CO2 sequestration by construction and demolition waste aggregates and effect on mortars and concrete performance - An overview

Gomes, Ricardo; Farinha, Catarina Brazão; Veiga, Rosário; Brito, Jorge de; Faria, Paulina; Bastos, David

doi:10.1016/j.rser.2021.111668

Cited by 40 publications

(14 citation statements)

References 71 publications

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“…As stated, carbonation has a positive impact on the decrease in RA's water absorption and its increase in compacity. Therefore, a similar trend is expected in relation to the w/b ratio [25]. This trend can be seen in mortars with a 50% replacement of NA with CRA-5h, in which the w/b is equal to that of REF-A (1.03), as opposed to the mortars with 50% of CRA-5d.…”

Section: Fresh-state Propertiessupporting

confidence: 69%

“…As expected, NA (sand) showed a considerably higher loose bulk density than that of the non-carbonated RA (CDW-A), mainly due to the greater porosity of the cementitious mortar that adhered to the RA's surface compared to NA's [21][22][23][24]. The forced and accelerated carbonation of recycled aggregates is expected to improve their characteristics, namely, their loose bulk density and porosity [25]; thus, it can be used as a treatment. It should be noted that these improvements can play a fundamental role in the behaviour of the mortars in which they will be included.…”

Section: Recycled Aggregatesmentioning

confidence: 67%

“…Concerning the non-carbonated aggregates, a d crease in strength is noticed only for a 100% replacement compared with the control mo tar. After carbonation for 5 h, an improvement in strength is obtained at 14 days, for bot for 50% and 100% replacement, proving the effectiveness of CO2 curing in increasing th compressive strength of mortars [25]. However, at 28 days, small decreases occur by com parison with the non-carbonated RA (12% and 1% for 50% and 100% substitution, respe tively).…”

Section: Compressive Strengthmentioning

confidence: 86%

“…The water absorption of aggregates is one of the main characteristics to account for when formulating mortars, as it greatly affects their workability [25]. Water absorption is expected to decrease with the exposure of aggregates to CO 2 .…”

Section: Recycled Aggregatesmentioning

confidence: 99%

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Mortars with CDW Recycled Aggregates Submitted to High Levels of CO2

Gomes¹,

Bastos²,

Farinha³

et al. 2021

Infrastructures

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Construction and demolition wastes (CDW) are generated at a large scale and have a diversified potential in the construction sector. The replacement of natural aggregates (NA) with CDW recycled aggregates (RA) in construction materials, such as mortars, has several environmental benefits, such as the reduction in the natural resources used in these products and simultaneous prevention of waste landfill. Complementarily, CDW have the potential to capture CO2 since some of their components may carbonate, which also contributes to a decrease in global warming potential. The main objective of this research is to evaluate the influence of the exposure of CDW RA to CO2 produced in cement factories and its effect on mortars. Several mortars were developed with a volumetric ratio of 1:4 (cement: aggregate), with NA (reference mortar), CDW RA and CDW RA exposed to high levels of CO2 (CRA). The two types of waste aggregate were incorporated, replacing NA at 50% and 100% (in volume). The mortars with NA and non-carbonated RA and CRA from CDW were analysed, accounting for their performance in the fresh and hardened states in terms of workability, mechanical behaviour and water absorption by capillarity. It was concluded that mortars with CDW (both CRA and non-carbonated RA) generally present a good performance for non-structural purposes, although they suffer a moderate decrease in mechanical performance when NA is replaced with RA. Additionally, small improvements were found in the performance of the aggregates and mortars with CRA subjected to a CO2 curing for a short period (5 h), while a long carbonation period (5 d) led to a decrease in performance, contrary to the results obtained in the literature that indicate a significant increase in such characteristics. This difference could be because the literature focused on made-in-laboratory CDW aggregates, while, in this research, the wastes came from real demolition activities, and were thus older and more heterogeneous.

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Section: Fresh-state Propertiessupporting

confidence: 69%

Section: Recycled Aggregatesmentioning

confidence: 67%

Section: Compressive Strengthmentioning

confidence: 86%

Section: Recycled Aggregatesmentioning

confidence: 99%

See 2 more Smart Citations

Mortars with CDW Recycled Aggregates Submitted to High Levels of CO2

Gomes¹,

Bastos²,

Farinha³

et al. 2021

Infrastructures

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“…The vast volumes of construction and demolition waste (CDW) generated globally is one of the types of industrial waste that has attracted the greatest researcher attention in recent years. Such waste is primarily applied as a recycled aggregate in eco-mortar and eco-concrete manufacture, which requires huge quantities of such materials [7][8][9][10][11]. The use of concrete waste as coarse aggregate is presently envisaged in many countries' structural legislation and codes [12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Concrete/Glass Construction and Demolition Waste (CDW) Synergies in Ternary Eco-Cement-Paste Mineralogy

et al. 2022

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The study described sought further understanding of the synergies in a mix of CDW pozzolans, containing (calcareous and siliceous) concrete and glass waste, used to prepare ternary eco-cement paste bearing 7% of the binary blend at concrete/glass ratios of 2:1 and 1:2. The mineralogical phases in the 2-day, 28-day, and 90-day cement matrices were identified and monitored using XRF, XRD-Rietveld, SEM-EDX, FT-IR, and NMR. The findings showed that changes in the reaction kinetics in the ternary blended pastes relative to OPC pastes depended on the nature of the recycled concrete and the glass content. Adding the binary mix bearing calcareous concrete (at a ratio of 2:1) favoured ettringite, portlandite, and amorphous phase formation, whilst the blends with siliceous concrete favoured C-S-H gel formation. Monocarboaluminate was detected in the 90-day siliceous concrete and glass pastes in amounts similar to those found in the reference OPC paste.

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