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25 pages, 17720 KiB

Open AccessArticle

Application of Construction and Demolition Waste in Civil Construction in the Brazilian Amazon—Case Study of the City of Rio Branco

by Fernando da Silva Souza, José Maria Franco de Carvalho, Gabriela Grotti Silveira, Vitória Cordeiro Araújo and Ricardo André Fiorotti Peixoto

Materials 2021, 14(9), 2247; https://doi.org/10.3390/ma14092247 - 27 Apr 2021

Cited by 8 | Viewed by 3594

Abstract

The lack of usable aggregates for civil construction in Rio Branco (capital of Acre, a Federal State in the Amazon region) makes the production and use of recycled aggregates from construction and demolition waste (CDW) an alternative of great interest. In this study, [...] Read more.

The lack of usable aggregates for civil construction in Rio Branco (capital of Acre, a Federal State in the Amazon region) makes the production and use of recycled aggregates from construction and demolition waste (CDW) an alternative of great interest. In this study, a comprehensive characterization of CDW collected from 24 construction sites of six building types and three different construction phases (structures, masonry, and finishing) was carried out. The fine and coarse recycled aggregates were produced and evaluated in 10 different compositions. The aggregates’ performance was evaluated in four mixtures designed for laying and coating mortars with a total replacement of conventional aggregates and a mixture designed for a C25 concrete with 50% and 100% replacement of conventional aggregates. CDW mortars showed lower densities and greater water retention, initial adhesion, and mechanical strength than conventional mortars. CDW concretes presented lower densities and greater resistance to chloride penetration than conventional concrete, with a small mechanical strength reduction. The recycled CDW aggregates proved to be technologically feasible for safe application in mortars and concrete; for this reason, it is believed that the alternative and proposed methodology is of great interest to the Amazonian construction industry, considering the high costs of raw materials and the need for defining and consolidating a sustainable development model for the Amazon region. Full article

(This article belongs to the Special Issue Recycled Concrete with Waste and By-Products)

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13 pages, 4274 KiB

Open AccessFeature PaperArticle

Reuse of Industrial and Agricultural Waste in the Fabrication of Geopolymeric Binders: Mechanical and Microstructural Behavior

by Jordi Payá, Lourdes Soriano, Alba Font, Maria Victoria Borrachero Rosado, Javier Alejandro Nande and Jose María Monzo Balbuena

Materials 2021, 14(9), 2089; https://doi.org/10.3390/ma14092089 - 21 Apr 2021

Cited by 4 | Viewed by 2387

Abstract

Resource recovery from waste is one of the most important ways to implement the so-called circular economy, and the use of alkali activated materials can become an alternative for traditional PC-based materials. These types of materials are based on waste resources involving a [...] Read more.

Resource recovery from waste is one of the most important ways to implement the so-called circular economy, and the use of alkali activated materials can become an alternative for traditional PC-based materials. These types of materials are based on waste resources involving a lower carbon footprint and present similar or high properties and good durability compared to that Portland cement (PC). This research work proposes using new waste generated in different types of industries. Four waste types were employed: fluid catalytic cracking residue (FCC) from the petrochemical industry; ceramic sanitary ware (CSW) from the construction industry; rice husk ash (RHA); diatomaceous waste from beer filtration (DB) (food industry). FCC and CSW were employed as precursor materials, and mixtures of both showed good properties of the obtained alkali activated materials generated with commercial products as activators (NaOH/waterglass). RHA and DB were herein used as an alternative silica source to prepare the alkaline activating solution. Mechanical behavior was studied by the compressive strength development of mortars. The corresponding pastes were characterized by X-ray diffraction, thermogravimetric analysis, and microscopy studies. The results were satisfactory, and demonstrated that employing these alternative activators from waste produces alkali activated materials with good mechanical properties, which were sometimes similar or even better than those obtained with commercial reagents. Full article

(This article belongs to the Special Issue Recycled Concrete with Waste and By-Products)

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25 pages, 10642 KiB

Open AccessArticle

Performance Evaluation of Modified Rubberized Concrete Exposed to Aggressive Environments

by Akram M. Mhaya, Mohammad Hajmohammadian Baghban, Iman Faridmehr, Ghasan Fahim Huseien, Ahmad Razin Zainal Abidin and Mohammad Ismail

Materials 2021, 14(8), 1900; https://doi.org/10.3390/ma14081900 - 11 Apr 2021

Cited by 29 | Viewed by 3085

Abstract

Recycling of the waste rubber tire crumbs (WRTCs) for the concretes production generated renewed interest worldwide. The insertion of such waste as a substitute for the natural aggregates in the concretes is an emergent trend for sustainable development towards building materials. Meanwhile, the [...] Read more.

