Research

Open AccessArticle

Cracking in Reinforced Concrete Cross-Sections Due to Non-Uniformly Distributed Corrosion

by

Magdalena German

and

Jerzy Pamin

Materials 2023, 16(18), 6331; https://doi.org/10.3390/ma16186331 - 21 Sep 2023

Viewed by 221

Abstract

Corrosion affecting reinforced concrete (RC) structures generates safety and economical problems. This paper is focused on the simulation of corrosion-induced fractures in concrete, whereby non-uniform corrosion growth is taken into account. In particular, the volumetric expansion of rust accumulated around reinforcement bars causes [...] Read more.

Corrosion affecting reinforced concrete (RC) structures generates safety and economical problems. This paper is focused on the simulation of corrosion-induced fractures in concrete, whereby non-uniform corrosion growth is taken into account. In particular, the volumetric expansion of rust accumulated around reinforcement bars causes cracking of the surrounding concrete. This phenomenon is simulated using the finite element (FE) method. In the analyses, concrete is described as a fracturing material by using a damage–plasticity model, steel is assumed to be elastic–plastic and rust is modeled as an interface between concrete and steel. The behavior of corrosion products is simulated as interface opening. Two-dimensional FE models of RC cross-sections with 2, 4 or 6 reinforcing bars are considered. Crack formation and propagation is examined. Moreover, interactions between cracks and patterns of possible failure are predicted. The most developed and complex crack pattern occurs around the side reinforcing bar. Conclusions concerning the comparison of results for uniform and non-uniform corrosion distribution as well as the prediction of concrete spalling are formulated. Full article

(This article belongs to the Special Issue Alternative, Traditional and Waste Materials Used in the Construction Industry: Research, Modeling and Design)

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Open AccessArticle

Cracking Behavior and Deflections in Recycled-Aggregate Beams Reinforced with Waste Fibers Subjected to Long-Term Constant Loading

by

Mateusz Zakrzewski

and

Jacek Domski

Materials 2023, 16(10), 3622; https://doi.org/10.3390/ma16103622 - 09 May 2023

Cited by 1 | Viewed by 823

Abstract

This report presents the results of long-term tests on concrete beams reinforced with steel cord. In this study, natural aggregate was wholly replaced with waste sand or with wastes from the production of ceramic products and ceramic hollow bricks. The amounts of individual [...] Read more.

This report presents the results of long-term tests on concrete beams reinforced with steel cord. In this study, natural aggregate was wholly replaced with waste sand or with wastes from the production of ceramic products and ceramic hollow bricks. The amounts of individual fractions used were determined in accordance with guidelines for reference concrete. A total of eight mixtures were tested; these differed in terms of the type of waste aggregate used. Elements with various fiber-reinforcement ratios were made for each mixture. Steel fibers and waste fibers were used in amounts of 0.0%, 0.5%, and 1.0%. Compressive strength and modulus of elasticity were determined experimentally for each mixture. The main test was a four-point beam bending test. Beams with dimensions of 100 mm × 200 mm × 2900 mm were tested on a stand, which was specially prepared so that three beams could be tested simultaneously. Fiber-reinforcement ratios were 0.5% and 1.0%. Long-term studies were conducted for 1000 days. During the testing period, beam deflections and cracks were measured. The obtained results were compared with values calculated using several methods, considering the influence of dispersed reinforcement. The results enabled the best methods for calculating individual values for mixtures with different types of waste materials to be determined. Full article

(This article belongs to the Special Issue Alternative, Traditional and Waste Materials Used in the Construction Industry: Research, Modeling and Design)

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Open AccessArticle

Modifying Water–Frost Resistance and Mechanical Properties of Lime Mortar Using Siliceous and Fluidised Bed Fly Combusted Ashes Activated with Cement

by

Dominik Logoń

,

Janusz Kobaka

and

Jacek Domski

Materials 2023, 16(8), 3013; https://doi.org/10.3390/ma16083013 - 11 Apr 2023

Cited by 1 | Viewed by 830

Abstract

The research focuses on pozzolanic additives, which are compatible with traditional lime mortars, and enable the modification of the rheological, physical and mechanical properties of tested composites. It was noted that lime mortars with fluidised bed fly ash require sand without impurities to [...] Read more.

