Concrete Mix Proportion Research Articles

Research on Application Technology of Molybdenum Tailings Sand Concrete

Molybdenum tailings sand is used as a fine aggregate to replace part of the construction sand, which can effectively solve the environmental pollution problems caused by the molybdenum tailings pond and has high utilization value. After tetsting the physical properties, chemical analysis, radioactivity and other indicators of molybdenum tailings sand, the results show that the molybdenum tailings sand basically meets the conditions of construction sand. By increasing the proportion of molybdenum tailings in concrete, the concrete performance will decrease in viscosity, slump loss and strength with the increase of the blending ratio. Therefore, the ratio of molybdenum tailings to substitute fine aggregate is between 40%-50%, should not exceed 60%. The problems of viscosity and strength of molybdenum tailings sand concrete still need to be solved through adjusting the concrete mix proportion or optimizing the admixture formula.

Inquiry on Mechanical Properties of M30 Grade Concrete with Partial Replacement of Copper Slag and Dolomite Powder for Fine Aggregate and Cement

Concrete plays an important role in every construction. This paper is an experimental investigation to study the mechanical properties of the concrete with partial replacement of cement by dolomite powder and fine aggregate by copper slag. So, in this investigation, by usage of Dolomite powder in concrete on one side improves density and other side improves strength and hardness. Copper slag also increases density of concrete and toughness of concrete. The cement content replaced with dolomite and fine aggregate replaced with copper slag from 5% to 25% at regular intervals of 5%. In the designed mix proportion of M30 grade concrete is 1:2.17:2.95. The Superplasticizer Master Rheobuild 920SH of 0.5% dosage used as chemical admixture is added to the concrete to maintain 0.45 the water-cement ratio. The concrete cubes, cylinders were casted. The different mechanical properties like compressive strength, split tensile strength, flexural strength were tested after 3 days, 7 days and 28 days of curing from 5 to 25% at regular intervals of 5% replacement of cement with dolomite powder and 10% to 50% at regular intervals of 10% replacement of fine aggregate with copper slag.

Bond behavior between basalt fiber‐reinforced polymer rebars and coral‐reef‐sand concrete conditioned in saline solution

AbstractThis paper studies the bond behavior between basalt fiber‐reinforced polymer (BFRP) rebars and coral‐reef‐sand (CRS) concrete exposed to a saline environment. The gradation and mix proportion of CRS concrete was firstly selected, through compressive tests on CRS concrete cubes. A series of pullout tests were conducted on a total of 84 pullout specimens after conditioning in a saline solution. The experimental variables included type of rebar (steel and BFRP), diameter of BFRP rebar, conditioning duration and temperature, and type of conditioning (continuous immersion and wet–dry cycle). The stress–slip curves and bond strength of the pullout specimens were analyzed and discussed. The results show that 0.54 is selected as the water/cement ratio for CRS concrete, among the range of analyzed concrete mixes. The bond behaviors of BFRP rebars depend on their diameter. BFRP rebars with 12‐mm‐diameter have the best bond durability after conditioning in a saline solution, when compared with their counterparts with 8‐ and 16‐mm‐diameters. The effects of conditioning temperature and type of conditioning on the bond behavior of 12‐mm‐diameter BFRP rebar are negligible. A design‐oriented formula was proposed for the prediction of the development length of a BFRP rebar in CRS concrete based on the experimental data. Furthermore, modified BPE models were calibrated to describe the bond–slip relationship of BFRP rebars in CRS concrete in a saline environment.

STUDY ON MIX PROPORTION DESIGN FOR CONCRETE USING FLY ASH (TYPE-II (JASS5 M-401))

In this study, I investigated the mix proportion of ready mixed concrete using fly ash for buildings. As a result, I obtained the useful information for mix proportion of concrete using fly ash of type-II (JASS5 M-401). As methods of using fly ash, the four methods (cement substitution, fine aggregate substitution, cement and fine aggregate substitution, unit FA amount constant method) are used. This paper describes the purpose of use and mix proportion design method for each of the four methods.

