Concrete Production Research Articles

Matrizes cimentícias com o uso de resíduos de construção e demolição para redução do impacto ambiental de blocos de pavimentação

The construction industry is responsible for the intensive consumption of natural resources and the generation of large volumes of construction and demolition waste (CDW), which are often disposed of improperly. This research developed concrete blocks using recycled CDW aggregates, promoting sustainability and circular economy by reusing these materials in urban infrastructure. Waste was collected from a recycling plant over five months, selecting Brita 1, Brita 0, and Pó de Brita to compose the concrete mixes. Particle size distribution, bulk density, and specific gravity tests were performed, and blocks and specimens were molded with 100% replacement of natural aggregates by CDW. The compressive strength tests were carried out at 14 and 28 days, while the abrasion test was performed only at 28 days. X-ray fluorescence (XRF) and Scanning electron microscopy (SEM) were used to characterize the products. The results indicated a compressive strength of 34.3 MPa at 28 days, close to the minimum required by the standard (35 MPa). XRF analysis showed a predominance of SiO₂, CaO, Al₂O₃, Fe₂O₃, MgO, SO₃, and K₂O oxides, all within normative limits. Leaching and solubilization tests, conducted according to NBR 10005 and NBR 10006, classified the waste as non-hazardous and non-inert. This study demonstrates that using CDW in concrete block production is a viable and sustainable alternative, contributing to waste reduction, material reuse, and the development of sustainable urban infrastructure.

Methods for restoring the mobility of a concrete mix

The relevance of the study is due to the fact that currently monolithic construction is characterized by a high rate of construction work, since in modern market conditions this indicator determines the final cost per square meter. As it is known, the life cycle of any concrete product or structure includes the preparation of a concrete mixture, transportation, laying, sealing, hardening and further operation.Therefore, the initial stage of the life cycle – the preservation of the properties of the concrete mixture over time will determine the technological and physico-mechanical properties, respectively, of the concrete mixture and concrete. An aggravating factor in maintaining the properties of the concrete mixture in the summer is the air temperature exceeding 30оC. The paper shows technological techniques that make it possible to level the temperature factor on the properties of the concrete mixture over time.It was found that the introduction of superplasticizers in the amount of 1% of the cement mass and the restoration of mobility at the construction site make it possible to obtain concretes with specified qualities. This study is relevant for manufacturers of concrete mixtures.

OTIMIZAÇÃO DE MISTURAS DE CONCRETO PARA REDUÇÃO DE CUSTOS COM USO DE POZOLANA

Concrete is the primary source for the development of civil engineering projects. In Brazil, its use reaches approximately 40 million cubic meters per year. As a result, concrete production is a central element in civil engineering, being used in a wide range of applications, from foundations to large structures. However, the costs associated with concrete production represent a significant portion of the total costs of a project. Therefore, the search for methods that can reduce these costs without compromising the quality and durability of structures is of utmost importance for the sector. The main objective of this work is to explore effective methods for optimizing concrete mixtures using additives or applying alternative materials in order to guarantee the quality of the product, with the aim of improving its physical-mechanical and economic characteristics. To achieve this goal, the following specific objectives were defined: to analyze the physical and mechanical properties of different concrete formulations, to identify the main factors that influence concrete production costs, to develop optimization models for concrete mixtures based on economic and performance criteria, and to evaluate the technical and economic feasibility of the proposed solutions in case studies. During the development of the research, comprehensive literature reviews were carried out to understand the latest trends and practices related to concrete production. In addition, laboratory experiments were conducted to analyze the physical and mechanical properties of different concrete formulations, taking into account the influence of variables such as type of aggregate and the use of pozzolan as an additive to improve concrete. Based on the data researched and the tests developed, it was possible to present pozzolan as a satisfactory additive for addition to concrete, since it reduces production costs while maintaining the essential properties of concrete, such as compressive strength, durability and workability. And because it is a more sustainable material, it reduces environmental damage.

