Concrete Mixture Proportions Research Articles

Film-forming ability of flowable cement pastes and its application in mixture proportioning of pervious concrete

In this paper, the concept of paste film-forming ability is introduced as a parameter for mixture proportioning of pervious concrete. Two new test methods are also developed. The two methods characterize film-forming ability in two conditions. The first method characterizes the ability of a cement paste to form a stable film on a smooth nonabsorbent vertical surface. The paste thickness measured from this test is called, Ideal PasteThickness (IPT). The second test characterizes the ability of cement paste to adhere and remain on an aggregate surface; this paste thickness is called ActualPasteThickness (APT). The IPT can be used as a standardized parameter to evaluate the film-forming ability of cement pastes. The APT can be used to study the formation of cement paste films on pervious concrete aggregates. In this study IPT and APT of sixteen superplasticized cement pastes were evaluated. The pastes were prepared from four water to cement (w/c) ratios (0.23, 0.27, 0.32 and 0.37).

Effects of specimen shape and size on the compressive strength of self-consolidating concrete (SCC)

The paper presents the results of an experimental and numerical study that examined the effect of specimen shape and size on the compressive strength of self-consolidating concrete (SCC). The study included casting specimens, cubes and cylinders, from three different SCC mixture proportions. Specimen size ranged between 50 and 150mm for the cubes. The slenderness ratio for the cylinders ranged from 0.5 to 2.0. Slump flow, V-funnel, and L-box tests were used to characterize the fresh properties of the SCC. All specimens were tested in compression at 28days. The results showed that the effect of specimen size became more of a factor as the slenderness ratio decreased. Specimens with a slenderness ratio of 2.0 or a lateral dimension of 100mm were independent of concrete mixture proportion. There was little influence on compressive strength from the specimens’ cross sectional shape. A correlation study was conducted and models for predicting compressive strength based on specimen geometry were proposed.

Recycled Aggregate Concrete Mixture Proportion Method Based on Pulp Content

Putting forward a new recycled aggregate concrete mixture proportion method based on the pulp content by researching the effect of pulp content on recycled coarse aggregate physical properties .Research on the cube compressive strength and splitting tensile strength of recycled aggregate concrete by the proposed method and results showed that:The proposed method can reduce the dosage of cement and sand, and increase the recycled aggregate concrete compressive strength and splitting tensile strength ;Establishing the relationship formula between splitting tensile strength and compressive strength of recycled aggregate concrete upon a large number of experimental data.

Development of a graphical user interface for determining the optimal mixture parameters of normal weight concretes: A response surface methodology based quadratic programming approach

The optimization of a normal weight concrete mixture proportions for determination of the desired concrete quality is an important issue for concrete manufacturers and users. In this study, the constrained quadratic programming methodology is based on meta-models developed by using response surface methodology for determining optimal normal weight concrete mixture proportions. We developed a graphical user interface to take the burden of numerous experiments and complex mathematical calculations away from laboratory experts and manufacturers. However, we developed a graphical user interface based on MATLAB® toolbox which allows performing optimization of normal weight concrete mixture proportions interactively. The GUI was tested through real case studies and satisfactorily results were obtained. The results showed that developed graphical user interface was functional, effective and flexible in solving the optimization problems of normal weight concrete mixture proportions.

Towards the classification of recycled concrete aggregates: influence of fundamental aggregate properties on recycled concrete performance

This study provides an in-depth evaluation of how fundamental aggregate properties affect mechanical properties of structural concretes produced using 100% coarse Recycled concrete aggregate (RCA) and constant mixture proportions. The key findings presented within this study will assist in developing a framework for classifying RCA sources for use in specific concrete applications. Fourteen mixture proportions were developed using three RCA types with compressive strengths of 30, 40, 50, and 60 MPa. Contrary to other studies, one RCA concrete type had compressive strengths up to 22% greater than the natural aggregate concrete. These results were confirmed by repeated batching and measured to be statistically significant. An analysis of the failure modes of RCA concrete and linking particular aggregate properties to the observed concrete failure mode were used to explain the results. Based on measured correlations, the modulus of elasticity of RCA concrete can be estimated based on the compressive strength and aggregate unit weight.

