Concrete Mix Proportion Research Articles

Introducing a New Quantitative Evaluation Method for Segregation of Normal Concrete

The aim of this research is to provide a quantitative method for evaluating concrete segregation. Because of various conditions of concrete materials, mix proportions, and delivery, concrete can be segregated. The acquisition inspection executed in construction field for supplied ready-mixed concrete is an important quality control process for concrete. Among the inspections conducted at the project site, segregation of concrete mixture should be evaluated before placing the concrete mixture, currently a qualitative inspection on concrete segregation was conducted. For a normal concrete mixture with slumping behavior, shear slump or collapse slump often occur as an indication of segregation. The suggested evaluation index of segregation for normal concrete (EISN) was induced from the shape of the concrete slumping: relation between the maximum distance of flow and the minimum distance of flow. To evaluate the feasibility of EISN, two different concrete mixture conditions were tested. The recommended EISN parameter of segregation is 1.09 using the three grades of concrete quality. This new quantitative method of evaluating segregation of the concrete mixture is expected to contribute to a more efficient quality control in concrete construction.

Coarse aggregate effectiveness in concrete: Quantitative models study on paste thickness, mortar thickness and compressive strength

The paste thickness is an essential parameter related to mix proportion and properties of concrete. The quantitative models of paste thickness could be classified as volume-based paste thickness (VPT) and surface area-based paste thickness (SPT), while the widely-used SPT doesn’t consider the dilatation effect of aggregate. The aim of this paper is to modify the SPT model by comparing the derivation of different quantitative models, then the mortar thickness is calculated and its relationship with compressive strength of concrete is investigated. Taking the dilatation effect (λ) into account, a modified SPT model is derived, which also could be more accurate than VPT as a parameter in mix design of concrete. Regarded the concrete as two-phase composites of mortar and coarse aggregate, the compressive strengths of mortar and concrete conform to the hyperbolic model proposed by de Larrard, and the interlocking-effect of coarse aggregate is quantitatively characterized. Besides, the compressive strength of concrete is linear to −0.13 power of mortar thickness, which provides a foundation for the prediction of compressive strength and the mixture design of concrete.

Development of geopolymer concrete mixes with ambient air curing

Mix design for geopolymer concrete is yet to evolve. Though geopolymer concrete has made the much required transition from laboratory to the field, due to inherent difficulties such as huge variation in the chemical composition of the raw material, the sensitivity of this composition and the chemicals involved in the fresh and hardened properties have led to most of the mix development through trials with the actual materials. The aim of the work reported in this paper was to design an optimum mix proportion for geopolymer concrete using fly ash and ground granulated blast furnace slag (GGBS) as an aluminosilicate source, which has good workability, slump retention, and compressive strength without special curing requirements. A total of 10 mixes were prepared with varying fly ash to GGBS ratios. Ambient curing for 28 days was adopted for all mixes; however, heat curing at 85°C for 24 hours, followed by ambient curing, was adopted for one mix alone. It was clear that with the increase in GGBS content, there was a reduction in setting time, and the mix set faster. However, with more GGBS, greater strength was achieved at a relatively milder alkali activator solution. When the GGBS content increased beyond a certain level, the slump retention time reduced to levels where the mixes were unfit for practical applications. However, it can be concluded that with a judicious choice of fly ash and GGBS proportions, a strength of as high as 60MPa can be achieved in geopolymer concrete without any special curing methods.

Comparison of tensile and compressive creep of hydraulic concrete considering loading/unloading under unified test conditions

In order to study the relationship between the magnitude of the tensile and compressive specific creep of concrete, and to compare the measured and predicted creep recovery based on the superposition principle. In this paper, combined with the concrete mix proportion of typical hydraulic engineering, creep tests of hydraulic concrete under loading/unloading with different loading ages (7, 28, and 60 days) are conducted under unified test conditions. Furthermore, the equivalent age theory is introduced to establish eight-parameter specific creep models of tension and compression considering the effect of temperature history, and an optimization algorithm is used to identify the parameters of the models. Finally, the recovery of specific creep under tensile and compressive different creep is discussed in detail based on the principle of superposition. The results show that the specific creep in tension is greater than that in compression in all three creep test groups, and the recovery of specific creep in tension and compression after unloading indicates that the predicted values of the recovery of specific creep obtained by superimposing compressive specific creep are in better agreement with the measured values.

