Production Of Sustainable Concrete Research Articles

Properties of Laterized Concrete Incorporating Sawdust Ash as A Partial Replacement for Cement

Ordinary Portland cement (OPC), the main binder in concrete, is the most expensive component and the major contributor to the embodied carbon of the composite. This necessitates alternative eco-friendly materials such as waste, with comparative binding properties as a part replacement for OPC to have economic and sustainable concrete production with minimal hazardous impact on the environment. This study uses Sawdust Ash (SDA) which is a waste product of the wood milling industry, to replace some proportion of OPC in concrete. To further reduce the cost and negative environmental impact of concrete, laterite was used to replace river sand, and fresh and hardened properties were investigated. The fresh property evaluated in this study is the slump, while the hardened properties investigated are the density and compressive strength. This study showed the viability of successfully incorporating SDA as a partial replacement of OPC and laterite soil to replace the conventional fine aggregate. An acceptable slump and compressive strength can be achieved using 10% SDA and 45% laterite as partial replacement of OPC and river sand, respectively.

Predicting Compressive Strength of Blast Furnace Slag and Fly Ash Based Sustainable Concrete Using Machine Learning Techniques: An Application of Advanced Decision-Making Approaches

The utilization of waste industrial materials such as Blast Furnace Slag (BFS) and Fly Ash (F. Ash) will provide an effective alternative strategy for producing eco-friendly and sustainable concrete production. However, testing is a time-consuming process, and the use of soft machine learning (ML) techniques to predict concrete strength can help speed up the procedure. In this study, artificial neural networks (ANNs) and decision trees (DTs) were used for predicting the compressive strength of the concrete. A total of 1030 datasets with eight factors (OPC, F. Ash, BFS, water, days, SP, FA, and CA) were used as input variables for the prediction of concrete compressive strength (response) with the help of training and testing individual models. The reliability and accuracy of the developed models are evaluated in terms of statistical analysis such as R2, RMSE, MAD and SSE. Both models showed a strong correlation and high accuracy between predicted and actual Compressive Strength (CS) along with the eight factors. The DT model gave a significant relation to the CS with R2 values of 0.943 and 0.836, respectively. Hence, the ANNs and DT models can be utilized to predict and train the compressive strength of high-performance concrete and to achieve long-term sustainability. This study will help in the development of prediction models for composite materials for buildings.

Improved strength performance of rubberized Concrete: Role of ground blast furnace slag and waste glass bottle nanoparticles amalgamation

Production of high strength and sustainable concrete by recycling various industrial wastes in an eco-friendly way to reduce the landfill problems remains challenging. Ever-increasing disposal of million tons of waste tyres worldwide posed serious environmental concern. The reuse of waste tyres in concrete as fine and coarse aggregates was shown to enhance its strength performance and solve the landfills-related environmental issues. Thus, new types of rubberized concrete mixes with improved bond zone and strength performance were produced by combining the waste rubber tyre aggregates (WRTAs), waste glass bottle nanoparticles (WGBNPs) and ground blast furnace slag (GBFS) with ordinary Portland cement (OPC). The designed concrete mixes contained 30% of crumb rubber as substitute of the natural fine and coarse aggregates wherein OPC was replaced by 20% of GBFS and various WGBNPs contents (3, 6, 9 and 12%). The workability performance, microstructures, and strength properties of the proposed mixes were evaluated using various tests. Concrete containing 6% of WGBNPs showed significant enhancement in the bond zone between cement paste and crumb rubber surface wherein the compressive strength was increased by 14% compared to the control specimen. The microstructures analyses of WGBNPs blended concretes displayed the formation of dense gels and less pores with acceptable engineering properties. It was asserted that concretes obtained by blending GBFS, WGBNPs and WRTAs with less OPC can be the potential green construction materials with immense benefits for the environment, thus minimizing the greenhouse gases emission and landfill requirements.

