Papers

@article{cantero_comparative_2026,

title = {Comparative assessment of binary alkali-activated mortars incorporating construction and demolition waste under dry and CO₂ curing conditions},

author = {Blas Cantero-Chaparro and Lucas Sequeira and Jorge Brito and Miguel Bravo},

url = {https://www.sciencedirect.com/science/article/pii/S0950061826015369},

doi = {10.1016/j.conbuildmat.2026.146630},

issn = {0950-0618},

year  = {2026},

date = {2026-07-01},

urldate = {2026-08-18},

journal = {Construction and Building Materials},

volume = {530},

pages = {146630},

abstract = {Construction and demolition waste (CDW) has attracted increasing attention as a potential precursor for alkali-activated materials, although its heterogeneous nature often limits mechanical performance. This study investigates the behaviour of binary alkali-activated mortars manufactured with different types of CDW: recycled concrete (RC), recycled brick (RB) and recycled tile (RT). The combination of these precursors with 30% fly ash (FA) as a supplementary precursor was also investigated. The mixes were subjected to two curing conditions—dry and CO₂—in order to evaluate the influence of precursor mineralogy and curing regime on their mechanical and physical performance. Compressive and flexural strengths, dynamic modulus of elasticity, ultrasonic pulse velocity (UPV), porosity, shrinkage and carbonation depth were determined. The results showed that precursor reactivity governs the overall behaviour. Tile-based systems (RT) achieved the highest strengths and lowest water-accessible porosity, followed by RB, whereas RC exhibited limited reactivity. Under CO₂ curing, RT70 reached 20.3 MPa at 28 days, representing a 53.9% increase compared to dry curing. In addition, CO₂ curing reduced water-accessible porosity by up to 15%. For a comparable compressive strength, CO₂-cured mixes exhibited higher flexural strength and dynamic modulus of elasticity than those cured under dry conditions. In contrast, RC systems showed a 21.5% reduction in compressive strength at 28 days under CO₂ curing, indicating that early carbonation may adversely affect low-reactivity, calcium-rich residues. The incorporation of 30% FA mitigated this effect, increasing the 28-day compressive strength under CO₂ curing from 7.7 MPa (RC100) to 14.3 MPa (RC70). Correlation analysis confirmed an exponential relationship between mechanical performance and water-accessible porosity, highlighting the governing role of pore structure. Overall, the combined use of FA and controlled CO₂ curing offers a viable strategy for enhancing selected CDW-based alkali-activated systems.},

keywords = {Alkali-activated mortars, CO₂ curing, Construction and demolition waste, Mechanical properties, Sustainable construction materials},

pubstate = {published},

tppubtype = {article}

}

@article{cantero_optimisation_2024,

title = {Optimisation of the performance of alkali-activated mortars using CDW binders from different sources},

author = {Blas Cantero-Chaparro and Renato Neves and Lucas Sequeira and Jorge Brito and Miguel Bravo},

url = {https://www.sciencedirect.com/science/article/pii/S0950061824028198},

doi = {10.1016/j.conbuildmat.2024.137677},

issn = {0950-0618},

year  = {2024},

date = {2024-09-01},

urldate = {2026-04-28},

journal = {Construction and Building Materials},

volume = {442},

pages = {137677},

abstract = {This study investigates the fresh-state properties and the hardened-state physical and mechanical properties of a total of 64 alkali-activated mortars incorporating different wastes as binders, such as fly ash (FA), recycled concrete (RC), recycled brick (RB), and recycled tile (RT). These waste materials were activated using sodium hydroxide (NaOH) and sodium silicate (Na2SiO3). Linear regression analysis was employed to evaluate the impact and significance of Na2O concentration (9 % or 15 %), modulus of silica (0.5 or 1), curing time in the oven (24 or 48 h), and temperature (50 °C or 70 °C) on the properties of the mortars. The results, analysed using ANOVA, indicate that all properties were affected by these parameters, except for the initial curing time in the oven for mortars made with construction and demolition waste (CDW), which showed no significant differences between periods of 24 and 48 h. Compared to mortars produced with RC, the contribution of these parameters to mechanical properties was more prominent in the mixes with RT and RB. The highest compressive strength at 28 days, for the mortars with CDW binders, was obtained by incorporating RT with 12 % of Na2O, modulus of silica of 1 and 70 °C for 48 h of initial curing, reaching 12.5 MPa. This value is 2.1 times higher than the strength obtained in mixes with RB or RC. The results also show that the performance of the mortars is highly related to the reactivity of the waste material (mortars with RT performed better) and prove that each raw material has its own optimum criterion.},