Recycling of the waste rubber tire crumbs (WRTCs) for the concretes production generated renewed interest worldwide. The insertion of such waste as a substitute for the natural aggregates in the concretes is an emergent trend for sustainable development towards building materials. Meanwhile, the enhanced resistance of the concrete structures against aggressive environments is important for durability, cost-saving, and sustainability. In this view, this research evaluated the performance of several modified rubberized concretes by exposing them to aggressive environments i.e., acid, and sulphate attacks, elevated temperatures. These concrete (12 batches) were made by replacing the cement and natural aggregate with an appropriate amount of the granulated blast furnace slag (GBFS) and WRTCs, respectively. The proposed mix designs’ performance was evaluated by several measures, including the residual compressive strength (CS), weight loss, ultrasonic pulse velocity (UPV), microstructures, etc. Besides, by using the available experimental test database, an optimized artificial neural network (ANN) combined with the particle swarm optimization (PSO) was developed to estimate the residual CS of modified rubberized concrete after immersion one year in MgSO₄ and H₂SO₄ solutions. The results indicated that modified rubberized concrete prepared by 5 to 20% WRTCs as a substitute to natural aggregate, provided lower CS and weight lose expose to sulphate and acid attacks compared to control specimen prepared by ordinary Portland cement (OPC). Although the CS were slightly declined at the elevated temperature, these proposed mix designs have a high potential for a wide variety of concrete industrial applications, especially in acid and sulphate risk. Full article

(This article belongs to the Special Issue Recycled Concrete with Waste and By-Products)

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14 pages, 1374 KiB

Open AccessEditor’s ChoiceArticle

Supersulfated Cement Applied to Produce Lightweight Concrete

by Liliya F. Kazanskaya, Olga M. Smirnova, Ángel Palomo, Ignacio Menendez Pidal and Manuel Romana

Materials 2021, 14(2), 403; https://doi.org/10.3390/ma14020403 - 15 Jan 2021

Cited by 18 | Viewed by 2745

Abstract

The physical and mechanical characteristics of expanded-clay lightweight concrete based on a supersulfated binder in comparison with lightweight concrete based on ordinary Portland cement were studied. In replacing CEM 32.5 with a supersulfated binder of 6000 cm²/g specific surface, one can [...] Read more.

The physical and mechanical characteristics of expanded-clay lightweight concrete based on a supersulfated binder in comparison with lightweight concrete based on ordinary Portland cement were studied. In replacing CEM 32.5 with a supersulfated binder of 6000 cm²/g specific surface, one can increase the tensile strength in bending up to 20% and can increase the ratio of the tensile strength in bending to the compressive strength that indicates the crack resistance increase of concrete. Compressive strengths at the age of 28 days were equal to 17.0 MPa and 16.6 MPa for the supersulfated binder of 3500 cm²/g specific surface and CEM 32.5, respectively. Shrinkage deformation of hardening concrete, indicators of fracture toughness, frost resistance, and thermal conductivity were determined during the experimental works. The coefficient of thermal conductivity decreased up to 12% compared to the use of CEM 32.5. An enhancement in concrete properties was associated with the increase of supersulfated binder fineness. Full article

(This article belongs to the Special Issue Recycled Concrete with Waste and By-Products)

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15 pages, 3878 KiB

Open AccessArticle

Utilization of Iron Tailings Sand as an Environmentally Friendly Alternative to Natural River Sand in High-Strength Concrete: Shrinkage Characterization and Mitigation Strategies

by Zhiqiang Zhang, Zhilu Zhang, Shaoning Yin and Linwen Yu

Materials 2020, 13(24), 5614; https://doi.org/10.3390/ma13245614 - 9 Dec 2020

Cited by 40 | Viewed by 2897

Abstract

The increasing annual emissions of iron ore tailings have proved a great threat to the natural environment, and the shortage of natural river sand, as well as the pursuit of sustainable development materials, provides motivation to reuse iron ore tailings as a fine [...] Read more.

The increasing annual emissions of iron ore tailings have proved a great threat to the natural environment, and the shortage of natural river sand, as well as the pursuit of sustainable development materials, provides motivation to reuse iron ore tailings as a fine aggregate in concrete. Due to the significantly different properties of iron tailings sand compared with natural river sand—such as the higher density, higher content of limestone particles smaller than 75 μm and its rough and angular shape—concretes prepared with iron tailings sand show remarkably higher shrinkage. This study presents the shrinkage characterization and shrinkage-reducing efficiency of three different methods on iron tailings, sand concrete and river sand concrete. The internal humidity was also monitored to reveal the shrinkage-reducing mechanism. The obtained results indicated that the autogenous and total shrinkage of iron tailings sand concrete were 9.8% and 13.3% higher than the river sand concrete at the age of 90 d, respectively. The shrinkage reducing agent (SRA) was the most effective shrinkage reducing method for river sand concrete, while for iron tailings sand concrete, super absorbent polymer (SAP) and controlled permeable formwork liner (CPFL) it worked best on autogenous shrinkage and drying shrinkage, respectively. Furthermore, the shrinkage mitigation strategies worked earlier for the drying shrinkage behavior of iron tailings sand concrete, while no such condition could be found for autogenous shrinkage. Full article

