
27. Strength, porosity and life cycle analysis of geopolymer and hybrid cement mortars for sustainable construction10.1016/j.scitotenv.2023.167839 ↗
28. Carbonation of alkali-activated and hybrid mortars manufactured from slag: Confocal Raman microscopy study and impact on wear performance10.1016/j.bsecv.2022.07.003 ↗
29. Mechanical properties of ambient cured one-part hybrid OPC-geopolymer concrete10.1016/j.conbuildmat.2018.07.160 ↗
30. Strength and drying shrinkage of reactive MgO modified alkali-activated slag paste10.1016/j.conbuildmat.2013.10.081 ↗
31. Chemical activation of binary slag cement with low carbon footprint10.1016/j.jclepro.2020.121455 ↗
32. Hybrid cements: Towards their use as alternative and durable materials against wear10.1016/j.conbuildmat.2021.125397 ↗
33. Review on corrosion of steel reinforcement in alkali-activated concretes in chloride-containing environments10.1016/j.conbuildmat.2021.123484 ↗
34. Evaluating the chloride diffusion coefficient of cement mortars based on the tortuosity of pore structurally-designed cement pastes10.1016/j.micromeso.2021.111018 ↗
35. Chloride transport in alkali-activated materials influenced by different reaction products: A review10.1680/jmacr.23.00285 ↗
36. Chloride binding of cement-based materials subjected to external chloride environment—A review10.1016/j.conbuildmat.2008.02.004 ↗
37. Effect of sulphate on the corrosion of reinforcing steel in concrete10.1016/j.conbuildmat.2022.129214 ↗
38. Choi, H., Inoue, M., Choi, H., Kim, J., Sudoh, Y., Kwon, S., Lee, B., and Yoneyama, A. (2019). Physicochemical study on the strength development characteristics of cold weather concrete using a nitrite–nitrate based accelerator. Materials, 12.10.3390/ma12172706 ↗
39. Recent advances in the use of inhibitors to prevent chloride-induced corrosion in reinforced concrete10.1016/j.cemconres.2022.106719 ↗
40. The inhibitive mechanisms of nitrite and molybdate anions on initiation and propagation of pitting corrosion for mild steel in chloride solution10.1016/j.apsusc.2015.07.037 ↗
41. Licorice (Glycyrrhiza glabra) as corrosion inhibitor of carbon steel reinforcing bars in mortar and its synergic effect with nitrite10.1016/j.jiec.2023.09.017 ↗
42. Shagñay, S., Ramón, L., Fernández-Álvarez, M., Bautista, A., Velasco, F., and Torres-Carrasco, M. (2020). Eco-efficient hybrid cements: Pozzolanic, mechanical and abrasion properties. Appl. Sci., 10.10.3390/app10248986 ↗
43. Xu, Z., and Ye, G. (2023). Understanding chloride diffusion coefficient in cementitious materials. Materials, 16.10.3390/ma16093464 ↗
44. Effects of seawater concentration on the drying shrinkage of seawater concrete10.1016/j.conbuildmat.2024.139437 ↗
45. Shrinkage mitigation strategies in alkali-activated slag10.1016/j.cemconres.2017.08.025 ↗
46. Correlation between reaction and expansion of alkali-carbonate reaction10.1016/0008-8846(95)00034-A ↗
47. Corrugated stainless steels embedded in mortar for 9 years: Corrosion results of non-carbonated, chloride-contaminated samples10.1016/j.conbuildmat.2015.04.060 ↗
48. Early age reaction of slag in composite cement: Impact of sulphates and calcite10.1016/j.cement.2023.100085 ↗
49. Physicochemical modelling in chlorides migration in concrete with account of multi-species coupling, reaction kinetic and pore evolution10.1016/j.conbuildmat.2024.139707 ↗
50. Vicente, M.A., Mena, Á., Mínguez, J., and González, D.C. (2021). Use of computed tomography scan technology to explore the porosity of concrete: Scientific possibilities and technological limitations. Appl. Sci., 11.10.3390/app11188699 ↗
51. Manufacture of hybrid cements with fly ash and bottom ash from a municipal solid waste incinerator10.1016/j.conbuildmat.2015.12.079 ↗
