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Concrete Engineering

Self Healing Concrete

Shubham Sunil Malu

Self-healing materials are a class of smart materials that have the structurally incorporated ability to repair damage caused by mechanical usage over time. The inspiration comes from biological systems, which have the ability to heal after being wounded. Initiation of cracks and other types of damage on a microscopic level has been shown to change thermal, electrical, and acoustical properties, and eventually lead to whole scale failure of the material. Usually, cracks are mended by hand, which is unsatisfactory because cracks are often hard to detect. A material (polymers, ceramics, etc.) that can intrinsically correct damage caused by normal usage could lower production costs of a number of different industrial processes through longer part lifetime, reduction of inefficiency over time caused by degradation, as well as prevent costs incurred by material failure. For a material to be defined strictly as self-healing, it is necessary that the healing process occurs without human intervention. Some examples shown below, however, include healing polymers that require intervention to initiate the healing process.

A good way to enable multiple healing events is to use living (or unterminated chain-ends) polymerization catalysts. If the walls of the capsule are created too thick, they may not fracture when the crack approaches, but if they are too thin, they may rupture prematurely.

In order for this process to happen at room temperature, and for the reactants to remain in a monomeric state within the capsule, a catalyst is also imbedded into the thermoset. The catalyst lowers the energy barrier of the reaction and allows the monomer to polymerize without the addition of heat. The capsules (often made of wax) around the monomer and the catalyst are important maintain separation until the crack facilitates the reaction.

There are many challenges in designing this type of material. First, the reactivity of the catalyst must be maintained even after it is enclosed in wax. Additionally, the monomer must flow at a sufficient rate (have low enough viscosity) to cover the entire crack before it is polymerized, or full healing capacity will not be reached. Finally, the catalyst must quickly dissolve into monomer in order to react efficiently and prevent the crack from spreading further.

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Experimental Investigation on Concrete with Replacement of Coarse Aggregate by Demolished Building Waste with Crushed Concrete

Vijayvenkatesh Chandrasekaran
Student, Department of Civil Engineering, St. Josephs College of Engineering & Technology, India

Large quantities of construction and demolition wastes are continuing being generated which are just being dumped in the landfills. This requires large areas of land which is becoming difficult to find. The best solution would be to recycle and reuse the demolished waste which would not only help in protecting the environment but also help in dealing with construction wastes. Consequently, it have a grave difficulty to produce ecological toxic waste and in addition, obligatory a huge sum of liberty. That says about the project reuse waste crushed concrete maters (WCC) from the lath wastage of crushed concrete replacing from coarse aggregate 20%, 30%, 40% (WCC), 3% of crushed coarse aggregate (lathe waste) to reduce the generation of demolition wastes. (The analysis of demolished crushed concrete aggregate (DCCA) concrete in regular mold cast is to be ready in (7, 14, 28) days hydration and examination to be conduct lying on concrete. Such as compressive strength, split tensile strength, & flextural strength.) The replacing of coarse aggregate uses of waste mater and required strength attain in the conventional M20 grade concrete.

Keywords – Demolished Crushed Concrete Aggregate (DCCA), OPC (53 grade) cement, Lathe waste, Fine aggregate, coarse aggregate.

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Partial Replacement of Cement With Marble Powder in Concrete

Vijayvenkatesh Chandrasekaran
Final year student, Department of Civil Engineering, St. Josephs college of engineering & technology, Thanjavur, India.

Marble powder is one of the most active research areas that encompass a number of disciplines including civil engineering and construction materials. The marble industry inevitably produces wastes, irrespective of the improvements introduced in manufacturing processes. In the marble industry, about 50 to 60% production waste. These waste create many environmental dust problems in now a day to day society. In requiring a suitable form of management in order to achieve sustainable development. In this paper explained about the behavior of concrete with partial replacement of cement with added percentage values of marble powder and attain required strength. Partial replacement of marble powder in cement accordingly in the range of 20%, 30%, 40%, by weight for M20 grade of concrete. With this experimental research work the problem of waste production management of this agro waste are will be solved. It analyzed the research work the compressive strength, flextural strength, split tensile strength values at 7, 14, 28 day. The test results show that the compressive strength, split-tensile strength and flexural strengths are achieved up to 30% to 40% replacement of cement with marble powder without affecting the characteristic strength of M20(1:1.5:3) grade concrete.

