Concrete Mix Proportion Research Articles

Empirical Equation for Concrete Made With PPC or OPC with Fly Ash by Accelerated Mix Design Method

Assessment of 28 days strength from accelerated strength (1 day) can be extremely helpful. Early prediction of 28 days compressive strength is required basically for two purposes. First, to finalize the concrete mix proportions in the laboratory and secondly, for quality control purpose during construction. Through this concept designers can easily identify the uncalculated errors during mix design or variations in materials and exposure conditions etc. and take necessary correction and modification measures to attain the desired strengths at 28 days. As per IS: 9013 methodology to predict the 28 days strength of concrete from accelerated cured strength are indicated only for normal/control concrete. In the past few year focus has shifted from Ordinary Portland Cement (OPC) to Portland Pozzolana Cement (PPC). Fly ash is also being used widely at sites as replacement of OPC. However, there is no such guideline available by which the assessment of 28 days strength of Indian fly ash concrete can be made from accelerated strength tests. In the present study an attempt has been made to predict the expected 28 days compressive strength of concrete having PPC or OPC with fly ash using accelerated temperature regime methods. The experimental study includes the use of 2 brands of PPC, 5 brands of OPC and 2 sources of fly ash for replacement of OPC ranging from 20% to 45 %. Two temperature regimes 900C and 820C were used for accelerated curing. The samples were cured for 7.5 hours and 20hours respectively in each regime for expected 28 day compressive strength. The mathematical equations to estimate the 28 days compressive strength of concrete, cured at 900C for 7.5 hours for mixes having PPC, OPC mixed with fly ash 20% to 35% is fexp28 = 1.223 facs +2.024. The mathematical equations to estimate the 28 days compressive strength of concrete, cured at 900C for 7.5 hours for mixes having PPC, OPC mixed with fly ash more than 35% and up to 45% is fexp28 = 0.993 facs + 6.044.

An Auto-Calibrating Semi-Adiabatic Calorimetric Methodology for Strength Prediction and Quality Control of Ordinary and Ultra-High-Performance Concretes.

A timely knowledge of concrete and ultra-high-performance concrete (UHPC) strength is possible through the so-called strength-equivalent time (Et) curves. A timely knowledge of concrete strength is useful, for instance, to precisely determine when the shores of a hardening structural element can be safely removed. At the present time, the preparation of the strength-Et curves requires time-consuming and labor-intensive testing prior to the beginning of construction operations. This paper proposes an innovative method to derive the strength-Et and total heat-Et curves for both normal strength and UHPC. Results confirmed that the proposed method is fast, inexpensive, self-calibrating, accurate and can detect any variation of the concrete mix proportions or components quality. In addition, the quality of predictions of strength–maturity curves can be constantly improved as the specimens’ population increases. Finally, results obtained with the proposed method were compared with those obtained using standard methods, showing a good agreement.

Ant lion algorithm for optimal design of high performance concrete mixes

This paper presents the development of Ant lion optimization (ALO) models for optimal mix proportioning of high volume fly ash concrete (HVFAC). The development of the model came through in two steps, firstly, a modest data pertaining to 450 mix designs that are generated either in laboratory or in field were garnered from the literature were statistically analyzed and 350 appropriate mix designs were retained and necessary constraints, upper and lower bounds, and rational ratios are elicited. In the second step ALO algorithm was applied to determine optimal proportions of fly ash, cement, and water corresponding to optimum compressive strength of concrete. Optimal mix proportions were computed for five ranges of compressive strengths using the objective function and constraints farmed in the first step. The optimized mix proportions for all the strength ranges are found to be highly acceptable and corroborate very well with experimental values with mean square error ranging between 2% and 4%, 7%−13%, and 10–12.5% in case of water, fly ash and cement respectively. Further, a systematic comparison of results obtained by the author in implementing other bio inspired algorithms namely, Ant colony optimization (ACO), Elitist genetic algorithm (EGA), Honey bee optimization (HBO), and Particle swarm optimization (PSO) is also made. It is found that the quantities of the ingredients are almost identical, however with marginal differences in the mean square error metric. It is found that GA was bit high in errors, followed by ALO, ACO, and HBO not appreciable though. However PSO showed low errors in the range 1.6%−3.2%, 5%−10%, and 5%−8.5% in the optimized quantities in respect of water, fly ash and cement respectively across five strength ranges.

