Carbonation-Related Microstructural Changesin Long-Term Durability Concrete

Silva, Claudio A. Rigo da; Reis, Rubens J. Pedrosa; Lameiras, Fernando Soares; Vasconcelos, Wander L.

doi:10.1590/s1516-14392002000300012

Cited by 18 publications

(6 citation statements)

References 6 publications

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“…In this figure, portlandite crystals can easily be detected in the interfacial transition zone between the cement paste and recycled aggregate. These hexagonal crystals, with a size higher than 10 µm in most cases, are similar to those reported for different types of concretes [66,67,68,69,70], including some recycled aggregates. Additionally, some calcium silicate hydrate gels (C–S–H) were also observed close to the portlandite crystals.…”

Section: Resultssupporting

confidence: 84%

Paving with Precast Concrete Made with Recycled Mixed Ceramic Aggregates: A Viable Technical Option for the Valorization of Construction and Demolition Wastes (CDW)

et al. 2018

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This research aimed to prove the feasibility of producing two types of precast elements widely used in construction, such as curbstones and paving blocks, using recycled concrete made with a 50% substitution of the natural gravel by recycled mixed aggregates with a significant ceramic content (>30%). In order to prove the quality of such mass concrete recycled precast elements, two different mixes were used: the first one was a conventional concrete mix provided by Prefabricados de Hormigón Pavimentos Páramo S.L., one of the collaborating companies in this study, and the other was a mixture in which wt 50% of the natural coarse aggregates were substituted for recycled mixed aggregates ceramic (RMAc). This recycled aggregate is a heterogeneous mixture of unbound aggregates, concrete, ceramic, etc., used as a secondary recycled aggregate and commonly produced in a lot of recycling plants in many European countries. This material was supplied by Tecnología y Reciclado S.L., the other collaborating company. Both mixtures were representative in order to establish the comparative behavior between them, taking into account that smaller percentages of replacement of the natural with recycled aggregates will also produce good results. This percentage of substitution represents a high saving of natural resources (gravel) and maintains a balanced behavior of the recycled concrete, so this new material can be considered to be a viable and reliable option for precast mass concrete paving elements. The characterization of the recycled precast elements, covering mechanical, microstructural, and durability properties, showed mostly similar behavior when compared to the analogous industrially-produced pieces made with conventional concrete.

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Section: Resultssupporting

confidence: 84%

Paving with Precast Concrete Made with Recycled Mixed Ceramic Aggregates: A Viable Technical Option for the Valorization of Construction and Demolition Wastes (CDW)

et al. 2018

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“…There is a possibility of the highest changes (pH value, temperature, evolved heat, etc.) occurring, and therefore the biggest influence taking place, because of the Zn 2+ and NO 3 − ions themselves [55]. In view of retardation time, the results from isothermal and isoperibolic calorimetry are comparable.…”

Section: Resultsmentioning

confidence: 99%

Application of Isothermal and Isoperibolic Calorimetry to Assess the Effect of Zinc on Hydration of Cement Blended with Slag

et al. 2019

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This work deals with the influence of zinc on cement hydration. The amount of zinc in cement has increased over recent years. This is mainly due to the utilization of solid waste and tires, which are widely used as a fuel in a rotary kiln. Zinc can also be introduced to cement through such secondary raw materials as slag, due to increased recycling of galvanized materials. The aim of this work was to determine the effect of zinc on the hydration of Portland cement, blended with ground blast furnace slag (GBFS). This effect was studied by isothermal and isoperibolic calorimetry. Both calorimetry methods are suitable for measurements during the first days of hydration. Isoperibolic calorimetry monitors the hydration process in real-life conditions, while isothermal calorimetry does so at a defined chosen temperature. Zinc was added to the cement in the form of two soluble salts, namely Zn(NO3)2, ZnCl2, and a poorly soluble compound, ZnO. The concentration of added zinc was chosen to be 0.05, 0.1, 0.5, and 1mass percent. The amount of GBFS replacement was 15% of cement dosage. The newly formed hydration products were identified by X-ray diffraction method (XRD).

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“…In contrast, other authors have reported an increase in the specific surface area after carbonation; e.g., Da Silva et al (2002) and Chindaprasirt (2009) conducted mercury porosimetry studies on concrete, Arandigoyen et al (2006) investigated nitrogen adsorption on cement pastes that consisted of a mixture of cement and lime and Kim et al (1995) examined the carbonation of portlandite and C-S-H.…”

Section: Introductionmentioning

confidence: 97%

Effects of Carbonation on the Microstructure of Cement Materials: Influence of Measuring Methods and of Types of Cement

Phạm

Prince

2014

Int J Concr Struct Mater

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The objective of this work was to examine the influence of carbonation on the microstructure of cement materials. Different materials, which were CEM I mortar and paste, CEM II mortar and paste, were carbonated at 20°C, 65 % relative humidity and 20 % of CO 2 concentration. The specific surface area and pore size distribution were determined from two methods: nitrogen adsorption and water adsorption. The results showed that: (1) nitrogen adsorption and water adsorption do not cover the same porous domains and thus, we observed conflicts in the results obtained by these two techniques; (2) the CEM II based materials seemed to be more sensible to a creation of mesoporosity after carbonation than the CEM I based materials. The results of this study also helped to explain why observations in the literature diverge greatly on the influence of carbonation on specific surface area.

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Carbonation-Related Microstructural Changesin Long-Term Durability Concrete

Cited by 18 publications

References 6 publications

Paving with Precast Concrete Made with Recycled Mixed Ceramic Aggregates: A Viable Technical Option for the Valorization of Construction and Demolition Wastes (CDW)

Paving with Precast Concrete Made with Recycled Mixed Ceramic Aggregates: A Viable Technical Option for the Valorization of Construction and Demolition Wastes (CDW)

Application of Isothermal and Isoperibolic Calorimetry to Assess the Effect of Zinc on Hydration of Cement Blended with Slag

Effects of Carbonation on the Microstructure of Cement Materials: Influence of Measuring Methods and of Types of Cement

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