ABSTRACT:
In this paper report we have discussed about the use of recycled concrete aggregate in the concrete and the effects on its compressive strength by progressively replacing the natural concrete aggregate (NCA) by recycled aggregate. It is the experimental study of recycled concrete aggregate (RCA) when it is compared with the natural concrete aggregate on account of its properties.
Cubes having dimension 150x150x150 mm3 were casted using recycled aggregate by replacing the natural aggregate by 0%, 25%, 50% and 75% and corresponding results of compressive strengths were noted. The 28 days compressive strength was noted by crushing the cube at 7, 14 and 28 days and it was found that performance of concretes with 0% and 25% replacement
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In this paper we have studied compressive strength of concrete by replacing natural aggregate with recycled aggregate by 25%, 50% and 75%.This mixture formed in the sample of cubes of dimension 150x150x150mm3.
The proportion of different constituents in mixture is as follows:
Notation RCA%
Constituents Kg/m3 RCA (kg) NCA(kg) Fine Agg. (Sand) Water (litre) Cement
M20 0% 0 64.68 29.71 9.74 20
M20 25% 16.17 48.51 29.71 9.74 20
M20 50% 32.34 32.34 29.71 9.74 20
M20 75% 48.51 16.17 29.71 9.74 20
The load test on cubes was performed on 7th days, 14th days and 28th days. The load to be applied by UTM machine to the opposite side of the cube and cast placed centrally between the plates. The load to be applied without shock increased continuously at the rate of approximately 140 kg/cm2/min. when the maximum load was applied cube got cracked in inclined direction.
The result of the load test was as below:
Mix RCA % 7 Days 14 Days 21 Days
M20 0% 1.60 1.72 20.6
M20 25% 1.58 1.67
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The slump flow of mix1 is 550 mm and for mix2 and mix3 it is greater than mix 1 whose slump values are 745 and 755 mm.The blocking ratio L-box (1,10) test of mix1 was 0.81 and of mix2 and mix 3 was 1.0.The higher blocking ratio means good deformability without blockage on closely spaced obstacles and it is capable of highly flow able concrete to self compacting.
Throughout the construction industry, technology plays a role to help ease the completion of a project to all of the parties involved. The amount of technology application in the industry supports the belief that technology has a positive impact on project productivity. One of the main materials used in the construction industry that surrounds us every day, in which we overlook, is concrete. Concrete is an art form, in which it takes time and talent in order for it to be used efficiently, to produce its high strength and longevity. However, the downfall of this material is that it is extremely costly and nearly impossible to form it to an aesthetically pleasing surface. In spite of this, what if I told you that there is hope? That the dream of a material made of concrete, producing the same qualities, can be formed to any shape, and used anywhere was a reality.
ement occupies approximately 50% of the mixed concrete volume and is responsible for physiomechanical properties of concrete. Cement production is essential to infrastructure and building construction, creating demands in very large quantities. Energy resources invested in the production process and resulting greenhouse gas emissions have become problematic. The cement production process has become among the world’s largest anthropogenic sources of carbon dioxide emissions, contributing to approximately 5% of global anthropogenic CO2 emissions, (WBCSD, 2009). Increased pressure is being placed on the industry to reduce CO2 emissions, owning to awareness regarding sustainability....
Concrete is one of the world’s most popular construction materials. Some six billion tonnes of concrete is produced each year in the world, making it approximately one ton of concrete for every human being per year (Fardis, 2012, p.116). However, the lifecycle of concrete does not make it the most sustainable building material at the moment. Because of limited natural resources, concerns over green house gases, and landfill problems, concrete production is being cut-back, or at least cannot be increased to keep up with population increase. In this essay, I will look at what makes concrete an unsustainable material and possible solutions to make concrete a more sustainable material.
Now a days HPC is expensive than conventional concrete. It require additional materials in some quantities as to meet specified performance.These additional materials are cement,silica fume,...
Concrete is a composite material used widely in the construction industry. Concrete is basically a mixture of cement, water, aggregates and admixture (sometimes). Cement is a fine gray powder that consists of oxidizes calcium, silicon and aluminum. The aggregate used is normally gravel, crushed stone or sand. Admixture is a solid or liquid substance that gives a certain characteristics of the concrete. The cement reacts with water chemically and binds the aggregates together through a process called hydration during hardening or curing of concrete. It means that water helps in the hardening of the concrete while the cement bind the aggregate and also react with water to form a solid mass.
