Concrete Mix Design Research Articles

Sustainable Concrete Mix Design with Zeolite as Partial Cement Replacement

Sustainable Concrete Mix Design with Zeolite as Partial Cement Replacement

Effectiveness of the Concrete Equivalent Mortar Method for the Prediction of Fresh and Hardened Properties of Concrete

Modern concrete mix design is a complex process involving superplasticisers, fine powders, and fibres, requiring time and energy due to the high number of trial tests needed to achieve rheological properties in the fresh state. Concrete batching involves the extensive use of materials, time, and the testing of chemical admixtures, with various methodologies proposed. Therefore, in some instances, the required design properties (physical and mechanical) are not achieved, leading to the loss of resources. The concrete equivalent mortar (CEM) method was introduced to anticipate concrete behaviour at fresh and hardened states. Moreover, the CEM method saves time and costs by replacing coarse aggregates with an equivalent sand mass, resulting in an equivalent specific surface area at the mortar scale. This study aims to evaluate the performance of fibre in CEM and concrete and determine the relationships between the CEM and the concrete in fresh and hardened states. Steel and polypropylene fibres were used to design three series of mixtures (CEM and concrete): normal-strength concrete (NSC), high-strength concrete (HSC), high-strength concrete with fly ash (HSCFA), and equivalent normal-strength mortar (NSM), high-strength mortar (HSM), and high-strength mortar with fly ash (HSMFA). This study used three-point bending tests and digital image correlation to evaluate load and crack mouth opening displacement (CMOD) curves. An analytical mode I crack propagation model was developed using a tri-linear stress–crack opening relationship. Post-cracking parameters were optimised using inverse analysis and compared to actual MC2010 characteristic values. The concrete slump is approximately half of the CEM flow; its compressive strength ranges between 78% and 82% of CEM strength, while its flexural strength is 60% of CEM strength. The post-cracking behaviour showed a significant difference attributed to the presence of aggregates in concrete. The fracture energy of concrete is 28.6% of the CEM fracture energy, while the critical crack opening of the concrete is 60% of that of the CEM.

Properties of concrete containing spent garnet as fine aggregate replacement

Abstract The use of river sand as a construction material has become a critical concern in many countries. Excessive mining for concrete production is one of the main issues that lead to environmental pollution. Simultaneously, environmental concern over discarding spent garnet from industry have led to research on using it as a partial replacement for fine aggregate in concrete. Different mixtures incorporating 10 %, 20 %, and 30 % spent garnet were studied to assess their impact on concrete’s workability, mechanical strength, and durability. This study used a concrete mix design to create concrete mixes for 48 cubes. Three types of tests such as slump, compressive strength, and water absorption test were conducted to evaluate the concrete’s properties. The findings indicate that as the amount of spent garnet used in concrete increases, the concrete becomes more workable. The optimum strength results were achieved when 20 % of the fine aggregate was replaced with spent garnet. Furthermore, concrete with up to 20 % spent garnet had lower water absorption compared to the control mix. Utilizing spent garnet as a substitute for sand in construction not only fosters sustainability but also addresses the challenge of effective waste disposal.

Learning On Concrete Performance Using E-Waste for Partial Coarse Aggregate Replacement

Abstract: Concrete holds a significant position in engineering, and its philosophy may be altered by substituting or adding substances that might prove more practical. This research presents a learning of concrete in which E trash is used to partially replace coarse material. M-30 grade concrete to be used in this project's concrete mix design. With the assistance of Indian standard codes according to specification, the qualities and attributes of materials for cement, coarse aggregate, and fine aggregate, and other supplemental components were investigated for concrete mix design. The split tensile strength, compression strength, and different coarse aggregate replacements (0%, 10%, 15%, and 20%) will be examined. M sand will be substituted for fine aggregate.

Characterization of porosities and optimization of mix design of pervious concrete using image analysis

Although pervious reduces surface runoff and replenishes groundwater resources, industrial applications are hindered by uncertainty in properties during mass productions. Most experimental studies correlated design parameters to performance parameters predominantly analysing porosity measured from water replacement method. This explains only a fraction of porosity and leads to inappropriate correlations between the influencing parameters. This study quantified porosity using a novel image analysis. 480 samples of pervious concrete were cast varying aggregate to cement ratio and compaction levels and performance parameters such as, wet-density, compressive strength, apparent, actual and effective porosities were assessed. The developed novel image analysis method facilitates accurate computation of porosity and actual, apparent and effective porosities was analysed quantified and optimised. An optimum A/C ratio was observed as 4.0 corresponding to 30 blows of compaction and a resultant actual porosity of approximately 0.2. Further the study establishes relationships between different types of porosities and their performance implications.