High-Performance Concrete from Rubber and Shell Waste Materials: Experimental and Computational Analysis

Waste and its environmental impact have driven the search for sustainable solutions across various industries, including construction. This study explores the incorporation of solid waste in the production of eco-friendly structural concrete, aiming to reduce pollution and promote ecological and sustainable construction practices. In this context, two types of eco-friendly concrete were produced using marine shells and recycled rubber as waste materials and compared with conventional concrete through experimental and computational approaches. The results demonstrated that the concrete with marine shells achieved a compressive strength of 32.4 MPa, 26.5% higher than conventional concrete, and a 1% reduction in weight. In contrast, the recycled rubber concrete exhibited a compressive strength of 22.5 MPa, with a 2 MPa decrease compared to conventional concrete, but a 4.3% reduction in density. Computational analysis revealed that porosity affects Young’s modulus, directly resulting in a reduction in the maximum achievable strength. This work demonstrates that it is feasible to produce eco-friendly structural concrete through the proper integration of industrial waste, contributing to decarbonization and waste valorization.

Long-short-term memory model for quantitative analysis of corrosion products in concrete

A quantitative analysis model is proposed to describe the content evolution of corrosion products in concrete structures subjected to sulfate or chloride attack. The model is inspired by the idea of the Long-Short-Term Memory (LSTM) algorithm in the machine learning field. For establishing the relationship between engineering data and theoretical computations, the training samples of the model are generated by solving the rate equations of the sulfate corrosion reactions in concrete with wide-range initial conditions and validated by the existing experimental data. The Pearson correlation coefficient is employed to determine the model features. The model performance is comprehensively evaluated and discussed. The results show that the proposed model has enough accuracy and feasibility. It could effectively predict the contents of the corrosion products during the sulfate attack by several input values rather than the initial contents of all chemical constituents. The proposed model builds a bridge between experimental methods and theoretical predictions, adequately inheriting their advantages.

An investigation on workability and strength on compression of GPC with addition of different aspect ratio glass fibers

The heating of limestone and other materials to high temperatures to produce Ordinary Portland cement (OPC), a key component in concrete releases of carbon dioxide CO2 which makes the construction industry a notable contributor to greenhouse gas emissions. The search for more sustainable alternatives has led to the exploration of alkali-activated materials as a replacement for OPC. Alkali-activated materials are a class of binders that can be used in concrete production without the need for traditional cement. These materials often include industrial by-products such as fly ash, GGBFS (sometimes also called GGBS) (Ground Granulated Blast Furnace Slag), and other waste materials. The development and adoption of alkali-activated materials represent a promising avenue for reducing the environmental impact of the construction industry. On-going research and collaboration are crucial to addressing technical challenges and promoting the widespread use of these alternative binders. The exploration and utilization of alternative materials such as GGBFS, fly ash, and geopolymer concrete play a crucial role in mitigating the environmental impact of the construction industry, particularly in terms of reducing CO2 emissions and utilizing industrial by-products effectively. A good concrete mix is obtained from combination of different size of aggregates. Addition of fibers plays a crucial role in enhancing the tensile strength of concrete. Similar synergy of addition of different aspect ratio of optimum dosages fibers as of different size of aggregates may improve strength and ductility of concrete. Short fibres can stop the propagation of micro-cracks with enhancement of toughness, and long fibres can stop the propagation of macro-cracks. From the aforementioned perspective, it is preferable to add the same volume of fibre with a different aspect ratio to improve the pre- and post-cracking performance of concrete. It also aids in boosting maximal strength.This study aims in preparing geopolymer concrete with graded glass fibres in order to investigate improvement the strength in compression and workability.

Influence of alkali molarity on compressive strength of high-strength geopolymer concrete using machine learning techniques based on curing regimes and temperature

