Mechanical and durability performance of mortars with fine recycled concrete aggregates and reactive magnesium oxide as partial cement replacement

Gonçalves, Teresa Diaz; Silva, Rui V.; Brito, Jorge de; Fernández-Rodríguez, José María; Esquinas, Álvaro Romero

doi:10.1016/j.cemconcomp.2019.103420

Cited by 101 publications

(62 citation statements)

References 30 publications

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“…Much finer particles were seen in WGCS than in RCS. XRD patterns of RCS and WGCS are shown in Figure 3 , where the main phases in CS were portlandite (Ca(OH) 2 , International Centre for Diffraction Data (ICDD) # 04-0733) and calcite (CaCO 3 , ICDD # 05-0586) [ 42 ]. Moreover, after the wet grinding treatment, the peak density of portlandite was decreased and one possible reason for this was that, during the grinding process, the crystal structure of portlandite was altered by the mechanical grinding forces [ 43 ].…”

Section: Methodsmentioning

confidence: 99%

Utilization of Carbide Slag by Wet Grinding as an Accelerator in Calcium Sulfoaluminate Cement

Tan

et al. 2020

Materials

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In this study, wet-ground carbide slag (i.e., WGCS) was utilized as an accelerator in calcium sulfoaluminate cement (CSA) for obtaining considerably faster setting processes for some special engineering processes such as plugging projects and rapid repair engineering. The WGCS–CSA system was designed, in which the replacement ratio of CSA by carbide slag was chosen as 4%, 8% and 12%. The setting time and compressive strength were measured, and the mechanism of the system hydration was studied in detail by means of calorimetry, XRD, thermogravimetry (TG) and SEM. The results showed that WGCS shortened the setting time of cement and significantly augmented the early strength. The addition of 8% of WGCS contributed to increasing the 2-h compressive strength from 4.2 MPa to 32.9 MPa. The decrease in the setting time and the increase in the initial strength were mainly attributed to the high initial pH value of the liquid phase and the high content of calcium ions in WGCS. Both these factors contributed to the ettringite formation and, at the same time, to the transformation of the morphology at a later time. Such results testify that WGCS can be used as an accelerator in the CSA system and also that it provides a novel approach to the reutilization of carbide slag.

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Section: Methodsmentioning

confidence: 99%

Utilization of Carbide Slag by Wet Grinding as an Accelerator in Calcium Sulfoaluminate Cement

Tan

et al. 2020

Materials

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“…The increase in water/binder ratio is the main reason for the decrease in dynamic modulus of elasticity of the mortars with these three types of MgO. Gonçalves et al [26] also concluded that the decrease in this property is most likely due to the need to add more water to obtain equivalent workability levels. In Figure 8b, as suggested by Yedra et al [40], it is possible to observe the relationship between the compressive strength and the dynamic modulus of elasticity of the mortars produced in this research.…”

Section: Dynamic Modulus Of Elasticitymentioning

confidence: 97%

“…Regarding flexural strength, Gonçalves et al [ 26 ] obtained decreases of between 27% and 30% in mortars, with MgO contents of up to 20%. In turn, Moradpour et al [ 23 ] studied the influence on flexural strength of the incorporation of nano-MgO in mortars at various contents (up to 5%) and carried out the test at different ages (between 7 days and 90 days).…”

Section: Introductionmentioning

confidence: 99%

Performance of Mortars with Commercially-Available Reactive Magnesium Oxide as Alternative Binder

et al. 2021

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This paper intends to analyze the performance of mortars with reactive MgO, as a sustainable alternative to cement. Six different MgOs from Australia, Canada, and Spain were used in the production of mortars as partial substitutes for cement, namely 5%, 10%, 15%, 20%, and 25% (by weight). MgOs with different levels of reactivity were used to analyze its influence on the performance of MgO mortars. In order to evaluate the mechanical performance of these mortars, compressive strength, flexural strength, dynamic modulus of elasticity, and ultrasonic pulse velocity tests were performed. Compressive strength tests showed that the use of 25% reactive MgO can cause a decrease of this property of between 28% and 49%. The use of reactive MgO affected the other mechanical properties less. This paper also intends to analyze the durability performance of mortars with reactive MgO. To that effect, water absorption by capillarity was assessed. In this research, the effect of using MgO on the shrinkage was also analyzed. It was found that shrinkage may decrease by more than a half in some cases.