Effects of w/b ratio, fly ash, and chloride content on corrosion of reinforcing steel

To predict the corrosion of reinforcing steel, the electrochemical properties of reinforcing steel with different concrete mix proportions and chloride content were studied. The water to binder ratio of concrete was varied (0.45 and 0.60). Coal fly ash was used to replace OPC (0 and 30% by weight of the total binder). The initial chloride was 0, 2, and 4% by weight of concrete. Potentiodynamic polarization testing was conducted by controlling the moisture of specimens. The Tafel slope, corrosion potential, and corrosion rate were analyzed from the testing results. Results show that chloride content significantly affects the electrochemical properties of reinforcing steel. The anodic Tafel slope decreased as chloride content increased. The cathodic Tafel slope increased when the water to binder ratio decreased, or when the fly ash content increased due to a denser concrete pore structure, limiting oxygen diffusion. Results from this study can be used to simulate the corrosion of reinforcing steel and predict the service life of reinforced concrete structures. Also, the electrochemical compatibility between existing and repaired sections can be evaluated to ensure the durability of repaired RC structures.

Study on Mechanical Properties of Self-Compacting Concrete and Its Filled in-Line Multi-Cavity Steel Tube Bundle Shear Wall

In this paper, five groups of C40 fly ash and silica fume self-compacting concrete (SCC) mix proportion tests and in-line multi-cavity steel tube bundle self-compacting concrete shear wall axial compression performance tests and numerical simulation are completed and presented. The influence of fly ash and silica fume additions on SCC mechanical properties and the filled in-line multi-cavity steel tube bundle shear wall mechanical properties are analyzed and studied. With an increase in the fly ash content from 10% to 40%, the compressive strength of self-compacting concrete increases firstly and then decreases. When the fly ash content is 30% and the silica fume content is 4%, the compressive strength of the 28 d age self-compacting concrete is the highest and the compressive strength formula of the wrapped curing SCC is proposed. The failure of steel tube bundle is multi-wave buckling failure. As the SCC is most obviously affected by the collar at the corner point of the steel tube bundle, its compressive strength is 110 MPa, and is 96 MPa higher than the concrete at the middle point of the web. The deformation resistance of SCC is obviously enhanced by the confinement effect.

Utilization potential of fly ash and copper tailings in concrete as partial replacement of cement along with life cycle assessment

Fly ash (FA) and copper tailings (CT) both are, anthropogenic wastes, spread all over the globe due to rapid growth in thermal power plants and progressive increase in the demand of copper. This study examines the feasibility of combined utilization of FA and CT in concrete as a partial replacement of cement by assessing compressive strength, cost, and environmental impact. Morphology and constituent minerals of FA and CT have been identified to understand the utilization potential. Subsequently, the concrete has been designed for 30 MPa target strength as per IS 10262:2009 for different mix proportions of FA and CT. Improvement (up to 8.27% compared to the control mix) in the compressive strength has been observed at combined replacement of 10% FA and 5% CT. The cost of concrete can also be reduced up to 16% without compromising its compressive strength. The environmental impact assessment of the modified concrete mix proportions has also been performed using life cycle assessment (LCA) as per ISO 14040:2006. Effect of all raw materials, electricity, and water consumption have been considered from their cradle to grave approach. One cubic meter concrete has been taken as a functional unit in LCA. Notable reduction has been observed in the chosen midpoint categories up to 38% in climate change, up to 32.6% in human toxicity, up to 33.6% in ozone depletion, up to 31.9% in agriculture land occupation, water depletion up to 34.3%, fossil depletion up to 34.8%, particulate matter up to 35.4%, and metal depletion up to 25.2%.

Properties and microstructure 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 as by-products (pozzolanic materials) such as fly ash, GGBFS, silica fume and metakaolin can be used to interchange partially cement and natural sand by manufacturing sand (M-sand). In this paper, the detailed experimental investigation was done to study the effect of partial replacement of, natural sand by M-sand in various percentages (0%,10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and 100%), with water–cement ratio of 0.45 and cement was partially substituted by 20% of pozzolanic materials. M30 grade of concrete mix proportions were designed as per IS 10262:2009 guidelines. The fresh concrete properties and tensile strength results, were checked for the different concrete mix proportions and compared with conventional concrete. The tests on hardened concrete were destructive in nature which includes tensile test on cylinder as per IS: 5816-1999 at 28 days of curing. From this research work, it can be concluded that for replacement of 60% natural sand by M-sand and 20% cement by silica fume yields maximum tensile strength and improves the microstructure than conventional concrete.

Mix Design and Mechanical Properties of High-Performance Pervious Concrete.