A Review Paper on Strength Classification of Rock Material Based on Particle Size and Mineralogical Composition for Production of Sustainable Concrete

A Review Paper on Strength Classification of Rock Material Based on Particle Size and Mineralogical Composition for Production of Sustainable Concrete

Effective Microorganism Solution and High Volume of Fly Ash Blended Sustainable Bio-Concrete.

Currently, the production of sustainable concrete with high strength, durability, and fewer environmental problems has become a priority of concrete industries worldwide. Based on this fact, the effective microorganism (EM) solution was included in the concrete mixtures to modify the engineering properties. Concrete specimens prepared with 50% fly ash (FA) as an ordinary Portland cement (OPC) replacement were considered as the control sample. The influence of EM solution inclusion (at various contents of 0, 5, 10, 15, 20, and 25% weight) in the cement matrix as water replacement was examined to determine the optimum ratio that can enhance the early and late strength of the proposed bio-concrete. The compressive strength, porosity, carbonation depth, resistance to sulphuric acid attack, and the environmental benefits of the prepared bio-concrete were evaluated. The results showed that the mechanical properties and durability performance of the bio-concrete were improved due to the addition of EM and FA. Furthermore, the inclusion of 10% EM could increase the compressive strength of the bio-concrete at 3 (early) and 28 days by 42.5% and 14.6%, respectively. The durability performance revealed a similar trend wherein the addition of 50% FA and 10% EM into the bio-concrete could improve its resistance against acid attack by 35.1% compared to the control specimen. The concrete mix designed with 10% EM was discerned to be optimum, with approximately 49.3% lower carbon dioxide emission compared to traditional cement.

Synthesis of Slag-Ash-Phosphate Based Geopolymer Concrete in the Production of Sustainable Concrete Under Ambient Curing Conditions

Synthesis of Slag-Ash-Phosphate Based Geopolymer Concrete in the Production of Sustainable Concrete Under Ambient Curing Conditions

Feasibility study on the use of processed waste tea ash as cement replacement for sustainable concrete production

In this study, processed waste tea ash (PWTA) generated by the boiler combustion of processed solid waste tea was used as a cement replacement at weights of 0%, 10%, 20%, 30%, and 40%. The effect of PWTA on the concrete properties was examined using the slump, density, compressive strength, porosity, chloride penetration depth, and microstructure as well as the embodied carbon content of concrete. Further, the contribution of the pozzolanic effect of PWTA to concrete strength was quantitatively analyzed using strength indices. The results showed that the slump and density of concrete decreased with the addition of PWTA. The concrete specimens with 10% PWTA achieved a similar compressive strength to that of control concrete at 28 days and a 4.57% higher value at 90 days due to the continuous pozzolanic reaction of PWTA. Strength indices also showed that the pozzolanic effect of 10% PWTA positively contributed to concrete strength at 90 days with a P value of 14.09%, which was higher than the percentage amount of PWTA used in the mixture. Owing to the pozzolanic reaction, the porosity and chloride penetration depth of 10% PWTA concrete at 90 days are lower by 4.2% and 9.4%, respectively, compared to those of control concrete. With the addition of PWTA up to 10%, the embodied carbon and carbon dioxide intensity could be reduced by 8.32% and 7.85%, respectively, compared with those of control concrete. These results suggest that PWTA is a useful replacement for up to 10% cement, enabling the production of innovative building materials for sustainable environment, with strengths similar to that of Portland cement.

Predictive modeling of compressive strength of sustainable rice husk ash concrete: Ensemble learner optimization and comparison

