In the present scenario, several buildings are being constructed ranging from ordinary residential buildings to sky-scrap structures. Invariably in all the structures, concrete plays a vital role in construction. Generally concrete is a mixture of cement, fine aggregate (River sand), coarse aggregate, water and type of admixtures used depends upon the situations. With increase in demand for construction materials, man has improved a lot in construction techniques of structures.
In earlier ages structures were constructed with heavy materials, but in this modern era of construction old techniques are being more costly due to heavy loading. So the uses of lightweight materials are started.
The aim of the project is to identify the material which makes the concrete float and it should also have the strength. Floating concrete is a type of concrete having density less than water and it floats on water. The conventional aggregates are replaced by light weight aggregates which makes the concrete lighter than the conventional concrete. Floating concrete is a type of light weight concrete which is light in weight and the
density is also less than the density of water.
To overcome from this crisis, partial replacement of cement with fly
ash and fine aggregate with Thermocol can be an economic alternative. This project focuses on investigating the characteristics of M25 grade of concrete with cement partially replace with fly ash 30%, 40% and Coarse aggregate replace with thermocol
3%, 5% respectively.
Chapter-1 INTRODUCTION
1.1 Concrete
Concrete is a versatile material, which is widely used for construction material in the world. It is obtained by mixing cementitious materials, water, aggregate and sometimes admixtures in required proportions. Fresh concrete or plastic concrete is freshly mixed material which can be moulded into any shape hardens into a rock-like mass known as concrete. The hardening is because of chemical reaction between water and cement, which continues for long period leading to stronger with age.
Concrete is the preferred construction material in India. The cement production has increased, thanks, mainly: to the renewed thrust on infrastructure development in the country. In the past five-six years mega construction projects involving the use of concrete have been executed in the country in alarge number. Some of them include construction of a large number of flyovers, Delhi metro rail, atomic and thermal power plants, golden quadrangle road project, and reconstruction of Gujarat after January 2001 earthquake, etc. The quality and type of concretes being employed have undergone a transformation with the use of state of the art concrete technology. Amongst the recent developments in the field of concrete such as high performance concrete (HPC), compacted reinforced concrete (CRC) reactive powder concrete (RPC), self-compacting concrete, etc., HPC could find applications in India in some ofthe prestigious projects.
[1.2] Concrete Properties:
The Properties of Concrete are its characteristics or basic qualities.
The four main properties of concrete are:
Workability
Cohesiveness
Strength
Durability
1.3 DIFFERENT TYPES OF CONCRETE
Some common and main types of concrete are:
Normal concrete
Self compacted concrete
Light weight concrete
High strength concrete
High performance concrete
Shotcrete
Air Entrained Concrete
Pervious Concrete
1.2.1 High Performance Concrete
High-performance concrete (HPC) exceeds the properties and constructability of normal concrete. Normal and special materials are used to make these specially designed concretes that must meet a combination of performance requirements. Special mixing, placing, and curing practices may be needed to produce and handle high-performance concrete. Extensive performance tests are usually required to demonstrate compliance with specific project needs. High-performance concrete has been primarily used in tunnels, bridges, and tall buildings for its strength, durability, and high modulus of elasticity. It has also been used in shotcrete repair, poles, parking garages, and agricultural applications.
High performance concrete characteristics are developed for particular applications and environments, some of the properties that may be required include:
• High strength
• High early strength
• High modulus of elasticity
• High abrasion resistance
• High durability and long life in severe environments
• Low permeability and diffusion
• Resistance to chemical attack
• High resistance to frost and deicer scaling damage
• Toughness and impact resistance
• Volume stability
• Ease of placement
• Compaction without segregation
• Inhibition of bacterial and mould growth
High-performance concretes are made with carefully selected high-quality ingredients and optimized mixture designs; these are batched, mixed, placed, compacted and cured to the highest industry standards. Typically, such concretes will have a low water cementing materials ratio of 0.20 to 0.45. Plasticizers are usually used to make these concretes fluid and workable.
High-performance concrete almost always has a higher strength than normal concrete. However, strength is not always the primary required property. For example, a normal strength concrete with very high durability and very low permeability is considered to have high performance properties. Demonstrated that 40MPa (6,000 psi) high performance concrete for bridges could be economically made while meeting durability factors for air-void system and resistance to chloride penetration.