The mechanical properties of traditional pervious concrete are insufficient, which limits its application. In view of the imperfections of traditional permeable concrete in mechanics, this paper aimed to find a suitable material composition that can be used as a feasible mix design of high-performance pervious concrete, to essentially improve its mechanical properties. Based on the view that concrete is a two-phase material, in order to understand the rheological properties of the matrix, it was subjected to a rheological test, and then the filler aggregate was uniformly incorporated into the aforementioned matrix to further explore the composition and properties of the resulting pervious concrete. For the matrix, the orthogonal array employed was L16(45), which consisted of five factors, each with four levels. Base on the fluidity and compressive strength of the tested matrix, three groups of suitable matrixes mix proportions were selected to serve as the matrix type for pervious concrete mix proportion design. Then, an orthogonal array L9(34), which consisted of four controllable three-level factors, was adopted in the pervious concrete. The parameters investigated included the coarse aggregate size, fine aggregate content, matrix type, and aggregate-to-binder ratio. The test results demonstrate that the key factors affecting the compressive strength of the matrix and the pervious concrete were closely related to the cementitious material. In the matrix, the proportion of the cementitious material was the most important factor, while in the pervious concrete, the type of matrix was the most important factor.

Performance of Self Compacting Concrete with Partial Replacement of Coarse Aggregate with Recycled Coarse Aggregate

Self Compacted Concrete (SCC) is an advanced approach for the purpose of placing of concrete.It is a concrete which does not require any external force,vibration or compaction and which is highly flowable, formwork is filled without any compaction and resistance to segregation. Workability tests for SCCin fresh state are Slump-flow, L-Box, J-Box,V-Box are carried out.By using recommended EFNARC guidelines the mix proportion of concrete was prepared for M40 grade concrete is 1:1.75:1.87.Water cement ratio of 0.35 is constant.In this paper Natural Coarse Aggregate(NCA) is partially replaced upto 50% with 10% interval by Recycled Coarse Aggregate(RCA).RCA is prepared by crushing of cubes which are taken from concrete technology lab. Construction and Demolition waste is also used as RCA. RCA is submerged in water for 24 hours before using for the concrete mix,this is because RCA absorbs more waterdue to adhered cement mortar to aggregate. The various tests and their results are shown in this paper.

Performance of various pozzolanic materials on the properties of concrete made by partially replacing natural sand by manufactured sand

Now a day’s concrete is the extreme broadly used construction material in civil engineering industry because of its extraordinary structural strength and stability. 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 as by-products (pozzolanic materials) such as fly ash, GGBFS, silica fume and metakolin can be used to interchange partially cement and natural sand by manufacturing sand (M-sand). This research aims to investigate the possibility of replacing natural sand by M-sand with 20% of above pozzolanic materials substitute in concrete. In this experimentation, natural sand was replaced by M-sand in various percentages (0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and 100%), with water–cement ratio of 0.45 and cement was partially substituted by 20% of pozzolanic materials. M30 grade of concrete mix proportions were designed as per IS 10262:2009 guidelines. The fresh concrete properties and compressive strength, tensile strength and flexural strength 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 sand by M-sand and 20% cement by silica fume yields maximum compressive strength, tensile strength and flexural strength than conventional concrete.

Preparation, performance test and microanalysis of hybrid fibers and microexpansive high-performance shaft lining concrete

To solve the leakage problem of shaft lining concrete drilled by the freezing method of extra-thick alluvium, hybrid fibers and microexpansion high-performance shaft lining concrete were prepared in this paper, and the related properties were studied experimentally. First, based on the mix proportion of the reference concrete, the high-performance shaft lining concrete with various mix proportions was prepared by optimizing the raw materials. Then, the physical and mechanical properties of high-performance shaft lining concrete with different mix proportions were tested and compared with those of the reference concrete. The results show that the hybrid fibers and microexpansive high-performance concrete can be obtained by adding 1.092 kg/m3 polyvinyl alcohol fiber (PVA), 5 kg/m3 imitation steel fiber (FST) and 32.8 kg/m3 CSA expansive agent. Under the restricted curing state, this combination has the advantages of increasing the compressive strength by 8.96%, increasing the splitting tensile strength by 28.2%, increasing the impermeability by 86.643%, and reducing the temperature stress by 43.099% and can completely avoid the occurrence of early cracks. Finally, through X-ray diffraction and scanning electron microscope microscopy analysis, the mechanism of improving crack resistance and impermeability of shaft lining concrete by the synergistic effect of the combination of hybrid fibers and expansive agent was revealed.

