Mix Proportions Research Articles

Effect of Macroscopic Composition on the Performance of Self-Compacting Concrete

In recent years, there has been significant interest in the development of self-compacting concrete (SCC). This study views SCC as a two-phase composite material and introduces a new aggregate spacing coefficient model based on the concept of Fullman’s mean free path and stereological theory. The validity of the aggregate spacing coefficient model was verified. The relationship between the fine and coarse aggregate coefficients and the properties of SCC are revealed. The results show that the slump and slump flow of SCC increase as the fine and coarse aggregate coefficients increase. The coarse aggregate spacing coefficient has a significant influence on the compressive strength and drying shrinkage of SCC. A significant linear relationship between the coarse aggregate spacing coefficient and SCC dry shrinkage properties is revealed. Compared to the conditional mixing proportion method, which considers the aggregate volume as a control factor, the aggregate spacing coefficient takes into account the aggregate volume and gradation, which can more accurately reflect the characteristics of the aggregate. Meanwhile, this new perspective on the macroscopic composition of SCC provides insights into the controlling factors of its performance.

AI-driven Modeling for the Optimization of Concrete Strength for Low-Cost Business Production in the USA Construction Industry

The need to develop ecologically friendly sustainable building materials is made apparent by the worldwide construction industry's substantial contribution to global greenhouse gas emissions. The use of supplemental materials in concrete is one potential solution to lessen the environmental footprint. Thus, the purpose of this work is to use Machine Learning (ML) algorithms to forecast and create an empirical formula for the Compressive Strength (CS) of concrete with supplemental materials. Six distinct ML models—XGBoost, Linear Regression, Decision Tree, k-Nearest Neighbors, Bagging, and Adaptive Boosting—were trained and tested using a dataset that included 359 experimental data of varying mix proportions. The most significant factors used as input parameters are cement, aggregates, water, superplasticizer, silica fume, ambient curing, and supplemental material. Several statistical measures, such as Mean Absolute Error (MAE), coefficient of determination (R2), and Mean Square Error (MSE), were used to evaluate the models. XGBoost model outperformed the other models with R2 values of 0.99 at the training stage. To ascertain how the input parameters affected the outcome, feature importance analysis using Shapely Additive exPlanations (SHAP) was conducted. It was demonstrated that curing age and cement type significantly affected the strength of concrete with high SHAP values. By eliminating experimental procedures, reducing the demand for labor and resources, increasing time efficiency, and offering insightful information for enhancing sustainable manufacturing of concrete, this research advances the low-cost production of concrete in the USA construction industry.

Utilizing municipal solid waste incineration fly ash for mine goaf filling: Preparation, optimization, and heavy metal leaching study.

Municipal solid waste incineration fly ash (MSWI FA) contains many harmful substances, such as heavy metals, which pose a great threat to the ecological environment. Its proper disposal is an urgent environmental problem that needs to be addressed. The large number of goaf areas in China's mines provides a new approach for MSWI FA treatment. Scientifically processed MSWI FA can be used for goaf filling; this reduces the stockpile of MSWI FA and improves the safety of mine goaf areas. In this study, paste backfill was prepared using MSWI FA and slag as cementitious materials and coal gangue as aggregates under the composite excitation of sodium hydroxide and water glass. The optimal mix ratio was determined using response surface methodology, and the leaching trend of the heavy metal ions inside the material and the micro mechanism of strength formation were studied. Molecular dynamics simulations were used to further examine the leaching pathways of the heavy metal ions. The experimental research showed that the optimal mix proportions of the backfill were 81.65%, 3.67% and 52.27% for the mass concentration, aggregate-to-cement ratio and fine gangue ratio, respectively. The main polymerization products were C-(A)-S-H and N-A-S-H silicate gel, and small amounts of ettringite (AFt), calcium aluminate chloride (3CaO • Al2O3 • 3CaCl2 • 30H2O) and CaCO3 were generated. Through Materials Studio (MS) software, the leaching pathway of the heavy metal ions in the backfill and the adsorption performance between the ions were examined, and the influence of the C-A-S-H gel on the leaching rates of the heavy metal ions of Pb2+, Cr3+, and Cd2+ was explored. The leaching rate was ranked as Pb2+>Cr3+>Cd2+. In this study, a pollution-free and structurally stable mine paste backfill material was prepared using MSWI FA solid waste.

