Sustainability and Sustainable Development

This study presents test results and in-depth discussion regarding the measurement of the fracture mechanics parameters of new concrete composites based on quaternary blended cements (QBC). A composition of the two most commonly used mineral additives, i.e., fly ash (FA) and silica fume (SF), in combination with nanosilica (nS), has been proposed as a partial replacement for ordinary Portland cement (OPC) binder. Four series of concrete were made, one of which was the reference concrete (REF) and the remaining three were QBC. During the research, the main mechanical parameters of compressive strength (fcm) and splitting tensile strength (fctm), as well as fracture mechanics parameters and the critical stress intensity factor KIcS, along with critical crack-tip opening displacements (CTODc) were investigated. Based on the tests, it was found that the total addition of siliceous materials, i.e., SF + nS without FA, increases the strength and fracture parameters of concrete by approximately 40%. On the other hand, supplementing the composition of the binder with SF and nS with 5% of FA additive causes an increase in all mechanical parameters by approximately 10%, whereas an increase by another 10% in the FA content in the concrete mix causes a significant decrease in all the analyzed factors by 10%, compared to the composite with the addition of silica modifiers only.

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Fracture Performance of Cementitious Composites Based on Quaternary Blended Cements

Disposal of the coal fly ash (CFA) generated from thermal power plants in huge quantities is one of the major concerns for the industry, as well as the natural environment. On the other hand, CFA can be used within a certain percentage range in the cement concrete mix as a replacement for cement. Nanomaterials can also be used to improve the properties of concrete. Therefore, this study investigated the effects of nanosilica (nS) on the mechanical parameters and microstructure of CFA cement concretes. This study utilized an nS content of 5%, along with three CFA contents, i.e., of 0, 15, and 25% by volume. Mechanical property tests and a thorough overview of changes in the structure of modified concrete were carried out to study the effect of the CFA content on the analyzed parameters of concrete containing nS. This study had the goal of elucidating the reinforcing mechanisms of CFA concrete by nS and providing design guidance for the practical engineering applications of CFA-nS composites. Based on the conducted studies, it was found that the combined usage of nS and CFA has synergistic and positive effects on improving mechanical parameters and microstructure in such concretes. The combined strengthening of a cement matrix by nS and CFA can fill the pores and microcracks in concrete composites and effectively improve the mechanical properties and microstructure of such materials. In this study, the optimal improvement was achieved when the concentration of additions was 5% nS and 15% CFA. The 28-day compressive strength and splitting tensile strength were increased by 37.68 and 36.21%, respectively, in comparison to control concrete. Tailored blended cements composed of nS and CFA content (up to 30% replacement level) can significantly improve the parameters of concrete composites, as well as reduce the carbon footprint of cement-based materials—constituting a step toward the production of eco-friendly concretes.

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Combined Effect of Coal Fly Ash (CFA) and Nanosilica (nS) on the Strength Parameters and Microstructural Properties of Eco-Friendly Concrete

The following article introduces, in a thorough manner, how the chemical pozzolanic reaction takes place in cement composites containing the fly ash (FA) additive. In the research part, however, the development of phases in the structure of the cement paste in the initial period of its curing and after 28 days from its preparation was traced. For this purpose, a Scanning Electron Microscope (SEM) was used. In order to accurately highlight all the characteristic stages of the formation of the structure of the composite containing FA, an analysis of the cement matrix was carried out between 0.5 and 28 days of their curing. Microstructural studies were complemented by tests of pozzolanic activity of FAs used. In order to conduct a full analysis of this feature, experiments were carried out using two types of research methods, i.e., chemical and physical. On the basis on the conducted studies it was found that: in cement composites with the addition of FA, in the period until the third day of curing, the development of the material structure is mainly the result of the hydration reaction, and between the seventh and fourteenth day after sample preparation, the first signs of the pozzolanic reaction on FA grains are visible; however, in the period between 14 and 28 days, there is a clear homogenization of the structure of the cement composite with the addition of FA, resulting from the change of disordered phases into compact and homogeneous forms and filling in the composite of porous places with pozzolanic reaction products. The use of cement composites based on materials whose application makes it possible to reduce GHG emissions to the atmosphere, reduce energy consumption, and reduce industrial waste landfills leads towards the development of ecological and sustainable building engineering.

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The Role of Pozzolanic Activity of Siliceous Fly Ash in the Formation of the Structure of Sustainable Cementitious Composites

https://ijraset.com/fileserve.php?FID=11408

A Review on Self Compacting Concrete

Repair, rehabilitation and retrofitting of reinforced concrete structures by using non-destructive testing methods

Mechanical properties of sustainable concrete by using RHA and hydrated lime

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Importance of Dynamic Analysis for RCC Structures

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Earthquake Resistant of RCC Structures

Geopolymer Concrete is a new innovative type of concrete, and it is used widely in the construction industries. This type of concrete comes into place due to reduced cement content usage in the construction of structures. Already we are using cement as a binding material widely in the construction sector, but the problem is due to the cement content Co2 emissions are mainly produced and one more problem is greenhouse gases are increasing rapidly during the manufacturing of cement. Then after a lot of researchers, finally we got a geopolymer as a replacement for cement. By replacing cement content with geopolymer, we can reduce the cost of construction and reuse the structural materials. So, this type of concrete is different from standard conventional concrete. We can minimize Co2 and greenhouse gases’ problem in the atmosphere and make the structure an environmentally friendly solution. So, this type of concrete is very famous in the construction industry, and there are benefits also excellent. So, it can be used widely in construction sectors worldwide. This paper may help understand Geopolymer Concrete for everyone quickly. It gives a quick review of the Geopolymer Concrete.

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Gomasa Ramesh

Papers

Repair, rehabilitation and retrofitting of reinforced concrete structures by using non-destructive testing methods

Mechanical properties of sustainable concrete by using RHA and hydrated lime

Importance of Dynamic Analysis for RCC Structures

Earthquake Resistant of RCC Structures

Geopolymer Concrete: A Review