Concrete Proportions Research Articles

Durability studies of concrete added with nanosilica

The performance of existing materials such as concrete has been improved significantly by blending it with specific property enhancement materials especially nanomaterials like nanosilica. Utilization of nanosilica has been proved to be beneficial because of its indispensable qualities, which helps in creating concrete with improved strength and durability. In this paper, the impact of nanosilica on toughness of cement has been researched. For this purpose, 3% of ideal measurement of nanosilica has been added to solid combinations of M40, M50, M60 grades of concrete. Additionally, the admixture Conplast SP 430 is utilized to build workability. For the experimental studies, M40, M50, M60 evaluations of cement with water concrete proportion of 0.48, 0.45, and 0.40 is used. Durability has been investigated through sorptivity, freeze & thaw, carbonation, rapid chloride porousness tests. Results of this current examination study indicated that nanosilica can be successful in improving the sturdiness of cement.

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.

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.

Carbonation model for concretes with fly ash, slag, and limestone calcined clay - using accelerated and five - year natural exposure data

Supplementary cementitious materials (SCMs) can be used in concrete to enhance sustainability and reduce the concrete industry's carbon footprint. However, some negative perceptions about their long-term carbonation resistance are obstacles for large-scale implementation of such concretes. This study evaluated the carbonation resistance of 34 concretes (with Ordinary Portland Cement, fly ash, blast furnace slag, and limestone calcined clay) in natural tropical exposure conditions (Open and Sheltered) for 5 years and in accelerated exposure conditions (1 and 3% CO2) for 112 days. Using these data and the square root of time function, the carbonation coefficients (KCO2, natl and KCO2, accl) of these concretes were estimated and a good correlation between them could not be observed. Hence, a more generic model (named as “A-to-N model”) to estimate the KCO2, natl using the KCO2, accl, CO2 concentration, and mixture proportion of concrete was developed, for which the mean absolute percent error is about 12% (reasonable accuracy). Using the A-to-N model, the carbonation depth at 50 years was estimated for various concretes. SCM concretes with low water-binder ratio and optimal binder content showed high resistance against carbonation at later ages; such information along with the target cover depth must be used while selecting materials for concrete design. Based on the model developed, a relatively simple ‘service life design chart’ was developed. This chart can be used by engineers to set the target KCO2, natl or KCO2, accl, and select the cover depth and binder type to provide the target service life (i.e., corrosion initiation time). This paper clearly shows that SCMs can be used to design concretes with comparable long-term carbonation depth as OPC concretes.

THE EFFECT OF USING RECYCLED CONCRETE ON THE MECHANICAL AND TECHNOLOGICAL PROPERTIES OF CONCRETE IN THE PRODUCTION OF PRECAST

The paper deals with the verification of the possibility of replacing natural aggregate with recycled aggregate concrete (RAC) in the production of precast concrete. In the practical experimental part, concrete mixtures with different proportions of recycled concrete are tested. The results shows that the use of recycled concrete as a substitute for aggregates is possible. However, the ratio of replaced aggregate is important because of the higher proportion of concrete recycled material would result in deterioration of the final properties of the concrete.

Optimization of mix proportions for high performance concrete using TOPSIS method

Optimization of mix proportions for high performance concrete using TOPSIS method

Physical Properties of Sustainable Concrete Bricks with Glass and Polyethylene Terephthalate Scales Wastes as Replacements for Coarse Aggregate

In order to improve the sustainable construction in Peru, throughout the recycling of non-biodegradable materials, a study of the influence of glass and Polyethylene terephthalate (PET) wastes in the physic properties of concrete bricks was carried out. They were made with a 1:5:2 cement, fine aggregate, and waste relation. Three proportions were studied named P-01, P-02, and P-03. Each proportion had a different content of glass and PET wastes, as a result, it was found that the average brick’s absorption was increased with PET wastes and it was reduced with glass wastes. On the other hand, the compressive strength value increased with glass wastes and it was reduced with PET wastes. Finally, it was found that P-02 was the most efficient concrete brick proportion to develop a sustainable construction, obeying the requirements of the Peruvian national building regulations.