(This article belongs to the Special Issue Recycled Concrete with Waste and By-Products)

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23 pages, 6865 KiB

Open AccessArticle

Reuse of Heat Resistant Glass Cullet in Cement Composites Subjected to Thermal Load

by Aleksandra Powęzka, Jacek Szulej and Paweł Ogrodnik

Materials 2020, 13(19), 4434; https://doi.org/10.3390/ma13194434 - 5 Oct 2020

Cited by 7 | Viewed by 3108

Abstract

The article describes the possibility of using waste glass cullet as an alternative aggregate for the production of cement composites. Three concrete mixes based on Portland cement CEM I 42.5 R with different contents of recyclate were designed. Borosilicate glass cullet was introduced [...] Read more.

The article describes the possibility of using waste glass cullet as an alternative aggregate for the production of cement composites. Three concrete mixes based on Portland cement CEM I 42.5 R with different contents of recyclate were designed. Borosilicate glass cullet was introduced into the batch by reducing the content of natural aggregate by 0%, 2.5% and 7.5%. Apparent density, water absorption and compressive strength at elevated temperature were measured. The temperature distribution, in cubic samples, was followed by thermocouples. The elements were heated in a special furnace at the temperatures of 200 °C, 400 °C, 600 °C and 800 °C. The composite topography and phase composition were observed using X-ray energy scattering electron microscopy. The results show that the appropriate modification of the cement composite with 2.5% heat-resistant glass cullet improves both the thermal and mechanical properties. Compressive strength reaches an average value of 48.6 MPa after 28 days. The increase in temperature weakens the structure of the composite. It was found that the obtained cement composite has good physico–chemical properties. The research results are presented in the article. Full article

(This article belongs to the Special Issue Recycled Concrete with Waste and By-Products)

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14 pages, 2110 KiB

Open AccessArticle

On the Development of a Technical Specification for the Use of Fine Recycled Aggregates from Construction and Demolition Waste in Concrete Production

by Miguel Bravo, António P. C. Duarte, Jorge de Brito, Luis Evangelista and Diogo Pedro

Materials 2020, 13(19), 4228; https://doi.org/10.3390/ma13194228 - 23 Sep 2020

Cited by 20 | Viewed by 2747

Abstract

The possibility of using recycled aggregates from construction and demolition waste (CDW) in concrete is rather widely agreed upon when it comes to the use of coarse recycled aggregates. However, this is not the case when fine recycled aggregates (FRA) are considered, as [...] Read more.

The possibility of using recycled aggregates from construction and demolition waste (CDW) in concrete is rather widely agreed upon when it comes to the use of coarse recycled aggregates. However, this is not the case when fine recycled aggregates (FRA) are considered, as it is deemed that these seriously impair the behaviour of concrete. Hence, this work presents a technical specification proposal for the use of FRA from CDW in concrete, to attempt to fill this gap in legislation. The specification is based on a wide collection of experimental results, from which it is shown that for low incorporation ratios (up to 25%), the properties of concrete with FRA from CDW are comparable to those of a reference concrete. The intended international scope of the specification is ensured by the fact that FRA from CDW are typified by composition (percentage of concrete, masonry, glass, etc.) rather than by geographical origin or construction type. It is shown that, after typifying the FRA and assuming, as per design, the acceptable percentage losses (relative to a reference concrete) of mechanical, durability-related and long-term physical properties, if the maximum incorporation ratios proposed of each type of FRA are used, the variation of properties remains within the limits established. Full article

(This article belongs to the Special Issue Recycled Concrete with Waste and By-Products)

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14 pages, 5035 KiB

Open AccessArticle

Sulfate Resistance in Cements Bearing Ornamental Granite Industry Sludge

by Gabriel Medina, Isabel F. Sáez del Bosque, Moisés Frías, María Isabel Sánchez de Rojas and César Medina

Materials 2020, 13(18), 4081; https://doi.org/10.3390/ma13184081 - 14 Sep 2020

Cited by 6 | Viewed by 2491

Abstract

This study explores the effect on sulfate resistance of the use of ornamental granite industry waste as a supplementary cementitious material (at replacement ratios of 10% and 20%) in cement manufacture. The present paucity of scientific knowledge of the behaviour of these new [...] Read more.