keywords = {Alkali activator, Construction and demolition waste, Geopolymer, Mechanical properties, Physical properties},

pubstate = {published},

tppubtype = {article}

}

@article{ghorbel_effect_2023,

title = {Effect of 10% recycled sands from various storage sites on the mortar’s properties},

author = {Elhem Ghorbel and George Wardeh and Belén González-Fonteboa},

url = {https://doi.org/10.1080/19648189.2023.2169766},

doi = {10.1080/19648189.2023.2169766},

issn = {1964-8189},

year  = {2023},

date = {2023-10-01},

urldate = {2026-08-13},

journal = {European Journal of Environmental and Civil Engineering},

volume = {27},

number = {14},

pages = {4067–4085},

publisher = {Taylor & Francis},

abstract = {This study investigates the effects of using 10% of recycled sand in mortars. Using the concrete equivalent mortar approach, the reference mortar was developed from a flowable natural aggregate concrete with a C35/45 strength class. Five mortars were manufactured by replacing 10% of the natural sand with recycled sand from various recycling platforms while keeping the formulation parameters constant. The fresh state results showed that recycled mortar had an increased air content, which increased yield stress and viscosity. In addition, mortars containing 10% recycled sand showed a faster rate of flow loss over time. There was no difference between the materials in the hardening state with regard to the evolution of the hydration heat or the setting time. The relationship between the qualities of mortars and sands revealed that the air content depends on the sand’s fineness and the presence of fines with a diameter less than 63 µm. A relatively small increase in porosity and water absorption capacity was observed with a decrease in the compressive and flexural strength with no obvious change in the elastic modulus. The total shrinkage was revealed to depend on the fines content and decreases when the fines content increases.},

keywords = {Mechanical properties, Mortar, Physical properties, Recycled sand, Workability},

pubstate = {published},

tppubtype = {article}

}

@article{sequeira_influence_2023,

title = {The Influence of Recycled Cement, Fly Ash, and Magnesium Oxide on the Mechanical Performance of Sustainable Cementitious Materials},

author = {Lucas Sequeira and Blas Cantero-Chaparro and Miguel Bravo and Jorge Brito and César Medina},

url = {https://www.mdpi.com/1996-1944/16/7/2760},

doi = {10.3390/ma16072760},

issn = {1996-1944},

year  = {2023},

date = {2023-01-01},

urldate = {2026-08-13},

journal = {Materials},

volume = {16},

number = {7},

pages = {2760},

publisher = {Multidisciplinary Digital Publishing Institute},

abstract = {In the construction industry, cement is the most widely used material. So, to achieve greater sustainability in this industry, it is imperative to improve the sustainability of this material. One way to reduce the ecological footprint of cement is to replace it, even if partially, with other more sustainable materials that can act as binders. This paper analyses the mechanical properties of more sustainable mortars containing recycled cement (RC), fly ash (FA), and magnesium oxide (MgO). Different types of binary, ternary, and quaternary mortars were used: containing recycled cement (5% and 10%), fly ash (10% and 20%), and MgO (7.5% and 15%). An experimental campaign was carried out analysing air content, density, compressive and flexural strengths, modulus of elasticity, and ultrasonic pulse velocity. The ternary mortars showed decreases between 0.4% (M-5RC10FA) and 35.3% (M-10RC15Mg) in terms of compressive strength at 365 days (compared to RM), when the theoretically expected decrease (the sum of the decreases obtained with the individual incorporation of these materials) would be between 16.6% and 41.5%, respectively. The results obtained allow for concluding that the joint use of these materials in ternary mortars improves the mechanical capacity, relative to the individual incorporation of each material in binary mortars.},

keywords = {Fly ash, magnesium oxide, Mechanical properties, quaternary mortars, recycled cement, Sustainability},

pubstate = {published},

tppubtype = {article}

}

@article{bello_constitutive_2022,

title = {Constitutive behaviour of masonry prisms using a full-field measurement technique},

author = {Ismail Bello and George Wardeh and Belén González-Fonteboa and Fernando Martínez-Abella and Elhem Ghorbel},