52. Yoneyama, A., Choi, H., Inoue, M., Kim, J., Lim, M., and Sudoh, Y. (2021). Effect of a nitrite/nitrate-based accelerator on the strength development and hydrate formation in cold-weather cementitious materials. Materials, 14.10.3390/ma14041006 ↗
53. Early hydration kinetics and microstructure development of hybrid alkali activated cements (HAACs) at room temperature10.1016/j.cemconcomp.2021.104200 ↗
54. Study on the effect of cellulose nanocrystals on the pore structure and drying shrinkage of alkali-activated recycled ultra-high performance concrete: A multifractal theory10.1016/j.conbuildmat.2025.140113 ↗
55. Influence of activator type on hydration kinetics, hydrate assemblage and microstructural development of alkali activated blast-furnace slags10.1016/j.cemconres.2010.11.016 ↗
56. New findings on the contribution of Mg-Al-NO3 layered double hydroxides to the hydration and chloride binding capacity of cement pastes10.1016/j.cemconres.2022.107037 ↗
57. Thermal behavior of the hydrotalcite-like layered structure of Mg and Al-layered double hydroxides with interlayer carbonate by means of in situ powder HTXRD and DTA/TG10.1016/S0167-2738(97)00494-3 ↗
58. Relationship between the particle size and dosage of LDHs and concrete resistance against chloride ingress10.1016/j.cemconres.2018.01.005 ↗
59. Preparation of Ca/Al layered double hydroxide and the influence of their structure on early strength of cement10.1016/j.conbuildmat.2018.06.186 ↗
60. Wear behavior in pastes of alkali-activated materials: Influence of precursor and alkali solution10.1016/j.triboint.2020.106293 ↗
61. Powder organic coatings functionalized with calcium ion-exchanged silica corrosion inhibitors10.1016/j.surfcoat.2024.130377 ↗
62. Chloride binding by layered double hydroxides (LDH/AFm phases) and alkali-activated slag pastes: An experimental study by RILEM TC 283-CAM10.1617/s11527-024-02311-3 ↗
63. Chloride binding of synthetic Ca-Al-NO3 LDHs in hardened cement paste10.1016/j.conbuildmat.2015.05.047 ↗
64. In-situ formation of layered double hydroxides in MgO–NaAlO2-activated GGBS/MSWI BA: Impact of Mg2+ on reaction mechanism and leaching behavior10.1016/j.cemconcomp.2023.105114 ↗
65. Effect of MgO, Mg-Al-NO3 LDH and calcined LDH-CO3 on chloride resistance of alkali activated fly ash and slag blends10.1016/j.conbuildmat.2020.118865 ↗
66. Numerical modeling of chloride convection-diffusion-reaction in reinforced concrete under external sulfate attack and drying-wetting cycles10.1016/j.conbuildmat.2025.140964 ↗
67. Effects of cyclic chloride exposure on penetration of concrete cover10.1016/S0008-8846(99)00073-3 ↗
68. Greening effect of concrete containing granulated blast-furnace slag composite cement: Is there an environmental impact?10.1016/j.cemconcomp.2020.103711 ↗
69. Concrete damage due to oxidation of pyrrhotite-bearing aggregate: A review10.21809/rilemtechlett.2021.138 ↗
70. Aggregate expansivity due to sulfide oxidation—II. Physico-chemical modeling of sulfate attack10.1016/S0008-8846(97)00148-8 ↗
71. Reinforcing steels in low-carbon mortars subjected to chloride attack and natural carbonation: Contradictory trends in passivation ability and corrosion resistance10.1016/j.cemconcomp.2024.105666 ↗
72. Electrochemical corrosion kinetics of steel bars in pseudo-transparent concrete under different alkaline properties and chloride contamination levels10.1016/j.conbuildmat.2024.135636 ↗
73. The effect of external load on the chloride migration resistance and the service life of reinforced concrete structures and repair mortars10.1016/j.conbuildmat.2024.137770 ↗
74. Investigation on drying-induced microcracks distribution characteristic and its formation mechanism in concrete10.1016/j.conbuildmat.2025.141216 ↗