The research focuses on pozzolanic additives, which are compatible with traditional lime mortars, and enable the modification of the rheological, physical and mechanical properties of tested composites. It was noted that lime mortars with fluidised bed fly ash require sand without impurities to avoid possible ettringite crystallisation. The work presents siliceous fly ash and fluidised bed combustion fly ash to modify the frost resistance and mechanical properties of traditional lime mortars with and without the addition of cement. The results show better effects using fluidised bed ash. Traditional Portland cement CEM I 42.5R was used to activate ash and increase the results. The possibility of a significant improvement of properties is indicated with a hybrid addition to the lime binder of 15–30% ash (siliceous or fluidised bed ash) and 15–30% cement. Changing the class and type of cement provides an additional opportunity to alter the properties of the composites. For architectural reasons relating to colour, the suitability of lighter fluidised bed ash instead of darker siliceous ash and of white Portland cement instead of the traditional grey cement can be used. The proposed mortars can be the basis for future modifications with admixtures and additives, e.g., metakaolin, polymers, fibres, slag, glass powder and impregnating agents. Full article

(This article belongs to the Special Issue Alternative, Traditional and Waste Materials Used in the Construction Industry: Research, Modeling and Design)

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Open AccessArticle

Comparative Analysis of Waste, Steel, and Polypropylene Microfibers as an Additive for Cement Mortar

by

Mateusz Zakrzewski

,

Mateusz Gancarz

,

Katarína Tvrdá

,

Joanna Laskowska-Bury

and

Jacek Domski

Materials 2023, 16(4), 1625; https://doi.org/10.3390/ma16041625 - 15 Feb 2023

Cited by 2 | Viewed by 779

Abstract

This study presents the results of laboratory experiments conducted to determine the mechanical parameters for cement mortar with various quantities of waste fibers, polypropylene microfibers, and steel microfibers. Waste fibers were used as samples and obtained using an end-of-life car tire recycling process. [...] Read more.

This study presents the results of laboratory experiments conducted to determine the mechanical parameters for cement mortar with various quantities of waste fibers, polypropylene microfibers, and steel microfibers. Waste fibers were used as samples and obtained using an end-of-life car tire recycling process. For comparison, samples with the addition of steel and polypropylene microfibers were tested. The same degrees of fiber reinforcement were used for all types of fibers. Ultimately, 22 mixtures of cement mortar were prepared. The aim of this study is therefore to present and compare basic mechanical parameter values. Compressive strength, flexural strength, fracture toughness, and flexural toughness were of particular interest. A three-point bending test was performed on three types of samples, without a notch and with a notch of 4 and 8 mm. The results show that the use of steel microfibers in the cement mortar produces a product with better properties compared to a mixture with steel cord or polypropylene fibers. However, the cement mortar with the steel cord provides better flexural strength and greater flexural toughness factors compared to the cement mortar with polypropylene fibers. This means that the steel cord is a full-value ecological replacement for different fibers. Full article

(This article belongs to the Special Issue Alternative, Traditional and Waste Materials Used in the Construction Industry: Research, Modeling and Design)

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Open AccessArticle

Effect of Chemical Admixtures on Mechanical and Degradation Properties of Metallurgical Sludge Waste Concrete

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Materials 2022, 15(23), 8287; https://doi.org/10.3390/ma15238287 - 22 Nov 2022

Viewed by 777

Abstract

This study extends the development of concretes with metallurgical sludge waste (MSW) by determining the effect of superplasticizers and air entrainment admixture (AEA). The MSW is a very fine powdery material, and in this case, it was used as a partial replacement of [...] Read more.

