A review on carbonation study in concrete
01 Nov 2017-Vol. 263, Iss: 3, pp 032011
TL;DR: In this article, the authors have reviewed the carbonation studies which are a vital durability property of concrete and endeavoured to focus and elucidate the gravity of importance, the process and chemistry of carbonate and how the various parameters like water/cement ratio, curing, depth of concrete cones, admixtures, grade of concrete, strength and porosity effect carbonation in concrete.
Abstract: In this paper the authors have reviewed the carbonation studies which are a vital durability property of concrete. One of the major causes for deterioration and destruction of concrete is carbonation. The mechanism of carbonation involves the penetration carbon dioxide (CO2) into the concrete porous system to form an environment by reducing the pH around the reinforcement and initiation of the corrosion process. The paper also endeavours to focus and elucidate the gravity of importance, the process and chemistry of carbonate and how the various parameters like water/cement ratio, curing, depth of concrete cones, admixtures, grade of concrete, strength of concrete, porosity and permeability effect carbonation in concrete. The role of Supplementary Cementitious Materials (SCMs) like Ground granulated Blast Furnace Slag (GGBS) and Silica Fume (SF) has also been reviewed along with the influence of depth of carbonation.
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TL;DR: In this paper, the authors investigated the durability characteristics of rubberized concrete up to 30% rubber content, including the carbonation depth, standard potential, water absorption, and initial rate of absorption.
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TL;DR: In this article, the authors present the chemical compound of eggshell and the suitability of the waste as cement replacement, and discuss the fresh, hardened and durability properties based on a variety of previous studies.
Abstract: Sustainable concrete is currently a widely studied topic in order to reduce the environmental impact of cement. Substitute materials are usually industrial and municipal wastes. Eggshell powder as cement replacement is a viable option to produce green concrete. At the same time, it improves the disposal of eggshell, which is thrown away as household waste and mostly ends up in the landfill. This paper reviews the constituents, production techniques and properties of eggshell concrete (ESC). The paper presents the chemical compound of eggshell and the suitability of the waste as cement replacement. This is followed by a discussion of the fresh, hardened and durability properties based on a variety of previous studies. At the optimal content of 10%, ESC has various advantages compared to conventional concrete. The advantages are associated with the high calcium content and good filling effect of eggshell powder. This includes improved hardened properties, reduced setting time, and increased resistance to water penetration and carbonation. Eggshell is also an accelerator to the hydration process. However, ESC shows weakness in chloride and sulphate environment due to the vulnerability of eggshell to these compounds. While studies on the material are available significantly, researches on durability properties of ESC should be enhanced.
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TL;DR: In this article, an indepth review of the recent advances on carbonation process, factors affecting carbonation resistance, and the effects of carbonation on hardened cement materials have been discussed.
Abstract: Blended cements are preferred to Ordinary Portland Cement (OPC) in construction industry due to costs and technological and environmental benefits associated with them. Prevalence of significant quantities of carbon dioxide (CO2) in the atmosphere due to increased industrial emission is deleterious to hydrated cement materials due to carbonation. Recent research has shown that blended cements are more susceptible to degradation due to carbonation than OPC. The ingress of CO2 within the porous mortar matrix is a diffusion controlled process. Subsequent chemical reaction between CO2 and cement hydration products (mostly calcium hydroxide [CH] and calcium silicate hydrate [CSH]) results in degradation of cement based materials. CH offers the buffering capacity against carbonation in hydrated cements. Partial substitution of OPC with pozzolanic materials however decreases the amount of CH in hydrated blended cements. Therefore, low amounts of CH in hydrated blended cements make them more susceptible to degradation as a result of carbonation compared to OPC. The magnitude of carbonation affects the service life of cement based structures significantly. It is therefore apparent that sufficient attention is given to carbonation process in order to ensure resilient cementitious structures. In this paper, an indepth review of the recent advances on carbonation process, factors affecting carbonation resistance, and the effects of carbonation on hardened cement materials have been discussed. In conclusion, carbonation process is influenced by internal and external factors, and it has also been found to have both beneficial and deleterious effects on hardened cement matrix.