The compressive strength behavior of high-strength geopolymer concrete (HSGPC) has been studied in this research work with varying alkali concentration using the novel machine learning techniques. The alkali concentration in the activation solution plays a significant role in the geopolymerization process and affects the resulting compressive strength. In this research work, the range between 4 M and 16 M for alkali molarity (M), 18 kg/m3 and 160 kg/m3 for NaOH and 41 kg/m3 and 229 kg/m3 for NaSi was collected from literature and used in the various design mixes of this exercise. This was necessary because higher alkali concentrations promote a more efficient dissolution and activation of the aluminosilicate compounds, leading to increased geopolymerization and the formation of more calcium silicate hydrate (C-S-H) gel. The increased C-S-H gel content contributes to improved strength development. However, there is an optimal alkali concentration range for the sustainable production of geopolymer concrete, and exceeding this range can have a negative impact on compressive strength and ecofriendly handling of concrete. A total of fifty-three records were collected from literature and deployed in modeling the compressive strength (Fc) considering various curing regimes. Three symbolic machine learning techniques such as genetic programming (GP), evolutionary polynomial regression (EPR), and the artificial neural network (ANN) are used in this research model. The relative importance values for each input parameter were also evaluated, which indicated that all factors have significant impacts on (Fc), but Age (i.e., curing regime) has the most influence compared to FA, NaOH, and CAg then the other inputs. From the model relations between the calculated and predicted values, it can be shown that the decisive model, ANN produced line of parametric equation of y = 0.995x, and produced performance indices; MAE of 2.13 MPa, RMSE of 2.86 MPa and R-squared of 0.981, which makes the ANN the most reliable model in agreement with previous applications of the technique. These are against the poor performance of the EPR and GP, which produced R-squared less than 0.8 with higher error rates. The Taylor chart and the variance distribution, which further compares the accuracy and variances of the developed models support the outcomes. Generally, alkali molarity has shown its potential in the production of HSGPC due to its role in the reactivity phases of the concrete formulation; hydration, activation, pozzolanic, and geopolymerization reactions producing the gel needed for the strength gain in HSGPC.

Performance of Molasses Waste as a Cement Replacement to Study Concrete Compressive Strength

To reduce the negative environmental impact of cement production and preserve natural resources, an experimental investigation was conducted to study the performance of concrete specimens at different curing ages and to determine the compressive strength of these specimens by replacing cement with molasses. Experimentation was carried out on the concrete specimens at a temperature range of 25 °C to 30 °C; six specimens were cast for each replacement ratio, except for 0.75% wt. of cement (86.55 g) and 1% wt. of cement (113.6 g), where five samples were considered for each ratio. The average 28-day compressive strength of the conventional concrete specimens came out to be 29 MPa, but increased to 40 MPa with the addition of 0.25% wt. of cement molasses (28.85 g). It was observed that as the percentage of molasses waste in the concrete mix was further increased by replacing the cement, the compressive strength of the concrete specimens increased gradually and then significantly decreased. The findings shed light on the prospect of using molasses waste instead of cement in the concrete mix. Also, it is worth mentioning that about 30% of the cost–benefit was obtained with reference to that of conventional admixtures available in the market for the production of concrete. However, it is notable that a long-term durability study needs to be conducted before making it viable. This work not only addresses a sustainable and innovative method of waste management (SDG12), but also contributes to low carbon emissions (SDG13). The novelty of this work lies in the fact that no such kind of study has been conducted in Pakistan so far, in addition to the very limited international literature available, and, in particular, no evidence on the compressive strength results at higher molasses dosages, i.e., 1% wt. of cement (113.6 g) and 2% wt. of cement (230.8 g).

Achieving sustainable performance: synergistic effects of nano-silica and recycled expanded polystyrene in lightweight structural concrete

Lightweight concrete, particularly polystyrene concrete, has been extensively utilized in civil engineering for decades. The incorporation of waste expanded polystyrene (EPS) as a filler material in the production of lightweight concrete presents significant advantages from a circular economy perspective. Prior research indicates that increasing the proportion of lightweight aggregates, such as EPS, typically results in reductions in strength and bulk density. The utilization of substantial amounts of EPS waste in the formulation of structural polystyrene concrete is crucial for advancing sustainable construction practices. This study investigates the effects of varying nano-silica content on the bulk density, compressive strength, flexural strength, splitting tensile strength, and water penetration depth of structural polystyrene concrete. Concrete specimens were prepared by substituting 25%, 50%, 75%, and 100% of sand with EPS waste, while evaluating nano-silica contents of 0.75%, 1%, and 1.25%. The findings reveal that increasing the volume fraction of EPS corresponds to a decrease in the concrete’s bulk density. This research provides critical insights into optimizing structural lightweight concrete, thereby promoting advancements in sustainable construction applications.