This study explores the effect on sulfate resistance of the use of ornamental granite industry waste as a supplementary cementitious material (at replacement ratios of 10% and 20%) in cement manufacture. The present paucity of scientific knowledge of the behaviour of these new cements when exposed to an external source of sulfates justifies the need for, and the originality of, this research. After characterising the waste chemically and mineralogically, cement paste specimens were prepared in order to determine the durability of the newly designed eco-cements using Köch–Steinegger corrosion indices. The new hydration products, which might induce microstructural, mineralogical, or morphological decay in the specimens, were also analysed by comparing the samples before and after soaking in a sodium sulfate solution for different test periods. Respect to the results, the damage to pastes bearing 10% granite sludge (GS) is the same as observed in OPC, whilst the former exhibit a higher Köch-Steinegger corrosion rate (1.61) than both OPC and OPC+20GS. Soaking the pastes in sodium sulfate induces matrix densification due to ettringite formation and gypsum precipitation in the pores. Further to those results, at an optimal replacement ratio of 10%, these alternative, eco-friendlier materials can be used in the design and construction of non-structural cement-based (mortar or concrete) members exposed to an external source of sulfate. Full article

(This article belongs to the Special Issue Recycled Concrete with Waste and By-Products)

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12 pages, 5376 KiB

Open AccessArticle

Comparative Research on Tensile Properties of Cement–Emulsified Asphalt–Standard Sand (CAS) Mortar and Cement–Emulsified Asphalt–Rubber Particle (CAR) Mortar

by Chaoyuan Li, Zanqun Liu, Juan Chen and Qiang Yuan

Materials 2020, 13(18), 4042; https://doi.org/10.3390/ma13184042 - 11 Sep 2020

Cited by 5 | Viewed by 2098

Abstract

The paper compared the tensile strength and elongation at break of cement–emulsified asphalt–standard sand (CAS) mortar and cement–emulsified asphalt–rubber particle (CAR) mortar. The tensile properties of CAS and CAR mortars were investigated. Microscopic analysis was carried out by Environmental Scanning Electron Microscopy and [...] Read more.

The paper compared the tensile strength and elongation at break of cement–emulsified asphalt–standard sand (CAS) mortar and cement–emulsified asphalt–rubber particle (CAR) mortar. The tensile properties of CAS and CAR mortars were investigated. Microscopic analysis was carried out by Environmental Scanning Electron Microscopy and Energy Dispersive Spectrometer. The test results showed that the tensile strength of the CAR mortar at 7 days improved by about 9.09% higher than that of the CAS mortar, and further increased to 17.76% higher at 28 days The values of elongation at break of the CAR mortars at 3 days, 7 days, and 28 days increased by about 70% higher than those of the CAS mortars. Microscopic analysis showed that in the hardened CAS mortar, an obvious bubble accumulation layer with many pores appeared at the interfacial transition zone (ITZ). In the hardened CAR mortar, asphalt wrapped both cement hydration products and rubber particles and formed an integrated structure where a relatively dense and strong ITZ was formed as a result. This paper proves that the CAR system has superior tensile properties and has a promising future in waste rubber disposal. Full article

(This article belongs to the Special Issue Recycled Concrete with Waste and By-Products)

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13 pages, 5931 KiB

Open AccessArticle

Compressive Strength and Durability of FGD Gypsum-Based Mortars Blended with Ground Granulated Blast Furnace Slag

by Min Pang, Zhenping Sun and Huihao Huang

Materials 2020, 13(15), 3383; https://doi.org/10.3390/ma13153383 - 30 Jul 2020

Cited by 20 | Viewed by 3220

Abstract

One new flue gas desulfurization (FGD) gypsum-based binder is attempted in this article, which is made up of FGD gypsum, ground granulated blast furnace slag (GGBS) and ordinary Portland cement (OPC). Influences of raw materials, chemical activators, and curing conditions on the compressive [...] Read more.

One new flue gas desulfurization (FGD) gypsum-based binder is attempted in this article, which is made up of FGD gypsum, ground granulated blast furnace slag (GGBS) and ordinary Portland cement (OPC). Influences of raw materials, chemical activators, and curing conditions on the compressive strength of this new binder-based mortar, as well as its durability performances and microscopic characteristics, are investigated in consideration of utilizing FGD gypsum as much as possible. Results show that the compressive strength of this new binder-based mortar under normal curing conditions could increase along with GGBS dosages from three days to 90 days. The compressive strength of one selected mix proportion (FG-4550), which contains the highest dosage of FGD gypsum (45 wt.%), is much the same as those containing the highest dosage of GGBS. A better compressive strength of FG-4550 under normal curing conditions could be gained if the fineness of GGBS is improved. The activated effect of CaCl₂ on the compressive strength of FG-4550 is superior to that of Ca(OH)₂ under steam curing conditions. FG-4550 shows a good capacity for resistance to water, a low shrinkage ratio, but poor compressive strength after 30 freeze-thaw cycles. Based on the mineralogy of X-ray diffraction, the morphology of scanning electron microscopy and the pore diameter distributions of ¹H nuclear magnetic resonance, the compressive strength of this FGD gypsum-based mortar mainly depends on clusters of ettringite. Full article

