Short- and Long-Term Mechanical and Durability Performance of Concrete with Copper Slag and Recycled Coarse Aggregate Under Magnesium Sulfate Attack
Sustainability in the construction sector has become a fundamental objective for mitigating escalating environmental challenges; given that concrete is the most widely used man-made material, extending its service life is therefore critical. Among durability concerns, magnesium sulfate (MgSO<sub&...
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2025-07-01
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| author | Yimmy Fernando Silva Claudia Burbano-Garcia Eduardo J. Rueda Arturo Reyes-Román Gerardo Araya-Letelier |
| author_facet | Yimmy Fernando Silva Claudia Burbano-Garcia Eduardo J. Rueda Arturo Reyes-Román Gerardo Araya-Letelier |
| author_sort | Yimmy Fernando Silva |
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| description | Sustainability in the construction sector has become a fundamental objective for mitigating escalating environmental challenges; given that concrete is the most widely used man-made material, extending its service life is therefore critical. Among durability concerns, magnesium sulfate (MgSO<sub>4</sub>) attack is particularly deleterious to concrete structures. Therefore, this study investigates the short- and long-term performance of concrete produced with copper slag (CS)—a massive waste generated by copper mining activities worldwide—employed as a supplementary cementitious material (SCM), together with recycled coarse aggregate (RCA), obtained from concrete construction and demolition waste, when exposed to MgSO<sub>4</sub>. CS was used as a 15 vol% cement replacement, while RCA was incorporated at 0%, 20%, 50%, and 100 vol%. Compressive strength, bulk density, water absorption, and porosity were measured after water curing (7–388 days) and following immersion in a 5 wt.% MgSO<sub>4</sub> solution for 180 and 360 days. Microstructural characteristics were assessed using scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis with its differential thermogravimetric derivative (TG-DTG), and Fourier transform infrared spectroscopy (FTIR) techniques. The results indicated that replacing 15% cement with CS reduced 7-day strength by ≤10%, yet parity with the reference mix was reached at 90 days. Strength losses increased monotonically with RCA content. Under MgSO<sub>4</sub> exposure, all mixtures experienced an initial compressive strength gain during the short-term exposures (28–100 days), attributed to the pore-filling effect of expansive sulfate phases. However, at long-term exposure (180–360 days), a clear strength decline was observed, mainly due to internal cracking, brucite formation, and the transformation of C–S–H into non-cementitious M–S–H gel. Based on these findings, the combined use of CS and RCA at low replacement levels shows potential for producing environmentally friendly concrete with mechanical and durability performance comparable to those of concrete made entirely with virgin materials. |
| format | Article |
| id | doaj-art-188a2c448cde424cb6691f458d2bcb9a |
| institution | DOAJ |
| issn | 2076-3417 |
| language | English |
| publishDate | 2025-07-01 |
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| spelling | doaj-art-188a2c448cde424cb6691f458d2bcb9a2025-08-20T03:02:55ZengMDPI AGApplied Sciences2076-34172025-07-011515832910.3390/app15158329Short- and Long-Term Mechanical and Durability Performance of Concrete with Copper Slag and Recycled Coarse Aggregate Under Magnesium Sulfate AttackYimmy Fernando Silva0Claudia Burbano-Garcia1Eduardo J. Rueda2Arturo Reyes-Román3Gerardo Araya-Letelier4School of Civil Construction, Faculty of Engineering, Pontificia Universidad Católica de Chile, Santiago 8331150, ChileDepartment of Construction Engineering and Management, School of Engineering, Pontificia Universidad Católica de Chile, Santiago 8331150, ChileSchool of Civil Construction, Faculty of Engineering, Pontificia Universidad Católica de Chile, Santiago 8331150, ChileDepartment of Mining Engineering, University of Antofagasta, Antofagasta 1270300, ChileSchool of Civil Construction, Faculty of Engineering, Pontificia Universidad Católica de Chile, Santiago 8331150, ChileSustainability in the construction sector has become a fundamental objective for mitigating escalating environmental challenges; given that concrete is the most widely used man-made material, extending its service life is therefore critical. Among durability concerns, magnesium sulfate (MgSO<sub>4</sub>) attack is particularly deleterious to concrete structures. Therefore, this study investigates the short- and long-term performance of concrete produced with copper slag (CS)—a massive waste generated by copper mining activities worldwide—employed as a supplementary cementitious material (SCM), together with recycled coarse aggregate (RCA), obtained from concrete construction and demolition waste, when exposed to MgSO<sub>4</sub>. CS was used as a 15 vol% cement replacement, while RCA was incorporated at 0%, 20%, 50%, and 100 vol%. Compressive strength, bulk density, water absorption, and porosity were measured after water curing (7–388 days) and following immersion in a 5 wt.% MgSO<sub>4</sub> solution for 180 and 360 days. Microstructural characteristics were assessed using scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis with its differential thermogravimetric derivative (TG-DTG), and Fourier transform infrared spectroscopy (FTIR) techniques. The results indicated that replacing 15% cement with CS reduced 7-day strength by ≤10%, yet parity with the reference mix was reached at 90 days. Strength losses increased monotonically with RCA content. Under MgSO<sub>4</sub> exposure, all mixtures experienced an initial compressive strength gain during the short-term exposures (28–100 days), attributed to the pore-filling effect of expansive sulfate phases. However, at long-term exposure (180–360 days), a clear strength decline was observed, mainly due to internal cracking, brucite formation, and the transformation of C–S–H into non-cementitious M–S–H gel. Based on these findings, the combined use of CS and RCA at low replacement levels shows potential for producing environmentally friendly concrete with mechanical and durability performance comparable to those of concrete made entirely with virgin materials.https://www.mdpi.com/2076-3417/15/15/8329copper slagmagnesium sulfaterecycled aggregatecompressive strengthmicrostructural analysis |
| spellingShingle | Yimmy Fernando Silva Claudia Burbano-Garcia Eduardo J. Rueda Arturo Reyes-Román Gerardo Araya-Letelier Short- and Long-Term Mechanical and Durability Performance of Concrete with Copper Slag and Recycled Coarse Aggregate Under Magnesium Sulfate Attack Applied Sciences copper slag magnesium sulfate recycled aggregate compressive strength microstructural analysis |
| title | Short- and Long-Term Mechanical and Durability Performance of Concrete with Copper Slag and Recycled Coarse Aggregate Under Magnesium Sulfate Attack |
| title_full | Short- and Long-Term Mechanical and Durability Performance of Concrete with Copper Slag and Recycled Coarse Aggregate Under Magnesium Sulfate Attack |
| title_fullStr | Short- and Long-Term Mechanical and Durability Performance of Concrete with Copper Slag and Recycled Coarse Aggregate Under Magnesium Sulfate Attack |
| title_full_unstemmed | Short- and Long-Term Mechanical and Durability Performance of Concrete with Copper Slag and Recycled Coarse Aggregate Under Magnesium Sulfate Attack |
| title_short | Short- and Long-Term Mechanical and Durability Performance of Concrete with Copper Slag and Recycled Coarse Aggregate Under Magnesium Sulfate Attack |
| title_sort | short and long term mechanical and durability performance of concrete with copper slag and recycled coarse aggregate under magnesium sulfate attack |
| topic | copper slag magnesium sulfate recycled aggregate compressive strength microstructural analysis |
| url | https://www.mdpi.com/2076-3417/15/15/8329 |
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