Engineering Properties and Prediction of Strength of High Performance Fibre Reinforced Concrete using Artificial Neural Networks

ABSTRACT: This paper presents the experimental and numerical studies on high performance fiber concrete (HPFRC) with water-cementitious materials (w/cm) ratios of 0.4- 0.3, steel fiber volume fraction (Vf) varying from 0- 1.5%, polypropylene fiber volume fraction varying from 0- 1% and silica fume replacement at 10% and 15%. Experimental results showed high improvements in 28 day cylinder compressive strength and flex-ural strength of steel fiber reinforced concrete at fiber volume fraction of 1.5%; for polypropylene (PP) FRC improvement in compressive and flexural strengths are marginal and moderate, respectively. Statistical models developed for compressive strength ratios and flexural strength ratios of HPSFRC indicate the prediction ca-pabilities of the models. Due to the complex mix proportions of HPSFRC and the non-linear relationship be-tween the concrete mix proportions and properties, research on HPSFRC has been empirical and no models with reliable predictive capabilities for its behavior have been developed. Based on the large data collected for HPSFRC mixes, a trained artificial neural network (ANN) model which adopts a back propagation algorithm to predict 28-day compressive strength of HPSFRC mixes was employed. This paper describes the comparison of the experimental results obtained for various mixes. Multiple linear regression (MLR) model with R2 = 0.78 was also developed for the prediction of compressive strength of HPSFRC mixes. On validation of the data sets by NNs, the error range is within 2% of the actual values. ANN models give the significant degree of ac-curacy compared to MLR model, and can be easily used to estimate the strength of concrete mixes.

Change of Strength of Recycled Concrete with Age

In this paper, a mathematical model of the relationship between the amount of various components of recycled concrete and its compressive strength is established by using a large number of experimental data on the strength performance of recycled concrete and BP artificial neural network technology. In this paper, the influence trend of water binder ratio and aggregate substitution rate on the strength of recycled concrete is studied by this model. Taking recycled concrete with different recycled aggregate as the research object, a nonlinear structural model reflecting the mapping relationship between mix proportion and strength of recycled concrete is established in this paper. In this paper, the predicted values of the model are compared with the experimental data. The research shows that the strength model of recycled concrete based on BP neural network established in this paper can predict the compressive strength of recycled concrete at the corresponding age according to the mix proportion of recycled concrete, and the prediction accuracy is high. The application of BP neural network effectively reduces the times of a large number of repeated mix proportion test when preparing recycled concrete in practical engineering, reduces the waste of human and material resources, and has good economic benefits.

A convolution-based deep learning approach for estimating compressive strength of fiber reinforced concrete at elevated temperatures

Fiber-reinforced concrete (FRC) exhibits high fire-resistance capacity and maintains structural integrity at elevated temperatures. However, conventional approaches for optimizing its mixture design and predicting its corresponding mechanical responses following fire exposure present particular difficulties in efficiency, accuracy, and safety issues. To address these issues, a convolution-based deep learning model was developed in the present paper. A dataset with 19 features, including concrete mix proportioning, heating profile, and fiber properties, was collected from previous experimental recordings to evaluate the model performance. The feasibility and generality of the proposed model were validated through the collected dataset and another widely used concrete dataset, where our model performs the best compared with multiple machine learning baseline models. In addition, the correlation between temperature and the relative compressive strength obtained by the proposed model echoes with Eurocode 2, which further demonstrates that our proposed model can accurately estimate the mechanical performances of FRC exposed to high temperatures. It is envisioned that the proposed deep-learning approach serves as an accurate and flexible property assessment tool that aids researchers and engineers in mixture design optimization and compressive strength estimation of FRC for different engineering needs.