Novel Analytical Method for Mix Design and Performance Prediction of High Calcium Fly Ash Geopolymer Concrete.

Despite extensive in-depth research into high calcium fly ash geopolymer concretes and a number of proposed methods to calculate the mix proportions, no universally applicable method to determine the mix proportions has been developed. This paper uses an artificial neural network (ANN) machine learning toolbox in a MATLAB programming environment together with a Bayesian regularization algorithm, the Levenberg-Marquardt algorithm and a scaled conjugate gradient algorithm to attain a specified target compressive strength at 28 days. The relationship between the four key parameters, namely water/solid ratio, alkaline activator/binder ratio, Na2SiO3/NaOH ratio and NaOH molarity, and the compressive strength of geopolymer concrete is determined. The geopolymer concrete mix proportions based on the ANN algorithm model and contour plots developed were experimentally validated. Thus, the proposed method can be used to determine mix designs for high calcium fly ash geopolymer concrete in the range 25–45 MPa at 28 days. In addition, the design equations developed using the statistical regression model provide an insight to predict tensile strength and elastic modulus for a given compressive strength.

PERFORMANCE OF FLY ASH CONCRETE AGAINST SULFATE ATTACK

In this research, the effect of using fly ash on sulfate resistance of concrete was investigated. Studied mixes in this work are part of a research project that investigates the influence of using binary and ternary cementitious materials on different properties of concrete. In this paper, three groups of concrete mixtures were studied; each group includes three mixes. The concrete mix proportions were adjusted to produce concrete with certain values of air content and slump. The used water / binder material ratios were 0.4, 0.5 and 0.6. Concrete samples were cured in water until testing day. After 28 days of water curing, samples were immersed in sodium sulfate solution for 6 months. The hardened concrete properties were investigated through destructive and nondestructive tests at various samples’ age. The research results showed that using fly ash improved the resistance of concrete to sulfate attack. Therefore, with considerable proportions, using fly ash in concrete industry improves the performance of concrete for sulfate resistance and its durability.

Mechanical properties of reactive powder concrete under distinct curing environment

Reactive Powder Concrete (RPC) is composed of fine powders (cement, sand, quartz powder and silica fume), steel fibres (optional) and superplasticizer. This gives good compaction and an impenetrable matrix is achieved, and this strong concentration gives RPC, an ultra-high strength and durability properties. In this research work, focus was aimed to produce reactive powder concrete (RPC) composite material with compression strength up to 100 N/mm2. Components for RPC mixture are carefully selected to achieve optimal mixture. Detailed concrete mix proportions are given in this research paper. Preparation and testing of material were produced in laboratory belonging to the Department of Civil Engineering in SRM Institute of Science and Technology. Casting of concrete cubes and beams was done for both M60 and M100 grades of concrete. This paper investigates mechanical and fresh concrete properties of reactive powder concrete for both the design mix. Laboratory investigations like; Compressive test, split tensile test and flexural strength were conducted to evaluate strength characteristics of RPC, under different curing conditions like oven, steam, and hot water with respect to time factor of T1 (60 min), T2 (61-90 min) and T3 (91-120 min). In every aspect of testing, the steam curing at 100°C shows improved results of 15.71-17.40% in compressive strength, 24.66-25.93% in tensile strength and 20% in flexural strength for both grades of concrete

Construction Characteristics and Quality Control Measures Under High Altitude and Cold Conditions

Restricted by the natural environment factors, the high altitude and cold regions have low air pressure, low air density, large temperature difference between day and night, and long freezing and cold time. During the construction, strict requirements are put forward for the material preparation, material transportation, construction machinery, construction technology, workers’ personal safety and other aspects. Based on the engineering construction in Tibet, this paper studies the optimization scheme of concrete mix proportion and the systematic insulation measures of concrete construction in high altitude and cold regions. The influence of ultra-low temperature on metal welding process is studied. The effects of welding wire selection, welding environment guarantee and worker training on welding quality assurance are studied. The calculation method of mechanical efficiency reduction and the influence of altitude on environmental factors and quota adjustment coefficient are studied. The results of this study provide reference and technical support for the construction in high altitude and cold areas.