Impact of treated sewage water on early strength development of calcium sulfoaluminate cement paste: A comparative study

This study investigates the use of treated sewage water (TSW) as a substitute for fresh tap water (FTW) in concrete production using calcium sulfoaluminate (CSA) cement. The research addresses concerns about freshwater scarcity and emphasizes CSA cement's rapid setting properties, crucial for emergency constructions like military airfield recovery. The focus is on the early-age properties of CSA paste mixed with TSW, with assessments conducted at 4 hours, 1 day, and 3 days post-mixing. Key parameters, including slump, setting times, and hardened characteristics, were evaluated. TSW contained significant metal concentrations and a high pH, with total dissolved solids exceeding FTW by 67%, yet all parameters remained within acceptable limits. Analytical techniques identified ettringite (AFt) as a primary hydration product, while ye'elimite (C4A3Š) was present as a component of the unhydrated clinker in the CSA cement. Simulations showed improved stability in the TSW-CSA interface compared to FTW, although early hydration was slower, likely due to delayed C4A3Š hydration and increased AFt formation. Initially, CSA/TSW pastes presented a refined microstructure, which altered by 3 days. Despite a 14% faster final setting time, compressive strength was 21% lower at 4 hours. These findings highlight TSW's potential as a sustainable alternative in CSA cement mixing, necessitating further research for long-term performance evaluation.

Durability and hardened characteristics of cement mortar incorporating waste plastic and Polypropylene exposed to MgSO4 attack

Annual waste plastic disposal has grown, harming nature. Utilising this waste in concrete production may help preserve building resources. This study tested cement mortar with polyvinyl chloride (PVC) and polypropylene (PP) substituted for sand aggregate at 0, 5, 10, 15, and 20%. The samples were nevertheless exposed to a 10% and 20% MgSO4 solution for a month. The properties of both fresh and hardened materials under these circumstances have been evaluated and contrasted with those evaluated under typical circumstances. For mixes including PP and PVC, the flow diameter increased. The rounded plastic particles provided fewer contact surfaces and less friction among mixtures, which reduced water consumption and improved workability, leading to an increase in slump flow. As the amount of plastic aggregate increases, the compressive strength decreased. Moreover, this pattern might be explained by the weakening of the bond between the surfaces of the plastic aggregate and cement paste. The hydration of cement may also be hampered by the hydrophobic properties of plastic aggregate. Like compressive strength, the splitting tensile strength decreased as the replacement level of plastic ratio increased regardless of its type under all conditions (normal and exposing to MgSO4). PP and PVC fine aggregate in mortar increases sorptivity under all situations. Following screening, those circumstances and PVC have the most impact on compressive strength. increasing PVC and PP at 10% for each of them leads to lower values of compressive and tensile strength. An optimization process was implemented to determine the optimum value of PVC, PP, and MgSO4. It shows that using PVC of 3.9%, PP of 10.1%, and MgSO4 of 19.59% leads to maximum compressive and tensile strength with the minimum cost and CO2 emissions.

A rheological model for concrete additive manufacturing

The advent of 3D construction printing has ushered in a revolutionary era, demanding deeper insights into the understanding of cementitious fluid materials. Despite notable progress in additive manufacturing technologies, traditional rheological models (i.e., Bingham Plastic and Herschel-Bulkley) due to asymptotic behaviors of its plastic viscosity term fall short in describing the fluid mechanical properties of 3D printable concrete. This poses substantial challenges to achieving precise control and consistency in its boundless possibilities of mix design formulation. In this paper, we introduce an original rheological model that broadly characterizes the physiomechanical behaviours of non-Newtonian fluids, with a primary emphasis on thixotropic 3D printable cementitious pastes. Contrary to conventional representations, it is successfully demonstrated and validated herein that flow characteristics of 3D printable concrete may be described by two distinct viscosity terms, both of which collectively defines an upper and lower bound apparent viscosity with respect to a proposed activation function.

Reuse of Secondary Treated Wastewater and Fly Ash for the Manufacturing of Concrete: A Sustainable Approach

Reuse of Secondary Treated Wastewater and Fly Ash for the Manufacturing of Concrete: A Sustainable Approach

Enhancement of Recycled Aggregate Concrete Properties Through the Incorporation of Nanosilica and Natural Fibers