Utilizing linear and nonlinear ultrasound for improved estimation of concrete strength

ABSTRACT This study investigated non-destructive concrete strength evaluation using in-situ cored samples. Data from various mix proportions and design strengths revealed inconsistent correlations between compressive strength and linear ultrasonic wave velocity (V p). This inconsistency arises because V p captures only linear elastic behaviour, whereas concrete strength reflects both linear and nonlinear behaviours. In contrast, the acoustic nonlinearity parameter (β re) exhibits superior sensitivity to microstructural conditions owing to its direct link to material nonlinearity. We proposed a new integrity index (M/β*) by combining the constrained modulus (M) derived from V p with β re to capture the entire elastic behaviour. This index demonstrated statistically significant correlation with the factor of safety (FS) across different design strengths and mix proportions. Next, we developed a risk stratification system based on M/β* using fuzzy c-means clustering, categorising concrete into three risk zones: critical (M/β* <40), moderate (40 < M/β* <75) and low (M/β* >75), providing a quantitative tool for assessing concrete quality. The results highlight the importance of integrating linear and nonlinear ultrasonic parameters for accurate strength prediction, particularly in field conditions where traditional V p–strength correlations are unreliable. This approach offers a new method for non-destructive concrete strength detection, thereby enhancing structural safety assessments.

A Study on Reactive Ultra-Fine Fly Ash and Sulfoaluminate Cement in Self-Leveling Mortar

The purpose of this study is to find appropriate mixtures for self-leveling mortar that meet the fluidity requirements without displaying segregation by using a combination of two types of cement (Type I Portland cement and sulfoaluminate cement (SAC)) with reactive ultra-fine fly ash (RUFA). Unlike the fly ash, RUFA has a strong strength activity index and exhibits a significant pattern of amorphous phase in XRD. Appropriate mix proportions of raw materials, including the superplasticizer, require investigation in depth. A fixed water-to-binder ratio of 0.6 was selected, with varying proportions of the two cementitious materials considered (the SAC volume percentages were 0%, 10%, 20%, and 30%) and different RUFA contents (the RUFA volume percentages were 5%, 10%, and 15%). Twelve experiments were conducted to examine the properties of the self-leveling mortars. We found that a higher RUFA volume percentage results in lower porosity, higher compressive strength, and better resistance to drying shrinkage, abrasion, and restrained shrinkage cracking. Increasing the SAC volume percentage increases the porosity of self-leveling mortar and its early compressive strength but decreases late-stage strength. At a 10% volume percentage level, SAC achieves an ideal balance among drying shrinkage, brasion, and shrinkage cracking.

Degradation and mechanical properties of concrete made with metallurgical sludge waste in long-term

Metallurgical sludge waste (MSW), a by-product of mining, energy, and metallurgical industries, has shown potential as a substitute for traditional aggregates. This research article focuses on studying the properties of concrete incorporating MSW itself and recycled concrete aggregate (RCA) containing MSW at both early and late ages. Great emphasis is placed here on the tests carried out one year after concreting. A total of ten concrete mix proportions were prepared with varying amounts of MSW and RCA, including a reference mix. In order to investigate the effects and role of MSW on the durability properties of concrete mixes, several laboratory tests, their numerical evaluation and energy dispersive spectroscopy were carried out. The investigation aims to provide insights into the performance, durability and long-term behaviour of MSW concrete.

Durability, sustainability and cost analysis of the effect of SNF superplasticizers on locally produced concrete in Ghana