AN EXPERIMENTAL STUDY ON EFFECTIVE USE OF EFFLUENT WASTEWATER IN CONCRETE PREPARATION

Nowadays fresh water is very limited in Oman and has lack of rain every year. But, concrete industry is still using fresh water to produce their product. This project is to investigate using treated effluent wastewater in concrete preparation as an alternative for using fresh water. The effluent discharge collected from Haya wastewater treatment plant, where the discharged effluent is collected in sewerage pipelines without affecting human and environment. According to this study, to make a value of treated effluent wastewater to be used in the construction industry in concrete casting and curing process. Chemical, physical and biological parameters in wastewater were collected directly from the treatment plant by using LIMS system. The produced concrete has a grade of C30 and the mixture consist of ordinary Portland cement, fine aggregate and coarse aggregate, and prepared by mixing with different water percentages of normal water and treated effluent wastewater. Based on American Concrete Institute requirement, the concrete mix proportions determined. Concrete quality checked with regarding to various tests and performing in the project study which are, slump test, compressive strength test, and split tensile strength test by using UTM. The purpose of these tests is to investigate the hardness and strength of the prepared concrete. The results conform using treated effluent wastewater with 100 % gives higher values in compressive strength and spilt tensile strength than use normal water. Also, heavy metals concentration results are within the limit of other standard effluent discharge standard, hence this test is important for checking the durability of concrete. Based on journals, the results of using treated effluent wastewater in concrete were investigated. The compressive strength and split tensile strength of the concrete is high and achieved the standard requirement. Also, was finding that the usage of acid solution is as removal for the toxic matter in concrete prepared with wastewater. So, usage of treated wastewater gives same normal water performance when added in concrete. However, all output from the literature review would be but into consideration in the project study.

EFFECT OF CONCRETE STRESS STATES ON CARBONATION DEPTH OF CONCRETE

Carbonation can lead to reduction of alkalinity of concrete and initiation of steel reinforcement corrosion. In durability design of concrete structures, the carbonation depth should be duly considered. However, the concrete stress state would influence the carbonation depth, and there has been inadequate research on such effect. In this study, it is proposed to introduce a stress influence coefficient to the concrete carbonation depth model. With reference to the experimental data from eleven research studies in the literature encompassing both tensile and compressive stress states, the relationship between stress influence coefficient and concrete stress ratio is quantitatively investigated, and mathematical equations relating the stress influence coefficient with the concrete stress ratio are established. Comparative study with three typical existing groups of equations shows that the proposed equations of stress influence coefficient are more reasonable and have a higher reliability. The effects of carbonation time, mix proportions of concrete on stress influence coefficient are also analysed, and the magnitudes of the effects are found to be approximately within ±10%. Finally, the modified carbonation depth models are proposed and verified by the experimental data, which suggests that the proposed models are of desirable accuracy. Adoption of the proposed equations as the modified formula of stress influence coefficient in the concrete carbonation depth model for practical applications is recommended.

Design method for the mix proportion of geopolymer concrete based on the paste thickness of coated aggregate

Geopolymer is an environmental-friendly cementitious material, but few systematic designed methods for the mix proportion of geopolymer concrete have been developed due to the multitudinous factors. In this paper, a method for the mix proportion of the geopolymer concrete was proposed based on the paste thickness of coated aggregate and the close packing theory. In this method, the water-to-metakaolin ratio was selected based on the minimum water requirement method. Aggregate gradation was designed according to the close packing theory and the amount of metakaolin was determined by the paste thickness of coated aggregate. In addition, geopolymer concretes with the paste thickness of 10 μm, 20 μm and 30 μm were prepared by the alkali activated-metakaolin at ambient temperature, while the effect of the paste thickness on the compressive strength, sulphate attack and electrical resistivity of geopolymer were examined. Results showed that geopolymer concrete had a well fluidity and the strength degree of C30∼C50 can be achieved. Moreover, the relation among alkali content, modulus and compressive strength of geopolymer mortar was proposed.

Performance of Various Pozzolanic Materials on Shear and Impact Strength of Concrete made with Partial Replacement of Natural Fine Aggregate by Manufactured Sand

Nowadays concrete is the widely used construction material in civil engineering field because of its extraordinary strength and durability. The over-utilization of cement and natural sand for civil industry has several undesirable social and ecological consequences. As an answer for this, industrial wastes called as by-products (pozzolanic materials) such as fly ash, GGBFS, silica fume and metakaolin can be used to interchange partially cement and natural fine aggregate by manufacturing sand (M-sand). This research aims to investigate the possibility of replacing natural fine aggregate by M-sand and with 20% of above pozzolanic materials substitute in concrete. In this experimentation, natural fine aggregate was partially replaced by M-sand in various percentages (0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and 100%), with 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 10262:2019 guidelines. The shear strength and impact strength results were checked for the different concrete mix proportions and compared with conventional concrete. From this research work, it is concluded that for partially replacing of 60% natural fine aggregate by M-sand and 20% cement by silica fume yields maximum shear and impact strength than conventional concrete.