One of the largest sources of greenhouse gas (GHG) emissions is the construction concrete industry which has alone 50% of the world's emissions. One possible remedy to mitigate the effect of environmental issues is the use of waste and recycled material in concrete. Today, immense agricultural waste is being used as a substitute for cement in the production of sustainable concrete. Therefore, this study is aimed to predict and develop an empirical formula of the compressive strength of rice husk ash (RHA) concrete using machine learning algorithms. Methods employed in this study includes gene expression programming (GEP) and Random Forest Regression (RFR). A reliable database of 192 data points was employed for developing the models. Most influential variables including age, cement, rice husk ash, water, super plasticizer, and aggregate were employed as input parameters in the development of RHA-based concrete models. Evaluation of models was performed using different statistical parameters. These statistical measures include mean absolute error (MAE), coefficient of determination (R2), performance index (ρ), root man square error (RMSE), relative squared error (RSE) and relative root mean square (RRMSE). The GEP model outperforms the RFR ensemble model in terms of robustness, with a greater correlation of R2 = 0.96 compared to RFR's R2 = 0.91. Ensemble modeling showed an enhancement of 1.62 percent for RFR compressive strength model when compared with individual RFR compressive strength model as illustrated by statistical parameters. Moreover, GEP model shows an enhancement of 37.33 percent in average error with an average error 2.35 MPa as compared to RFR model with average error of about 3.75 MPa. Cross validation was used as external check to avoid overfitting issues of the models and confirm the generalized model output. Parametric analysis was performed to determine the impact of the input parameters on the output. Cement and age were shown to have a substantial impact on the compressive strength of RHA concrete using sensitivity analysis.

Effect of elevated temperatures on mechanical and microstructural properties of alkali-activated mortar made up of POFA and GGBS

Alkali-activated cement systems (Geopolymers) are essential alternatives to OPC in the sustainable concrete production industry. In general, the alkali-activated mortar and concrete have good fire resistance due to their ceramic-like properties. Due to the limited resources investigating POFA-GGBS based geopolymer exposed to elevated temperatures, this study will help researchers for the first time understand the geopolymeric binder characteristics after exposure to elevated temperature on strength, thermo-physical stability, and microstructure properties. The main objective is to investigate the role of calcium coupled with aluminum and their effect on geopolymeric gel stability. The alkali-activated mortar was synthesized with liquid sodium silicate and sodium hydroxide. Cubic specimens were heated to a range of temperatures between 100 °C and 800 °C to evaluate strength loss and gel thermal microstructure damage. Scanning electron Microscopy test confirmed the finding of the ability of POFA with GGBS to be used as a novel environmentally-friendly material to produce sustainable mortar and concrete with advanced performance under high temperatures. Thermal-physical stability of POFA-GGBS mortar due to the spherical pore system allows the vaporized water to be released outside the samples. FTIR spectra results revealed two mechanisms explaining the effect of GGBS by lowering the wavelength through shifting Si-O peaks with the aluminium substitution producing C-A-S-H and changing the FTIR spectra by generating new peaks. TGA/DTG and DSC tests confirmed the formation of a robust gel with a higher degree of crystallinity and very high thermal stability due to the Ca and crosslink effect of Al in the geopolymeric system. The excellent thermal performance of POFA-GGBS mortar under elevated temperature would increase the applications for this novel environmentally-friendly material.

Sustainable concrete production with recycled concrete wash water beneficiated with CO2

A significant amount of wastewater is generated through the cleaning of equipment utilized within the ready mixed concrete production cycle. The reuse of concrete wash water as mix water is limited by the negative material performance impacts associated with the suspended solids; the effects are exacerbated with increasing solids contents and water aging. A novel carbon dioxide treatment to allow the use of high solids wash water (specific gravity 1.10) as mix water was examined. Seven batches of concrete were produced and compared: a reference mix, two batches with untreated wash water and four batches with CO2 treated wash water. The carbon dioxide treatment mineralized CO2 at 28% by mass of the treated solids. Acceptable concrete was produced through adjusting admixtures for workability. The compressive strength at 1, 7, 28 and 56 days was improved relative to both the reference and the concrete produced with untreated wash water. The suspended solids containing mineralized CO2 served as a viable cement replacement. The avoided cement and bound carbon dioxide served to lower the carbon impact of the concrete by about 14%. The approach allows three waste streams (CO2, wash water and wash water solids) to be reused to produce more sustainable concrete.