Using conventional methods of concrete production to achieve expected results is challenging, hence the use of chemical admixtures which is also little researched in Ghana. The study conducted a concrete mix design for project construction, following significant challenges encountered in attaining the desired strength of 30MPa at a slump of S3 (100-150mm). To address the challenge, a concrete mix design was produced according to EN 206 standard mix design at the laboratory of the Council for Scientific and Industrial Research (CSIR)-Building and Road Research Institute (BRRI)-Ghana. A chemical admixture consisting of high-range water-lowering sulfonated naphthalene formaldehyde (SNF) was used in the design. Once the laboratory mix design was completed, the concrete mix proportions were adopted for field application. When employing 385kg/m3 of Portland cement, a water-to-cement ratio of 0.49, a water content of roughly 189kg/m3, and an admixture content of 3.28kg/m3, the laboratory mix design yielded a 28-day compressive strength of 37 MPa (5366 psi). After 28 days of curing, both the laboratory (37MPa) and field-prepared (31MPa) concretes met the minimum strength of 30MPa with the laboratory-controlled concrete exhibiting compressive strength results that were approximately 16% greater than those of the field-prepared concretes. The report revealed that the use of SNF resulted in 18% savings in cement thereby reducing carbon emissions and 5% savings in cost, urging a case for the use of chemical admixtures for structural and non-structural concrete components of the project for the sake of durability, sustainability and cost.

The Application of X-Ray Fluorescence to Assess Proportions of Fresh Concrete

Any transportation infrastructure system is concerned with durability and performance issues. The proportioning and uniformity control of concrete mixtures are critical factors that directly affect the longevity and performance of concrete pavements. Currently, the only means available to monitor mix proportions of any batch are to track batch tickets created at the batch plant. This does not take into account potential errors in loading materials into storage silos, calibration errors, and addition of water after dispatch. Therefore, there is a need for a rapid, cost-effective, and reliable field test that estimates the proportions of as delivered concrete mixtures. In addition, performance based specifications will be more easily implemented if there were a way to readily demonstrate whether any given batch is similar to the proportions already accepted based on laboratory performance testing. This paper describes a preliminary investigation into the potential use of a portable x-ray fluorescence (XRF) technique to assess the proportions of concrete mixtures as they are delivered. Tests were conducted on the raw materials, paste and mortar samples using a portable XRF device. There is a reasonable correlation between the actual and calculated mix proportions of the paste samples, but data on mortar samples was less reliable.

NEED BASED ADVANCEMENTS IN MAKING CONCRETE PAVEMENTS

Presently, innovations in concrete pavements are completely changing its design and construction. New-age concrete of compressive strengths more than 200 MPa also has very high tensile strength with or without the inclusion of steel/ synthetic structural fibers. Similar types of concrete mix proportions are referred in IRC: SP: 83-2008 under “Early Opening to Traffic” (EOT) concrete pavements, for maintenance of rigid pavement. Among other special concrete, Self-Consolidating Concrete (SCC) eliminates the need of mechanical consolidation and electrical energy at site and yields a required surface finish without segregation and undulation. Recently, it has been recommended in IRC:SP-62-2014 for construction of low volume concrete pavements in villages where skilled labour and mechanical/ electrical energy may not be easily available. Other similar technologies which are cost effective and environment friendly are given as under: i) Recycled concrete pavements, ii) Roller compacted concrete pavements (IRC:68-2005), iii) Ultra high performance concrete pavements(IRC:SP:76-2015), iv) High volume processed fly ash concrete pavements (IRC:SP:68-2005), v) Fibre reinforced concrete pavements (IRC:SP:46-2013), vi) Continuously reinforced concrete pavements- IRC:118-2015, vii) No joint sealant concrete pavements as per ACPA viii) Two lift concrete pavement/bonded concrete pavement (IRC:58-2015) ix) Sound reduction technologies x) Evaluation of Rigid pavement using falling weight deflectometer (IRC:117-2015) The paper thus describes new, cost effective, ecofriendly and practically need based advancements for making good quality concrete pavements and their evaluation for saving time and energy which are essential requirements for more infra-structure development with the creation of more jobs to the semi-skilled younger generation.