Machine learning guided iterative mix design of geopolymer concrete

Current mix design methods for Geopolymer concrete (GPC) require substantial efforts of trial-and-error experiments and is applicable only to those formulated by specific precursor materials. In this work, a machine learning (ML) guided mix design method for GPC is proposed, which can considerably reduce the experimental workload and be versatile with a broad range of precursor materials. First, a database for the slump and compressive strength of GPC was established, and ML prediction models were developed with these as objectives. Subsequently, the mix design for GPC was conducted using the particle swarm optimization (PSO) algorithm. The designed mixture proportions underwent experimental validation, and if targets were not met, results were then used for model iteration until desired performance targets were achieved. The results showcase the excellent performance of the established slump and compressive strength prediction models, with an accuracy and coefficient of determination of 94 % and 0.95, respectively. The developed ML guided model effectively generates concrete mix achieving compressive strengths of 20 MPa, 40 MPa, and 60 MPa, while concurrently satisfying slump requirements. The experimentally validated results for the three designated target strengths after iterations were 25.2 MPa, 43.8 MPa, and 66.6 MPa, respectively. These positive results emphasize the ability of the proposed optimized mix design method to meet both the strength and workability targets in GPC via a minimum number of trail experiments.

Mix design strategy and optimization considering characteristic evaluation of geopolymer concrete

In this study, a unique strategy for mix design of geopolymer concrete (GPC) was suggested by integrating fly ash, silica fume, and GGBFS as precursors with varied alkali activator molarities in both ambient and oven curing environments. GPC's crystalline and microscopic qualities were assessed by X-ray diffraction and scanning electron microscopy tests; while its' mechanical properties were assessed using compressive strength test (CST). The experimental results showed a rising trend between the alkali activator (NaOH) concentration and the compressive strength of the GPC. GGBFS precursor based GPC had the highest compressive strength of 87.53 MPa at 14 molarity of NaOH after oven curing at 60°C. Furthermore, Artificial Neural Network (ANN) and Response Surface Method (RSM) were used to evaluate significant correlation and interaction between different parameters considered in mix design. By incorporating six input variables from the experimental test data, namely total precursor content used, secondary precursor content used, curing temperature, number of curing days, total aggregate content, and molarity of NaOH used, and compressive strength as output/response variable. The R-value for ANN found to be 0.99, while the R2 value for the RSM model was 0.98, indicating a satisfactory fit having a good interaction and optimization of GPC parameters. The optimize values of different independent parameters evaluated can obtain maximum CST value of 111.104 MPa.

Energy Storage in Lightweight Aggregate and Pervious Concrete Infused with Phase Change Materials

This study explores the feasibility of utilizing pervious concrete (PC) incorporating diverse lightweight aggregates (LWAs) integrated with phase change materials (PCM) for applications where forced air cooling would be advantageous. The use of such a component provides latent and sensible heat that can cool forced air applications, offsetting ambient temperature increases that occur during the day. Macro- and microencapsulation techniques were used to incorporate inorganic PCM in the PC. The macro-encapsulation technique involved enclosure of PCM within a stable shell prior to addition into the concrete. The microencapsulation technique involved the impregnation of PCM into porous lightweight aggregate. To overcome the PCM reaction with the concrete constituents, an epoxy coating was utilized. The design of the PCM concrete mix and comprehensive laboratory assessment of porosity, water permeability, PCM absorption capacity, compressive strength, and microstructure of the LWAs are detailed. The test results indicate that LWAs have high PCM impregnation rates ranging from 32 % to 57 % by volume. The compressive strengths of PC using LWAs were reduced by 25 % to 65 % when using microencapsulation. The use of microencapsulation was found to reduce the pressure drop under air flow due to the increase in aggregate size as a result of the coating thickness. PCM-PC with a shell thickness of 100 mm, resulted in a pressure drop of less than 100 Pa at a velocity of 0.35 m/s. The use of macro-encapsulated PCM in PC was sensitive to the phase of the PCM, where the liquid phase reduced the compressive strength by 67 %. The failure occurred within the macro-encapsulated PCM at the liquid phase temperatures and at the interface between the encapsulated PCM at solid phase temperatures. The heat transfer provided by the LWA infused PCM when used in a packed aggregate bed or in PC, was shown to match expected latent and sensible heat estimates based on the thermal properties of the materials. This systematic investigation provides valuable insights into LWAs and PCM performance in pervious concrete, offering a comprehensive understanding of their interaction in cooling applications.