1.2.1.1 Salient Features of HPC
• High Compressive strength
• Low water-binder ratio
• Reduced flocculation of cement grains
• Wide range of grain sizes
• Dignified cement paste
• No bleeding homogeneous mix
• Less capillary porosity
• Discontinuous pores
• Stronger transition zone at the interface between cement paste and aggregate
• Low free lime content
• Endogenous shrinkage
• Powerful confinement of aggregates
• Little micro-cracking until about 65-70% of fck
• Smooth fracture surface
1.3 FIBRE REINFORCED CONCRETE
In convectional concrete, micro cracks develop even before loading because of drying shrinkage and other causes of volume change. When the structure is loaded, the micro cracks open up and propagate. The development of such micro-cracks is the main reason of inelastic deformation in concrete.
The weakness can be removed by inclusion of small, closely spaced and uniformly dispersed fibres in concrete. The addition of fibres in concrete substantially improves its static and dynamic properties. These fibres offer increased resistance to crack growth, through a crack arresting mechanism and improve tensile strength and ductility of concrete.
Fibre reinforced concrete(FRC) can be defined as a composite material consisting of concrete and discontinuous, discrete, uniform dispersed fine fibres. The continuous meshes, woven fabrics and long wires or rods are not considered to be discrete fibres.
The inclusion of fibres in concrete and shotcrete generally improves material properties like ductility, flexural, strength, toughness impact resistance and fatigue strength. There is little improvement in compressive strength. The type and amount of improvement is dependent upon the fibre type, size, strength and configuration and amount of fibre.
Those where the elastic modulus of fibres is less than the elastic modulus of the matrix: ie. Cellulose fibre, polypropylene fibre, poly acrylonitrile fibre, etc.
Those where the elastic modulus of fibres is greater than the elastic modulus of the matrix: ie. Glass fibre, steel fibre, carbon fibre, aramid fibre, asbestos fibres, etc. Many of the current applications of fibre reinforced concrete involve the use of fibres ranging around 1.0 per cent by volume of concrete.
1.4 Self compacted concrete:
Development of self-compacting concrete (SCC) is a desirable achievement in the construction industry in order to overcome problems associated with cast-in-place concrete. The gradual reduction in skilled workers in construction industry has led to a similar reduction in the quality of construction work. One solution for the achievement of durable concrete structures independent of the quality of construction is the employment of self-compacting concrete. It is now widely use for highly congested reinforced concrete structures in seismic region.
SCC has a high flow ability and a moderate viscosity, and no blocking may occur during flow. Self compacting concrete is cast so that no additional inner or outer vibration is necessary for the compaction and which is at the same time cohesive enough to be handled without segregation or bleeding. It flows like “honey” and has a very smooth surface level after placing. SCC usage is also reported to lower the noise level on the construction site and diminish the effect on the environment. Consequently, the use of SCC as a construction material has gradually increased over the last few years.
1.5 Light Weight concrete:
Lightweight concrete can be defined as a type of concrete which includes an expanding agent in that it increases the volume of the mixture while giving additional qualities such as ability and lessened the dead weight.
Lightweight concrete maintains its large voids and not forming laitance layers or cement films when placed on the wall. This research was based on the performance of aerated lightweight concrete. However, sufficient water cement ratio is vital to produce adequate cohesion between cement and water. Insufficient water can cause lack of cohesion between particles, thus loss in strength of concrete. Likewise too much water can cause cement to run off aggregate to form laitance layers, subsequently weakens in strength.
Lightweight concrete has extreme importance to the construction industry. Most of current concrete research focuses on high-performance concrete, by which is meant a cost-effective material that satisfies demanding performance requirements, including durability. Lightweight concrete can be defined as a type of concrete which includes an expanding agent in that it increases the volume of the mixture while giving additional qualities such as lessened the dead weight. It is lighter than the conventional concrete. The use of lightweight concrete has been widely spread across countries such as USA, United Kingdom and Sweden.
The other main specialties of lightweight concrete are its low density and thermal conductivity. So its advantages are that there is a reduction of dead load, faster building rates in construction and lower transport and handling costs.
Lightweight concrete maintains its large voids and not forming laitance layers or cement films when placed on the wall. Sufficient water cement ratio is vital to produce adequate cohesion between cement and water. Insufficient water can cause lack of cohesion between particles, thus loss in strength of concrete.
Lightweight concrete is concrete weighing substantially less than that made using gravel or crushed stone aggregates. This loose definition is generally agreed to cover a broad spectrum of concretes ranging in weight from 12 to 120 pounds per cubic foot. Many types of concrete fall within this range; some are cellular concretes made with foam or foaming agents; some are made with lightweight aggregates; and some cellular concretes also contain lightweight aggregates. Other lightweight concretes may contain some normal weight sand. Lightweight aggregate concrete is usually chosen for structural purposes where its use will lead to a lower overall cost of structure than would be expected with normal weight concrete. The generally higher unit cost of lightweight structural concrete is offset by reduced dead loads and lower foundation costs. The generally higher unit cost of lightweight structural concrete is offset by reduced dead loads and lower foundation costs.
