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Murugan Muthu

Bio: Murugan Muthu is an academic researcher from Technische Universität Darmstadt. The author has contributed to research in topics: Cement & Portland cement. The author has an hindex of 5, co-authored 7 publications receiving 75 citations. Previous affiliations of Murugan Muthu include Nanyang Technological University.

Papers
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TL;DR: In this paper, the effect of reduced graphene oxide, alumina and silica nanoparticles on the deterioration characteristics of 28-day cured cementitious pastes after storage in 0.5 MOL/L HNO3 solution for a period of 56 days is reported.
Abstract: Acid attack on cement concrete results in the development of a degraded layer surrounding the unaffected material, which causes a deterioration of mechanical properties. The effect of reduced graphene oxide, alumina and silica nanoparticles on the deterioration characteristics of 28-day cured cementitious pastes after storage in 0.5 moL/L HNO3 solution for a period of 56 days is reported in this paper. Samples were collected from the degraded pastes at different time periods and then characterised using various techniques like scanning electron microscopy with energy dispersive spectroscopy, optical microscopy, thermogravimetric analysis, mercury intrusion porosimetry, X-ray computed tomography and nanoindentation. While the porosimetry results showed that the presence of reduced graphene oxide and nano alumina decreased the amount of capillary pores (10 nm–10 μm) by up to 46% and 51% than the control paste after storage in acidic solution for 28 days, the details of the relative zones formed in the paste along with their characteristics were revealed by the microscopy and nanoindentation techniques. Overall, the results suggest that the presence of these nanomaterials refined the pore structure of the cementitious matrix and thereby increased the resistance to leaching of calcium ions from the binder phases exposed to aggressive aqueous media.

62 citations

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TL;DR: Results points out that geopolymer-based mortars have improved acid resistance, which can be used as a potential alternative to conventional cement concretes that have been exposed to agro-industrial environments.
Abstract: In this paper, we comparitvley studied acetic acid attacks on geopolymer (GP-M), calcium aluminate (CAC-M), and Portland cement (PC-M)-based mortars. Consequent formations of deteriorated or transition layers surrounding the unaltered core material was classified in these three mortars, according to different degradation levels depending on what binder type was involved. Apart from mass loss, hardness, and deterioration depth, their microstructural alterations were analyzed using test methods such as scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), mercury intrusion porosimetry (MIP), powder X-ray diffraction (XRD), and thermogravimetric analysis-differential scanning calorimeter (TGA-DSC), which showed the different mechanisms for each binder type. Elemental maps revealed the decalcification (PC-M and CAC-M) and depolymerization (GP-M) that occurred across the mortar sections. The mass loss, hardness, and porosity were the least affected for GP-M, followed by CAC-M. These results points out that geopolymer-based mortars have improved acid resistance, which can be used as a potential alternative to conventional cement concretes that have been exposed to agro-industrial environments.

30 citations

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TL;DR: In this paper, the effects of accelerated carbonation and hydraulic retention time (HRT) on the lead removal in pervious concrete filter (PCF) were investigated, and it showed that the CO2 uptake by PCF marginally improved the Pb fixation.

24 citations

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TL;DR: In this paper, the effect of graphene oxide (GO) dosage on the performance of cement pastes against an extreme nitric acid environment was investigated, and a significant volume of cement matrix was affected because of such attack.

22 citations

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TL;DR: In this article, the authors investigated the changes in the performance and microstructure of two concrete formulations, whose binder component was made up of RMC with and without 50 % FA substitution.
Abstract: MgO cement (RMC)-based mixes are known to gain strength via carbonation. While the strength gain mechanism of RMC mixes has been studied, their durability under aggressive environments is relatively unknown. This study investigated the changes in the performance and microstructure of two concrete formulations, whose binder component was made up of RMC with and without 50 % FA substitution. These concrete specimens were initially carbonated for 28 days to gain strength, followed by immersion in 0.5 M nitric acid for 14 days. The degradation of both specimens was recorded in terms of changes in their strength, mass, composition and microstructure. The use of FA led to a lower hydration and subsequent carbonation due to the lower RMC content, thereby limiting initial strength development. While the leaching of Mg-based phases into the external solution was recorded, most hydrate and carbonate phases were still present after acid exposure. The ∼56 % reduction in strength experienced by both specimens was accompanied with the formation of micro cracks.

11 citations


Cited by
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TL;DR: The engineered biochar with hierarchical pores can impregnate iron nanoparticles, serve as an adsorbent, and enhance metal reduction/precipitation and can be a novel biowaste-derived material for wastewater treatment.

238 citations

Journal ArticleDOI
Li Zhao, Xinli Guo1, Luguang Song, Yang Song, Guozhong Dai, Jiaping Liu1 
TL;DR: In this paper, a review on the reinforcing effects and mechanisms of GO on cement composites by consulting a lot of correlative literature, mainly focusing on the following aspects: (I) the dispersion issue of GO in the alkaline cement paste; (II) the effects of the GO on the macro-performance (workability, mechanical strength, and durability) of cement composite materials; (III) the reinforcing mechanisms of the materials including hydration kinetics, C-S-H structure, pore structure, and interfacial bonding with cement matrix.

111 citations

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TL;DR: X-ray computed tomography (CT) is a non-destructive technique that offers a 3D insight into the microstructure of thick (opaque) samples with virtually no preliminary sample preparation as mentioned in this paper.

109 citations

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TL;DR: P porous magnetic biochar with excellent surface area and recovery rate using corn stalks and waste iron as precursors is prepared using as-synthesized artificial humic acid (A-HA) as an activator.

101 citations

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TL;DR: In this article, the authors focused on the effects of carbonation curing on the durability of cement-based composites and the underlying mechanisms, especially for some critical aspects such as alkali-silica reaction, corrosion, and sulfate attack.
Abstract: To tackle the rising CO2 concentration in atmosphere, technologies of carbon sequestration are emerging. As one of these technologies, carbonation curing of cement-based composite at early age shows a great potential because its wide application and benefits to provide cement-based composite with enhanced mechanical properties and durability. However, carbonation curing is mostly investigated on lab-scale, due to two main challenges that should be addressed before it can be widely applied for industrial-scale production: (1) CO2 sequestration rate is still low, which is around 20 %–50 % of the theoretical potential because of the limitation of CO2 diffusion into matrix during the carbonation curing; and (2) the effect carbonation curing on the durability of cement-based composites and the underlying mechanisms remains unclear, especially for some critical aspects such as alkali-silica reaction, corrosion, and sulfate attack. Therefore, this paper focuses on discussing: (1) factors affecting CO2 sequestration in cement-based composite during each stage of carbonation curing and the optimization methods of carbonation curing for high CO2 sequestration rate without mitigating mechanical properties and durability, and (2) effects of carbonation curing on different aspects of durability and the corresponding mechanisms. Based on the review, future studies on addressing current challenges are inspired to comprehend and promote the carbon sequestration by carbonation curing of cement-based composites.

101 citations