Optimization of concrete mix design for enhanced performance and durability: integrating chemical and physical properties of aggregates

Optimization of concrete mix design for enhanced performance and durability: integrating chemical and physical properties of aggregates

Parametric study on the decarbonization potential of structural system and concrete mix design choices for mid-rise concrete buildings

Mid-rise reinforced concrete buildings are projected to continue being the predominant typology for urban development. Thus, reducing the carbon footprint of such buildings is critical for achieving a sustainable built environment. Reducing the amount of concrete and steel in a building through structural and mix design optimization is identified as a primary resource efficiency strategy. This paper is among the first to present evidence of the decarbonization potential of these dematerialization strategies on a building level. The study combines structural design choices such as slab system design, steel reinforcement optimization and span width with materials-based strategies, such as low binder concrete and low-carbon binders. For each scenario, material quantities are calculated following design prescriptions by EN1992–1–1 while state-of-the art life cycle inventory data are adopted to calculate the carbon footprint. Results show that shifting towards more efficient structural systems (i.e., waffle slab system) could save up to 20% of the carbon footprint on the building level compared to more traditional systems, such as slab on beams and flat slabs. In addition, reducing the spans from 7.5 to 5 m can save up to 20% more. Finally, the use of low-clinker cement in low-binder concrete can save another 50% in terms of CO2 impact per built-up area. Realistically, results of the case study concluded that implementing these three strategies could reduce the typical 232 kg CO2e/m2 value of the carbon footprint of structural elements of a mid-rise building up to only 58 kg CO2e/m2, i.e., a four-fold reduction.

Physico-mechanical and thermal properties of vibrating and self-compacting sand concrete based on recycled aggregate from concrete

This study explores the use of recycled aggregates (RA) from concrete, replacing 100% of Cruched Sand (CS) by volume. It focuses on their processing methods and their performance compared to Self-Compacting Sand Concrete (SCSC) and Vibrated Concrete (VC). Fresh properties, including workability, are affected by RA, but RA-based SCSC meets standards. While RA-based SCSC initially had lower strength than CS-based SCSC, it improved after 28 days, yielding similar mechanical properties. RA use led to lower density compared to CS in concrete. Thermal conductivity was insulating, slightly lower in RA-based SCSC. Porosity decreased with age in all mixtures, with RA-based concrete having initial higher porosity and capillary absorption. Microstructure showed finer crystal growth in RA-based concrete. RA in SCSC exhibit a superior Interfacial Transition Zone (ITZ) compared to CS concrete, enhancing homogeneity and durability. This research supports sustainable RA use in concrete, that contingent on precise mix design and method processing of waste concretes, as well-designed SCSC. RA in construction provide scalable and economic benefits, including cost savings, infrastructure investment, sustainability, and market expansion. This contributes to the provision of environmentally friendly building materials and the sustainability of the industry.

Effect of mix dosage on rubberized concrete mechanical performance: A multivariable prediction model towards design provisions

The accumulation of end-of-life tires generates significant environmental/economic/social problems worldwide; however, these tires can potentially be used in engineering applications when recycled as crumb rubber (CR). One possibility is to use CR as a replacement for river sand in concrete to reduce the disposal of CR and the use of sand as well as to improve some of concrete’s properties, such as thermal performance and carbon footprint at the expense of some compressive strength reduction. In this study, a novel and simple multivariable model was developed to predict the compressive strength reduction of rubberized concrete (RC) based on a dataset of 287 concrete mixtures from 38 different studies. The approach used in this study quantified the significance of the impact of 10 mix design variables on the evaluation of compressive strength reduction. The final model proposed in this paper considers six explanatory variables (i.e., volume replacement of sand by CR, CR quantity, fine aggregate quantity, coarse aggregate quantity, cement quantity, and water quantity) to predict the compressive strength reduction in which a logarithmic transformation was implemented to achieve a more precise model. The proposed model reached a coefficient of determination of 0.89, significantly better than other existing models with which the proposed model was compared, resulting in a highly accurate and yet easy-to-implement model. Finally, practical design considerations were provided to be used in concrete mix design or the design of minor structural elements.

