Carbon Dioxide Absorption by Blast-Furnace Slag Mortars in Function of the Curing Intensity

Sanjuán, Miguel Ángel; Estévez, Esteban; Argiz, Cristina

doi:10.3390/en12122346

Cited by 24 publications

(18 citation statements)

References 20 publications

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“…It is true that there is a direct relationship between carbonation rate and concrete's compressive strength when the correlation is determined with the cement itself, the type of aggregates, additives, etc. However, when one of these factors is modified, different correlations are found [21]. Therefore, it is not possible to generalize the results compiled in Table BB.1 and to apply them to all the cements that are manufactured in Europe or for all the environments to which concrete is exposed.…”

Section: Co2 Uptake Of Concretes Manufactured With Portuguese Cementsmentioning

confidence: 99%

Carbon Dioxide Uptake by Mortars and Concretes Made with Portuguese Cements

Sanjuán¹,

Andrade

Mora

et al. 2020

Applied Sciences

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As the cement industry continues to address its role in the climate crisis, Portugal’s cement industry has started to calculate its net CO2 emissions to become an entirely carbon neutral sector. These emissions are calculated by simply subtracting the total CO2 uptake due to mortar and concrete carbonation from the total CO2 that is emitted during the calcination process (clinker production). However, the procedures given in the Intergovernmental Panel on Climate Change (IPCC) Guidelines for National Greenhouse Gas (GHG) Inventories to report GHG emissions do not contain any element that would grant this calculation method the status of an internationally recognized procedure. Therefore, some climate models are not accurate because they do not account for the carbon dioxide uptake due to concrete and mortar carbonation, as is evidenced in this paper. Climate models have improved since the IPCC’s Fourth Assessment Report (AR4), but they can further improve by implementing carbon dioxide uptake by cement-based materials. In the present paper, a quick and easy method of evaluating net CO2 emissions is utilized (simplified method) along with an advanced method. Portuguese net CO2 emissions of the cement produced from 2005 to 2015 were calculated while taking carbon dioxide uptake during the service-life and end-of-life and secondary usage stages into account. Following the simplified method, 8.7 million tons of carbon dioxide were found to be uptake by mortars and concretes made with Portuguese cement over the ten-year period, in which 37.8 million tons were released due to the calcination process. In addition, an advanced method has been used to estimate the carbon dioxide uptake, which provided only slightly higher results than that of the simplified method (9.1 million tons).

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Section: Co2 Uptake Of Concretes Manufactured With Portuguese Cementsmentioning

confidence: 99%

Carbon Dioxide Uptake by Mortars and Concretes Made with Portuguese Cements

Sanjuán¹,

Andrade

Mora

et al. 2020

Applied Sciences

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“…The mineralogical composition of the cement paste ground and sieved to 45 µm [ 40 ] was determined on a Bruker AXS DB Advance X-ray diffractor (Bruker, Madrid, Spain) configured without a monochromator, fitted with a 3 kW (Cu Kα1.2) copper anode X-ray source and a wolfram cathode. A 30 mA current was applied to the X-ray tube at a voltage of 40 kV.…”

Section: Methodsmentioning

confidence: 99%

“…Standardised active additions such as fly ash, natural pozzolans, slag and silica fume, in turn, are known to effectively inhibit chloride and sulfate ingress [ 38 , 39 ], enhancing durability, although their presence in concrete impacts carbonation resistance adversely [ 13 , 16 ]. That is significant, for any decline in carbonate resistance is a primary long-term concern because it favours reinforcement corrosion [ 40 , 41 , 42 ] and the associated economic loss. The importance of seeking additions that either favour or at least are not detrimental to concrete durability cannot, therefore, be overstated.…”

Section: Introductionmentioning

confidence: 99%

Reduced Carbonation, Sulfate and Chloride Ingress Due to the Substitution of Cement by 10% Non-Precalcined Bentonite