A simplified geopolymer concrete mix design considering five mineral admixtures

The mix design procedure for geopolymer concrete has not been standardised as there are so many variables to consider. Industrial wastes primarily fly ash, metakaolin, silica fume, GGBS and rice husk ash were used in this study individually and in combination along with sodium-based alkaline solutions. By taking into account of numerous elements that affect the qualities of geopolymer concrete, 243 geopolymer concrete blends were developed. The percentage of coarse aggregate and combined aggregate, sodium hydroxide to sodium silicate ratio, concentration of NaOH, curing temperature are all the factors taken into account of this study to arrive a mix design procedure for geopolymer concrete. Based on the findings, an approach for determining the mix proportion for geopolymer concrete was derived. These data can be used to produce geopolymer concrete grades ranging from 15 to 80 MPa.

Effect of the compounding of an antifoaming agent and a viscosity modifying agent on the frost resistance of mold bag concrete

Channel lining mold bag concrete in the cold area of ​​northern China needs to achieve high frost resistance under the conditions of large fluidity and low strength grade. However, the extensive use of a high range water reducer (HRWR) and an air entraining agent (AEA) brings about the problems of a large air content loss, a large fluidity loss and many harmful big bubbles to fresh concrete, reducing the pumping performance and frost resistance of mold bag concrete. In this study, the effects of compounding an AEA, an antifoaming agent (AFA), and a viscosity modifying agent (VMA) on the workability, mechanical properties and frost resistance of concrete are studied by using the response surface methodology (RSM). The results showed that AEA and AFA were significant factors that affected the relative dynamic elasitic modulus. The interaction of AFA and VMA on the relative dynamic elasitic modulus was significant. The compounding of AFA and VMA achieved the effects of synergistically improving the workability, air-void structure and frost resistance of concrete. When the dosage of AEA was 0.0055%, the compounding of AFA and VMA synergistically reduced the air content loss rate by 42.30%, reduced the slump flow loss rate by 47.29%, reduced the number of large bubbles by 57.96%, increased the number of fine bubbles by 16.55%, reduced the spacing factor by 18.09%, increased the specific surface area by 41.16%, increased the relative dynamic elasitic modulus by 16.11%. Using RSM optimization and validation, an optimal mix proportion for mold bag concrete with a desirability of 0.998 was proposed to be the following: AEA of 0.006%, AFA of 0.176%, and VMA of 0.019%.

Study on Calculation Model for Compressive Strength of Water Saturated Recycled Aggregate Concrete

It has been proved that the compressive strength of water saturated concrete is lower than that of air dry concrete. Due to the water absorption of recycled aggregate (RA) is noticeably higher than that of natural aggregate (NA), the mechanical properties of water saturated recycled aggregate concrete (RAC) are quite different from those of water saturated natural aggregate concrete (NAC). At the same time, the calculation of concrete compressive strength is the first step of concrete mix proportion design. Therefore, it is essential to investigate the compressive strength of RAC in water saturated state. In this study, firstly, the water content and effective water absorption of NA, recycled brick aggregate (RBA) and recycled concrete aggregate (RCA), as well as the water content and effective water absorption of concrete specimen were tested; secondly, the effects of water/cement ratio, water saturation and coarse aggregate types on the compressive strength of water saturated concrete were studied; finally, the calculation model for compressive strength of water saturated concrete was proposed. The test results show that: Within 120 hours, the maximum effective water absorption of NA, RCA and RBA is 0.32%, 0.61% and 8.18%, respectively. Within 240 hour, the maximum effective water absorption of NAC, recycled concrete aggregate concrete (RCAC) and recycled brick aggregate concrete (RBAC) is 0.73%, 0.81% and 1.89%, respectively. In air dry and water saturated state, the descending order of compressive strength of concrete is: NAC > RCAC > RBAC. The average relative error of the calculation model for compressive strength of water saturated concrete is 7.1%. In the calculation model, water/cement ratio, effective water absorption, water saturation and coarse aggregate types are considered. The results of this study have great significance for the mix proportion design of water saturated concrete.