Experimental Investigation of Sustainable Concrete Production using Blast Furnace as A Cement Substitute- A art of Review

The pursuit of sustainable construction practices has led to a growing interest in alternative materials that can reduce the environmental impact of traditional concrete production. This experimental study focuses on the utilization of blast furnace slag as a substitute for cement in concrete, aiming to assess its mechanical properties, environmental impact, and overall sustainability. The primary objectives of this research are threefold. Firstly, the study seeks to evaluate the mechanical properties of concrete by varying the content of blast furnace slag in the mix, with a specific emphasis on strength, durability, and structural performance. This involves conducting a comprehensive analysis of the concrete's compressive strength, flexural strength, and other relevant mechanical characteristics. Secondly, a life cycle assessment (LCA) will be employed to analyze the environmental impact of the concrete mixtures. This assessment will compare carbon dioxide (CO2) emissions, energy consumption, and overall sustainability of the concrete produced with varying percentages of blast furnace slag. The LCA will provide valuable insights into the environmental implications of using slag as a cement substitute, aiding in the identification of eco-friendlier concrete production practices. Lastly, the research aims to assess the environmental impact of blast furnace slag itself when employed as a cement substitute. This involves examining the production, transportation, and incorporation of blast furnace slag into the concrete mix, providing a holistic view of its sustainability across the entire life cycle. The experimental approach involves the meticulous design of concrete mixes with different percentages of cement replaced by blast furnace slag. The varying mix designs will be tested for mechanical properties, and the data obtained will be used to draw correlations between slag content and concrete performance. In summary, this research endeavors to contribute to the body of knowledge surrounding sustainable concrete production by exploring the mechanical, environmental, and sustainability aspects of utilizing blast furnace slag as a cement substitute. The findings of this study are anticipated to provide valuable insights for the construction industry to adopt more environmentally friendly practices while maintaining or enhancing concrete performance.

Modification of Concrete Mix Design with Crystalline Admixture for Self-healing Improvement

Modification of Concrete Mix Design with Crystalline Admixture for Self-healing Improvement

Low carbon concrete for prefabricated modular construction in circular economy: An integrated approach towards sustainability, durability, cost, and mechanical performances

The construction industry accounts for significant global resource consumption and carbon emissions through cement production, concrete mix design and building operation, which can be affected by the constituent composition, mechanical and thermal performance of concrete mix. Prefabrication and circular economy nowadays can be a game-changer for the construction industry. This study investigates the effects of concrete mix design on the sustainability, carbonation-induced durability, cost, and mechanical performances of a standard module of prefabricated modular construction throughout the whole life cycle in circular economy. Sixteen concrete mixes, including ordinary Portland cement (OPC) concrete blended with supplementary cementitious materials, ultra-lightweight cement composite (ULCC) with calcined clay and limestone replacement, and foam concrete, are examined. Comprehensive life cycle cost, mechanical, durability and sustainability assessments are conducted for the concrete mixes, considering expected service lives of 50, 100, and 150 years. Results indicate that prolonging service life from 50 years to 150 years in circular economy can improve the annual sustainability performances by up to 20 %. Utilizing lightweight concrete (ULCC and foam concrete) can reduce energy consumption for air-conditioning by 17 % and decrease transportation-related costs by from 30 % to 15 %. ULCC mix demonstrates superior overall performance due to its reduced weight, low thermal conductivity, and enhanced durability, showing improvements up to 25 % compared to OPC concrete.

Effect of uniaxial loading on the spalling of concrete panels for Melbourne's Metro Tunnel Project

AbstractThe Metro Tunnel is a Victorian Government funded infrastructure project which will create a new end‐to‐end rail line from Sunbury in the west to Cranbourne/Pakenham in the south east, with bigger and better trains, next generation signaling technology and five new underground stations. This article provides a detailed summary of the structural fire testing requirements for the platform tunnel side wall and arch lining in the Metro Tunnel's State Library and Town Hall stations. Contrasted to building fires, tunnel fires are more significant within a few minutes due to the confined space which can cause concrete spalling and jeopardize the bearing capacity of the tunnel, which is a significant concern to designers. The catastrophic European tunnel fire events in 1999 and 2001 led to the development of innovative regulations and recommendations, including guidelines endorsed by the European Federation of National (EFNARC 132F r3:2006) and Efectis R0695:2020. This paper explains the methodology taken to design the fire rated concrete test for the platform tunnel side wall and arch lining in the State Library and Town Hall stations of Melbourne's Metro Tunnel Project for structural stability for the period of a serious fire event. For the first time, uniaxial loading (500T) was applied to five large‐scale flat concrete panels (1800 × 1800 × 400 mm) which are normally unloaded during fire exposure and exposed to the RABT ZTV (rail) fire curve. The first testing program investigated the influence of polypropylene dosage in the concrete mix design and its effect on the magnitude and severity of concrete spalling. The results indicated that the recommended 2.0 kg/m3 polypropylene dosage requirement as specified by Eurocode is conservative. Concrete mix designs with a stable aggregate and the correct curing regime can mitigate spalling at significantly lower polypropylene dosage rates. The water pooling effect was evident during the fire testing and the surface cracking that developed was vertical to the surface, allowing for the release of the pore water pressure build‐up.

