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The reactive powder concrete (RPC) is one of the special concrete types that characteristics with high cement content which means high production cost and CO 2 emissions to the atmosphere. Therefore, to enhance the environment as well as to develop green RPC, alternatives to cement, such as supplementary cementitious materials (SCMs) were used. Lim...
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Context 1
... MK was prepared by burning the kaolin (brought from Anbar province, west of Iraq) in a controlled oven at 700°C for one hour [16]. The physical and chemical properties of SF (which is conformed to ASTM C1240 [17]), FA and MK (which are conformed to ASTM C618 [18]) are illustrated in Table 3. The properties of SF are adopted from [19]. ...Context 2
... relating to the control mixture, it can be noticed that the average detraction rates of SF + FA combinations were much lesser than those for MK + FA combinations. This behavior is due to the higher pozzolanic activity index of SF (125 %) compared to MK (85 %), as shown in Table 3, together with the lower density of MK + FA mixtures compared with SF + FA mixtures as confirmed by the density results of the present study. According to above, it can be concluded that though those mixtures incorporated a high volume fraction of SCMs showed lower compressive strength than the control mixture, the SF + FA combinations mixtures revealed better performance than MK + FA mixtures. ...Context 3
... MK was prepared by burning the kaolin (brought from Anbar province, west of Iraq) in a controlled oven at 700°C for one hour [16]. The physical and chemical properties of SF (which is conformed to ASTM C1240 [17]), FA and MK (which are conformed to ASTM C618 [18]) are illustrated in Table 3. The properties of SF are adopted from [19]. ...Context 4
... relating to the control mixture, it can be noticed that the average detraction rates of SF + FA combinations were much lesser than those for MK + FA combinations. This behavior is due to the higher pozzolanic activity index of SF (125 %) compared to MK (85 %), as shown in Table 3, together with the lower density of MK + FA mixtures compared with SF + FA mixtures as confirmed by the density results of the present study. According to above, it can be concluded that though those mixtures incorporated a high volume fraction of SCMs showed lower compressive strength than the control mixture, the SF + FA combinations mixtures revealed better performance than MK + FA mixtures. ...Similar publications
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Alternative to traditional concrete, sustainable concrete reduces cement content, waste management issues, and CO2 emissions. To achieve sustainable concrete, waste materials can be used as supplementary cementitious materials (SCMs) to partially replace cement. Fly ash, ground-granulated blast furnace slag, and silica fume have been heavily studie...
In this paper, the prediction of flexural strength was investigated using machine learning methods for concrete containing supplementary cementitious materials such as silica fume. First, based on a database of suitable characteristic parameters, the flexural strength prediction was carried out using linear (LR) model, random forest (RF) model, and...
Self-compacted concrete (SCC) is a special type of concrete; it is a liquid mixture appropriate for structural elements with excessive reinforcement without vibration. SCC is commonly produced by increasing the paste volume and cement content. As cement production is one of the huge factors in releasing CO2 gas into the atmosphere, by-product mater...
Since Since last few years marble has been considered one of the most important decorative building materials. Marble Powder (MP) and Fly Ash (FA) are one of the materials which affects the environment and health problems. MP produced from sawing, shaping and polishing process of marble. FA is a residue collected from combustion of powdered coal. T...
Citations
... However, excessive use of either cement or SF causes increased production costs, increased hydration heat, and RPC shrinkage. Cement substitutes include phosphorous slag [9], fly ash (FA) [5], ground granulated blast-furnace slag (GGBFS) [10], and metakaolin [11] are being explored as a means of mitigating these negative impacts. Numerous advantages of using FA for concrete have been shown by published studies, including a decrease in environmental pollutants and an improvement in the material's durability and engineering qualities [12,13]. ...