Numerical study on percolation and dam slope’s stability of impermeable wall composed by clay and concrete for earth-rock dam

In order to study the percolation and dam slope’s stability of an impermeable wall composed by clay and concrete for earth-rock dam, the steady seepage field of a reservoir in Jiangxi is numerically simulated by using finite element method based on the basic principles of saturated and unsaturated seepage under different ratios of clay to concrete. The results of the flow field of steady seepage are carried out and the dam slope’s stability is analyzed. We found relatively minor impacts of concrete proportion on the discharge of seepage per unit width and the dam slope’s stability. In this study, the impermeability performance of the impermeable wall is concerned. The results showed that impermeable effect of the impermeable wall has not obviously changed if the concrete proportion is below 0.43. When the proportion of concrete exceeds 0.43, the anti-seepage effect of the impermeable wall begins to change significantly. Besides, when the proportion of concrete reaches 1.0, the reduction of water level at front and behind impermeable wall, the discharge of seepage per unit width, and the safety factor of the Bishop method are all infinitely close to the value of the best anti-seepage performance and the most stable state of the dam slope.

Heuristic algorithm-based semi-empirical formulas for estimating the compressive strength of the normal and high performance concrete

It is a big challenge to design mixture proportions of the high-performance concrete due to highly nonhomogeneous relationships and coherent among many components. Although machine learning (ML) algorithms have been employed effectively to solve this problem, they are black box models and do not show an explicit relation between the compressive strength and mixture proportions. In order to overcome this inherent weakness, this paper proposes general semi-empirical formulas involving nondimensionalization and optimisation techniques. The optimisation process employs the Nelder–Mead simplex algorithm and takes into account the behavior of uncertain variables, which may occur in experimental data. Successful compressive strength predictions of five datasets with high accuracy in compared to available ML models indicate that the proposed framework has the universal capacity, which can be used for various datasets. Furthermore, the explicit relation of semi-empirical formulas may be a useful tool for engineers and researchers in this area for the prediction purposes.

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.

Geometric optimisation analysis of Steel–Concrete hybrid wind turbine towers

Steel–concrete hybrid towers have been proposed for onshore tall wind turbine tower installations. Their bottom sections are built with concrete and top sections with steel. The primary advantages of such hybrid towers include construction using low-cost durable material and avoidance of transport barriers associated with all-steel towers. In this study, a set of design constraints governing the geometry of hybrid towers was proposed to determine the optimal combination of concrete and steel sections. The primary constraint in tower design involves avoiding resonance because a resonant response can significantly damage the tower and trigger turbine fault conditions. A sensitivity analysis was conducted to explore the correlation between the natural frequency and geometry of a tower. The results demonstrated that an increase in the proportion of concrete can lead to a pronounced effect on the first modal frequency of taller towers. Additionally, geometric optimisation was performed on a 160 m tall tower. This resulted in a 12.7% reduction in the total cost compared with that of the initial design.

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.

Investigative study of Periodic Thermal and Mechanical Characteristics of Fiber Reinforced Concrete

Concrete is a key basic material in the mankind’s history. lt is a compound made by blending concrete which is a coupling material with fine, coarse aggregates and water in required extents. Concrete is great in strength. The investigation of submission to fire concrete incredibly expanded after 9-11 attack on the World Trade Centre. The Zeal towards structures for fire expanded rapidly. A portion of the limited component models of auxiliary made in deciding the temperatures in a segment by heat examination have been utilized by certain specialists. This paper gives a synopsis of conduct of cement concrete in fire. Concrete has high compressive quality, yet in addition essentially lower elasticity. The compressive quality is commonly controlled with the water, concrete proportion, while framing the solid. In this investigation three different grades of concrete i.e. M20, M25 and M30 used for the experiments. The specimens of all the grades are prepared with and without fibers. All the concrete samples are tested for the compressive strength, split tensile strength and flexural strength. The samples of concrete exposed to 200°C, 400°C and 600°C after 28 days of curing. The results show the reduction in hardened properties of concrete.