(This article belongs to the Special Issue Recycled Concrete with Waste and By-Products)

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17 pages, 5245 KiB

Open AccessArticle

Effects of Plastic Waste on the Heat-Induced Spalling Performance and Mechanical Properties of High Strength Concrete

by Abrahão Bernardo Rohden, Jessica Regina Camilo, Rafaela Cristina Amaral, Estela Oliari Garcez and Mônica Regina Garcez

Materials 2020, 13(15), 3262; https://doi.org/10.3390/ma13153262 - 23 Jul 2020

Cited by 10 | Viewed by 2836

Abstract

This paper investigates a potential application of hard-to-recycle plastic waste as polymeric addition in high strength concrete, with a focus on the potential to mitigate heat-induced concrete spalling and the consequent effects on the mechanical properties. The waste corresponds to soft and hard [...] Read more.

This paper investigates a potential application of hard-to-recycle plastic waste as polymeric addition in high strength concrete, with a focus on the potential to mitigate heat-induced concrete spalling and the consequent effects on the mechanical properties. The waste corresponds to soft and hard plastic, including household polymers vastly disposed of in landfills, although technically recyclable. Mechanical and physical properties, cracking, mass loss, and the occurrence of spalling were assessed in high strength concrete samples produced with either plastic waste or polypropylene fibers after 2-h exposure to 600 °C. The analysis was supported by Scanning Electron Microscopy and X-Ray Computed Tomography images. The plastic waste is composed of different polymers with a thermal degradation between 250 to 500 °C. Polypropylene (PP) fibers and plastic waste dispersed in concrete have proved to play an essential role in mitigating heat-induced concrete spalling, contributing to the release of internal pressure after the polymer melting. The different morphology of plastic waste and polypropylene fibers leads to distinct mechanisms of action. While the vapor pressure dissipation network originated by polypropylene fibers is related to the formation of continuous channels, the plastic waste seems to cause discontinuous reservoirs and fewer damages into the concrete matrix. The incorporation of plastic waste improved heat-induced concrete spalling performance. While 6 kg/m³ of plastic increased the mechanical performance after exposure to high temperature, the incorporation of 3 kg/m³ resulted in mechanical properties comparable to the reference concrete. Full article

(This article belongs to the Special Issue Recycled Concrete with Waste and By-Products)

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16 pages, 3329 KiB

Open AccessArticle

Ilmenite Mud Waste as an Additive for Frost Resistance in Sustainable Concrete

by Filip Chyliński and Krzysztof Kuczyński

Materials 2020, 13(13), 2904; https://doi.org/10.3390/ma13132904 - 28 Jun 2020

Cited by 9 | Viewed by 2604

Abstract

Sustainable development leads to the production of building materials that are safer for the environment. One of the ways to achieve sustainability in materials is the addition of industrial wastes and by-products, especially to concrete. However, the addition of waste to concrete often [...] Read more.

Sustainable development leads to the production of building materials that are safer for the environment. One of the ways to achieve sustainability in materials is the addition of industrial wastes and by-products, especially to concrete. However, the addition of waste to concrete often decreases its durability and the scope of aggression of the environment in which the concrete is used has to be reduced. Making sustainable concrete, which is also durable in more aggressive environments, is rather difficult. This article presents the results of tests performed on concrete containing ilmenite mud waste from the production of titanium dioxide, which was exposed to frost aggression with and without de-icing salts. The results have shown that a sustainable and frost resistant concrete can be made. After 200 freeze–thaw cycles, the compressive strength of the tested concretes decreased by less than 4%. Concretes were highly resistant for scaling and after 112 freeze–thaw cycles in water with de-icing salt, the scaled mass was less than 0.02 kg/m². The air void distribution has also been analyzed. The results suited the requirements for frost resistance concrete and were similar to those obtained for a reference concrete with fly ash. The examination of the microstructure using scanning electron microscopy (SEM) has not shown any potential risks that might affect the durability of concrete. Particles of waste were thoroughly combined in the binder and some of its constituents seem to be an active part of the cement matrix. Long-term tests of shrinkage (360 days) have not shown any excessive values that would differ from the reference concrete with fly ash. The presented results have shown that sustainable concrete containing ilmenite mud waste from the production of titanium dioxide might also be resistant to frost aggression. Full article