Containing a high quantity of both fine powders and steel fiber makes reactive powder concrete (RPC) a unique kind of ultra-high strength concrete. However, the cost of manufacture, shrinkage, and hydration heat are increased when silica fume and cement are used in significant amounts. To mitigate these negative consequences and the environmental impact, this study assessed the use of fly ash (FA) with high volume combined with natural-fine river sand (NFRS) in the manufacturing of RPC. FA was utilized to partially substitute cement at 0, 20, 40, and 60 wt% in RPC mixtures that had a set water/binder ratio of 0.2. Thermal conductivity, porosity, water absorption, and compressive strength tests were performed. Furthermore, RPC's microstructure was examined using a scanning electron microscope (SEM). This study also included a cost and global warming potential analysis of RPC production. Test results indicated that a modified RPC with a 60 MPa compressive strength value could be created by using NFRS and a large amount of FA. In comparison to the reference mixture, a higher compressive strength, reduced water absorption, and lesser porosity were observed in RPC when the FA replacement amount was less than 40%. Many FA particles did not engage in the hydration reaction when the FA replacement level was more than 40%, which had a detrimental impact on the RPC's characteristics. In general, using FA to produce RPC has certain benefits for the economy and the environment. It is recommended that 40% of FA be used in actual practice.
... Cement, the main binding material in concrete, is responsible for about 7% of global CO2 emissions. Therefore, using recycled or waste materials in the concrete industry is a means to promote alternatives to the current usage of concrete materials and contribute to the global objective of sustainable development [4,5]. To promote sustainable development, research has focused on extending the service life of concrete structures and developing low-carbon concrete materials and systems [6]. ...
Cement is among the important contributors to carbon dioxide emissions in modern society. Researchers are studying solutions to reduce the cement content in concrete to minimize the negative impact on the environment. Among these solutions is replacing cement with other materials, such as waste, which also poses environmental damage and requires landfill areas for disposal. Among these wastes are eggshell powder ash (ESPA) and wheat straw ash (WSA), which were utilized as cement substitutes in green mortar production. Thirteen mixtures were cast, one as a reference without replacement and twelve others that included replacing ESPA and WSA (single and combined) with cement in 2%, 4%, 6%, and 8% proportions of cement's weight. The mechanical (compressive and flexural strength), microstructural (SEM), and thermogravimetric analysis (TG/DTA) properties of all mixtures were examined. The results showed a remarkable improvement in mechanical properties, and the best improvement was recorded for the (4%ESPA+4%WSA) mixture, which reached 73.3% in compressive strength and 56% in flexural strength, superior to the reference mixture. Furthermore, SEM analyses showed a dense and compact microstructure for the ESPA and WSA-based mortars. Therefore, the WSA and ESPA wastes can be recycled and utilized as a substitute for cement to produce an eco-friendly binder that significantly improves the microstructural and mechanical characteristics of mortar. In addition, combining the two materials also presents a viable option for creating a sustainable ternary blended binder (with cement) that boasts superior properties compared to using the WSA or ESPA individually. Doi: 10.28991/CEJ-2024-010-01-05 Full Text: PDF
... Among all construction materials, concrete is by far the most widely utilized [3]. The concrete industry is the most important source of CO2 emission and the most important consumer of depleted natural resources (virgin materials) [4][5][6][7]. Therefore, to maintain the sustainable concept, two important methods must be taken into account: recycling waste materials and lowering emissions of carbon dioxide. ...
Challenges posed by industrial solid waste, particularly Electrical Cable Waste (ECW), have been increasingly recognized due to their environmental implications and substantial decomposition timelines. ECW, a byproduct of aggressive demolition and reconstruction in Iraq, has seen limited investigation regarding its potential use as an aggregate substitute and fiber additive in concrete applications. This study endeavors to repurpose ECW as a partial replacement for natural sand and as fiber reinforcement, with a focus on both short-term and long-term performance. A fixed ratio of natural sand was substituted with ECW (10%), and waste fibers were integrated at varying concentrations (0.5%, 1%, 1.5%, 2%, 2.5%, and 3%). For comparative purposes, a control mix devoid of ECW and fibers was also examined. Evaluations were conducted on the flow rate, along with compressive strength, flexural strength, and density at intervals of 7, 28, and 360 days. Results indicate that despite a reduction in flowability and a decrease in hardened density to under 2000 kg/m 3 , inclusion of ECW can yield a sustainable lightweight mortar without significant compromise on strength. This study thus underscores the potential of waste repurposing as a viable solution for waste management and environmental enhancement. Additionally, this approach can help mitigate natural resource depletion, such as that of natural sand, fostering a move towards sustainable construction practices.