KEYWORDS: Cement (53 grade), Marble powder, Fine aggregate (M-sand), Coarse aggregate (20mm size).

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Evaluation of Concrete Strength by Partially Replacing Cement by Red Mud And Fly Ash

Guided By: Mr. Anil Kumar Suman
Submitted By: Rashmi Sahu

Chhattisgarh Swami Vivekanand Technical University
Bhilai (C.G.), India
Shri Shankaracharya Technical Campus
Ssgi-bhilai (C.G)

Red Mud is a hazardous waste generated in the Bayer process Alumina production (AL2O3) from Bauxite ore which contains high levels residual alkalinity and toxic heavy metal. Therefore, Red Mud is a hazardous waste of Alumina Industry. The volume of Red Mud which generated in the alumina processing plant depends on the quality of crude Bauxite ore, may be greater than the volume of alumina 1-1.5 times. The alumina processing plant usually disposes liquid Red Mud into reservoirs, which cause the risk of major environment pollution for lowland. The particle dimension of red mud usually less than 1mm . Therefore, dry red mud easy spread into the air and causes dust pollution. It is often exposured to dust cause skin and eyes diseases. Red mud in an liquid state causes harmful effect to human skin. Composition and properties of red mud in the world have been presented by many researchers in their publications.

Fly Ash is a byproduct of coal-fired electric generating plants. The coal is pulverized and blown into burning chamber for immediate combustion. Heavier ash particle (Bottom Ash or Slag) fall to the bottom burning chamber and the lighter ash (fly ash) fly out with exhaust gas, thus the term fly ash. Before leaving the stack, these fly ash particle are removed and collected by electrostatic precipitation, bag houses or other methods.

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Understanding the Concept of Bubble Deck

Shubham Sunil Malu

As the infrastructure is developing there is need for some changes in the construction field, as one cannot rely on the same method for a long time as it can have different consequences. The main consequence is the shortage of material and manpower. Also, money matters a lot in construction department along with it the machines, equipment and technology in some region is not at a level, which we want. Hence in order to satisfy these results Bubble deck slab is one of the most effective slab techniques to replace conventional slab in terms of money and materials. Also, it requires less time to construct as compared to conventional slab.

Bubble Deck is a revolutionary method of virtually eliminating concrete from the middle of a floor slab not performing any structural function, thereby dramatically reducing structural dead weight. Bubble Deck is based on a new patented technique- the direct way of linking air and steel. Void formers in the middle of a flat slab eliminates 35% of a slabs self-weight removing constraints of high dead loads and short spans.

Incorporation of recycled plastic bubbles as void formers permits 50% longer spans between columns. Combination of this with a flat slab construction approach spanning in two directions – the slab is connected directly to insitu concrete columns without any beams -produces a wide range of cost and construction benefits including:-

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High Performance Concrete – Methods for preparation, Advantages and Drawbacks

Sagar Sanjay Phatale
Department of Civil Engineering
University of Texas at Arlington

High performance concrete provides high durability, strength, low water-cement ratio and longer life span of the structure. Special ingredients such as plasticizers, optimum aggregate size and fiber steel reinforcement are used to make this type of concrete admixture. This type of concrete type is used in special and complex construction structure such as bridges and tunnels. High performance concrete also helps in reducing the duration of the project, as there is low water cement ratio in making the admixture for the concrete. This type of concrete is useful for fast track construction where owner required the possession of the property as soon as possible. High performance concrete have several advantages over traditional Portland cement concrete.