Replacement of Sand by Quarry Dust in Concrete

The role of quarry dust in the construction of building and other structures to eliminate the demand of nature sand by using quarry waste to replace the use of natural sand. We are investigating the potential of using quarry waste and its effect on the strength and workability of concrete. Initially cement concrete cube was studied with various proportion of cement concrete +quarry dust (M20 & M25). The experimental result showed that the additional of quarry dust as fine aggregate ratio of 30%, 40% and 50% was found to enhance the compressive properties. The compressive strength of concrete cubes at the age of 7 and 28 days were obtained at room temperature. These raw materials of concrete, i.e., river sand and gravel, are also struggling to cope with the rapidly growing demand in many areas around the globe. The sources of good quality river sand and gravel are depleting very fast. According to United Nations Environment Program (UNEP) report, “Sand-rarer than one thinks”, published in March2014, sand and gravel has now become the most widely used natural resource on the planet after water. These are now being extracted at a rate far greater than their renewal. Crushed sands, fine aggregate produced from stone crushing, has become very popular in areas where natural sand is not abundantly available or where there is scarcity in the supply of natural sand. The Mumbai-Pune express highway was a project, where there is a difficulty in procurement of natural sand. This made the construction company to use crushed sand for making approximately 20 lakh cum of concrete necessary for the construction. However, such type of sands contains a large amount of micro-fines, i.e., particles finer than 75 microns, which can have an adverse effect on properties of concrete. So proportioning of different raw materials at the time of mix design is very important, when crushed sand is used in concrete The availability of sand at low cost as a fine aggregate in concrete is not suitable and that is the reason to search for an alternative material. Quarry dust satisfies the reason behind the alternative material as a substitute for sand at very low costIt is found that 40% replacement of fine aggregate by quarry dust gives maximum result in strength than normal concrete and then decreases from 50%. The compressive strength is quantified for varying percentage and grades of concrete by replacement of sand with quarry dust.

Interpretation of bi-material interface through the mechanical and microstructural possessions

Composite concrete is a crucial consideration for the stability and reliability of two different structural materials. This paper's main objective is to investigate the bonding force of bi-material concrete that includes mesh-type polypropylene fibres depicting the soil's smooth texture. To measure interface properties and multifaceted quantities of concrete fibre, investigative experiments have been performed. Microstructural properties of interface observed and scrutinized by several techniques, namely Scanning Electron Microscope (SEM), Fourier Transform Infrared Radiation spectroscopy (FTIR), and Raman spectroscopy performed on bi-material fibred concrete. The paper describes FTIR and Raman spectroscope used to establish and validate the fibre concrete phase composition and microstructure. The dry condition experiments were conducted to evaluate the compressive, flexural and durable properties of the heterogeneous concrete proportion, contributing to the fire resistance. In bi-material concrete, anonymous effects of compressive and flexural strength were achieved. The estimated opted value found in bi-material concrete is explicitly a combination of reinforced concrete and conventional concrete. The results show advanced knowledge of bi-material interfaces and improvement in the cementitious fibre material's experimental performance.

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.

Analysis of Concrete Block by Partial Replacement of Cement with Fly Ash

The objective of this research is to enhance the properties of concrete by using Fly Ash as a partial substitution of concrete. Tests carried out on cement are Initial and Final setting time and on aggregates, specific gravity and sieve analysis. The mean target strength with given compressive strength at 28 day and quality control level is calculated. Concrete blend proportions for the first tryout mix is calculated and casting of cube of 15mm size with curing for 28 days, and then test for strength using UTM/CTM machines. C-S-H gel as well as Calcium hydroxide as bi product when reacts with water. C-S-H gel has an ability to keep the ingredients together by making a proper bond whereas lime which is freely available can react with atmospheric moisture and cause efflorescence. In such cases if we use fly ash, it reacts with free lime and produces C-SH gel again and water as bi product. We have used Fly ash as a partial replacement of cement with variation of fly ash in percentage. In this study fly ash add in increment of 5%, 10%, 15%, 20%, 25%, 30% and 35% replacement of cement which has shown satisfactory results in the strength of the concrete. Fly Ash improved the workability of the concrete, decreases the bleeding, surface finish and increases the cohesiveness. Compressive strength is comparatively increased. The initial strength of concrete with fly ash has lower strength but acquires higher strength after 56 days; which shows that more the nos. of curing days more will be the strength. Thus, it can be used in areas of construction such as dams, pavements etc.