Preparation and flexural fatigue resistance of self-compacting road concrete incorporating nano-silica particles

In this study, the mix proportion of self-compacting road concrete with ternary cementitious materials was optimized by incorporating nano-silica particles to improve its flexural fatigue performance. The filling property and compressive strength were selected as evaluating indicators to design L9(33) orthogonal test, and then four kinds of mix proportions were selected to prepare the nano-modified self-compacting concrete (SCC) according to the results of grey relational analysis and comprehensive weighting method. The four-point flexural fatigue tests were conducted to establish the probabilistic fatigue equations of nano-modified SCC based on the two-parameter Weibull distribution with survival rates of 50% and 95%, respectively. The modification mechanism was revealed with the help of scanning electron microscopy and X-ray diffraction phase analysis. The results indicate that the optimal mix proportion of self-compacting road concrete could be obtained when nano-silica accounts for 1% of the mass of cementitious materials. The specimens with 1% nano-silica particles showed the best flexural fatigue performance, with the reduction factor of flexural strength increased by 1.5%–5.0% and the sensitivity of fatigue life to the stress levels decreased by 2.1%–9.7% at survival rate of 50%. The nanoparticles provided a physical filling effect and facilitated the formation of low-density calcium silicate hydrate gel, filling the internal micro-pores to make the structure more compact. Nano-silica improved the flexural fatigue performance of self-compacting road concrete to a certain extent.

Near-Surface and Chloride Permeability of Concrete Using Pozzolanic Materials and Manufactured Sand as Partial Replacement of Fine Aggregate

The overuse level of cement and natural sand for civil industry has several undesirable social and ecological consequences. As an answer for this, industrial wastes called by-products (pozzolanic materials) like fly ash, GGBFS, silica fume and metakaolin can be used to interchange partially cement and natural fine aggregate by manufacturing sand (M-sand). Thus, the present research work reported in this article deals with the feasibility study of using manufactured sand as sand replacement and pozzolana as cement replacement materials in concrete. So this will solve two problems simultaneously, viz. the bulk utilization of pozzolanic materials and saving the natural quarries of sand. Thus, the research work presented here specifically dealt with the potential utility of manufactured sand as sand replacement and pozzolana as cement replacement material and its effect on the durability and microstructure properties. Thus, the main objective of this experimental investigation is to find out the durability properties of concrete produced by replacing natural sand by manufactured sand in varying percentages like 0%, 10%, 20%, 30%, 40%, 50%, 60% 70%, 80%, 90% and 100%, and 20% cement replacing with pozzolanic materials. In this experimentation, natural fine aggregate was partially replaced by M-sand in various percentages 0–100% with 10% interval, water–cement ratio of 0.45, and cement was partially substituted by 20% of pozzolanic materials. M30 concrete grade proportions were considered as per IS 10262:2009 guidelines. The durability properties like water absorption, sorptivity and chloride permeability results were checked for the different concrete mix proportions and compared with conventional concrete. From this research work, it can be concluded that for replacement of 60% natural fine aggregate by manufactured sand (M-sand) and 20% cement by silica fume yields minimum water absorption, sorptivity, chloride permeability and denser microstructure than conventional concrete.

Design of Concrete Mix Proportion Based on Particle Packing Voidage and Test Research on Compressive Strength and Elastic Modulus of Concrete

