Assessment of the Permeability to Aggressive Agents of Concrete with Recycled Cement and Mixed Recycled Aggregate

Abstract

Acceptance by the construction industry of recycled concrete as a sustainable alternative material is contingent upon a reliable assessment of its permeability to corrosive agents. This study analyses the transport mechanisms associated with chloride (Cl−), oxygen (O2) and carbon dioxide (CO2) ions in concrete with cement made with 10% or 25% ground recycled concrete (GRC) separately or in combination with 50% mixed recycled aggregate (MRA). The findings show that, irrespective of aggregate type, concrete with GRC exhibited lower resistance to ingress than conventional concrete due to its greater porosity. Nonetheless, O2 permeability was consistently below 4.5 × 10−17 m2 and CO2 penetration, under 4 mm/year0.5, indicative of concrete with high quality. Resistance to CO2 and Cl− penetration in the materials with 10% GRC was similar to the values observed in conventional concrete. On the other hand, the incorporation of 25% GRC increased the penetration of CO2 and Cl- by 106% and 38%, respectively. Further to those findings in normal carbonation environments, reinforcement passivity would be guaranteed in such recycled materials over a 100 year service life.

A Study on Mechanical and Microstructural Characteristics of Concrete Using Recycled Aggregate

“…The complex components of MCRA lower its density [ 10 ] and flakiness index [ 11 ] and increase its water absorption [ 12 ] and crushing index [ 13 ]. Thus, it is a challenge to reuse MCRA efficiently as a conventional aggregate [ 14 ]. Still, the author reported that of the concretes containing less than 50% of mixed recycled coarse aggregates, both the compressive and flexure strength do not vary considerably.…”

“…This encouraging research has cleared the path for more efficient utilization of construction and demolition waste [ 19 , 20 ], as well as the durability study on the permeability of aggressive agents through the permeability of oxygen and chloride ions and the resistance to carbonation in concrete with 10 or 25% ground recycled cement (GRC) and 50% MCRA. The reinforcement’s passivity is not compromised by using up to 10% GRC as a cement replacement and/or 50% MCRA as a NA substitute in accordance with the service life prediction model proposed in the Spanish code of EHE-08 [ 14 ]. Most of the researchers enhanced the inferior properties of MCRA through various treatments such as CO 2 curing [ 21 ], carbonation [ 22 ], acid treatment [ 23 ], heating [ 24 ], heating and scrubbing [ 25 ], the combination of mechanical, chemical, and thermal treatment [ 26 ], and the addition of various supplementary cementitious materials [ 27 , 28 , 29 , 30 ].…”

Increasing the Corrosion Resistance and Durability of Geopolymer Concrete Structures of Agricultural Buildings Operating in Specific Conditions of Aggressive Environments of Livestock Buildings

“…It is conditionally possible to divide the studies conducted by other authors by grouping them into several groups of factors. For example, some authors [12,15,[18][19][20][23][24][25]34,36] were engaged in research aimed at improving the corrosion resistance of cement-based concrete, which are the most traditional type of concrete in current construction but are not environmentally friendly and cheap, leaving a high carbon footprint and not in line with the modern ESG agenda. Other authors [7][8][9][10][11]22,27,29,31,35] were engaged in developing compositions of geopolymer concrete aimed at improving the mechanical properties of such concrete: their strength and improvement of deformation properties.…”

“…At the same time, concrete of increased resistance, as a rule, has good resistance to aggressive environments, regardless of the type and origin of the aggressive environment. Therefore, it seems expedient to increase the inherent resistance of concrete structures, using the variability and adaptability of its structure to environmental conditions, ensuring the durability of structures at several levels [34][35][36][37].…”

Durability of Ternary Cements Based on New Supplementary Cementitious Materials from Industrial Waste

“…The use of C&DW ultrafines as SCMs in new cements is an innovative line of work undertaken in recent years by a number of authors, whose interest has focused primarily on the mechanical performance of pastes and/or mortars bearing those materials as partial (3% to 30%) cement replacements. The consensus conclusion reached [14][15][16][17][18] is that GRC contains SiO 2 , Al 2 O 3 and Fe 2 O 3 (44% ≤ SiO 2 + Al 2 O 3 + Fe 2 O 3 ≤ 59%), along with CaO (42% to 16%) and exhibits low pozzolanicity and hydraulicity. Its filler effect likewise-identified would favour hydration, providing nucleation sites that would densify the cement matrix microstructure.…”