url = {https://www.sciencedirect.com/science/article/pii/S2352012422010475},

doi = {10.1016/j.istruc.2022.11.008},

issn = {2352-0124},

year  = {2022},

date = {2022-12-01},

urldate = {2022-12-01},

journal = {Structures},

volume = {46},

pages = {1726–1736},

abstract = {To obtain analytical models for the compressive behaviour of masonry structures, it is crucial to accurately measure the compressive strengths of its constituents, i.e., brick and mortar. The mechanical properties and the stress-strain relationship under uniaxial compression are essential for thoroughly investigating and evaluating masonry structures. The present work aims to validate a non-contact measuring technique for obtaining full-scale strain and failure patterns and investigate joint mortar composition's effect on masonry behaviour. Forty masonry prisms were manufactured in this study using two distinct types of brick and five different types of mortar varying according to cement and lime contents. The results showed that 2D Digital Image Correlation (DIC) could generate full-strain assessments of masonry prisms, resulting in a full-scale stress-strain analysis. It was also found that, in the post-peak region, prisms with lower cement content exhibit a more ductile behaviour with strain localisation at the joint mortar level. Based on current experimental results and data from the literature, new analytical relationships were presented to predict masonry mechanical properties and masonry complete stress-strain compressive behaviour.},

keywords = {Analytical model, Compressive strength, Digital image correlation (DIC), Masonry, Mechanical properties, Stress-Strain law},

pubstate = {published},

tppubtype = {article}

}

@article{martinez-lage_sustainability_2020,

title = {Sustainability evaluation of concretes with mixed recycled aggregate based on holistic approach: Technical, economic and environmental analysis},

author = {Isabel Martínez-Lage and Pablo Vázquez-Burgo and Mirian Velay-Lizancos},

url = {https://www.sciencedirect.com/science/article/pii/S0956053X19307986},

doi = {10.1016/j.wasman.2019.12.044},

issn = {0956-053X},

year  = {2020},

date = {2020-03-01},

urldate = {2026-08-06},

journal = {Waste Management},

volume = {104},

pages = {9–19},

abstract = {This research combines technical, economic and environmental analysis of the use of recycled aggregates from construction and demolition wastes in concrete production. Firstly, an experimental campaign to evaluate the effect of recycled aggregate on mechanical properties was developed. The mixture designs studied were: a reference concrete (without recycled aggregate), two concretes with 20% and 100% replacement of coarse natural aggregate by recycled concrete aggregate; and three concretes with 20, 50 and 100% replacement of coarse natural aggregate by mixed recycled aggregate. To analyze their technical feasibility, these concretes were made in the laboratory and in a concrete plant. The economic viability was also studied indicating the additional costs incurred due to the utilization of recycled aggregate in different economic scenarios. Finally, the differences in environmental impacts were analyzed for each concrete. For this purpose, energy consumption, global warming, eutrophication, acidification, photochemical ozone creation, waste generation, and abiotic depletion were accounted. 20% replacement of recycled concrete aggregates does not cause practically variations in the cost or the environmental loads, only a reduction of waste generation and abiotic depletion of 8% and 10.6% respectively. In contrast, the use of 100% replacement by mixed aggregates may increase the global warming indicator an 11% when double transport distance is assumed. But in exchange, the waste generation decreases 35% and the abiotic depletion 50%. Aggregate transport distance is a key factor that will determine the cost, energy consumption, and global warming of the mixed recycled aggregate.},

keywords = {Economic viability, Environmental impact, Mechanical properties, Recycled aggregate, Sustainable construction},

pubstate = {published},

tppubtype = {article}

}

@article{González-Taboada20171,

title = {Tools for the study of self-compacting recycled concrete fresh behaviour: Workability and rheology},

author = {Iris González-Taboada and Belén González-Fonteboa and Javier Eiras-López and Gemma Rojo-López},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019157098&doi=10.1016%2fj.jclepro.2017.04.045&partnerID=40&md5=dc483461bc80b8981beee59d6b2ab36b},

doi = {10.1016/j.jclepro.2017.04.045},

year  = {2017},

date = {2017-01-01},

urldate = {2017-01-01},

journal = {Journal of Cleaner Production},

volume = {156},

pages = {1 – 18},

abstract = {This work studies the fresh behaviour of self-compacting recycled concrete (SCRC) with different replacement percentages of recycled concrete coarse aggregate (20, 50 and 100%). To control the high absorption of recycled aggregate, three different mixing methods are also used in each studied concrete: M1 (dry aggregate and extra water), M2 (pre-soaked aggregate) and M3 (aggregate with a 3% of natural moisture and extra water). The fresh-state properties are measured with empirical and rheological tests, both carried out at 15, 45 and 90 min from the water-cement contact. Results obtained lead to conclude that rheology is the best tool to control fresh state behaviour of SCRC mixes and that Bingham 5-lowest is the suitable model to describe their rheological behaviour. Additionally, it has been concluded that the best method to produce SCRC is to compensate the recycled aggregate absorption during mixing using an extra quantity of water. With this method, self-compacting behaviour can be maintained with all replacement percentages until 45 min, and even until 90 min when the replacement ratio does not exceed 50%. Moreover, the use of the recycled coarse aggregate with a previous moisture content involves a greater difficulty to control workability and rheology than its use in dry-state condition. © 2017 Elsevier Ltd},