Performance Evaluation and Microstructure Study of Pervious Concrete Prepared from Various Solid Waste Admixtures

Solid waste materials (SWM) are commonly used in the preparation of building materials due to their structural characteristics and chemical composition. Pervious concrete (PC) is a green infrastructure material that offers advantages such as reducing surface runoff and purifying water quality, making it an important component of sponge cities. This study aims to investigate the physical properties and micro-structure of PC prepared from various SWM and determine the optimal mix proportion. In this study, three common SWM, including muck, steel slag (SS) and fly ash (FA), are used as raw materials. The chemical composition and physical properties of SWM are analyzed. A five-level and five-factor test scheme is developed using the orthogonal test method. This scheme considers the target porosity, water–cement ratio, muck content, SS content, and FA content as variables. The mechanical properties and permeability of PC, including compressive strength, porosity and permeability coefficient are evaluated. The internal structure of PC is observed using a scanning electron microscope (SEM). The results indicate that the optimal mix proportion for preparing PC is determined through efficiency coefficient method analysis: target porosity of 25%, water–cement ratio of 0.36, muck content of 10%, SS content of 10%, and FA content of 12.5%. The corresponding performance indicators of the PC sample are measured as follows: porosity of 24.67%, compressive strength of 15.78 MPa, and permeability coefficient of 2.23 mm/s. This study provides valuable insights for the rapid and flexible batching and performance optimization research of PC based on SWM.

Optimizing mix proportioning of high-performance concrete using genetic algorithm

Optimizing mix proportioning of high-performance concrete using genetic algorithm

Optimizing concrete mix proportions with zeolite, GGBS, and CDW: a data-driven approach integrating experimental analysis and machine learning models

Abstract The depletion of natural sand resources and the environmental impact of cement production necessitate sustainable alternatives in concrete manufacturing. This study evaluates the potential of zeolite, ground granulated blast-furnace slag (GGBS), and construction and demolition waste (CDW) as partial replacements for sand in concrete mix proportions. Experimental investigations revealed that the optimal mix proportion, identified as Mix Batch M4 (60% Sand, 20% Zeolite, 10% GGBS, and 10% CDW), achieved a compressive strength (CS) of 67.37 MPa, flexural strength (FS) of 6.80 MPa, split tensile strength (ST) of 5.61 MPa, and notable reductions in water absorption (WA) to 4.00% and drying shrinkage (DS) to 4.02%. Additionally, durability improvements included a 30% reduction in rapid chloride permeability and enhanced ultrasonic pulse velocity (UPV) and rebound hammer (RH) values. Advanced machine learning models were utilized to analyze and optimize the mix designs, integrating the Sparrow Search Algorithm (SSA) with models such as Extreme Gradient Boosting (XGB), Backpropagation Neural Network (BPNN), Support Vector Regression (SVR), Random Forest Regression (RFR), Gradient Boosting Regression (GBR), and LightGBM. The XGB model demonstrated the highest predictive accuracy with an R2 of 1.000. Multi-objective optimization techniques, including Non-dominated Sorting Genetic Algorithm II (NSGA-II), Multi-Objective Particle Swarm Optimization (MOPSO), and Genetic Algorithm with Fuzzy models, were employed to refine mix proportions further, balancing mechanical properties, material sustainability, and environmental benefits. This study highlights significant reductions in natural sand consumption and waste generation while enhancing concrete performance. Practical implications include reduced environmental impact, improved resource efficiency, and the promotion of circular economy principles. These findings provide a pathway toward innovative and sustainable concrete solutions, aligning with global sustainability goals in the construction industry.

An Experimental Study on Foam Concrete By Partial Replacement of Cement using Rice Husk Ash and Silica Fumes

A type of lightweight aerated concrete called foam concrete lacks coarse particles, making it comparable to aerated mortar. Foam concrete is created when slurry and pre-formed foam are combined. The foam's job is to create air pockets in the slurry made of cement. The foam is made separately with a foam generator by diluting the foaming ingredient with water and aerating it. The slurry forms a shell surrounding the bubbles of foam, and as the foam begins to break down, the paste's strength keeps it in place around the air holes. The ratio of water to cement (w/c) typically varies from 0.4 to 1.25. As the quantity decreases, the foam concrete mixture becomes excessively rigid, which breaks the bubbles, However, when the combination's water content increases, it becomes too thin to support the bubbles, which causes the bubbles to separate from the mixture. You can make foam concrete with any dry density between 300 and 1850 kg/m3. In this experiment, there are two foam concrete mixtures created using silica fumes and rice husk ash, and efforts have been produced to choose the foam concrete mix's proportions. A collection of 36 cube specimens is created and subjected to mixture testing. Following this, their actual state (density) and particular structural (compressive strength) qualities are examined, with the findings being reported. Important terms: Foam Concrete, Foaming Agent, Rice Husk Ash, Silica Fumes, Density.