This study introduces an innovative approach to enhancing recycled aggregate concrete (RAC) by incorporating nanosilica (NS) and natural fibers (NF), specifically sisal fiber (SF) and palm fiber (PF). This novel combination aims to overcome the inherent limitations of RAC, such as reduced strength and durability, while promoting sustainability in construction. The research focuses on evaluating the mechanical properties of RAC, including compressive and flexural strengths, through the integration of NS and NF. Our findings reveal that NS significantly improves the microstructure of RAC by enhancing the interface transition zone (ITZ) and filling nanovoids, resulting in a denser and more durable concrete matrix. Specifically, the addition of 3% NS increased the compressive strength of RAC by up to 22.5% and the flexural strength by up to 25.6% at a 100% replacement ratio of recycled aggregate. The addition of NF, treated to withstand the alkaline environment of concrete, further strengthens the RAC by providing a bridging effect that enhances flexural strength by up to 46.7%. This work not only advances the performance of recycled concrete but also aligns with the broader goal of environmental sustainability by utilizing waste materials and reducing the carbon footprint of concrete production. The findings have the potential to influence future construction practices, encouraging the adoption of more durable and eco-friendly building materials.

Roles of superabsorbent polymers (SAPs) and palm oil fuel ash (POFA) on the strength, cost analysis and CO2 emission of lightweight concrete: Comparison with aluminum-based aerated concrete

This work investigated the effects of superabsorbent polymers (SAPs) as pore-forming agent and palm oil fuel ash (POFA) as sand replacement (0-100% by weight) on the strength, economic feasibility, and CO2 emissions for lightweight concrete production. The product properties were compared with the traditional aerated concrete (with aluminum powder), which aimed to shed light on the use of SAPs and POFA for manufacturing a more sustainable lightweight concrete. The use of POFA to replace sand increased the cost of production by approximately 1-7% and CO2 emissions by approximately 3-12% due primarily to the transportation of the POFA from the oil palm fuel power plant, which could be avoided if produced on site of or near the power plant. The use of SAPs in the preparation of the lightweight concrete led to a reduced compressive strength compared to the aerated concrete, especially in the autoclaved samples, calculated as 15-33% for 28 days and 44-56% for autoclaved curing, possibly due to a collapse of the porous structure under high temperature and pressure. These drawbacks could be eliminated if the natural SAPs in the form of fine particle size were treated with Ca2+ in agro-waste ash so as to facilitate and enhance the pozzolanic reaction during the curing phase. The fossil-based SAPs could then be replaced with the organic-based ones, which would be a more sustainable construction material for a lower-carbon society. However, further investigations into other aspects of these materials should be conducted.

Effects of CaO-based expansive agent on carbonation resistance of marine concrete

Marine concrete contains a high volume of supplementary cementitious materials, which benefits low-carbon concrete production. However, they may also increase the risk of cracking and accelerate the carbonation due to the pozzolanic reaction. Theoretically, the CaO-based expansive agent (CEA) can inhibit shrinkage cracks and introduce external calcium sources that aid in the carbonation resistance of concrete. A comprehensive understanding of the impact of CEA on the carbonation resistance of marine concrete is currently scarce.In this study, marine concretes with varying dosages of CEA were exposed to 20% CO2 for 28 days. The carbonation depth, carbonation coefficient, air permeability, pore structure characteristics and CO2 buffer capacity of concrete were investigated. When the CEA dosage was less than 6%, the carbonation resistance and air permeability approached the reference groups in normal-strength concrete (NSC) and high-strength concrete (HSC). However, more than 6% CEA significantly decreased the carbonation resistance of concrete, particularly for HSC. For NSC, there was an excellent correlation between the carbonation coefficient and compressive strength, while for HSC, the carbonation coefficient correlated well with porosity. Also, CO2 buffer capacity was essential to assess the carbonation resistance of marine concrete.

Assessing the Usage of Barytes Powder and Cuddapah Stone Dust as Supplementary Cementitious Materials in Concrete of Grade M30 and M35

This research studied the effects of using Barytes powder and Cuddapah stone waste as substitutes for cement in M30 and M35 grade concrete using OPC. Cement production is known to harm the environment and consume a lot of energy, making the search for alternative materials to replace cement in concrete important.In this study, different amounts of Barytes powder and Cuddapah stone waste were added to concrete mixes as partial replacements for cement. The resulting concrete was tested for compressive strength and compared to normal concrete. The experiment involved making concrete samples with varying percentages of cement replacement, ranging from 0% to 50%, using Barytes powder, Cuddapah stone waste and Combination. The samples underwent standard curing and testing according to Indian standards.The research analysed the results to find the optimum percentage of cement replacement that provided satisfactory mechanical properties. This study determined the feasibility and effectiveness of using Barytes powder and Cuddapah stone waste as partial replacements for cement in concrete production.