... Silica fume, for instance, can optimize the internal pore structure of UHPC and significantly enhance the compactness of the system, resulting in improved compressive strength and flexural resistance [9][10][11]. Fly ash contributes to improving the compatibility and the flowability of UHPC, which reduces the consumption of high-priced superplasticizers [12][13][14][15][16]. Moreover, the addition of slag can decelerate the hydration process and refine the microstructure of UHPC, ultimately resulting in the improved mechanical properties of Figure 1 illustrates the process of predicting UHPC properties and optimizing mix design through machine-learning algorithms and the analytic hierarchy process. ...
Ultra-high-performance concrete (UHPC) is widely used in the field of large-span and ultra-high-rise buildings due to its advantages such as ultra-high strength and durability. However, the large amount of cementitious materials used results in the cost and carbon emission of UHPC being much higher than that of ordinary concrete, limiting the wide application of UHPC. Therefore, optimizing the design of the UHPC mix proportion to meet the basic properties of UHPC with low carbon and low cost at the same time will help to realize the wide application of UHPC in various application scenarios. In this study, the basic properties of UHPC, including the compressive strength, flexural strength, fluidity, and shrinkage properties, were predicted by machine-learning algorithms. It is found that the XGBoost algorithm outperforms others in predicting basic properties, with MAPE lower than 5% and R2 higher than 0.9 in four output properties. To evaluate the comprehensive performance of UHPC, a further analysis was conducted to calculate the cost- and carbon-emissions-per-unit volume for 50,000 UHPC random mixes. Combined with the analytical hierarchy process (AHP) model, the comprehensive performance of UHPC, including basic properties, cost-per-unit volume, and carbon-emissions-per-unit volume, was evaluated. This study proposes an optimized UHPC mix proportion, based on low-cost or low-carbon emission, oriented to comply with the excellent overall performance and obtain its corresponding various properties.
... Concrete is among the most widely used building substances [2,3], and therefore, this increase in building requirements will be reflected in greater depletion of natural resources such as aggregates [4], as well as a further increase in the production of cement [5,6], which is the main binding material in concrete. Cement production is accompanied by high carbon dioxide emissions [7][8][9], estimated at about 7% of the total production around the world [10][11][12][13]. The fabrication of 1 ton of cement is associated with the emission of about 1 ton of CO 2 [14]. ...
Sustainability and reducing environmental damage caused by CO2 emissions have become issues of interest to researchers in the construction sector around the world. Reducing the cement content in concrete by partially substituting it with by-products or waste falls within this field as the cement industry is responsible for 7% of global CO2 emissions. On the other hand, self-compacting concrete (SCC) is one of the special types of concrete that contains a large amount of powder (most of which is cement) to ensure its flow under the influence of its weight without separating its components. Therefore, to produce eco-friendly SCC, many researchers have replaced part of the cement with clay brick waste powder (CBWP) since brick units are among the most widely used building materials after concrete. Accordingly, this study aims to review previous research that included using CBWP in SCC. The effect of these wastes on the fresh, mechanical, durability and microstructural properties of cement was reviewed. Additionally, a comparison between the environmental impacts of SCCs with different CBWP contents has been conducted using the life cycle assessment (LCA) approach. It was found that the highest value of CBWP that can be used without negatively affecting the different properties of concrete is 10% by weight of cement. Moreover, regarding environmental impact, using CBWP as a substitute for cement reduces environmental damage, and the lowest environmental impact that can be achieved per strength unit (MPa) is 37.5%.