According to the basic principle of dense packing of particles, and considering the interaction between particles, a dense packing model of granular materials in concrete was proposed. During the establishment of this model, binary particle packing tests of crushed stone and sand were carried out. The fitting analysis of the test results determines the relationship between the particle size ratio and the remaining volume fraction of the particle packing, and then the actual void fraction of the particle packing was obtained, based on which the water–binder ratio was combined to determine the amount of various materials in the concrete. The proposed concrete mix design method was used to prepare concrete, and its compressive strength and elastic modulus were tested experimentally. The test results show that the aggregate volume fraction of the prepared concrete increased, and the workability of the concrete mixture with the appropriate amount of water reducing agent meets the design requirements. When the water–binder ratio was 0.42, 0.47, or 0.52, the compressive strength of the concrete increased compared with the control concrete, and the degree of improvement in compressive strength increased with the decrease in water–binder ratio; when the water-binder ratio was 0.42, 0.47, or 0.52, the static elastic modulus of the concrete increased compared with the control concrete, and the degree of improvement in elastic modulus also increased with the decrease in water–binder ratio. The elastic modulus and compressive strength of the prepared concrete have a positive correlation. Findings show that the concrete mix design method proposed by this research is feasible and advanced in a sense.

Influence of concrete mix proportions on lifetime flexural load-bearing capacity of RC beams under chloride corrosion of rebars

In this research, the effects of mix design parameters on chloride ion diffusion in concrete and corrosion of rebars have been investigated. Effect of parameters such as cement, water to binder ratio, slump, aggregates, and characteristic compressive strength are analyzed using response surface method (RSM). Regression analysis is used to evaluate the electrical resistivity related with each concrete mixture. Subsequently, the corrosion rate is obtained by using the electrical resistivity and chloride migration coefficient. To validate the regression analysis and investigate the effect of rebar corrosion on the flexural behavior of the beam, a finite element software is employed. Corrosion is applied to a selected beam and the load-displacement plots are obtained by analyzing four laboratory samples. The plots show good agreement between numerical and experimental results. Also, the effect of changing only one parameter is observed on the flexural capacity of the selected beam and its life cycle. It is observed that increasing the water to binder ratio, aggregate content, and slump, decrease the flexural capacity of the beam, while increasing the cement content and characteristic compressive strength leads to a positive effect on flexural capacity.

Experimental and analytical investigation on the age-dependent tensile strength of low-calcium fly ash-based concrete

In this study, the age-dependent splitting and flexural tensile strength have been investigated by incorporating the various percentages of fly ash in the plain concrete mixes. The partial replacement of cement by fly ash was varied from 0 to 60% on an equal weight basis. Standard concrete specimens were cast for measuring splitting and flexural tensile strength at different ages, i.e., 7, 28, 56, 90, 150, and 180 days, for all plain and fly ash concrete mixes. Experimental results show that the fly ash produced a significant effect on the tensile strength of concrete mixes. It has been observed that the fly ash concrete mixes gain considerable tensile strength with respect to age beyond 28 days. In the low-calcium fly ash concrete mixes, the rate of development of tensile strength from 28 to 180 was observed higher in comparison with the plain concrete mixes. The assessment of the existing models for the estimation of age-dependent tensile strength recommended by design codes and researchers with experiments has also been done on various mixes of plain and fly ash concrete. New models to predict the age-dependent splitting and flexural tensile strength of concrete having different percentages of fly ash are proposed. The present experimental and analytical study will be helpful for the designers and practicing engineers for fixing preliminary dimensions of reinforced and prestressed concrete members and mix proportioning of low-calcium fly ash concrete mixes.

Studies on self-curing self-compacting concretes containing zeolite admixture

Abstract The process of infrastructural advancements resulting in development of any sub-continent primarily depends on the construction activities which facilitates safe and sustainable buildings for livelihood and high-quality transportation networks. Out of all the construction materials used concrete plays a major role. Hence, field engineers are posed with various challenges in maintaining the quality of concrete. Moreover, the attempt to reduce the use of cement content in concrete requires the utilization of mineral admixtures. The present work focuses to study the performance of self-curing self-compacting high-performance concretes containing calcined and uncalcined zeolite with polyethylene glycol (PEG) as self-curing agent. Two sets of concretes were formulated for investigations, the first set consists of 5 concrete mix proportions with control concrete and self-curing concrete’s replacing cement with 5% of calcined and uncalcined zeolite containing 1% and 2% of PEG in both. The second set of concretes were formulated to replace 10% of cement content with calcined and uncalcined zeolite containing 1% and 2% of PEG in both. A relative comparison of the performance characteristics were evaluated by determining the mechanical and durability characteristics of proposed self-curing self-compacting concretes.