Microstructural analysis of geopolymer pastes contaminated with crude oil: Impact on efflorescence, physical properties, and mechanical performance

Geopolymer concrete represents a more sustainable alternative to traditional cement in particular production processes, reducing carbon emissions, recycling industrial by-products, and promoting energy efficiency. However, a notable challenge is the potential for efflorescence, which can impair material performance due to microstructural changes from alkali leaching and carbonation. Various additives have been explored to mitigate efflorescence. Using oil-contaminated sand in geopolymer and concrete cement production is emerging as a cost-effective rehabilitation strategy that also addresses environmental concerns. This study investigates the impact of crude oil contamination on geopolymer pastes, focusing on efflorescence susceptibility. Under normal ambient conditions, the geopolymer pastes did not show signs of efflorescence. However, exposure to water led to the formation of efflorescence-type products. Notably, crude oil contamination significantly influenced this outcome. Crude oil significantly decreased the occurrence of efflorescence, mainly when contamination levels ranged from 2 % to 10 %. This reduction is attributed to the oil’s effects on the paste’s pore structure, fluid migration dynamics, and viscosity, which affected water adhesion and movement through the paste. Additionally, crude oil contamination altered the chemical properties of the geopolymer pastes, causing fluctuations in the pH of leaching solutions, which affected chemical equilibrium and electrical conductivity. Compressive strength improved with 1 % crude oil contamination but decreased with higher contamination levels. Geopolymer paste with 1 % crude oil content generally increases material density and reduces porosity, enhancing mechanical properties and reducing efflorescence. However, excessive contamination undermined these benefits and negatively impacted material performance. Therefore, moderate oil contamination can be effectively used as an additive to reduce efflorescence and enhance geopolymer concrete's physical and mechanical properties. The findings provide valuable insights into the potential applications and limitations of using fly ash-based geopolymers in environments prone to oil contamination.

Durability and mechanical properties of concretes with limestone filler with particle packing

This study aims to present alternatives to reduce the demand of cement in concrete production based on particle packing concepts. Physical and mechanical characteristics of concretes, as well as the resistance to chlorides action were analyzed. The tests conducted in this study included compressive strength, chloride migration, capillary absorption tests and wetting and drying cycles in 1M sodium chloride solution. Mixtures containing limestone filler presented satisfactory results compared to the reference mixture with particle packing. Excellent results were obtained for concrete with cement consumption of 253.34 kg.m-3 in terms of compressive strength, binder index, capillary absorption and depassivation time of rebars, thus reinforcing the concept that partial cement replacement by limestone filler yields positive results in these properties. Worse results were obtained for concrete with a cement consumption of 161.86 kg.m-3, because it had a higher proportion of filler than cement. The electrochemical monitoring of the steel bars also shows that the packing of the aggregates was essential to delay the initiation of corrosion.

Enhancing concrete sustainability by incorporating crushed ceramic tiles as a partial replacement for fine aggregate in concrete mixture

In this study, the possibility of partially replacing ceramic tiles with fine particles in concrete mixtures is investigated in order to increase the sustainability of concrete. Recycling and utilizing ceramic waste are essential because its disposal causes environmental problems. In this study, we examine how the amount of crushed ceramic tile affects many aspects of concrete, such as compressive strength, durability, and environmental impact. According to our research, adding crushed ceramic tiles to concrete reduces waste while also demonstrating promising outcomes in terms of strength and durability, making it a more environmentally friendly choice than using traditional fine aggregates. Utilizing ceramic waste in concrete production offers the opportunity to be cost-effective and environmentally sustainable, advocating for resource efficiency and eco-friendly construction practices. let's break down how we're going to carry out this project in simple terms. First, we'll gather all the materials we need, like regular concrete stuff and crushed ceramic tiles. Then, we'll mix them up in different ways to see what works best. After that, we'll make small samples and test how strong and durable they are. We'll repeat these tests a few times to make sure our results are reliable. Along the way, we'll keep track of everything we do, so we can explain it to others and make sure our project is solid.