Introduction
Concrete is most widely used material for various applications in this world. India is second largest producer of concrete in world. As this is used in various applications its base properties which are obtained by preparing concrete with required raw materials must be enhanced by adding some other material to it. There comes the role of admixtures by which one can extract required property from concrete. There are various two basic classifications of admixtures. Chemical and Mineral admixture. There are various types of mineral admixtures. Most of mineral admixtures are by-products available from some production industry. Silica fume is a mineral admixture which is obtained as by-product of silicon industry is a costliest material but is very desirable material for normal concretes. Footprint of Nanotechnology which is defined as science of controlling the properties at nanometer scale which can make revolutionary changes in bulk material properties [23] in construction field has great impact in improving the properties of concrete . There are many types of nano-materials like nano-silica, nano-alumina, carbon tubes etc.. This paper describes how the properties of concrete are enhanced by adding nano-silica to it and compares with concrete containing microsilica. Both nano-silica and micro-silica are siliceous admixtures having higher contents of amorphous silica but nano-silica is the one having 1/10th size of silica-fume which is major advantage for nano-silica to enhance different properties of concrete to larger extent than microsilica.
Silica Fume
It is by-product of silicon industry and contains very large amounts of amorphous silicondioxide (about 90%). (ACI-116R)[1]
It is 100 times smaller than cem...
... middle of paper ...
...ay be due to reduced size and total volume of pores. Not much difference was found between addition of NS or MS to these concretes.[16]
Effect on self-compacted concrete
On addition of NS to self-compacted concrete one can observe reduction in bleeding, segregation and flowability. Experimental results showed improved compressive strength, split tensile strength and flexural strength. Higher electrical resistivity and resistance to chloride ion penetration was also observed in NS incorporated Self compacting concretes.[17][18]
Effect on rice husk ash concrete
Author observed that overall performance of concrete was increased and there is huge reduction in water absorption [19]
Effect on eco-concrete
Delayed setting and very low early strengths are major defects of eco-concrete which can be counteracted by incorporating NS into these concretes. [20]
Conclusion: In support of my hypothesis, it is found that the mystery powder is one of the five known compounds. Through experimenting the chemical reaction in spot plates, it is concluded that the mystery powder is icing sugar. It was fairly straightforward because we just have to see which substances matched the reaction of the mystery powder. All in all, my hypothesis is correct and through researching the interpretation, icing sugar is the mystery substance.
they're not. Concrete is to cement as a cake is to flour. Concrete is a mixture
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....
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
...nerally their major constituent is also fine aggregate. Confusion sometimes exists over the difference between the terms fine aggregate and sand, there is in fact no difference the two words may be interchanged. Fine aggregate quality is affected by a number of factors: The mean particle size, grading, presence of impurities, shape, texture of the paricles. The selection of suitable aggregates, which are capable of producing a product with the optimum properties, is most important. The design of mortar mixes is based on the concept that the voids in the fine aggregate, which are generally in the range 25- 40%, will be filled with binder. Where the voids are not completely filled there is an increasing risk that the mortar will not be durable. Aggregate may be natural, manufactured or recycled [EDUCATIONAL GUIDE TOAGGREGATES, Experts in Mortar, Cemex Mortar][3][4].
The improvements involved a combination of improved compaction, improved paste characteristics and aggregate matrix bond, and reduced porosity. In these systems a significant decrease in water-to-cement ratio is achieved through the use of plasticizers, further enrichment of some properties have been obtained through the addition of mineral micro fillers (supplementary cementing or pozzolanic materials such as silica fume and fly ash). Despite the fact that high performance concrete has the same basic ingredients as the normal concrete, its much higher qualitative and quantitative performances present them as new materials. High performance concrete is one in which certain characteristics are developed for a particular application and environment. High performance concrete gives excellent performance in the structure in which it will be placed, in the environment to which it will be exposed, and with the loads to which it will be subjected during its design life. Self Compacting Concrete (SCC) is a High performance concrete which has been developed for use in situations where sufficient vibration by external agency is difficult and reinforcing steel is highly congested. Self Compacting Concrete is a remarkable achievement in the construction industry that helped to surmount the problems associated with cast-in-place concrete. Unlike normal concrete, Self Compacting Concrete is unaffected by the skill of workers, the shape and amount of reinforcing bars or the arrangement of a structure and, due to its high-fluidity and resistance to segregation it can be pumped longer distances. Professor Hajime Okamura was the first who propounded the concept of Self Compacting Concrete in 1986, but the prototype was first developed in 1988 in Japan, by Professor Ozawa at the University of Tokyo. Self Compacting Concrete was developed at
Valeria Corinaldesi, et al. evaluated compressive strength of concrete. The Compressive strength of concrete was determined at 3, 7 and 28 days age of curing. The addition of both red and blue pigments caused a certain strength loss never higher than 3 MPa. Moreover, the use of CaO together with shrinkage reducing admixture (SRA) allowed to fully recovering the slight strength loss due to the red pigment addition. At the dosage of 20 kg/m³ slightly reduces concrete compressive strength. The use of shrinkage reducing admixture and CaO proves to be very effective in reducing the risk of concrete cracking and it also gives positive contribution on concrete compressive strength
Concrete is mixture of cement, aggregate (fine and course), water and chemical admixture is also added when needed. About 75% of total concrete material is acquired by aggregate. So, it is important to choose the right type, quality and quantity of aggregate. The main matrix of concrete is made by aggregate. The aggregate particles are bounded with each other by cement and water. There are two types of aggregate: (1) coarse aggregate and (2) fine aggregate (sand). The course aggregate forms the main matrix and the fine aggregate forms the filter matrix by filling up the space between the course aggregate. With the
Concrete is an extraordinary and key structural material in the human history. As written by Brunauer and Copeland (1964), “Man consumes no material except water in such tremendous quantities”. It is no doubt that with the development of human civilization, concrete will continue to be a dominant construction material in the future. However, the development of modern concrete industry also introduces many environmental problems such as pollution, waste dumping, emission of dangerous gases, depletion of naturalresources etc.
Conventional normal cement concrete is normally used as construction material of buildings. The impervious nature of concrete
A concrete consists of sand, coarse aggregate (gravel, stone and etc…), cement and water are mixed and hardened to form a stone like material.