This study extends the development of concretes with metallurgical sludge waste (MSW) by determining the effect of superplasticizers and air entrainment admixture (AEA). The MSW is a very fine powdery material, and in this case, it was used as a partial replacement of fine aggregate in the mixture. The reference ordinary concrete mixtures without MSW were created for evaluation. The results of concrete density, compressive strength, electrical resistivity, and rapid chloride permeability were obtained and some of them were measured continuously to determine the influence of the chemical admixtures on these characteristics over time. It was found that in general, the MSW substitution slightly lowers the mechanical and durability parameters, but MSW in combination with the chemical admixtures improves the compressive strength in comparison to the reference concrete with the addition of AEA. Full article

(This article belongs to the Special Issue Alternative, Traditional and Waste Materials Used in the Construction Industry: Research, Modeling and Design)

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Open AccessArticle

The Use of Marble Dust, Bagasse Ash, and Paddy Straw to Improve the Water Absorption and Linear Shrinkage of Unfired Soil Block for Structure Applications

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Materials 2022, 15(21), 7786; https://doi.org/10.3390/ma15217786 - 04 Nov 2022

Cited by 1 | Viewed by 1084

Abstract

Unfired admixed soil blocks are made up of soil plus stabilizers such as binders, fibers, or a combination of both. Soil is abundant on Earth, and it has been used to provide shelter to millions of people. The manufacturing and usage of cement [...] Read more.

Unfired admixed soil blocks are made up of soil plus stabilizers such as binders, fibers, or a combination of both. Soil is abundant on Earth, and it has been used to provide shelter to millions of people. The manufacturing and usage of cement and cement blocks raise several environmental and economic challenges. Due to disposal issues, agricultural and industrial waste is currently the biggest hazard to the environment and humanity in the world. Consequently, environmental degradation brought on by agricultural waste harms the ecology. As a result, researchers are attempting to develop an alternative to cement blocks, and various tests on unfired admixed soil blocks have been done. This investigation uses agricultural waste (i.e., paddy straw fiber and sugarcane bagasse ash) and industrial waste (i.e., marble dust) in manufacturing unfired admixed soil blocks. Under this investigation, the applicability of unfired soil blocks admixed with marble dust, paddy straw fiber, and bagasse ash was studied. The marble dust level ranged from 25% to 35%, bagasse ash content ranged from 7.5% to 12.5%, and the content of paddy straw fiber ranged from 0.8% to 1.2% by soil dry weight. Various tests were conducted on the 81 mix designs of the prepared unfired admixed soil blocks to find out the physical properties of the block followed by modeling and optimization. The findings demonstrate that the suggested method is a superior alternative to burned bricks for improving the physical properties of admixed soil blocks without firing. Full article

(This article belongs to the Special Issue Alternative, Traditional and Waste Materials Used in the Construction Industry: Research, Modeling and Design)

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Open AccessArticle

Proposition for Determining the Residual Strength of Fiber-Reinforced Cement Composite

by

Wiesława Głodkowska

and

Joanna Laskowska-Bury

Materials 2022, 15(21), 7546; https://doi.org/10.3390/ma15217546 - 27 Oct 2022

Viewed by 662

Abstract

Designing bending elements made of fiber composites requires knowledge of the residual strengths. Residual strengths determined according to PN-EN 14651, regardless of the type of matrix and the fibers used, are characterized by a very-high coefficient of variation, about 30%. The variability of [...] Read more.

Designing bending elements made of fiber composites requires knowledge of the residual strengths. Residual strengths determined according to PN-EN 14651, regardless of the type of matrix and the fibers used, are characterized by a very-high coefficient of variation, about 30%. The variability of this feature is so large that the normal distribution adopted in statistical analyses, which is consistent for compressive strength or tensile strength, may, in the case of residual strengths, result in a significant overdesign of the elements. Therefore, the article proposes a novel method of determining the residual strength with the use of centrally bent square plates simply supported at the perimeter. The coefficient of variation of this characteristic in the case of plate testing is about 8%. Full article