Mixture Proportioning and Testing of Fiber-Reinforced Self-Consolidating Concrete

An extensive testing program was undertaken to evaluate the applicability of a mixture-proportioning method proposed for shrinkage control in fiber-reinforced concrete (FRC) in proportioning fiber-reinforced self-consolidating concrete (FR-SCC). The study also proposed test methods to evaluate workability of FR-SCC. The investigated fibers included polypropylene, steel, and hybrid fibers of different properties with fiber lengths of 5 to 50 mm (0.20 to 1.97 in.). Fiber volume (Vf) ranged between 0.25 and 0.75%. The study also aimed to determine the impact of fiber type and addition on key properties of the fresh and hardened concrete. Hardened properties included compressive, splitting tensile, and average residual strengths. Test results indicate that the proposed methodology to maintain constant mortar thickness over coarse aggregate and fibers can reduce any significant drop in workability of FR-SCC, resulting from an increase in fiber factor. In general, a Vf of 0.5% is found to be an upper limit for the production of SCC. A greater Vf can hinder the self-consolidating characteristics. For the assessment of the passing ability of FR-SCC, a modified J-ring setup containing six or eight bars instead of 16 bars is proposed. The passing ability of FR-SCC can be expressed as the ratio of diameter:height at the center of the J-ring test. The passing ability can also be evaluated using the L-box with a single bar instead of three bars. A superworkable concrete (SWC) requiring low consolidation energy can still be produced with a Vf of 0.75% when a viscosity- modifying admixture is incorporated to prevent segregation and blockage. For the tested fiber types, the average residual strength (ARS) in flexure is shown to increase with Vf. Steel fibers exhibited the highest ARS value.

A Statistical Approach to Optimizing Concrete Mixture Design

A step-by-step statistical approach is proposed to obtain optimum proportioning of concrete mixtures using the data obtained through a statistically planned experimental program. The utility of the proposed approach for optimizing the design of concrete mixture is illustrated considering a typical case in which trial mixtures were considered according to a full factorial experiment design involving three factors and their three levels (33). A total of 27 concrete mixtures with three replicates (81 specimens) were considered by varying the levels of key factors affecting compressive strength of concrete, namely, water/cementitious materials ratio (0.38, 0.43, and 0.48), cementitious materials content (350, 375, and 400 kg/m3), and fine/total aggregate ratio (0.35, 0.40, and 0.45). The experimental data were utilized to carry out analysis of variance (ANOVA) and to develop a polynomial regression model for compressive strength in terms of the three design factors considered in this study. The developed statistical model was used to show how optimization of concrete mixtures can be carried out with different possible options.

Study on the Influence from Concrete Mixture Proportions to Polycarboxylate Super Plasticizer Utility

In this paper,study the influence from concrete mixture proportions to poly carboxylate super plasticizer utility, discuss the net of gelled material pulp of liquidity and concrete slump collapse performance issues,analysis fresh concrete and gradation impact on the performance of concrete ,according to the concrete engineering practice.The conclusion is that the above situation can give an explanation in the super plasticizer mechanism level,and can be used in the selective use of admixture ,as well as reference for the choice of materials of concrete .

Application of Statistical Analysis for Mixture Design of High-Strength Self-Consolidating Concrete Containing Metakaolin

A statistical design of experiments method was applied to optimize the mixture proportions of high-strength self-consolidating concrete (SCC) incorporating metakaolin (MK). The optimization involved varying three mixture factors (variables) at five different levels. These factors included total binder content, percentage of MK in the mixture, and water-to-binder ratio. The statistical analysis was exploited to determine the most significant factors affecting the properties of SCC and the optimum level of each variable. A total of 27 mixtures were tested at both the fresh and hardened states to obtain the best SCC mixture containing MK and to compare its results with SCC mixtures containing other supplementary cementing materials. The fresh properties tests included slump flow, V-funnel, L-box, J-ring, and air content tests. On the other hand, at 28 days, the compressive strength of SCC samples under two curing regimes was evaluated. The results showed that the optimized high-strength SCC mixture had a superior performance in the fresh and hardened states compared with the SCC mixtures containing silica fume, fly ash, or slag. The results of the numerical optimization for SCC mixture containing MK showed optimum levels of total binder content of 490 kg/m3, water-to-binder ratio of 0.39, and replacement of cement by MK of 19.9%. The results also showed that MK replacement proved to be the most significant factor affecting the 28-day compressive strength of all tested mixtures regardless of curing techniques.