Modeling Mechanical Properties of Concrete with Bida Natural Stones as Coarse Aggregate

This paper presents the results of statistical models for the mechanical properties of concrete made using Bida natural stones (pebbles) as coarse aggregate. Fresh and hardened concrete properties were analyzed using response surface methodology (RSM). The research employed central composite design using three (3) independent variables with equivalent ranges as Water to Cement ratio (W/C) = 0.4, 0.5, 0.6, Coarse Aggregate to Total Aggregate ratio (CA/TA) = 0.55, 0.615, 0.68 and Total Aggregate to Cement ratio (TA/C) = 3.0, 4.5 and 6.0. Minitab 14 (2004) selected 20 possible mix proportions for the experiment. The concrete specimens that were used for this research work include 150mm x 150mm x 150mm concrete cube, Ø150mm x 300mm concrete cylinder and 100mm x 100mm x 500mm concrete prism for compressive strength, elastic modulus/splitting tensile strength and flexural strength respectively. For each mix, five numbers of specimens were cast and cured for 7, 14, 21 and 28days. The twenty-eight days measured responses were used to develop models for the mechanical properties. Statistical and experimental model validations were employed. The p-value for all individual terms were less than 0.05, p-values for lack of fit were also greater than 0.05 in all cases tested, coefficient of determination (R2), adjusted coefficient of determination (adjR2) were in the range of 89.7% to 100% for compressive strength, splitting tensile strength, elastic modulus, flexural strength, and slump respectively which indicated adequate model validity. The predicted responses closely agree with experimental values, this further confirms the validity of the models developed. The study therefore suggested interaction, pure quadratic, reduced full quadratic, interaction models for the mechanical properties and slump respectively for the concrete made using Bida natural stones as coarse aggregate. The concrete with mix constituent mentioned above can be used for structural application such as reinforced concrete slabs, beams, columns and foundations.

STUDIES ON COMPATIBILITY AND ITS TEST METHOD OF EXTREMELY DRY CONCRETE USED FOR ROLLER COMPACTED CONCRETE PAVEMENTS

As extremely dry concrete for roller compacted concrete (RCC) pavements, maximum stiffness is preferred for the operation of vibratory rollers. On the other hand, a less stiff mix is appropriate for attaining full consolidation. Accordingly, it is very difficult to select consistencies suitable for RCC. This paper reports a fundamental study on the compactibility of RCC. Samples of RCC were consol­idated with a magnetic table vibrator. The settle­ ment of fresh concrete during vibration was meas­ ured at very short intervals of time and was input into a personal computer. Then the data was converted to consolidation curves, which show the process of the increase in the filled volume ratio due to the vibrating energy. The consolidation curves vary depending on the materials used and the mix proportions, and are ex­pressed as a function. The consolidation behavior can be explained by four indices derived from the consolidation function.

Enhancement of Air-Entrained Grout-Enriched Vibrated Cemented Sand, Gravel and Rock (GECSGR) for Improving Frost and Thawing Resistance in CSGR Dams.

Cemented Sand, Gravel, and Rock (CSGR) dams have traditionally used either Conventional Vibrated Concrete (CVC) or Grout-Enriched Roller Compacted Concrete (GERCC) for protective and seepage control layers in low- to medium-height dams. However, these methods are complex, prone to interference, and uneconomical due to significant differences in the expansion coefficient, elastic modulus, and hydration heat parameters among CSGR, CVC, and GERCC. This complexity complicates quality control during construction, leading to the development of Grout-Enriched Vibrated Cemented Sand, Gravel, and Rock (GECSGR) as an alternative. Despite its potential, GECSGR has limited use due to concerns about freeze-thaw resistance. This project addresses these concerns by developing an air-entrained GECSGR grout formulation and construction technique. The study follows a five-phase approach: mix proportioning of C1806 CSGR; optimization of the grout formulation; determination of grout addition rate; evaluation of small-scale lab samples of GECSGR; and field application. The results indicate that combining 8-12% of 223 kg/m3 cement grout with 2-2.23 kg/m3 of admixtures, mud content of 15%, a marsh time of 26-31 s. and a water/cement ratio of 0.5-0.6 with the C1806 parent CSGR mixture achieved a post-vibration in situ air content of 4-6%, excellent freeze-thaw resistance (F300: mass loss <5% or initial dynamic modulus ≥60%), and permeability resistance (W12: permeability coefficient of 0.13 × 10-10 m/s). The development of a 2-in-1 slurry addition and vibration equipment eliminated performance risks and enhanced efficiency in field applications, such as the conversion of the C1804 CSGR mixture into air-entrained GECSGR grade C9015W6F50 for the 2.76 km Qianwei protection dam. Economic analysis revealed that the unit cost of GECSGR production is 18.3% and 6.33% less than CVC and GERCC, respectively, marking a significant advancement in sustainable cement-based composite materials in the dam industry.