The behavior of sustainable self-compacting concrete reinforced with low-density waste Polyethylene fiber

Sustainable concrete production and recycling the construction wastes are of utmost importance for today’s sustainable urban development. In this study, low-density polyethylene waste was recycled in the form of fibers (LDPF) to produce eco-friendly fiber-reinforced sustainable self-compacting concrete (SCC). The content of LDPF ranged from 0.5% to 3.5% at a raise of 0.5% of the mix’s volume. The SCC’s features in fresh and hardened states were tested. The slump flow diameter, T500, V-funnel, and L-box ratio were measured for the fresh properties. The compressive, splitting tensile and flexural strengths were tested at the age of 28 days. However, the outcomes indicated that LPDF had some negative effect on the workability features, but all the results of SCC mixtures were within the standard limitations of SCC except that related to the L-box, which satisfied the standards up to 2% of LDPF. However, the incorporation of LDPF enhanced the mechanical properties, especially the flexural strength. The optimum ratio for the LPDF was 2%, which satisfies the required workability and the highest strength with modulus of elasticity. The thermal conductivity decreased with increasing LDPF content in the SCC mixtures.

Combined reusing of sorghum husk ash and recycled concrete aggregate for sustainable pervious concrete production

The huge amounts of natural resources and high level of energy consumption in concrete production necessitate the use of agricultural and demolition wastes as alternative construction materials. The present study explores pervious concrete (PC) that includes sorghum husk ash (SHA) and recycled concrete aggregate (RCA) as alternatives to cement and natural aggregate (NA) in standard PC mixtures. PCs were prepared from mixtures derived from replacement levels 0%, 5%, 10%, 15%, 20% and 25% of cement with SHA and 0%, 20%, 40%, 60%, 80% and 100% of NA with RCA. The density, compressive strength and hydraulic properties (void ratio and hydraulic conductivity) of the samples were determined at 28-day using ACI standards. Sustainability efficiency of incorporating SHA and RCA on PC was also investigated using structural efficiency and carbon dioxide (CO2) emission. Their cost effectiveness was equally examined. Results revealed that densities of PC decreased with increase in SHA and RCA amount. Compressive strength and structural efficiency reduced with increase in SHA except at 5% where they were higher than the control. On the other hand, the incorporation of RCA decreased the compressive strength but improved the PC hydraulic properties. CO2 emission and production cost were found reduced with increase in SHA as well as RCA. The maximum reduction of CO2 emission (38.23%) and production cost (51.29%) were obtained when 25% SHA was combined with 100% RCA. The combined usage of SHA and RCA as raw materials in PC was found to be effective in boosting PC's hydraulic properties at an appropriate compressive strength. The reduction of CO2 discharge and in production cost attributed to the construction materials demonstrates their impacts on mitigating global warming problems and lowering costs of PC production.

Geometrical, physical, mechanical, and compositional characterization of recycled concrete aggregates

Recycling, being one of the strategies in minimizing waste, offers three benefits: it lessens the demand for new resources, reduces transportation and production energy costs, and beneficially reutilizes waste, which would otherwise be lost in landfill sites. While it is believed that recycled concrete aggregate (RCA) can be effectively incorporated in new concrete, its use is limited, mostly due to the absence of effective characterization of RCA. Current specifications and characterization methods mostly include only basic parameters such as specific gravity and absorption, which are not necessarily representing critical properties such as mechanical properties, residual mortar content, and freeze/thaw resistance. Many test methods that are currently used for RCA are either not suitable for RCA or present human error in the procedure and thus not accurate and repeatable. The goal of this study is, therefore, to develop a testing protocol to characterize RCA effectively. A set of different test methods were used in this study to evaluate RCA collected from various sources. Test methods to identify aggregate crushing value and residual mortar content were modified to accurately characterize a variety of RCA without excessive variability introduced by human factors. The freeze-thaw resistance test with a modified data analysis protocol proved to be capable of differentiating the level of air-entrainment of parent concrete. Aggregate shape and texture were shown to significantly impact the void content of an aggregate granular matrix. A better understanding of RCA physical, mechanical, and compositional properties was achieved, which is critical in designing new concrete and evaluating the effect of RCA on new concrete. The success of the study will greatly encourage the use of RCA in daily concrete production and ultimately lead to a cleaner and more sustainable concrete production.