(This article belongs to the Special Issue Recycled Concrete with Waste and By-Products)

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17 pages, 5486 KiB

Open AccessArticle

Potential of Stainless Steel Slag Waste in Manufacturing Self-Compacting Concrete

by Julia Rosales, Francisco Agrela, José Antonio Entrenas and Manuel Cabrera

Materials 2020, 13(9), 2049; https://doi.org/10.3390/ma13092049 - 28 Apr 2020

Cited by 17 | Viewed by 3649

Abstract

The volume of slags generated from the steel industry is a source of possible resources which is constantly increasing. Specifically, in the production of stainless steel, specific and singular slags with unique characteristics are obtained, which allows considering an approach aimed at their [...] Read more.

The volume of slags generated from the steel industry is a source of possible resources which is constantly increasing. Specifically, in the production of stainless steel, specific and singular slags with unique characteristics are obtained, which allows considering an approach aimed at their use in new recycling ways. This work shows the feasibility of using stainless steel slag as a substitute for limestone filler in the manufacture of self-compacting concrete. The influence of different treatments applied to slags on physical and chemical properties was studied. On the other hand, the mechanical behaviour, as well as the durability acquired in self-compacting concrete, has been analysed. Very encouraging results were obtained, since this research demonstrates the possible application of this stainless steel slag as a construction material, improving sustainability and promoting circular economy processes, which are achieved through the minimisation of the waste disposal and accumulation. Full article

(This article belongs to the Special Issue Recycled Concrete with Waste and By-Products)

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20 pages, 3813 KiB

Open AccessArticle

Use of Slag from the Combustion of Solid Municipal Waste as A Partial Replacement of Cement in Mortar and Concrete

by Monika Czop and Beata Łaźniewska-Piekarczyk

Materials 2020, 13(7), 1593; https://doi.org/10.3390/ma13071593 - 31 Mar 2020

Cited by 26 | Viewed by 3812

Abstract

In Europe, the use of wastes in the cement and construction industry follows the assumptions of sustainability and the idea of circular economy. At present, it is observed that cement plants introduce wastes to the cement in the form of so-called mineral additives. [...] Read more.

In Europe, the use of wastes in the cement and construction industry follows the assumptions of sustainability and the idea of circular economy. At present, it is observed that cement plants introduce wastes to the cement in the form of so-called mineral additives. The most often used mineral additives are: fly ash with silica fume, granulated blast furnace slag and silica fume. The use of mineral additives in the cement is related to the fact that the use of the most expensive component of cement—Portland cement clinker—is limited. The purpose of the article is a preliminary evaluation of the suitability of slag from the municipal solid waste incineration plant for its use as a replacement of cement. In this article, slag from the municipal solid waste incineration (MSWI) replaces cement in the quantity of 30%, and presents the content of oxides and elements of slag from the MSWI. The obtained results are compared to the requirements that the crushed and granulated blast furnace slag need to meet to be suitable for use as an additive of type II to the concrete. The conducted analyses confirmed that the tested slag meets the requirements for the granulated blast furnace slag as an additive to the concrete in the following parameters: CaO ≤ 18.0%, SO3 ≤ 2.5% and Cl ≤ 0.1%. At the same time, mechanical features were tested of the designed mortars which consisted of a mixture of Portland cement (CEM I) with 30% of slag admixture. The designed mortar after 28 days of maturing reached a compressive strength of 32.0 MPa, and bending strength of 4.0 MPa. When compared to the milled granulated blast furnace slag (GBFS), the obtained values are slightly lower. Furthermore, the hardened mortars were subject to a leachability test to check the impact on the environment. Test results showed that the aqueous extracts from mixtures with 30% of slag admixtures slightly exceed the limits and do not pose a sufficiant threat to the environment as to eliminate the MSWI slag from economical use. Full article

(This article belongs to the Special Issue Recycled Concrete with Waste and By-Products)

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31 pages, 11243 KiB

Open AccessArticle

Low-Carbon Concrete Based on Binary Biomass Ash–Silica Fume Binder to Produce Eco-Friendly Paving Blocks

by André Henrique Campos Teixeira, Paulo Roberto Ribeiro Soares Junior, Thiago Henrique Silva, Richard Rodrigues Barreto and Augusto Cesar da Silva Bezerra

Materials 2020, 13(7), 1534; https://doi.org/10.3390/ma13071534 - 27 Mar 2020

Cited by 19 | Viewed by 5698

Abstract

The civil construction industry consumes huge amounts of raw materials and energy, especially infrastructure. Thus, the use of eco-friendly materials is indispensable to promote sustainable development. In this context, the present work investigated low-carbon concrete to produce eco-friendly paving blocks. The binder was [...] Read more.