Effect of the Electric Field on the Distribution Law of Chloride Ions and Microstructure in Concrete with the Addition of Mineral Admixtures.

Migration testing of chloride under an electric field is a fast and effective method to determine the corrosion resistance of reinforced concrete against chloride. In this study, a series of admixture-involved (fly ash and slag) concrete specimens were produced for an accelerating chloride diffusion test in 3% NaCl solution under an electric field and natural chloride diffusion in 165 g/L NaCl solution under immersion conditions. Then, the chloride profile and pore structure of concretes aged 56 and 91 days were compared to investigate the effect of the electric field on chloride diffusion as well as the microstructure of the concrete. The results showed that, under accelerating electric field conditions, the degree to which chloride refined the internal pore structure of the concrete was weaker than that under natural immersion conditions. The applied electric field changed the pore structure inside the concrete, but it had little effect on the distribution of total, free, and bound chlorides and their mutual relationship. In addition, it is necessary to consider that the electric field effect on chloride migration varies with the concrete mix proportions.

Experimental study on the vegetation characteristics of biochar-modified vegetation concrete

Vegetation concrete is an effective material to beautify the landscape, reduce pollution and protect the environment. To further improve the plant compatibility of vegetation concrete, this paper recommends an improved method of adding biochar particles to vegetation concrete. In this research, different masses of biochar were mixed into concrete to study the trend in porosity, permeability and plant compatibility. According to the growth status of three types of common grass species, ryegrass was selected as the best grass species in this study. As the content of biochar increased, the porosity and permeability coefficient of vegetation concrete continued to decrease, while the effect of biochar on plant growth promotion at first showed an increase to the maximum and then a gradual decrease. When the biochar content was 5 kg/m3, ryegrass showed the best growth. Compared with the experimental group of vegetation concrete without biochar, the plant height, root length and germination rate increased by 22.2%, 21.1% and 12%, respectively, on day 25, and the compressive strength also increased slightly. Therefore, adding a suitable amount of biochar can improve the characteristics of vegetation concrete. Furthermore, the optimum mix proportion of biochar-modified vegetation concrete was recommended.

Cracking Behavior of Reinforced Lightweight Concrete Beam Using Hot Water Pre-treated Oil Palm Shell Coarse Aggregate

As one of the largest palm oil producers in the world, by-products of this commodity are also produced in Indonesia. One of the solid by-products that are obtained from palm oil production is called Oil Palm Shell (OPS). These days, this material is interesting to be studied as it has a lightweight but sufficiently tough and rough outer surface. In previous studies done in laboratory, OPS was used as alternative coarse aggregate in concrete mix proportion. The designed compressive strength of OPS concrete is in the range of 20-23 MPa. In this research, the authors are interested in studying the crack behaviour of reinforced lightweight concrete beams using OPS replacing natural coarse aggregates. First, pre-treatment of OPS is performed by using hot water at 50-°C as based on previous studies. Second, two samples of identical beam with 15 × 25 × 300 cm3 of dimension were cast and tested under four-point loading using force control hydraulic actuator. Third, crack opening evolution due to flexural test that occurs in OPS lightweight concrete beam is measured, to be precise, on the pure bending area. The crack opening is compared to service limit cracks from building code to find the corresponding loading application.

Flexural behaviour of reinforced lightweight concrete beam using hot water pre-treated oil palm shell coarse aggregate

Along with the increasing demand for habitation in Indonesia, the need for concrete as the most favourable housing material is escalating. Oil Palm Shell (OPS) as coarse aggregate material is a possible alternatives material in concrete mix proportions. This possible choice of material not only can fulfil the requirements of the materials, but is also capable of reducing the problem of OPS waste in Indonesia. As OPS concrete compressive strength in previous studies in laboratory is in the range of 20-23 MPa, studies on larger elements of structure become interesting. This research presents flexure behaviour of lightweight concrete beams using OPS replacing natural coarse aggregates under four-point loading application. OPS is firstly pre-treated using hot water at 50°C based on previous research. In this study, a series of tests was conducted on two samples of identical beam with dimension of 15×25×300 cm. This size represents the typical dimension of beam used in two-storey houses in Indonesia. Mechanical response due to bending that occurs in OPS lightweight concrete beam is presented. Observation on the beam is emphasised on the pure bending area.