Damping enhancement of concrete doped nano materials and damping model of frame structure

The research of damping is an important and urgent topic in the research of structural vibration. Concrete material is one of the main bulk materials in civil engineering. The purpose of this study is to study the damping enhancement of concrete doped nano materials and the damping model of frame structure. Based on the experimental test method, the example method and the variable comparison method, combined with the damping motion and energy formula, the research carried out the concrete nano material mix proportion design and forming experiment. The results show that 0.0197 of 0% nano-SiO2 continues to rise to 0.0672 of 4% nano-SiO2, with an increase of 241.11%. The effect of damping enhancement is significant, and then the amount of Nano-SiO2 increases, but it falls back. Therefore, it is concluded that the optimal effect of damping enhancement of concrete is 2.94 times of that of plain concrete when the content of Nano-SiO2 is about 4%. This study has played an important role in improving the overall performance of the damping reinforced gradient structure concrete.

Behavior of Geopolymer Concrete Reinforced by Sustainable Copper Fiber

The execution of sustainable expansion in civil engineering scope has led to the employment of new materials with a reduction in environmental influence. Ordinary Portland cement (OPC) is the essential material in the production of concrete traditionally. But, the industry of OPC causes environmental consideration by producing of CO2. Recycled fly ash and blast furnace slag, the most in common use industrially by-products and sustainable material as a replacement to Portland Cement, helps to reduce CO2in the atmosphere. This paper showed the details of adding sustainable fibers to normal and geopolymer concrete and its role in improving mechanical properties such as compressive strength, split tensile strength, flexural strength. The results exhibit enhances in characteristics of two types of concrete. The geopolymer mixes had prepared using a blend of slag (ggbfs) and low calcium fly ash class F, which act by alkaline solution. The mixture compositions of fly ash to slag were (0.75:0.25, 0.65:0.35, 0.55:0.45) %, respectively. Then select the best percentage between them that achieves the goal, which is to produce green concrete that is less expensive and environmentally friendly, and its mechanical properties higher than conventional concrete. Conventional concrete mix proportion 1:1.5:3 (cement: fine agg.: coarse agg.) Respectively. The copper fiber was used as recycled material from electricity devices waste such as (machines, motors, wires, and electronic devices) to enhance the mechanical properties of concrete and used with the percentage of 0.5% by volume of concrete for all mixes. The heat curing system at 40°C temperature was used for geopolymer and water curing for normal concrete. The results revealed that the mix proportion of 0.45 blast furnace slag: 0.55 fly ash produced the best findings of strength and showed a denser and workable mixture.

Evaluation of Interlocking Brick

Abstract: The main aim of this project is to evaluate mechanical properties of interlocking bricks using coir fiber powder as a substitute of cement and rubber tire waste as a substitute of fine aggregate (sand) with varying percentages of 0%, 1%, 2% & 3% and 0%, 5%, 10% & 15% in concrete and to help in solving environmental problem produced from disposing of waste tires and coir husk partially. Additionally fly ash was also added with varying percentages of 5%, 10% and 15% as a substitute to cement in a concrete mix. Several laboratory tests such as compressive strength test, flexural strength test, split tensile strength test, water absorption test and density of concrete etc., were conducted on hardened concrete specimen to achieve the optimum usage of crumb rubber tire waste and coir fiber powder in mix proportion of concrete. It is found that the maximum compressive strength value of coir fiber based crumb rubber interlocking brick was obtained at 1%CF + 5%FA + 5%CR, flexural strength value and split tensile strength value of coir fiber based crumb rubber concrete block was obtained at 1%CF + 5%FA + 5%CR. From the final conclusion or outcome of the project, optimum usage of coir fiber powder is 3% and crumb rubber is 5%. Keywords: coir fiber powder, crumb rubber tire waste, mechanical properties, interlocking bricks & optimum usage.