Use of waste glass and demolished brick as coarse aggregate in production of sustainable concrete

Reduction, recycling, and repurposing of waste materials continue to be an important part because they protect natural resources from further depletion and reduce greenhouse gas emissions and lead to a more sustainable environment. In this research, we have identified whether it is possible to use recycled glass waste and demolished bricks as a substitute for natural coarse aggregate in conventional concrete mixes. Crushed waste glass aggregate (WGA) and demolished brick (DB) are used in the concrete mix to replace the coarse aggregate in the mix was varied from 0%, 25%, 50% and 100% by weight. Three, seven, and twenty-eight-days curing of concrete cubes with dimensions of 150x150x150mm and concrete cylinders with dimensions of 100 mm diameter by 200 mm were used to conduct mechanical tests. A total of 80 concrete cube specimens and 40 concrete cylinder specimens were made for investigating the effect of WGA and DB. It is revealed by the slump tests result that the workability of concrete decreases with increasing amounts of glass and demolished brick. When comparing the hardened concrete to the control concrete, the compressive and split tensile strengths of the hardened concrete decreased as the waste glass content in the hardened concrete increased. But the concrete mix containing 50% waste glass and 50% demolished brick outperformed the control concrete by a significant margin and could be used to produce standard concrete with only minor modifications as compared to control concrete.

Application of mine tailings sand as construction material – a review

Tailings are found during the exploration and processing of mineral ores. They contain a mixture of grounded rocks, processed effluent, and some trace elements that have the potential to damage the environment. Recent urbanisation has led to a large stockpile of tailings in many mining environment constituting health hazard. It becomes very important to develop disposal techniques that will reduce the huge mountain of tailings in mining environment. One of such method is the application of tailings in sustainable concrete production. It is shown that physical and chemical characteristics of tailings are comparable to crusher sand used in engineering construction and therefore, tailings can be used to partially replace sand in bituminous and concrete mixtures. In this review, specific interest has been given to iron, copper, and gold tailings, this is due to their dominance in mining areas of Kwa-Zulu Natal province of South Africa.

Performance of manufactured aggregate in the production of sustainable lightweight concrete

This study examines the performance of lightweight concrete incorporating manufactured lightweight aggregates with industrial by-products. The physical and mechanical properties of cold-bonded aggregates manufactured through pelletization technique with 80% fly ash, 10% cement, and 10% metakaolin with the addition of 0.2% alkali-resistant glass fibers. The manufactured aggregates have been tested with different properties like production efficiency, bulk density, specific gravity, water absorption, and impact strength thereby compared with natural aggregate results. Further, the study on properties of lightweight concrete produced with the replacement of ordinary portland cement (OPC) by ground granulated blast furnace slag (GGBFS) at different percentages varies from 0% to 50%. The lightweight concrete performance was assessed based on the slump cone test, density, compressive strength, split tensile strength, and water absorption at different curing ages. It was noticed from the results that the optimum performance of lightweight concrete was attained at 40% replacement with GGBFS. It is observed from the results that the replacement of natural aggregate by manufactured aggregates and cement by GGBFS achieved desired strength to be used as a structural material. Usage of industrial by-products in aggregates and concrete production results in both economic and environmental benefits.

Experimental Evaluation of Recycled Aggregates, Washing Water and Cement Sludge Recovered from Returned Concrete

In this paper, a new innovative technology for the treatment of returned concrete is proposed. This method is based on the application of physical–mechanical processes that allow to obtain new quality products: recycled aggregates, microfiltered water and cement sludge. Specifically, by means of a mechanical system equipped with buffer and Archimedes screws, fine (d < 5 mm) and coarse (d > 5 mm) aggregates are obtained. The water coming from the washing process is sent to a microfiltration process, where a filter membrane separates the liquid phase (microfiltered water) from the solid phase (cement sludge) and no type of potentially toxic additive is added. In this context, this paper investigates the feasibility of using all these components as new raw materials for sustainable concrete production. In particular, according to the requirements imposed by technical standards, an experimental program was developed, aimed at evaluating the physical, chemical, and mechanical properties of the analyzed materials. The results showed that both recycled aggregates, the microfiltered water and the cement sludge can be used to produce new structural concrete. In particular, it was proven that also the cement sludge, which generally represents the most critical component destined for disposal, can be reused as filler in the partial replacement of sand.