... Accordingly, scientists have searched for ways to reduce this damage, including reducing the cement content in concrete mixes. This is achieved by replacing it with other materials with fewer emissions, and, among these, are the by-products of other industries and waste [6,7]. On the other hand, solid waste constitutes a great burden on the governments of countries as a result of the difficulty of its decomposition [8]; it may be toxic in addition to its need for large waste dumps for landfills. ...
Carbon dioxide emissions are one of the problems that arouses the interest of scientists because of their harmful effects on the environment and climate. The construction sector, particularly the cement industry, is a significant source of CO2. On the other hand, solid waste constitutes a major problem facing governments due to the difficulty of decomposing it and the fact that it requires large areas for landfill. Among these wastes are LCD waste glass (WG) and used rope waste. Therefore, reusing these wastes, for example, in concrete technology, is a promising solution to reduce their environmental impact. Limited studies have dealt with the simultaneous utilization of glass waste as a substitute for cement and rope waste (nylon) fiber (WRF). Therefore, this study aimed to partially replace cement with WG with the addition of rope waste as fibers. Thirteen mixtures were poured: a reference mixture (without replacement or addition) and three other groups containing WG and WRF in proportions of 5, 15 and 25% by cement weight and 0.25, 0.5 and 0.75% by mortar weight, respectively. Flow rate, compression strength, flexural strength, dry density, water absorption, dynamic modulus of elasticity, ultrasonic pulse velocity and electrical resistivity were tested. The results indicate that the best ratio for replacing cement with WG without fibers was 5% of the weight of cement. However, using WRF increased the amount of glass replacement to 25%, with an improvement in strength and durability characteristics.
... With the rapid development of the construction and building industry, cement, especially ordinary portland cement, has become the most popular construction material [1] . However, the cement industry is known for not only its high energy consumption, but also for large CO 2 emissions. ...
... After 28 days of hydration, the characteristic peaks of C 4 A 3 S _ and CaSO 4 phases disappeared completely, but those of AFt dramatically increased. This indicates that the hydration reaction between C 4 A 3 S _ and CaSO 4 , completely consuming both reactants, could have generated a large amount of AFt phase [26] : (1) Besides, the characteristic peaks of the AFm phase could be observed. This is because, under the condition of insufficient CaSO 4 content, C 4 A 3 S _ hydrated to form the AFm phase(Eq.2) [26] , and there was a conversion from AFt to the AFm phase (Eq. ...
The effects of coal metakaolin on the mechanical properties of high-belite sulphoaluminate cement under compressive loading were investigated. The composition and microstructure of hydration products at different hydration times were analyzed by X-ray diffraction and scanning electronic microscopy. The hydration process of blended cement was studied via electrochemical impedance spectroscopy. In particular, replacing a part of cement with CMK (10%, 20%, and 30%) was found to promote the hydration process, to refine the pore size, and to improve the compressive strength of the composite. The best compressive strength of the cement was achieved at a CMK content of 30% after 28 days hydration, being improved by 20.13 MPa, or 1.44 times relative to that of undoped specimens. Furthermore, the compressive strength is shown to correlate with the impedance parameter RCCP, which allows the latter to be used for nondestructive assessment of the compressive strength of blended cement materials.
... As a result, extensive research projects have been conducted recently to adverse the durability and sustainability of concrete by using different industrial waste and by-products to replace, partially or totally, Portland cement and natural aggregates in ordinary concrete. These include silica fume [3], fly ash [4], metakaolin [5], recycled aggregates [6], etc. However, less attention is given to lowering water consumption in concrete production. ...