First, high performance concrete provides better strength and durability. Water cement ratio majorly affect the workability of the concrete (Naik et. Al., 2012). According to Naik et al., (2012, p. 463), increase in the water cement ratio, which can be obtained by increasing the water content in the concrete admixture, increases the workability and slump ratio of the concrete.

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Research Paper on Floating Concrete

Vikramaditya Pandey

Floating concrete is a fluid mixture of density less than water, which is suitable to build floating structures, reducing the consumption of land for buildings. This project report addresses the procedure of preparation of mix proportion of floating concrete, materials used & various test results of compressive strength at the age of 7 days & flow, for acceptance of this concrete. Also, it presents an application of this concrete for canoe construction along with a light weight but, strong reinforcement. Despite the self weight of the canoe, it can bear a certain amount of external load.

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Design of RCC Flat Slab Structure Under Earthquake Loading Using Etabs

1- Post Graduate student, Department of civil Engineering,VFSTR university , Vadlamudi.
2-Assistant Professor, Department of civil Engineering, VFSTR university, Vadlamudi.

The FLAT SLAB SYSTEM being used in majority of the constructions. It elevates more clear space in architecting the construction design in easy manner and duration of construction would be short due to the flat slabs size. Compare to the traditional concrete construction slab system is more viable due to the fact that it avoids the heavy beams, which are the big vulnerability in case of earthquakes. Objective of this paper is to investigate the behavior of flat slab system in few different use cases.

1. Flat slab structure without drop.
2. Flat slab structure with column drop.
3. Flat slab structure with shear wall.
4. Flat slab structure with column drop and shear wall together through response spectrum method by using ETABS software.

The behavior of flat slab is investigated in terms of the following factors:
1. Frequency
2. Base Shear
3. Storey level accelerations

Also most severe problem in flat slabs as follows:
1. Failure punching shears
2. Shear stresses during ground unbalance
3. Slab column connections to brittle punching shear stresses during earthquakes.

Also this paper investigates about the combinations that can produce less punching shear at slab column joint.

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Experimental Investigation On The Effect Of Bagasse Ash And Rubber Tyre Waste In Concrete

Pravesh Shukla

The utilization of industrial and agricultural waste produced by industrial process has been the focus on waste reduction research for economical, environmental and technical reasons. SCBA is a fibrous waste product of the sugar refining industry, along with ethanol vapour. Bagasse ash mainly contains aluminium ion and silica. The use of SCBA as a pozzolonic material for producing high strength concrete. OPC is partially replaced with finely SCBA. At present the disposal of waste tyre is becoming a major waste management problem in the world. In this project, the bagasse ash has been chemically and physically characterized and partially replaced in the ratio of 0%, 5%, 15% and 25% by weight of cement in concrete. The mix proportion for M30 grade concrete was derived. Rubber tyre waste has been used as coarse aggregate with replacement of conventional coarse aggregate and it is taken as constant of 10%.

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Plastic Cracking of Concrete

Shubham Sunil Malu

Cracking is one of the major issues in concrete. Since concrete has various physical and chemical properties it is prone to cracking. Its elimination is not possible totally but it can be restricted or reduced to a certain extent. Mostly, cracking goes on a microscopic scale and does not appear visibly as a fault. If the cracking goes on a macroscopic scale it can result in loss of strength, stability and durability. It can also cause decrease in sound insulation and overall efficiency besides affects aesthetics to a greater extent.

The main causes of cracking are as follows:

  • Ageing – Carbonation
  • Foundation problems
  • Weathering Actions
  • Improper or modified use of the structure
  • Poor maintenance
  • Progressive loading
  • Deficiencies in design
  • Poor quality of concrete material
  • Improper concrete mix
  • Movement of concrete arising from physical properties
  • Poor workmanship and negligence
  • Over trowelling and impermeable formwork
  • Reduced continuity of the structural member
  • Defects and errors in construction practices
  • Improper structural repairs or modification
  • Chemical attacks by Chlorides and Sulphates
  • Differential thermal stress – Heat of hydration of cement

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