(This article belongs to the Special Issue Alternative, Traditional and Waste Materials Used in the Construction Industry: Research, Modeling and Design)

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Open AccessArticle

Non-Destructive Methods and Numerical Analysis Used for Monitoring and Analysis of Fibre Concrete Deformations

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Materials 2022, 15(20), 7268; https://doi.org/10.3390/ma15207268 - 18 Oct 2022

Cited by 3 | Viewed by 862

Abstract

The aim of the research was to check the possibility of using the non-destructive method of acoustic emission to assess the condition of concrete without dispersed reinforcement and with various additions of curved steel fibres, during three-point bending. An important aspect of the [...] Read more.

The aim of the research was to check the possibility of using the non-destructive method of acoustic emission to assess the condition of concrete without dispersed reinforcement and with various additions of curved steel fibres, during three-point bending. An important aspect of the research proposed in the article is the use of a hybrid method of analysis, which involves complementing the results of strength tests, the results of numerical calculations and the results of strain distributions recorded with a digital image correlation system (DIC System, in this research GOM Suite optical system). The operation of the concrete material under load, depending on the amount of fibres added, is reflected in the recorded acoustic emission (AE) signals. The differences concern the number of signals of individual classes and their distribution over time. The differences exist for both low and high load values, which confirms the possibility of using the acoustic emission method to monitor the condition of the material. It was shown that the numerically determined effective stress levels decreased as the proportion of steel fibres in the concrete increased, while the maximum levels of the first principal stresses increased. During the analyses, a preliminary comparison of the deformation results obtained using the finite element method and the DIC System was also carried out. Full article

(This article belongs to the Special Issue Alternative, Traditional and Waste Materials Used in the Construction Industry: Research, Modeling and Design)

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Open AccessArticle

Numerical Analysis of Experimental Research in a Lightweight Floor System (LFS) with Heat Diffuser

by

Karpiesiuk Jacek

and

Tadeusz Chyży

Materials 2022, 15(18), 6466; https://doi.org/10.3390/ma15186466 - 17 Sep 2022

Viewed by 927

Abstract

The article presents the results of research on a lightweight floor system (LFS) with a heat diffuser made of metal lamellae. It differs from traditional layered floors in the absence of a screed layer, which reduces thermal inertia and predisposes it to be [...] Read more.

The article presents the results of research on a lightweight floor system (LFS) with a heat diffuser made of metal lamellae. It differs from traditional layered floors in the absence of a screed layer, which reduces thermal inertia and predisposes it to be used with renewable energy sources. As part of the research, a real model of the floor, consisting of nine ceramic tiles, was made. Polyurethane adhesive was used to connect the individual layers of this composite. The model was subjected to a thermal action. It was constructed with the measuring equipment consisting of strain gauges. These were located at the boundaries of the composite layers and measured the material’s deformation. The measurement results were verified by numerical calculations. For this purpose, a computational model was made using FEM (finite element method). Comparable results of deformations were obtained (the differences did not exceed 6.1%), which made it possible to perform numerical calculations of light floor materials stresses. Additionally, the displacement of the tested model was measured and numerically verified. The results of these verifications can be useful not only in the heated/cooled LFS with aluminium lamellae, but also in other building partitions inside and outside the building. Full article

(This article belongs to the Special Issue Alternative, Traditional and Waste Materials Used in the Construction Industry: Research, Modeling and Design)

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Open AccessArticle

Axial Compressive Properties of Self-Compacting Concrete Filled Steel Tube Short Columns with Ground Desulfurization Slag

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Materials 2022, 15(18), 6306; https://doi.org/10.3390/ma15186306 - 11 Sep 2022

Cited by 1 | Viewed by 678

Abstract

Desulfurization slag (DS) is the solid waste discharged from the bottom of the circulating fluidized bed (CFB) boiler. It has good pozzolanic activity, self-hardening property and large expansibility. In this paper, ground desulfurization slag (GDS) is used as mineral admixture to replace cement [...] Read more.