Investigating the rheological characteristics of alkali-activated concrete using contemporary artificial intelligence approaches

Abstract Using artificial intelligence-based tools, this research aims to establish a direct correlation between the alkali-activated concrete (AAC) mix design factors and their performances. More specifically, the machine learning system was fed new property data obtained from AAC mixes used in laboratory experiments. The rheological parameters (yield stress [static/dynamic] and plastic viscosity) of AAC were predicted using the multilayer perceptron neural network (MLPNN) and bagging ensemble (BE) models. In addition, the R 2 values, k-fold analyses, statistical checks, and the dissimilarity between the experimental and predicted compressive strength were employed to assess the performance of the created models. Also, the SHapley additive exPlanation (SHAP) approach was used for examining the relevance of influencing parameters. The BE approach was found to be significantly accurate in all prediction models, with R 2 greater than 0.90, and MLPNN models were found to be moderately precise, with R 2 slightly below 0.90. However, the error assessment through statistical checks and k-fold analysis also validated the higher precision of BE models over the MLPNN models. Building models that can calculate rheological properties of AAC for different values of input parameters could save a lot of time and money compared to doing the tests in a laboratory. In order to ascertain the required amounts of raw materials of AAC, investigators, as well as businesses, may find the SHAP study helpful.

Additively manufactured steel reinforcement for small scale reinforced concrete modeling: Tensile and bond behavior

Small scale (∼1:30–1:40) Reinforced Concrete is useful for centrifuge testing. However, manufacturing the reinforcing cages by hand at this scale is practically difficult. This paper suggests that small scale reinforcement can be manufactured using a metal 3D printer. Mechanical properties of 3D printed submillimeter rebars are discussed and compared to properties of typical prototype rebars. Different model concrete mix designs are tested to identify optimal mixes. Pullout tests of rebars with different surface rib configurations embedded in different concrete mixes are discussed.Based on the test results, by modulating the printing parameters it seems feasible to obtain 3D printed submillimeter bars that can be used as physical models of prototype rebars. A gypsum-based model concrete was more similar to prototype concrete than cement-based mixes. Most importantly, bond slip behavior that is comparable to full-scale concrete could be achieved, something that is vital and has never been reported before.

Mix design optimisation of self-sealing concrete containing microcapsules with polyurethane shell and water repellent cargo

Despite the robust ability of microcapsules (MIC) to break and release agent for healing/sealing efficacy, the reduction of concrete strength has been a major issue when using MIC. In this study, the optimisation of concrete mix design was initiated with employing three main parameters: MIC size (56, 93 μm), MIC dosage (0, 3, 6% by weight of cement) and water-cement (w/c) ratio (0.40, 0.50, 0.60). The used microcapsules consisted of water repellent agent core acting as a sealing agent and polyurethane as the shell material. Results confirmed the MIC dosage as the most significant factor affecting the mechanical properties, while no significant effect on the MIC size. Further, the MIC effect can be reduced by changing the concrete mix design from low to high w/c. The sealing efficiency of concrete was remarkably improved with the inclusion of MIC and a good bond between the capsules and concrete matrix was attained.

Exploring the physical and mechanical characteristics of multi-generation recycled aggregate concrete at equivalent compressive strengths

The concrete industry has been responsible for significant depletion of natural resources and at end-of-life significantly contributes to global waste production. To date experimental studies have typically explored the use of single generation recycled aggregates (RA) in concrete production, however, to move towards a circular economy the concrete industry needs to embrace the use of multi-generation recycled aggregate concrete (MGRAC). In this paper the physical and mechanical performance of 45 concrete mix designs over 4 generations of concrete production is explored. At each generation a series of mixes are conducted at various water to cement ratios (w/c) and with a range of blends of virgin and recycled aggregates from differing generations to capture the impact on material properties. The physical and mechanical properties are quantified for both the aggregates and the concretes at each generation. The results show that the physical properties and some mechanical properties of the concrete and RA decrease with respect to virgin aggregate concrete and virgin aggregate but, implementing a 50% replacement of VA can slow down intergenerational degradation. Furthermore, the blending RA from a range of generations can also slow intergenerational degradation but to a lesser extent. Effective aggregate properties are determined, and direct relationships confirmed indicating potential for informed mix design based on an understanding of a few simple aggregate properties.