Andrade

Martínez-Serrano

Sanjuán³

et al. 2021

Materials

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The Portland cement industry is presently deemed to account for around 7.4% of the carbon dioxide emitted annually worldwide. Clinker production is being reduced worldwide in response to the need to drastically lower greenhouse gas emissions. The trend began in the nineteen seventies with the advent of mineral additions to replace clinker. Blast furnace slag and fly ash, industrial by-products that were being stockpiled in waste heaps at the time, have not commonly been included in cements. Supply of these additions is no longer guaranteed, however, due to restrained activity in the source industries for the same reasons as in clinker production. The search is consequently on for other additions that may lower pollutant gas emissions without altering cement performance. In this study, bentonite, a very common clay, was used as such an addition directly, with no need for precalcination, a still novel approach that has been scantly explored to date for reinforced structural concrete with structural applications. The results of the mechanical strength and chemical resistance (to sulfates, carbonation and chlorides) tests conducted are promising. The carbonation findings proved to be of particular interest, for that is the area where cement with mineral additions tends to be least effective. In the bentonite-bearing material analysed here, however, carbonation resistance was found to be as low as or lower than that observed in plain Portland cement.

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“…e process of Portland cement production is energy intensive, releasing a huge amount of CO 2 [1,2], both of which are likely to have a significant impact on the environment. According to Sanjuan et al (2020), Sanjuan et al (2019), and Mo and Panesar [3][4][5], the production of cement was responsible for about 7.4%, 6.7%, and 5% of the global CO 2 emission, respectively. On the other side, some studies have been conducted to find the carbonation uptake in order to verify a better carbonation emission balance.…”

Section: Introductionmentioning

confidence: 99%

Performance of GGBS Cement Concrete under Natural Carbonation and Accelerated Carbonation Exposure

Zhao

Wang

Bezabih

2021

Journal of Engineering

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One of the primary problems related to reinforced concrete structures is carbonation of concrete. In many cases, depth of carbonation on reinforced concrete structures is used to evaluate concrete service life. Factors that can substantially affect carbonation resistance of concrete are temperature, relative humidity, cement composition, concentration of external aggressive agents, quality of concrete, and depth of concrete cover. This paper investigates the effect of varying the proportions of blended Portland cement (ordinary Portland cement (OPC) and ground granulated blast-furnace slag (GGBS)) on mechanical and microstructural properties of concrete exposed to two different CO2 exposure conditions. Concrete cubes cast with OPC, and various percentages of GGBS (0%, 30%, 50%, and 70%) were subjected to natural (indoor) and accelerated carbonation exposure. The aim of this paper is to present the research findings and authenticate the literature results of carbonation by using GGBS cement in partial replacement of OPC. The concretes with OPC are compared to concretes with various percentages of GGBS, to assess the carbonation depth as well as rate of carbonation of GGBS-based concretes, under both accelerated carbonation and natural carbonation exposure conditions. Even though GGBS cement increases the carbonation depth, the results are not the same with different GGBS replacement percentages. A correlation is made between concrete samples exposed to 15 ± 2% carbon dioxide (CO2) concentration and those exposed to natural CO2 concentration. The results reveal that the products formed by carbonation are similar under both exposure conditions. The experimental tests also revealed that GGBS cement concrete has a lower carbonation resistance than OPC concrete, due to the consumption of portlandite by the pozzolanic reaction. The combination of 70% OPC and 30% GGBS behaved well enough with respect to accelerated carbonation exposure, the depth of carbonation being roughly equivalent to that of control group (100% OPC). The results also show that rate of carbonation becomes more sensitive as the percentage of GGBS replacement increases (binder ratio), rather than duration of curing. Concretes exposed to natural carbonation (indoor) achieved lower carbonation rates than those exposed to accelerated carbonation.

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Carbon Dioxide Absorption by Blast-Furnace Slag Mortars in Function of the Curing Intensity

Cited by 24 publications

References 20 publications

Carbon Dioxide Uptake by Mortars and Concretes Made with Portuguese Cements

Carbon Dioxide Uptake by Mortars and Concretes Made with Portuguese Cements

Reduced Carbonation, Sulfate and Chloride Ingress Due to the Substitution of Cement by 10% Non-Precalcined Bentonite

Performance of GGBS Cement Concrete under Natural Carbonation and Accelerated Carbonation Exposure

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