Prediction of Compressive Strength of Fly Ash-Recycled Mortar Based on Grey Wolf Optimizer-Backpropagation Neural Network.

The evaluation of the mechanical performance of fly ash-recycled mortar (FARM) is a necessary condition to ensure the efficient utilization of recycled fine aggregates. This article describes the design of nine mix proportions of FARMs with a low water/cement ratio and screens six mix proportions with reasonable flowability. The compressive strengths of FARMs were tested, and the influence of the water/cement ratio (w/c) and age on the compressive strength was analyzed. Meanwhile, a backpropagation neural network (BPNN) model optimized by the grey wolf optimizer (GWO), namely the GWO-BPNN model, was established to predict the compressive strength of FARM. The input layer of the model consisted of w/c, a cement/sand ratio, water reducer, age, and fly ash content, while the output layer was the compressive strength. The data set consisted of 150 sets from this article and existing research in the literature, of which 70% is used for model training and 30% for model validation. The results show that compared with the traditional BPNN, the coefficient of determination (R2) of GWO-BPNN increases from 0.85 to 0.93, and the mean squared error (MSE) of model training decreases from 0.018 to 0.015. Meanwhile, the convergence iterations of model validation decrease from 108 to 65. This indicates that GWO improved the prediction accuracy and computational efficiency of BPNN. The model results of characteristic heat, kernel density estimation, scatter matrix, and the SHAP value all indicated that the w/c was strongly negatively correlated with compressive strength, while the sand/cement ratio and age were strongly positively correlated with compressive strength. However, the relationship between the contents of fly ash, the water reducer, and the compressive strength was not obvious.

A data-driven method for the design and calculation of recycled concrete mix proportions based on carbon footprint

A data-driven method for the design and calculation of recycled concrete mix proportions based on carbon footprint

Preparation of alkali-activated oil shale residue-slag geopolymer-based binder using calcium carbide slag and sodium carbonate as alkali activator.

Based on the reuse of industrial solid wastes such as calcium carbide slag, slag, and oil shale residue, this work utilizes oil shale residue and slag as precursor materials, calcium carbide slag and sodium carbonate as alkaline activator to prepare a geopolymer-based binder. Mix proportion experiments of the geopolymer-based binder with varying oil shale residue contents were designed. Chemical composition and microstructure of the alkaline-activated oil shale residue-slag geopolymer-based binder system were analyzed using X-ray Fluorescence Spectrometer (XRF), X-ray Powder Diffractometer (XRD), and Scanning Electron Microscope (SEM). Meanwhile, the fluidity and mechanical properties of the material were also investigated. The results indicate that as the oil shale residue content increases, the fluidity and 3-day compressive strength and splitting tensile strength of the filling slurry gradually decrease, while the 28-day strength first rises and then falls, reaching a maximum when the oil shale residue content is 20%. When the oil shale residue content is below 20%, the hydration product content gradually increases, and the microstructure tends to be denser. However, as the oil shale residue content further increases, the hydration product gradually decreases, and the microstructure becomes poorer. Therefore, the optimal oil shale residue content is 20%. The geopolymer-based binder system prepared in this paper is a low-carbon, environmentally friendly, and high-performance material system, its research and development are of great significance to the human society.

Preparation of vegetative concrete with recycled aggregate: Mix proportion orthogonal test, curing methods, and microstructure

Preparation of vegetative concrete with recycled aggregate: Mix proportion orthogonal test, curing methods, and microstructure