Desulfurization slag (DS) is the solid waste discharged from the bottom of the circulating fluidized bed (CFB) boiler. It has good pozzolanic activity, self-hardening property and large expansibility. In this paper, ground desulfurization slag (GDS) is used as mineral admixture to replace cement to prepare self-compacting concrete (SCC). In order to find out the influence laws of different factors on the axial compressive properties of the self-compacting concrete filled steel tube (CFST), seven types of SCC are prepared and nine groups of CFST short column are fabricated. Filling ability test, compressive strength test and axial compressive test are performed. The filling ability and the compressive strength of the SCCs are investigated, and the axial compressive properties of the CFSTs are researched. The results show that the amount of polycarboxylate superplasticizer (PS) increases with the amount of GDS, and the addition of GDS decreases the 3d, 7d and 28d compressive strength of the SCCs. The optimum amount of GDS for SCCs and CFSTs is 30%. When the amount of GDS is 30%, the ultimate bearing capacity of CFST short column (GP3) is the highest, which is 33.6% higher than that of GP1 without GDS. The influence law of the GDS’s amount on the CFSTs’ ultimate bearing capacity is quite different from that of the GDS’s amount on the SCCs’ compressive strength. The ultimate bearing capacity of CFSTs can be significantly improved by adding GDS. Sodium sulfate can improve both the compressive strength of the SCC and the bearing capacity of the CFST. Full article

(This article belongs to the Special Issue Alternative, Traditional and Waste Materials Used in the Construction Industry: Research, Modeling and Design)

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Open AccessArticle

Analysis of the Significance of Changes in the Number and Energy Parameters of Acoustic Emission Signals on the Assessment of the Strength of Fibre–Cement Boards

by

Anna Adamczak-Bugno

,

Grzegorz Świt

,

Aleksandra Krampikowska

and

Edoardo Proverbio

Materials 2022, 15(16), 5757; https://doi.org/10.3390/ma15165757 - 20 Aug 2022

Cited by 2 | Viewed by 813

Abstract

The article presents the results of three-point bending tests carried out for samples cut from full-size fibre–cement boards subjected to typical and exceptional conditions. The tests were carried out with the simultaneous acquisition of acoustic emission signals. It has been noted that some [...] Read more.

The article presents the results of three-point bending tests carried out for samples cut from full-size fibre–cement boards subjected to typical and exceptional conditions. The tests were carried out with the simultaneous acquisition of acoustic emission signals. It has been noted that some factors significantly deteriorate the strength parameters of the samples as well as cause the occurrence of differences in the number of acoustic emission signals of various classes and their energy parameters. A statistical analysis was carried out in order to repeat the relationship between the strength parameters of the samples and the acoustic emission parameters. Based on the research, it was found that the MOR bending strength for specimens exposed to fire and high temperature is more than 50% lower than for air-dried specimens and specimens exposed to water. The increased number of freeze–thaw cycles also has an impact on the strength of the specimens. Components exposed to more than 10 freeze–thaw cycles had a strength more than 30% smaller than the reference specimens soaked in water and exposed to bath-drying cycles. A similar dependency was indicated by the number of signals of the individual classes, their energy parameters and their frequencies. The number, strength, duration and frequency also decreased along with the increase in the test case number. On this basis, conclusions were drawn concerning the suitability of acoustic emission for the evaluation of the strength of fibre–cement elements. Full article

(This article belongs to the Special Issue Alternative, Traditional and Waste Materials Used in the Construction Industry: Research, Modeling and Design)

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Open AccessArticle

Use of Fluidized Bed Combustion Fly Ash as a Partial Substitute for Cement in Underwater Concrete Mixes

by

Elżbieta Horszczaruk

and

Cyprian Seul

Materials 2022, 15(14), 4809; https://doi.org/10.3390/ma15144809 - 10 Jul 2022

Cited by 1 | Viewed by 821

Abstract

Despite limitations to coal combustion energy production, many countries face the still-unresolved problem of utilising the wastes from fluidised bed coal combustion. One direction of rational utilisation can be using these wastes in the building materials industry. The study aimed to analyse the [...] Read more.