Most people may not realise but concrete plays a vital part in our lives daily. It shapes and creates the built environment in which we are surrounded by, such as schools, bridges, roads, housing, hospitals, dams and so much mores. Concrete is the most used man made material in the world, averaging around 3 tonnes annually for each person. In comparison with other building materials such as wood, steel, plastic and aluminium, over twice as much concrete is used globally than any of these materials. It is the material choice of most purposes due to its strength, durability, thermal mass and its cost.
Moreover, the demolition of concrete structures and disposal of the associated wastes is an environmental problem. Rejected construction materials and building derived materials (BDM) constitutes the single largest portion of these wastes, amounting to 2.40 – 3.67 million tonnes per annum (Meyer, 2004). For example, in the US, approximately 49% of the utility wastes (e.g. fly ash which can be produced while generating electricity from coal) are simply landfilled, 41% are contained in surface impoundments, and about 10% are disposed of by discharging into old quarry operations (Provis and van Deventer, 2009). Thus, it is imperative to adopt innovative technqiues to utilize rejected concrete wherever applicable, instead of producing fresh
Concrete is composite consisting cement, aggregates, water and mixtures. It is a material that can be cast into different shapes such as hollow block, pipes or drainage and many more. It is durable and the most attractive construction material in terms of compressive strength. Also, its increasing use is fundamental for sustainable construction.
Constituent materials are the fundamental materials required to produce concrete. The constituent materials of concrete consist of mainly three materials which are cement, aggregate and water, with admixtures included as addictive to alter the characteristics of the concrete (Scalenghe et al., 2011). “Cement is the chemically active constituent but its reactivity is only brought into effect on mixing with water” (Dhir & Yap, 1984). According to Bye (1999), in the industry, Portland cement, which was developed in 1824 by using calcium carbonate found in calcareous rocks, namely limestone or chalk and silica, alumina, and iron oxide found in sedimentary rock, namely clay or shale. Bye (1999) said that cement is produced by grinding the quarried limestone to powder form, blending it with water and heat with pulverized coal to drive out water at 100°C, carbon dioxide at 800°C and clinker at 1400°C, which is then cooled, grounded and mixed with 1%-5% gypsum to alter it fineness and goes through final grinding and the cement is ready to be distributed to the market. According to Sismondo & Sergio (2009), aggregate, which builds up the majority of the volume stability and the durability of the resulting concrete and is of lower price than cement, is always used to the maximum extend as possible in the production of concrete for maximum profit. Aggregates ar...
One of the most important properties of concrete is the measurement of its ability to withstand compressive loads.. The compression tests performed in this project were completed in accordance with IS standard 516 “Methods of Tests for Strength of Concrete”. The apparatus used to determine the compressive strength of concrete in this project was a testing
In order for specimen to have satisfactory failure, the surface area has to be parallel and right angle to the platens on testing machine which may not have been achieved for our group. The specimens may not be placed in exact center in the compressive test machine during concrete testing. Surface of specimens may be uneven due to honeycomb and
The development of new technology in the material science is progressing rapidly. In last three decades, lot of research was carried out throughout globe in order to improve the performance of concrete in terms of strength and durability. Consequently concrete has no longer remained a construction material but has rather becomes an engineered custom tailored material with several new constituents to meet the specific needs of construction industry. The growing use of concrete in special architectural configurations and closely spaced reinforcing bars have made it very important to produce concrete that ensures proper filling ability, better structural performance and adequate durability. Concrete technology has under gone from macro to micro level study in the enhancement of concrete properties (strength and durability) from early eighties onwards.
...oduced by the process of construction. It has been estimated that around 8,000 lbs of waste are typically thrown into the land infill during the construction of a 2,000 square foot home. There are many technologies used for the recycling and reuse of the waste that is generated from the construction. The advancement in the technology has opened many doors and ways for the recycling of the construction waste that was not possible few days back. There is a huge amount of the construction material that is either not up to the quality for the construction or cannot be used for certain reasons (Aadland et al., 2006, pp. 855-874). All the waste falls in to the category of the construction waste. The amount of concrete produced while demolition of any building is a considerable amount to use it for the earth infill and many other construction methods (Boerschig & De Young)