Compressive strength and durability of Metakaolin blended concrete exposed to acid and sulphate attack

Sustainable development of the cement and concrete industry requires the utilization of industrial and agricultural waste components. At present, for a variety of reasons, the concrete construction industry is not sustainable. In general, high strength concrete made with ordinary cement is not durable and does not have good resistance to acids except for some weak acids if the exposure is occasional. Metakaolin is a supplementary cementitious material used as an admixture to produce high strength and high-performance concrete. The objective of this study is to arrive at Optimal quality of metakaolin that can partially replace the cement for M20, M30, M40, M50, M60, M70, M80 grades of concrete to get better strength and durability. The mix proportions of OPC concrete are obtained for M20, M30, M40, M50, M60, M70, M80 as per IS 10262 2009 [1]. Mix proportions with partial replacements of cement by 0%, 10%, 15%, 20%, 25%, 30% of Metakaolin with concrete were determined. Concrete specimens for compressive strength (150 mm x 150 mm x 150 mm cubes) are cast and Durability studies are conducted for all grades with partial replacement of cement by Metakaolin for 1% and 0.5% concentrations of HCl and H2SO4. From the results, it was concluded that the compressive strength of concrete is maximum at 15% replacement of cement by Metakaolin. The compressive strength of concrete showed better result at 15% replacement of Metakaolin for 0.5% and 1% HCl and H2SO4 at the age of 28days of strength. The effect of HCl on strength of the Metakaolin concrete is lower than the effect of H2SO4.

Experimental investigation of compressive strength for fly ash on high strength concrete C-55 grade

High-strength concrete is used for resisting high compressive load and improved strength. The Cement content of the mix proportion for high-strength concrete is incredibly high compared with conventional concrete strength. Fly ash is the by-product of coal burning. Such material was used as a partial replacement of cement in high strength concrete, reducing carbon-dioxide gas emissions into the atmosphere and minimizing the negative impact on the environment released from industrial waste disposal as landfill. The objective of this study is to investigate the effect of fly ash on high-strength concrete properties. Experimental laboratory tests were conducted. Slump height is measured to determine the workability of fresh concrete. The Cube size is (150mmx150mmx150mm) which is used for testing compressive strength for the age of 7, 14, and 28 days of curing. Cement's percentage replacement with fly ash varies from 0% to 30% by the increment of 5%. The total numbers of samples conducted are one hundred twenty-six. The study results show that the replacement of cement by fly ash up to10% increases the slump values. However, the replacement of cement beyond 10% by fly ash decreases the workability of fresh concrete. Regarding density and compressive strength, the replacement of cement by fly ash decreased the density of concrete. The compressive strength of concrete becomes improved and increased when the cement is replaced by fly ash up to 10%. At the curing age of 28th days, the concrete containing 5% and 10% fly ash as cement gained 1.66% and 2.97% of strength, respectively. This study suggests that the partial replacement of cement by fly ash up to 10% increases the capacity of high strength concrete and fresh concrete's workability. The optimum percentage of fly ash to replace cement is 10% for high strength concrete.

Study on Engineering Performance of Green Porous Sponge Ecological Concrete

To meet the needs of sponge city construction, based on the design method of mix proportion of green porous sponge ecological concrete, the engineering performance of green porous sponge ecological concrete was studied with orthogonal experimental. The results show that the compressive strength of the specimens peaked at the 0.9% admixture of sponge; based on the optimal admixture of sponge, the compressive strength of the specimens peaked at the 12% admixture of mineral powder; compared with the ordinary concrete, the water‐retaining property of green porous sponge ecological concrete is twice than ordinary, and green porous sponge ecological concrete has high permeability and low evaporation; under the same external temperature, the maximum temperature of concrete surface is lower than ordinary; and under three work conditions, the volumes of water going through the green porous sponge ecological concrete, respectively, are 1.78 kg/(s·m2), 1.47 kg/(s·m2), and 1.62 kg/(s·m2), and the value of second totally dry condition is minimum because of water blocking affection of the internal sponge. The research results will provide help for the infrastructure construction of sponge city and play an important guiding significance to promote the construction of resource‐saving and environment‐friendly cities.