Analysis of Concrete Block by Partial Replacement of Cement with Fly Ash

The objective of this research is to enhance the properties of concrete by using Fly Ash as a partial substitution of concrete. Tests carried out on cement are Initial and Final setting time and on aggregates, specific gravity and sieve analysis. The mean target strength with given compressive strength at 28 day and quality control level is calculated. Concrete blend proportions for the first tryout mix is calculated and casting of cube of 15mm size with curing for 28 days, and then test for strength using UTM/CTM machines. C-S-H gel as well as Calcium hydroxide as bi product when reacts with water. C-S-H gel has an ability to keep the ingredients together by making a proper bond whereas lime which is freely available can react with atmospheric moisture and cause efflorescence. In such cases if we use fly ash, it reacts with free lime and produces C-SH gel again and water as bi product. We have used Fly ash as a partial replacement of cement with variation of fly ash in percentage. In this study fly ash add in increment of 5%, 10%, 15%, 20%, 25%, 30% and 35% replacement of cement which has shown satisfactory results in the strength of the concrete. Fly Ash improved the workability of the concrete, decreases the bleeding, surface finish and increases the cohesiveness. Compressive strength is comparatively increased. The initial strength of concrete with fly ash has lower strength but acquires higher strength after 56 days; which shows that more the nos. of curing days more will be the strength. Thus, it can be used in areas of construction such as dams, pavements etc.

Experimental Study on Subgrade Performance of Collapsible Loess Mixed with Concrete Gravel

Collapsible loess-like and concrete breccia is a rare special soil type in China, which is widely distributed in Baoji area. The paper preliminarily studied its collapsibility mechanism and engineering properties. The experimental results show that mixing 30% concrete crushed gravel has the best compressive effect and the best bearing ratio in California. Scanning by electron microscope found that after collapsible loess was mixed with concrete gravel, as the proportion of concrete increased, its internal structural stability increased. Concrete gravel recycling projects in subgrade engineering in collapsible loess areas have a certain feasibility, and its economic value is great. In future studies, it can be studied for higher proportions of concrete gravel.

Experimental Study on Water Percolating Concrete

This paper addresses two aspects namely a new method for manufacturing of percolating concrete blocks using different proportions of concrete mixture such as Portland cement, Coarse aggregates, fine aggregates, limestone, and water have been designed. Apart from this an attempt has also been made by adding small quantities of additives such as fly ash, rice husk ash etc. for its strength and suitability on par with the normal Concrete blocks. Another is a partial replacement of cement with supplementary cementation materials such as fly ash and metakaolin in different proportions for reducing high grade cement consumptions been proposed. The design of a Pervious Concrete is made in such a way that it allows the entire surface run off water to percolate down without retaining any drop/quantity in it. Thus, it is named as water percolating Pervious Concrete/ porous concrete. An alternative for reducing cement usage in concrete makes concrete eco-friendly. Thus, there comes an idea of partially replacing cement with supplementary cementations materials, The concern has been growing in recent years towards reducing the pollutants in water conservation and the environment. The continual urbanization has led to the increase in impervious surface area of the cities, further leading to blockage in percolation of precipitation from rainfall. This result is excess surface run off. To counteract this, pervious concrete is the solution. Hence, the pervious concrete having 15% to 35% interconnected pores by volume, allows direct infiltration of water through its structure. Since the strength of this block for highway suitability of roads is not yet tested. The main aim of this paper is to improve the strength characteristics of porous concrete. However, on comparison, with the published data it is suitable for foot paths/ pathways and parking lots and as driveways in the residential and small rural areas where less vehicular traffic. This will help in reducing the risk of water clogging and recharges the nearby ground water level. The Maintenance of the slab is also minimum and can be repaired and cleaned easily. Thus, it is worthy and useful in many ways