35 citations
TL;DR: In this article, a growing need in the construction industry to improve transfer and durability aspects of Portland pozzolana cement was identified, and Ureolytic bacteria have recently emerged as potential micro-organisms w...
Abstract: There is a growing need in the construction industry to improve transfer and durability aspects of Portland pozzolana cement. Ureolytic bacteria have recently emerged as potential micro-organisms w...
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TL;DR: In this paper, the authors detail the enhancement in most of the prominent characteristics of cement mortar cubes fabricated by admixing with reduced graphene oxide (rGO) as an additive to a standard mix design.
Abstract: In this paper, we detail the enhancement in most of the prominent characteristics of cement mortar cubes fabricated by admixing with reduced graphene oxide (rGO) as an additive to a standard mix design. After curing the fabricated cement mortar cubes for 28 days, 0.1% rGO impregnated cement mortar cubes (0.1% rGOCMC) display higher compressive strength of 36.23 MPa in contrast to all other specimens (0.05%, 0.15% and 0.2%). Besides compressive strength, tests for water absorption, ultrasonic pulse velocity, carbonation, fire resistance, and acid attack further validate the superior performance of 0.1% rGOCMC over control mortar cubes. From all the obtained results, it is clear that 0.1% rGOCMC has the best characteristics of cement mortar to protect embedded metal reinforcement from corrosion and can be used as an effective structural material in the building industry.
20 citations
References
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TL;DR: In this paper, the performance of slag, fly ash, and silica fume concretes under four different curing regimes was investigated and the compressive strength was determined at various ages, and the resistance to chloride-ion penetration was measured according to ASTM C 1202 at different ages up to 180 days.
Abstract: This paper reports an investigation in which the performance of slag, fly ash, and silica fume concretes were studied under four different curing regimes. The water-cementitious materials ratio of all the concrete mixtures was kept constant at 0.50, except for the high-volume fly ash concrete mixture, for which the ratio was 0.35. The concrete specimens were subjected to moist curing, curing at room temperature after demoulding, curing at room temperature after two days of moist curing, and curing at 38 °C and 65% relative humidity. The compressive strength was determined at various ages, and the resistance to chloride-ion penetration was measured according to ASTM C 1202 at different ages up to 180 days. Mercury intrusion porosimetry tests were performed on the 28-day old mortar specimens for comparison purposes. The results indicate that the reduction in the moist-curing period results in lower strengths, higher porosity and more permeable concretes. The strength of the concretes containing fly ash or slag appears to be more sensitive to poor curing that the control concrete, with the sensitivity increasing with the increasing amounts of fly ash or slag in the mixtures. The incorporation of slag or silica fume, or high volumes of fly ash in the concrete mixtures, increased the resistance to chloride ions and produced concretes with very low permeability.
403 citations
TL;DR: In this article, the carbonation of fly ash concrete is studied by using two types of Fly Ash with different CaO contents, and it is observed that under natural exposure environments, the Carbonation rate is the highest when specimens are exposed in the city.
292 citations
TL;DR: In this paper, an accelerated carbonation test was carried out in order to assess the carbonation of fly ash (FA) concrete, and the results showed that FA concrete made with 70% replacement ratio was carbonated more than that of 50% FA replacement concrete and normal Portland cement (NPC) concrete.
285 citations
TL;DR: In this paper, the governing equations of moisture, heat and carbon dioxide flows through concrete within the framework of a distributed parameter model, and a numerical procedure based on the finite element method is developed to solve the set of equations.
275 citations
TL;DR: In this article, the influence of fly ash and slag replacement on the carbonation rate of concrete concretes was studied, and according to Fick's law of diffusion theoretical equations were proposed as a guild for estimating the carbonated rate of fly-ash and blast-furnace slag concrete.
270 citations