note = {Cited by: 88},

keywords = {Aggregates, Concrete mixing, Concretes, Elasticity, Fresh behaviour, Mechanical properties, Mixing, Moisture, Recycled aggregates, Recycled coarse aggregate, Recycled concrete coarse aggregate, Recycled concretes, Recycling, Replacement ratio, Rheological behaviour, Rheology, Self compacting concrete, Water absorption, Workability},

pubstate = {published},

tppubtype = {article}

}

@article{González-Taboada2016,

title = {Study of recycled concrete aggregate quality and its relationship with recycled concrete compressive strength using database analysis},

author = {Iris González-Taboada and Belén González-Fonteboa and Fernando Martínez-Abella and Diego Carro-López},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84980384778&doi=10.3989%2fmc.2016.06415&partnerID=40&md5=d0b512908542256f34e134a2e082e989},

doi = {10.3989/mc.2016.06415},

issn = {04652746},

year  = {2016},

date = {2016-01-01},

urldate = {2016-01-01},

journal = {Materiales de Construccion},

volume = {66},

number = {323},

publisher = {Inst. de Ciencias de la Construccion Eduardo Torroja},

abstract = {This work studies the physical and mechanical properties of recycled concrete aggregate (recycled aggregate from concrete waste) and their influence in structural recycled concrete compressive strength. For said purpose, a database has been developed with the experimental results of 152 works selected from over 250 international references. The processed database results indicate that the most sensitive properties of recycled aggregate quality are density and absorption. Moreover, the study analyses how the recycled aggregate (both percentage and quality) and the mixing procedure (pre-soaking or adding extra water) influence the recycled concrete strength of different categories (high or low water to cement ratios). When recycled aggregate absorption is low (under 5%), pre-soaking or adding extra water to avoid loss in workability will negatively affect concrete strength (due to the bleeding effect), whereas with high water absorption this does not occur and both of the aforementioned correcting methods can be accurately employed. © 2016 CSIC.},

note = {cited By 59},

keywords = {Compressive strength; Concrete mixing; Concretes; Database systems; Physical properties; Recycling; Water absorption, Concrete strength; Concrete wastes; Database analysis; Physical and mechanical properties; Recycled aggregates; Recycled concrete aggregates; Recycled concretes; Sensitive properties, Mechanical properties},

pubstate = {published},

tppubtype = {article}

}

@article{Herrador2009201,

title = {Mechanical behavior model for ASR-affected dam concrete under service load: Formulation and verification},

author = {Manuel F. Herrador-Barrios and Fernando Martínez-Abella and Rodrigo Del Hoyo Fernández-Gago},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-59449094172&doi=10.1617%2fs11527-008-9378-6&partnerID=40&md5=49bfc2f04c14519524506cb60614c32b},

doi = {10.1617/s11527-008-9378-6},

issn = {13595997},

year  = {2009},

date = {2009-01-01},

urldate = {2009-01-01},

journal = {Materials and Structures/Materiaux et Constructions},

volume = {42},

number = {2},

pages = {201-212},

abstract = {In this paper, a mechanical behavior model for concrete undergoing Alkali-Silica Reaction (ASR) expansions is presented. The relation between evolution of expansions and external pressure is specifically taken into account in the model, including a procedure to calculate inhibition pressure (defined as the compressive stress threshold beyond which no expansion can take place) from experimental data. Creep is represented by means of an eight element ageing Maxwell chain based on the shape proposed in the B3 model. An application of the model is provided for a case study using experimental data. Verification of the model is performed against data from the same batch of tests different from those used for calibration. © 2008 RILEM.},

note = {cited By 12},

keywords = {Ageing; Alkali-Aggregate reaction; Expansion; Experimental datum; External pressures; Mechanical behaviors; Modeling; Service loads, Aggregates; Chemical reactions; Mechanical engineering; Remelting; Silica, Mechanical properties},

pubstate = {published},

tppubtype = {article}

}