The civil construction industry consumes huge amounts of raw materials and energy, especially infrastructure. Thus, the use of eco-friendly materials is indispensable to promote sustainable development. In this context, the present work investigated low-carbon concrete to produce eco-friendly paving blocks. The binder was defined according to two approaches. In the first, a binary binder developed with eucalyptus biomass ash (EBA) and silica fume (SF) was used, in total replacement for Portland cement. In the second, the mixture of residues was used as a precursor in alkali-activation reactions, forming alkali-activated binder. The experimental approach was carried out using five different mixtures, obtained by varying the amount of water or sodium hydroxide solution. The characterization of this new material was carried out using compressive strength, expandability, water absorption, deep abrasion, microstructural investigation, and organic matter degradation potential. The results showed that the EBA-SF system has a performance compatible with Portland cement when used as an alternative binder, in addition to functioning as a precursor to alkali-activated concrete. The blocks produced degraded organic matter, and this degradation is more intense with the incidence of UV. In this way, the EBA-SF binder can be successfully used for the manufacture of ecological paving blocks with low carbon emissions. Full article

(This article belongs to the Special Issue Recycled Concrete with Waste and By-Products)

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20 pages, 8773 KiB

Open AccessArticle

Feasibility of Utilizing Recycled Aggregate Concrete for Revetment Construction of the Lower Yellow River

by Pan Feng, Honglei Chang, Guodong Xu, Qiaoling Liu, Zuquan Jin and Jian Liu

Materials 2019, 12(24), 4237; https://doi.org/10.3390/ma12244237 - 17 Dec 2019

Cited by 13 | Viewed by 2805

Abstract

To explore the feasibility of utilizing recycled aggregate concrete (RAC) in revetment construction of the lower Yellow River, a series of mix proportions with local recycled aggregates (RA) were designed to evaluate its mechanical properties and durability. The morphology and micro-hardness of the [...] Read more.

To explore the feasibility of utilizing recycled aggregate concrete (RAC) in revetment construction of the lower Yellow River, a series of mix proportions with local recycled aggregates (RA) were designed to evaluate its mechanical properties and durability. The morphology and micro-hardness of the interface transition zone (ITZ) were also characterized to explain the performance of RAC. Based on the compressive strength data of 13 groups of mixtures, which is larger than 30 MPa, and with the RA substitution rate not less than 50%, the RAC containing 50% recycled fine aggregate (RFA) (HDX50), 70% RFA (HDX70), and 50% recycled coarse aggregate (RCA) (HDC50) were selected. The experiment results suggest that the mechanical performance, frost resistance, and carbonation resistance of the selected RAC is generally poorer than that of natural aggregate concrete (NAC), but can meet the performance requirement of concrete for the revetment construction of the lower Yellow River. The comprehensive performance of these three mixtures ranks as: HDX50 > HDX70 > HDC50. When considering the RA substitution ratio as a priority, HDX70 would be the best choice and can be applied in the revetment engineering. A number of defects are observed on the surface of RA with old pastes attached. Furthermore, the ITZs formed around RA are loose and with low micro-hardness, which is deemed to be the dominating reasons leading to the weaker performance of RAC than that of NAC. Full article

(This article belongs to the Special Issue Recycled Concrete with Waste and By-Products)

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29 pages, 19380 KiB

Open AccessArticle

Discrete Element Mesoscale Modeling of Recycled Lump Concrete under Axial Compression

by Yong Yu and Bo Wu

Materials 2019, 12(19), 3140; https://doi.org/10.3390/ma12193140 - 26 Sep 2019

Cited by 11 | Viewed by 3217

Abstract

In the past decade, directly reusing large pieces of coarsely crushed concrete (referred to as demolished concrete lumps or DCLs) with fresh concrete in new construction was demonstrated as an efficient technique for the recycling of waste concrete. Previous studies investigated the mechanical [...] Read more.

In the past decade, directly reusing large pieces of coarsely crushed concrete (referred to as demolished concrete lumps or DCLs) with fresh concrete in new construction was demonstrated as an efficient technique for the recycling of waste concrete. Previous studies investigated the mechanical properties of recycled lump concrete (RLC) containing different sizes of DCLs; however, for actual application of this kind of concrete, little information is known about the influence of the spatial locations of DCLs and coarse aggregates on the concrete strength. Moreover, the mechanical responses of such a concrete containing various shapes of DCLs are also not well illustrated. To add knowledge related to these topics, two-dimensional mesoscale simulations of RLC containing DCLs under axial compression were performed using the discrete element method. The main variables of interest were the relative strength of the new and old concrete, the distribution of the lumps and other coarse aggregates, and the shape of the lumps. In addition, the differences in compression behavior between RLC and recycled aggregate concrete were also predicted. The numerical results indicate that the influence tendency of the spatial locations of DCLs and coarse aggregate pieces on the compressive stress–strain curves for RLC is similar to that of the locations of coarse aggregates for ordinary concrete. The strength variability of RLC is generally higher than that of ordinary concrete, regardless of the relative strength of the new and old concrete included; however, variability has no monotonic trend with an increase in the lump replacement ratio. The mechanical properties of RLC in compression are little influenced by the geometric shape of DCLs as long as the ratio of the length of their long axis to short axis is smaller than 2.0. The compressive strength and elastic modulus of RLC are always superior to those of recycled aggregate concrete designed with a conventional mixing method. Full article