Effect of Calcination on the Chemical and Microstructural Properties of Rice Husk Ash

This research study is aimed to evaluate the effects of different calcination temperatures on the properties of rice husk ash such as the chemical and microstructural properties. Rice husk ash is not utilized properly; it is not dumped with proper handling which is also causing environmental issues. Currently researchers are working on supplementary cementitious materials in concrete, in light of which, this research study is aimed to evaluate the effects of burning on Rics Husk Ash (RHA) structure and its pozzolanic reactivity for utilizing it in concrete. The rice husk is burnt at temperatures of 600-800°C for a duration of 8, 16 and 24 hours and for evaluating different chemical and structural properties through tests of X-ray Diffraction (XRD), X-Ray fluorescence (XRF) and Fourier Transform Infrared Spectroscopy (FTIR). It is concluded that burning of rice husk at 600-800°C for duration of 24 hours gives us more reactive and amorphous material and can be used as a cement substitute for sustainable concrete production.

Synergic effect of metakaolin and groundnut shell ash on the behavior of fly ash-based self-compacting geopolymer concrete

The sustainable self-compacting geopolymer concrete (SCGC) production is an eco-efficient concrete with a lower carbon footprint than conventional concrete. This experimental work was performed on the fly ash based SCGC mixtures which blended metakaolin and groundnut shell ash individually and combined them into 5–20% with an increment of 5% as replacement of fly ash in the mixtures. The main theme of this research work is to determine the fresh properties in terms of filling ability (slump flow, V-Funnel and T50 flow) and passing ability (J-Ring and L-box) tests and hardened properties in terms of compressive, splitting tensile and flexural strengths, and water permeability of the SCGC mixture. However, a total of 260 concrete specimens were made and tested at 28 days. The outcomes of this research work revealed that the addition of metakaolin and groundnut shell ash separate and combined as partial replacement of fly ash in the SCGC mixtures that causes a reduction in the workability, while the hardened properties of SCGC are significantly enhanced by using metakaolin and groundnut shell ash individually and combined up to 10% by the weight of fly ash. Moreover, the compressive, splitting tensile and flexural strengths of SCGC were measured as 56.42 MPa, 4.68 MPa and 5.12 MPa for the mix contained 5% of groundnut shell ash and metakaolin together at 28 days, respectively. Furthermore, the water penetration depth declined as the extent of metakaolin and groundnut shell ash as replacement of fly ash separate and combined rises in the mixtures.

The Effect of Nanomaterials on the Properties of Limestone Dust Green Concrete

Portland cement is considered the most involved product in environmental pollution. It is responsible for about 10% of global CO2 emissions [1]. Limestone dust is a by-product of limestone plants and it is produced in thousands of tons annually as waste material. To fulfill sustainability requirements, concrete production is recommended to reduce Portland cement usage with the use of alternative or waste materials. The production of sustainable high strength concrete by using nanomaterials is one of the aims of this study. Limestone dust in 12, 16, and 20% by weight of cement replaced cement in this study. The study was divided into two parts: the first was devoted to the investigation of the best percentage of replacement of waste lime. The second part of the study evaluated the performance of concrete when adding nanomaterials. Three percentages of cement replacement 0.5%, 1%, and 1.5% with nano-Al2O3 were used. The most efficient content of hydrated lime used in this study which achieves sustainability and maintains the quality of concrete was (16%). On the other hand, it was found that the best percentage of nano-Al2O3 as a partial replacement of cement is 1.5%.