Despite limitations to coal combustion energy production, many countries face the still-unresolved problem of utilising the wastes from fluidised bed coal combustion. One direction of rational utilisation can be using these wastes in the building materials industry. The study aimed to analyse the possibility of using fluidised bed combustion fly ashes as a partial substitute for cement in the underwater concrete (UWC). Two groups of concrete mixes were tested, containing 20 to 50% of fluidised bed combustion fly ashes. Investigations of the rheological properties of the concrete mixes and the mechanical performance of the hardened concrete confirmed the possibility of replacing cement in UWC with fluidised bed combustion fly ash up to 30% of the cement mass. The higher content of the fly ashes significantly worsens the UWC strength as well as the consistency and wash-out loss of the concrete mixes, excluding its use in underwater concreting. Full article

(This article belongs to the Special Issue Alternative, Traditional and Waste Materials Used in the Construction Industry: Research, Modeling and Design)

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Open AccessArticle

Assessment of Limestone Waste Addition for Fired Clay Bricks

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Traian Florin Marinca

Materials 2022, 15(12), 4263; https://doi.org/10.3390/ma15124263 - 16 Jun 2022

Cited by 4 | Viewed by 1220

Abstract

Our aim was to investigate the feasibility of using limestone waste resulting from stone processing for the manufacturing of fired clay bricks. Waste materials were considered as a partial replacement for clays to reduce the exploitation of natural resources and as a response [...] Read more.

Our aim was to investigate the feasibility of using limestone waste resulting from stone processing for the manufacturing of fired clay bricks. Waste materials were considered as a partial replacement for clays to reduce the exploitation of natural resources and as a response to the climate neutrality commitments. The samples were prepared to have a waste content of up to 15% and were fired at a temperature of 900 °C. The chemical and mineralogical composition and the physical analysis of raw materials were investigated by using SEM–EDS and XRD diffraction. The result showed an increase in CaO in the clay mixture due to the presence of limestone, which reduced the shrinkage of the products’ compressive strength, up to 55% for samples with a higher content of limestone (15 wt.%), and influenced the samples’ color by making them lighter than the reference sample. Full article

(This article belongs to the Special Issue Alternative, Traditional and Waste Materials Used in the Construction Industry: Research, Modeling and Design)

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Open AccessArticle

Comparative Analysis of Waste Materials for Their Potential Utilization in Green Concrete Applications

by

Kaushal Kumar

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Saurav Dixit

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Rishabh Arora

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Nikolai Ivanovich Vatin

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Jarnail Singh

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Olga V. Soloveva

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Svetlana B. Ilyashenko

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Vinod John

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Dharam Buddhi

Materials 2022, 15(12), 4180; https://doi.org/10.3390/ma15124180 - 13 Jun 2022

Cited by 13 | Viewed by 1686

Abstract

The utilization of solid waste in useful product is becoming a great deal of worth for individuals, organizations, and countries themselves. The powder of waste glass and silica fumes are also considered major waste materials across the globe. In this paper, the physico-chemical, [...] Read more.

The utilization of solid waste in useful product is becoming a great deal of worth for individuals, organizations, and countries themselves. The powder of waste glass and silica fumes are also considered major waste materials across the globe. In this paper, the physico-chemical, thermal, and morphological properties of both waste powders are investigated in order to determine their suitability for use as a partial replacement for cement in basic concrete. They are suitable for use in concrete due to their pozzolanic and other basic properties. Extensive testing, in terms of the compressive strength test, the slump test, and the flexural strength test, has been carried out to study the replacement of cement in the range of 5–15% by waste glass powder for curing ages of 7 and 28 days. The FTIR analyses of both materials are studied for determining the effect of characteristics of chemical bonding and intense bands with bending vibrations of O–Si–O bonds. Experimental results indicate towards the potential utilization of wastes in concrete in terms of green concrete. Full article