The rapidly growing world population and the accompanying increase in concrete production to meet building and infrastructure needs have led to significant increase in potable water consumption, which resulted in several environmental problems. This paper investigates the feasibility of replacing potable water with highly mineralized treated wastewater in concrete mixing in order to make concrete production more eco-friendly in an arid region. Concrete specimens were prepared using saline treated wastewater (saline-TWW) as mixing water and compared to those mixed with distilled water (DW) and with the performance requirements given by the mixing water quality standards. The results revealed that the concrete mixes produced using saline-TWW exhibited higher early strength and a similar long-term strength than the control mix produced using DW. It was also found that the use of saline-TWW increased the setting times of cement paste but had no remarkable effect on the workability of fresh concrete mixture. Furthermore, the microstructural characteristics of the hardened concrete were assessed by water-permeability test, SEM image analysis, and X-ray diffraction tests. The results revealed that saline-TWW concrete exhibited a more compact microstructure and smaller pore sizes than their counterparts of DW, which means an improvement in the durability of saline-TWW concrete. Moreover, an electrochemical test was conducted to estimate the extent of corrosion of the steel embedded in reinforced mortar specimens prepared using saline-TWW and DW. The electrochemical test results showed that the use of 100% saline-TWW as mixing water of concrete resulted in a high corrosion rate of the embedded steel.
... The water/binder of RPC is low (maybe less than 0.2). One of the determinants of the widespread use of RPC is its high initial cost as a result of containing a large amount of cementitious materials that may exceed 800 kg/m 3 [4,5]. In addition to the fact that this high amount of cementitious materials increases the cost of RPC, the high content of cement has a negative influence on the environment as a result of high carbon dioxide emissions during cement manufacturing [6]. ...
Reactive powder concrete (RPC) is one of the distinctive kinds of concrete whose benefits are high mechanical performance and durability. It contains a high content of cement, which means a high amount of carbon dioxide emitted during manufacturing. Scientists have tended to search for a way to reduce environmental damage, and one solution is to partially replace cement with mineral admixtures, waste from other industries, or by-products. There are restricted studies involving the use of high content of compounding mineral admixtures in the making of RPC. Therefore, this research aims to produce sustainable RPC with a low cement content (50%). The main objective of this research is to study the impact of substituting cement with 50% of silica fume (SF) + fly ash (FA) on the mechanical characteristics of RPC. Three mixtures containing various percentages of SF + FA were poured, in addition to the reference mixture. Flowability, flexural and compressive strengths, ultrasonic pulse velocity (UPV), and density were examined. The results showed that a sustainable RPC can be produced by substituting the cement with 10% SF and 40% FA with an improvement in workability and compressive strength and an insignificant reduction in other properties.
... In addition to influence of FA on workability as cement replacement, investigation was also carried out by replacing SF and QP with FA. Nasr et al., [70] found that flowability of UHPC improve when SF is partially replaced by FA and no effect on workability was noted when full QP content was substituted with FA [71]. In addition to FA content, the particle size also has an influence on the workability of UHPC. ...
... The below optimum content of FA, filler and pozzolanic effect was noted that made microstructure dense, while dilution effect was dominated beyond optimum content [79]. The negative effects of using FA as cement replacement on the CS of UHPC was observed in different studies [66,68,70,80,81]. Ahmed et al., [68] incorporated high volume Class F FA in UHPC up to 70% as cement replacement. ...
Ultra-high-performance concrete (UHPC) is a new type of cement-based material. It has excellent different properties such as high workability, superior mechanical properties and durability. It has been proved to be a promising material for building, structural rehabilitation and retrofitting, and bridge engineering. However, despite its many benefits, its wide applicability is hindered due to its high cost. The high cost of UHPC is mainly associated with the high cost of its constituents such as cement, silica fume (SF), quartz powder (QP), quartz sand, superplasticizer (SP), and fibers. In this review paper, the use of different materials such as fly ash (FA), ground granulated blast furnace slag (GGBS), glass powder (GP), rice husk ash (RHA), limestone powder (LP), natural fine and coarse aggregate to reduce the content of cement, SF, QP, quartz sand, and SP and the corresponding decrease in the cost of UHPC have been reviewed. The total cost (USD/m 3) and strength-normalized cost (USD/MPa/m 3) were calculated when these materials were used in UHPC as partial/full replacement of cement/SF/QP/quartz sand. In addition, the effects of FA, GGBS, GP, RHA, LP, fine and coarse aggregate on workability, mechanical properties (compressive strength, splitting tensile strength, flexural strength and elastic modulus), drying and autogenous shrinkage, and durability characteristics were reviewed. In the end, a future research need was summarized.