Fundamental Study of the Potential Application of Steel Fiber Reinforced Concrete to Enhance the Impact Resistance of Nuclear Power Plant Structures

Concrete has been used as one of the major building materials for nuclear power plant (NPP) structures. While NPP structures of conventional concrete mixtures are considered to provide sufficient shielding capacities in terms of both structural containment and radiation barrier, further demands have been added to ensure and enhance the structural safety with considerations of aircraft impacts and/or earthquakes. To improve the impact resistance of the concrete itself, this paper presents the potential application of steel fibers as additives with no variation of the concrete mixture proportions that are currently used for NPP structures in Korea. Different types of steel fibers with variations of addition volumes were applied to the concrete mixtures and various kinds of mechanical properties such as strength, toughness, and fracture energy were evaluated. From the experimental results, a practical addition proportion and a type of steel fiber were chosen for the potential application to NPP structures. .

Computer Aided High Strength Concrete Mixture Proportion using Mat Lab

Computer Aided High Strength Concrete Mixture Proportion using Mat Lab

Compressive strength model for concrete

A predictive compressive strength model accounting for the type of cement, cement degree of hydration, aggregates type and gradation, mixtures proportion and air content was developed. This paper presents the formulation, implementation, calibration and validation of the proposed strength model for normal concrete. The theoretical formulation postulates that particles' interaction is governed by excess paste theory from which an average paste thickness model is developed to account for concrete mixture proportions and aggregate gradation. In addition, the model accounts for the cement compressive strength and aggregate to cement paste bond strength. An experimental programme, developed to evaluate the model, accounts for the following variables: water to cement ratio, water content, bulk volume and maximum size of coarse aggregate, and air content. The proposed model is found to accurately predict the strength of concrete mixtures at 3, 7, 28 and 191 days. The measured 3-day and 28-day strength range from 8·5 to 32·7 MPa and from 13·6 to 43·8 MPa, respectively. The corresponding standard error and correlation coefficient for the 3-day predictions are 2·1 MPa and 0·95, and 1·8 MPa and 0·96 for the 28-day predictions.

A TOPSIS-based Taguchi optimization to determine optimal mixture proportions of the high strength self-compacting concrete

In general, the optimization problems contain more than one response, which often conflict with each other. This paper proposes the TOPSIS-based Taguchi optimization approach to determine the optimal mixture proportions of the high strength self-compacting concrete (HSSCC) in a ready-mixed concrete plant. The performance criteria are identified for the following: the average convective heat transfer coefficient, the percentage of air content, the slump flow, the T50 time, the water absorption, the compressive strength, the splitting tensile strength, and the production cost. Five factors having three control levels and one factor having two control levels affect these identified performance criteria. The data of the HSSCC quality criteria are obtained by running scenarios that combine factor levels in Taguchi design, while signal to noise (S/N) ratios are calculated for the data. After a decision matrix is generated by the S/N ratios, the TOPSIS (Technique for Order Preference by Similarity to an Ideal Solution) method is then used to transform the multi-response problem into a single-response problem. The anticipated improvement rate is also determined by finding the levels of the factors in order to optimize the system which uses Taguchi's single response optimization methodology.

Improving Surface Durability of High Volume Fly Ash Concrete with Application of Alkali Solution

This study aims to determine whether the surface durability of high volume fly ash (HVFA) concrete can be improved by applying alkali solution on its hardened surface. Concentrations of alkali solution and methods of application were studied on several w/cm ratios and replacement percentage of fly ash in concrete mixture proportion to investigate the durability performance. Durability tests conducted were accelerated sulfuric acid attack and ion chloride penetration to investigate the improved durability of HVFA concrete. From the results, it was shown that applying alkali solution on the surface of HVFA concrete can increase its durability performance. The different w/cm ratio and the percentage of fly ash used affect the increase in durability performance. The optimum alkali solution concentration and method of application need further research to determine their effectivity.

Effect of Admixed Recycled Aggregate on Properties of Recycled Concrete

The mixture proportion of recycled concrete was discussed by orthogonal design method. The influence of water-cement ratio, recycled aggregate quantity on workability, cube compressive strength of recycled concrete was analyzed. The experimental results indicated that，Recycled concrete mix proportion design should consider the impact of the water absorption of recycled aggregate. Unit water amount of recycled concrete should be plain concrete unit water consumption and recycled aggregate additional amount of water. Sand ratio should increase in the corresponding ordinary aggregate concrete sand ratio on the basis of 1 to 3 percent. When the water-cement ratio is 0.36 and construction waste content of 40% slag content of 20%, 28d compressive strength of concrete is 48.1MPa, slightly higher than the reference concrete (48.0MPa).

