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High Performance Concrete – Methods for preparation, Advantages and Drawbacks

By
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

By
Vikramaditya Pandey

Abstract
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

By
M.RAJAGOPAL REDDY 1, P.RAJESH 2
1- Post Graduate student, Department of civil Engineering,VFSTR university , Vadlamudi.
2-Assistant Professor, Department of civil Engineering, VFSTR university, Vadlamudi.

ABSTRACT
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

By
Pravesh Shukla

Abstract
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

By
Shubham Sunil Malu

1.0 INTRODUCTION:
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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