Improving Marine Concrete Performance Based on Multiple Criteria Using Early Portland Cement and Chemical Superplasticizer Admixture.

This study sought to examine the performance design of concrete mix proportions to ensure chloride resistance and early strength with respect to C35 (35 MPa), which is the minimum compressive strength class of concrete used in a marine environment. For the proposed concrete mixture, C24 (24 MPa) was selected and binders for concrete were manufactured using a blend of OPC (ordinary Portland cement), EPC (early Portland cement), and GGBS (ground granulated blast-furnace slag). The results of the experiment confirmed that the combined use of EPC and GGBS greatly improve the early-strength development and chloride resistance of concrete. An analysis revealed that the time for removal of forms can be reduced by 5–9 h from the aspect of early concrete strength. Moreover, in terms of construction productivity, EPC and GGBS were reduced by up to 16.39 h/cycle compared to other concretes. Regarding economic and environmental impacts, EPC and GGBS were more effective than C35 concrete. This study is significant as its findings help make it possible to examine the most economical concrete mix design in relation to strength development according to the application of EPC, GGBS, and PC-based admixtures.

Mix proportion design method of recycled brick aggregate concrete based on aggregate skeleton theory

Due to the specific gravity of recycled brick aggregate (RBA) is less than that of natural aggregate (NA), the traditional mix proportion design of concrete can not be used. The purpose of this study is to propose a new mix proportion design method, which is suitable for recycled brick aggregate concrete (RBAC) or lightweight aggregate concrete. In this test, RBA volume fraction, sand volume fraction and water/cement ratio were considered; calculation formula of paste thickness on coated aggregate was established; calculation model of RBAC compressive strength was established, in which RBA volume fraction, the compressive strength of cement mortar and water/cement ratio were considered; mix proportion design method of RBAC based on aggregate skeleton theory was established. The results show that: when the volume fraction of RBA is between 44% and 47%, and the total volume fraction of RBA and sand is about 70%, the compressive strength of RBAC reaches the maximum; when the volume fraction of RBA is between 40% and 50%, the skeleton contribution strength of RBA is greater than that of cement mortar. When sand/cement ratio is about between 0.35 and 2.1, the sand skeleton contribution strength is higher. When the volume fraction of RBA is between 40% and 50%, the actual average paste thickness on coated coarse aggregate (APTCCA) is between 10.04 mm and 5.86 mm and the APTCCA simulated by PFC3D software is between 9.21 mm and 5.75 mm. In the compressive strength calculation model of RBAC, the relative errors of the predicted values are concentrated within 10%, the average relative error is 0.53%, and the correlation coefficient between the predicted values and the test values is 0.96; Compared with ACI 211.2 and ACI 211.6, the mix proportion design method proposed in this paper is to mix more RBA and less sand and cement in concrete mix proportion under the condition of ensuring concrete strength and slump, which is beneficial to protect the environment.

Mix Proportion of Lightweight Straw Ceramsite Concrete

To reduce air pollution of straw burning, and also to improve the ratio of straw comprehensive utilization, this paper presents a lightweight concrete with straw based on the mix proportion research. Firstly, the mix proportion of lightweight ceramsite concrete was designed by a volumetric method. Then, a series of lightweight ceramsite concrete mix proportion experiments were conducted to verify the validity of the design and to evaluate the effect of the admixtures on the performance of the concrete. Finally, the lightweight straw ceramsite concrete mix proportion experiments were conducted by adding straw to lightweight ceramsite concrete for studying the impact of the straw amount on the concrete strength and density. The experimental results show that the compressive strength of lightweight straw ceramsite concrete can reach the requirement of engineering application. The concrete strength and density were descended obviously with the increasing of straw amount. It was suggested that the straw amount should be limited in 20% of the concrete volume.