Strength Targeted PBMD of HSC based on One-parameter Bayesian Probabilistic Method

This paper is about application of recently proposed Performance Based Mixture Design (PBMD) for mix proportion design of high strength concrete (HSC) that can satisfy required performances. The PBMD method is a performance oriented concrete mix proportion design procedure easily applicable to any conditions and environments for a possible replacement to the current prescriptive design standards. Based on extensive experimental results obtained for various material and performance parameters of HSC, the application feasibility of the developed PBMD procedure for HSC has been verified. Also, the proposed PBMD procedure has been used to perform application examples to obtain desired target performances of HSC with optimum concrete mixture proportions using locally available materials, local environmental conditions, and available concrete production technologies. The validity and precision of HSC mix proportion design obtained using the PBMD method is verified with the experimental and ACI presented results to check the feasibility for actual design usage.

Comparing Lightweight Polystyrene Concrete Using Engineered or Waste Materials

This paper investigates the difference between using manufactured or waste-expanded polystyrene (EPS) as an aggregate replacement in concrete. Concrete mixture proportions are held constant, whereas two types of EPS—reground waste material (RGD) and manufactured spherical bead (BD)—replace a portion of the fine aggregate. The plastic state and hardened state properties are quantified and compared between test batches and the plastic state measures of consistency, air content, and unit weight are reported in this paper. The measures hardened state properties include compressive strength, elastic modulus, strength-weight ratio, and energy-related toughness as determined using compression load-deflection curves. The results indicate that, for comparable concrete mixtures, BD mixtures exhibited improved workability and reduced air entrapment or entrained air as compared to RGD mixtures due to differences in EPS particle surface characteristics. Furthermore, statistically significant increases in compressive strength and energy-related toughness are demonstrated for BD mixtures in comparison to RGD mixtures.

Effect of Recycled Concrete Aggregate Properties on Mixture Proportions of Structural Concrete

This study focuses on characterizing several recycled concrete aggregate (RCA) sources, developing concrete mixture proportions that incorporate RCA as coarse aggregate, and investigating the effect of coarse aggregate properties on the main mixture proportion parameters [i.e., cement content, water demand, and water–cement (w/c) ratio]. Four aggregate types were investigated: one control virgin aggregate source and three RCAs produced from the crushing of hardened concrete. Numerous aggregate tests, including density, absorption, abrasion resistance, adhered mortar content, and crushing value, were performed. Fourteen mixture proportions were developed with the use of three mixture proportion scenarios (control, direct replacement, and strength based) and two compressive strength levels (40 and 60 MPa). The effect of RCA on compressive strength and workability was evaluated by replacement of natural coarse aggregate with RCA. Contrary to numerous studies, one of the RCA concretes (RCA-1) had compressive strengths up to 12% higher than the equivalent control mixture. Mixture proportions (water, cement, and w/c ratio) were later adjusted to ensure that the RCA concretes had compressive strength and slump values similar to the control concretes. Variations in water demand, cement content, and w/c ratio could then be directly attributed to the properties of the RCA source. RCA-1 concrete required less cement (and a higher w/c ratio) to achieve strengths and slumps similar to the control concrete. The findings and recommendations of this research will assist concrete producers, engineers, and field technicians involved in the selection of RCA sources in developing mixture proportions for structural-grade RCA concrete.

Effect of Concrete Mixture Proportions on the Chloride Resistance

Effect of Concrete Mixture Proportions on the Chloride Resistance

The effect of recycled concrete aggregate properties on the bond strength between RCA concrete and steel reinforcement

The purpose of this study was to investigate the influence that replacing natural coarse aggregate with recycled concrete aggregate (RCA) has on concrete bond strength with reinforcing steel. Two sources of RCA were used along with one natural aggregate source. Numerous aggregate properties were measured for all aggregate sources. Two types of concrete mixture proportions were developed replacing 100% of the natural aggregate with RCA. The first type maintained the same water–cement ratios while the second type was designed to achieve the same compressive strengths. Beam-end specimens were tested to determine the relative bond strength of RCA and natural aggregate concrete. On average, natural aggregate concrete specimens had bond strengths that were 9 to 19% higher than the equivalent RCA specimens. Bond strength and the aggregate crushing value seemed to correlate well for all concrete types.