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“…Currently, many scholars have done some research on material substitution for cement so as to improve sustainability [88,89]. Gonçalves et al (2020) used the recycled concrete aggregate and reactive magnesium oxide to replace the cement material, which can promote the mechanical and environmental performance.…”

Section: Recycling Materials Replacementmentioning

confidence: 99%

Environmental Sustainability Assessment of a New Sewage Treatment Plant in China Based on Infrastructure Construction and Operation Phases Emergy Analysis

Zhang

2020

Water

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Due to excessive resource consumption and pressing environmental issues of the sewage treatment industry, there is extensive attention in China. Given the unique craft production process in the sewage treatment system, a series of integral emergy indicators have been used to evaluate the environmental sustainability based on infrastructure construction and operation stage emergy analysis. Taking a new typical sewage treatment plant as an example, this paper performed a case study. The results illustrate that (1) the infrastructure construction process emergy (approximate 92.6%) is more critical than sewage treatment process emergy; (2) nonrenewable resource is the primary factor for the emergy analysis, followed by energy (23.5%) and purchased supply (7%); (3) cement, steel, and gravel have dominant impacts on the nonrenewable resource emergy; (4) the emergy sustainability index is 0.001101, which displays weak environmental sustainability; (5) the unit emergy value (UEV) of the new sewage treatment plant is 3.40 × 10 12 sej/m 3 ; (6) sensitivity analysis results of the hypothesis demonstrate that nonrenewable resources have significant fluctuations (6.903%) while, for the indicators, emergy sustainability index (ESI) (4.8072%) has the most significant impact; and (7) wastewater is a major contributor. In light of comprehensive discussions, two positive measures are proposed in order to ameliorate the environmental sustainability.Water 2020, 12, 484 2 of 23 between the environment in the sewage treatment industry using biological perspective analysis [5][6][7][8], lifecycle assessment (LCA) perspective [9], ecology models perspective [10], energy and economy performances [11], sewage treatment and water supply efficiency [12], chemical and physical angles [13,14], construction in the wastewater treatment plants [15], integrating wastewater treatment and incineration plants for energy-efficient study [16], sampling strategy for the sewage sludge survey [17], soil and the treatment of sewage treatment plant [18], and systematic assessment framework [19].However, these studies have the following drawbacks: (1) for the isolated angles analysis, only one or some perspectives are chosen to demonstrate the interaction between environmental issues and the sewage treatment industry, resulting in a few unilateral conclusions; (2) ignorance of natural resources assessment leads to a negative impact on sustainability in the sewage treatment industry; (3) undifferentiated contribution degrees from different resource types could cause deviation inaccuracy to some extent; (4) there is a lack of a unified platform to evaluate sustainability in the sewage treatment industry, for example, an integrated method assessment should comprise resources, energy, labor, and others; and (5) some studies are unable to consider multiple pollutant emissions simultaneously, such as exhaust gas, wastewater, and solid waste. It will have a harmful effect on sustainability in the sewage treatment industry. In summary, the above studies cannot disp...

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Mechanical and durability performance of mortars with fine recycled concrete aggregates and reactive magnesium oxide as partial cement replacement

Cited by 101 publications

References 30 publications

Utilization of Carbide Slag by Wet Grinding as an Accelerator in Calcium Sulfoaluminate Cement

Utilization of Carbide Slag by Wet Grinding as an Accelerator in Calcium Sulfoaluminate Cement

Performance of Mortars with Commercially-Available Reactive Magnesium Oxide as Alternative Binder

Environmental Sustainability Assessment of a New Sewage Treatment Plant in China Based on Infrastructure Construction and Operation Phases Emergy Analysis

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