(This article belongs to the Special Issue Alternative, Traditional and Waste Materials Used in the Construction Industry: Research, Modeling and Design)

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Open AccessArticle

Predicting the Mechanical Properties of RCA-Based Concrete Using Supervised Machine Learning Algorithms

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Krzysztof Adam Ostrowski

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Fahid Aslam

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Panuwat Joyklad

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Tomasz M. Majka

Materials 2022, 15(2), 647; https://doi.org/10.3390/ma15020647 - 15 Jan 2022

Cited by 36 | Viewed by 2329

Abstract

Environment-friendly concrete is gaining popularity these days because it consumes less energy and causes less damage to the environment. Rapid increases in the population and demand for construction throughout the world lead to a significant deterioration or reduction in natural resources. Meanwhile, construction [...] Read more.

Environment-friendly concrete is gaining popularity these days because it consumes less energy and causes less damage to the environment. Rapid increases in the population and demand for construction throughout the world lead to a significant deterioration or reduction in natural resources. Meanwhile, construction waste continues to grow at a high rate as older buildings are destroyed and demolished. As a result, the use of recycled materials may contribute to improving the quality of life and preventing environmental damage. Additionally, the application of recycled coarse aggregate (RCA) in concrete is essential for minimizing environmental issues. The compressive strength (CS) and splitting tensile strength (STS) of concrete containing RCA are predicted in this article using decision tree (DT) and AdaBoost machine learning (ML) techniques. A total of 344 data points with nine input variables (water, cement, fine aggregate, natural coarse aggregate, RCA, superplasticizers, water absorption of RCA and maximum size of RCA, density of RCA) were used to run the models. The data was validated using k-fold cross-validation and the coefficient correlation coefficient (R²), mean square error (MSE), mean absolute error (MAE), and root mean square error values (RMSE). However, the model’s performance was assessed using statistical checks. Additionally, sensitivity analysis was used to determine the impact of each variable on the forecasting of mechanical properties. Full article

(This article belongs to the Special Issue Alternative, Traditional and Waste Materials Used in the Construction Industry: Research, Modeling and Design)

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Open AccessArticle

Influence of Waste Glass Powder Addition on the Microstructure and Mechanical Properties of Autoclaved Building Materials

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Materials 2022, 15(2), 434; https://doi.org/10.3390/ma15020434 - 07 Jan 2022

Cited by 12 | Viewed by 1083

Abstract

Lime quartz samples in which ground quartz sand was gradually substituted with waste glass powder (GP) were obtained under hydrothermal conditions to determine the influence of GP addition on the microstructure (observed by SEM), phase composition (analyzed by XRD), and compressive strength of [...] Read more.

Lime quartz samples in which ground quartz sand was gradually substituted with waste glass powder (GP) were obtained under hydrothermal conditions to determine the influence of GP addition on the microstructure (observed by SEM), phase composition (analyzed by XRD), and compressive strength of autoclaved building materials. An additional series containing analytical grade NaOH and no GP was formed to evaluate the effect of sodium ions on tobermorite formation and its impact on the mechanical properties of the samples. GP addition hindered the formation of tobermorite during autoclaving. Instead, a higher amount of an amorphous and semi-crystalline C–S–H phase formed, leading to the densification of the composite matrix. Nevertheless, tobermorite-like structures were found during both XRD and SEM analyses, proving that the presence of small amounts of Al³⁺ ions allowed, to an extent, for the stabilization of the phase despite the high sodium content. The compressive strength values indicate that the presence of alkali in the system and the resulting formation of additional portions of C–S–H have a beneficial influence on the mechanical properties of autoclaved composites. However, the effect fades with increasing glass powder content which, together with a slight expansion of the samples, suggests that at high sand substitution levels, an alkali–silica reaction takes place. Full article

(This article belongs to the Special Issue Alternative, Traditional and Waste Materials Used in the Construction Industry: Research, Modeling and Design)

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