(This article belongs to the Special Issue Recycled Concrete with Waste and By-Products)

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24 pages, 2528 KiB

Open AccessArticle

Performance of Foundry Sand Concrete under Ambient and Elevated Temperatures

by Hazrat Bilal, Muhammad Yaqub, Sardar Kashif Ur Rehman, Muhammad Abid, Rayed Alyousef, Hisham Alabduljabbar and Fahid Aslam

Materials 2019, 12(16), 2645; https://doi.org/10.3390/ma12162645 - 20 Aug 2019

Cited by 37 | Viewed by 3838

Abstract

Waste foundry sand (WFS) is the by-product of the foundry industry. Utilizing it in the construction industry will protect the environment and its natural resources, and enable sustainable construction. WFS was employed in this research as a fractional substitution of natural sand by [...] Read more.

Waste foundry sand (WFS) is the by-product of the foundry industry. Utilizing it in the construction industry will protect the environment and its natural resources, and enable sustainable construction. WFS was employed in this research as a fractional substitution of natural sand by 0%, 10%, 20%, 30%, and 40% in concrete. Several tests, including workability, compressive strength (CS), splitting tensile strength (STS), and flexural strength (FS), ultrasonic pulse velocity (USPV), Schmidt rebound hammer number (RHN), and residual compressive strengths (RCS) tests were performed to understand the behavior of concrete before and after exposure to elevated temperatures. Test findings showed that the strength characteristics were increased by including WFS at all the phases. For a substitute rate of 30%, the maximum compressive, splitting tensile, and flexural strength were observed. Replacement with WFS enhanced the 28-day compressive, splitting tensile, and flexural strength by 7.82%, 9.87%, and 10.35%, respectively at a 30% replacement level, and showed continuous improvement until the age of 91 days. The RCS of foundry sand concrete after one month of air cooling at ambient temperature after exposing to 300 °C, 400 °C, 500 °C, 600 °C, 700 °C, and 800 °C was found to be in the range of 67.50% to 71.00%, 57.50% to 61.50%, 49.00% to 51.50%, 38% to 41%, 31% to 35% and 26% to 31.5% of unheated compressive strength values for 0% to 40% replacement of WFS, respectively. The RCS decreases with increasing temperature; however, with increasing WFS, the RCS was enhanced in comparison to the control samples. In addition, the replacement of 30% yielded excellent outcomes. Hence, this study provides a sustainable construction material that will preserve the Earth’s natural resources and provide a best use of WFS. Full article

(This article belongs to the Special Issue Recycled Concrete with Waste and By-Products)

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Review

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27 pages, 6193 KiB

Open AccessReview

Green and Durable Lightweight Aggregate Concrete: The Role of Waste and Recycled Materials

by Jiyu Wang, Kai Zheng, Na Cui, Xin Cheng, Kai Ren, Pengkun Hou, Lichao Feng, Zonghui Zhou and Ning Xie

Materials 2020, 13(13), 3041; https://doi.org/10.3390/ma13133041 - 7 Jul 2020

Cited by 23 | Viewed by 5442

Abstract

Lightweight aggregate concrete manufactured by solid waste or recycled by-products is a burgeoning topic in construction and building materials. It has significant merits in mitigating the negative impact on the environment during the manufacturing of Portland cement and reduces the consumption of natural [...] Read more.

Lightweight aggregate concrete manufactured by solid waste or recycled by-products is a burgeoning topic in construction and building materials. It has significant merits in mitigating the negative impact on the environment during the manufacturing of Portland cement and reduces the consumption of natural resources. In this review article, the agricultural and industrial wastes and by-products, which were used as cementitious materials and artificial lightweight aggregate concrete, are summarized. Besides, the mechanical properties, durability, and a few advanced microstructure characterization methods were reviewed as well. This review also provides a look to the future research trends that may help address the challenges or further enhance the environmental benefits of lightweight aggregate concrete manufactured with solid waste and recycled by-products. Full article

(This article belongs to the Special Issue Recycled Concrete with Waste and By-Products)

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