Assessing the influence of fly ash and polypropylene fiber on fresh, mechanical and durability properties of concrete

This paper focuses on the investigation of fresh, mechanical, and durability properties of concrete with the influence of fly ash and polypropylene fiber. In this study, cement was partially replaced by 15 % and 30 % fly ash content in weight, whereas polypropylene fiber was incorporated in concrete mixes at 0.06 %, 0.12 %, and 0.18 % by volume. Twelve concrete mix proportions were developed, and slump, density, ball penetration, and compacting factor tests were conducted to examine the fresh concrete properties. Besides, mechanical characteristics, including the uniaxial compressive and splitting tensile strength of concrete, were evaluated at 7, 28, and 90 days. Further tests of concrete durability, including rapid chloride permeability test, sorptivity, and water penetration, were performed at 90 days. The results exhibited that the incorporation of fly ash developed fresh concrete properties, while polypropylene fiber decreased the fresh characteristics of concrete. Furthermore, the combination of fly ash and polypropylene fiber in concrete was substantially attained to improve the mechanical and durability characteristics compared to the control mix. Mix proportion of 15 % fly ash and 0.12 % polypropylene fiber exhibited a pronounced influence on compressive strength, chloride permeability, sorptivity, and water penetration compared to other concrete mixtures.

Experimental study on mix proportion of green environmental protection type three-doped fair-faced concrete

Fair-faced concrete has been favored by the majority of architectural and structural designers. In response to the sustainable development strategy of our government, this paper studies the green environment-friendly fair-faced concrete mixed with agricultural and industrial wastes. Based on the statistical analysis of the existing literature on fair-faced concrete, the green environmental protection of fair-faced concrete was considered comprehensively. The mix proportion of “three-doped” fair-faced concrete mixed with ground rice husk ash, fly ash and mineral powder, which replaced the cement amount by 8%, 20% and 6% respectively, and its influence on compressive strength were studied through experiments. The experimental results show that the green environmental protection type fair-faced concrete mixed with rice husk ash, fly ash and mineral powder can achieve requirements of the compressive strength by the design. And the growth rate of compressive strength from the 28th day to the 56th day is higher than that of ordinary fair-faced concrete. At the same time, the curve equation of the relationship between the compressive strength and the age is put forward, and the fit is good, which can provide reference for the design of similar concrete mix proportion.

Experimental study on Mechanical Properties of green and environmental friendly self-compacting recycled concrete

By replacing cement with 5% of ground rice husk powder, 4% of corn stalk powder and 30% of fly ash, and replacing natural aggregate with 25% recycled aggregate, the Mechanical Properties of green and environment-friendly self-compacting recycled concrete were studied. The experimental results show that the early strength of the concrete is lower than the common self-compacting concrete. However, the strength of 56 days is up to the design requirement and the volume stability is good. According to the test value of the compressive strength of the concrete block, the curve equation of the relationship between the compressive strength and the age is put forward, and it provides a reference for similar concrete mix proportion design.

PREDICTION OF CONCRETE MIX DESIGN USING DATA MINING TECHNIQUES - A REVIEW

Concrete mix proportioning is one of the critical process and it involves a lot of precautionary measures to arrive at the right proportions of ingredients like cement, aggregate, water, and admixtures. Even though there are technical specifications that are managed mix proportionating, the procedure is not totally in the realm of science. Due to imprecise codal provisions, impreciseness, and fuzziness involved in the various stages of mix proportioning. This paper reviews the various data mining and machine learning techniques developed by the researchers for making concrete mix design for various codal provisions more realistic and scientific.

Development of pervious oyster shell habitat (POSH) concrete for reef restoration and living shorelines

This study investigated the development of a more durable and sustainable cementitious composite substrate for oyster reef restoration using recycled oyster shells and low cement content. The effects of concrete mix proportions (w/c ratio, sand content, and cement content) on the physical properties of the hardened concretes were investigated. Increasing the water, sand, cement, and high-range water reducing admixture content improved both the compressive and flexural strength mostly by improving the coating of cementitious materials around the shells. The proposed material for reef restoration is superior in terms of cost, durability, environmental benefits, and carbon footprint.