The Influence of the Use of Cement Brands on the Physical and Mechanical Properties of Reactive Powder Concrete (RPC)

The most popular building material today is concrete. Concrete is used for buildings, industrial structures, bridges, railroad sleepers, roads, dams and more. Along with the development of concrete technology is increasingly developing and innovative so as to achieve better characteristics, cheaper prices and environmentally friendly. In the early days of the development of concrete it is explained to us about the origin from ancient times to civilization to the present century of its development. In current developments, concrete already has a very high compressive strength up to 200-800 MPa, this is also called Ultra Hight Concrete (UHC). It is developed by the Reactive Powder concrete (RPC) method. Where in the research conducted, the manufacture of reactive material, namely Reactive Powder concrete (RPC) was given with a compressive strength of up to 52 MPa. The components of the RPC mixture consist of cement, fine aggregate, silica fume, superplasticizer and water. To produce a compressive strength of 52 MPa, the composition of the mixture used previous research. Detailed RPC concrete mix proportions are given in this study. Preparation and testing of materials are made in the laboratory of the Faculty of Civil Engineering in Untan. The results that will be obtained are the physical and mechanical properties of RPC Concrete. As previously explained, the manufacture of RPC concrete requires basic ingredients that include cement, fine aggregate, silica fume, superplasticizer and water mixed together. Of course, with basic ingredients with good and correct composition, the physical and mechanical properties of RPC concrete will reach the planned quality. Cement sold in the market today has PPC and PCC types. Therefore, the cement which is a binder of powder materials into a solid one plays a very important role in the formation of the best physical and mechanical properties of RPC concrete. With cement as a binding material, it is certain that the strength of RPC concrete is determined by the binding capacity of the type of cement to be used, thus RPC concrete will be obtained according to the planned quality of the plan. From the cement brands on the Indonesian market consisting of PPC and PCC cement types, it can be concluded that one of the cements using the PCC type cement brand has better physical and mechanical properties than the PPC type cement brand. And all brands of cement with PCC type produce compressive strength > 52 MPa. So, in the manufacture of RPC concrete it is recommended to use a cement brand with PCC type.

A review on sustainable concrete mix proportions

The need for reducing the carbon footprint and effect of hazardous gases, etc., released from the construction sectors and other product manufacturing industries on the environment is the need of the hour. In this regard, the construction sector has been utilizing some of the wastes generated from various sources in making concrete. Notable among them is the Ground granulated blast furnace slag (i.e. GGBS) as a partial substitution of cement. Further, waste foundry sand, a by-product of the foundry industry is observed to be an appropriate alternative to partial replacement of fine aggregate and demolition waste as a partial replacement of coarse aggregate. These waste utilizations have addressed some of the global environmental concerns like solid waste management, scarcity of landfilling, sustainability etc. but there is still is inefficient, given the rate at which we are producing waste. This paper presents an overview of some of the recent research published on the utilization of wastes in the production of sustainable RMC/SMC. It also presents the effect of waste utilization in concrete on mechanical, microstructural and durability factors.

Study on nano-alumina in concrete

Nano-materials in concrete helps in effective utilization pore space occupation leading to minimal etrringate formation which in-turn improving overall durability and improved performance of concrete on long-term. The present study aims at experimental investigation on Nano-alumina in concrete, its optimizations and its effects in concrete overall strength. Nano-alumina has been added to the concrete mix proportions of 1%, 2%, 3% and 4%.Totally108 cubes, cylinders and prism were casted for the grades of M30 and M40 of concrete and their respective compressive strength, spilt tensile strength and flexural strength has been analyzed by experimental investigation. The distribution of ultra-sonifcated, nano-alumnia in concrete has been analyzed by means of Scanning Electron Microscopic image patterns. Based on the experimental study Nano-alumina with 1% has showed better distribution along the matrix of concrete and also efficient in terms of improved compressive strength, split tensile strength and flexural.