1.5.1 Advantages of light weight concrete:
There are several benefits for the use of lightweight concrete on current roof applications.
• When provided with insulation, a thermal R-value of R-30 can be easily achieved without insulation delaminating, warping or attachment concerns.
• The lightweight concrete also provides a sound substrate for membrane application, and it can be formed to achieve proper slope without adding costly and complicated tapered insulation. It also provides a higher fire rating for the system.
• In addition, lightweight concrete provides the building owner with long-term cost savings. This frees space in landfills and substantially reduces removal costs, which can be as high as 50 percent of the total project costs.
• In overall construction practices, light- weight concrete is used to reduce the dead load of a structure. The decrease of the dead load allows the designer to save costs through reduction in the size of the columns, footings and other load- bearing elements.
• The decrease in size does not decrease strength. Lightweight concrete can achieve similar strengths as standard concrete, and it produces a more efficient strength-to-weight ratio in structural elements.
• Lightweight concrete used in roof deck construction typically consists of Port- land cement, foam, water, and admixtures.
• Lightweight insulating concrete includes the application of expanded polystyrene (EPS) insulation boards. The EPS insulation must have a minimum density of 1 pound per cubic foot and have keyholes properly spaced throughout the boards for concrete flow through the boards.
• Lightweight concrete is typically applied as composite slabs over vented metal decks that meet the requirements of ASTM A653 and are of the proper type and gauge to withstand the structural live and dead loads for the facility.
• Lightweight concrete can also be applied as a topping slab over structural concrete decks.
• In LWIC applications, the EPS board is set in a slurry coat of lightweight concrete and allowed to set up for up to 24 hours.
• The generally higher unit cost of lightweight structural concrete is offset by reduced dead loads and lower foundation costs. The generally higher unit cost of lightweight structural concrete is offset by reduced dead loads and lower foundation costs.
.
Chapter-2 LITERATURE REVIEW
Sr. no Title Author Conclusion
1 Construction and Improvement of T.P. Schemes Road Network for Rajkot City
(2008) Raimundo Kennedy Vieira P-10
The results indicate that it is possible to produce a polymerized concrete with compressive strength above 15
.
2 Lightweight Concrete Made from Waste Polystyrene and Fly Ash
B.A. Herki, J.M. Khatib and E.M. Negim P-5
There is a tendency for the compressive strength and UPV to decrease when natural sand and Portland cement are replaced with the increasing amounts of Stabilised. Polystyrene (SPS) aggregate and fly ash, respectively.
3 Polystyrene Aggregate Concrete
S.G. Park and D. H. Chisholm P-12
Placing and compacting the polystyrene aggregate concrete can be quite difficult as normal vibratory compaction techniques do not work as well as with normal weight concrete.
4 The properties of concrete Sandwich Beam with polystyrene concrete
MOHAMED E. SHENDY EL BARBARY P-11
The advantages possessed by both sandwich construction and cement concrete suggest the desirability of the application of sandwich elements in concrete structures.
5 Analysis of total chloride contents in concrete.
Saleh A. Al-Saleh P-8
The analysis also used the maximum total chloride limits of British Standards for the concrete in conjunction with other ingredients required for the mix.
6 Fly Ash concrete A technical analysis For compressive strength.
Dr S L Pati1, J N Kale , S Suman P-5
It is observed that replacement of cement in any proportion lowers the compressive strength of concrete as well as delays its hardening
7. Optimization of concrete mix proportioning
M. Shariq , J. Prasad, A. K. Ahuja P-9
optimum concrete mix for different mix proportions is proposed.s
8. Investigate the engineering properties of fly ash cement concrete for rigid pavement construction.
Er.Amit Kumar Ahirwar , Prof. Rajesh Joshi, Er. Kapil Soni
Incorporation of fly ash in concrete can save the coal & thermal industry disposal costs and produce a "greener"concrete for construction.
9. Lightweight high strength concrete with expanded polystyrene concrete
Tengku Fitriani P -7
polystyrene beads can be used as lightweight concrete making material and environmentally save.
10. Polystyrene aggregated gypsum block
B. SAYIL and E. GÜRDAL P-9
The lightweight gypsum with polystyrene foam is a perfect heat insulating material with good mechanical strength
11 The Study on Strength Properties of Light Weight
Concrete using Light Weight Aggregate B. Devi Pravallika,
K. Venkateswara Rao
Pumice and vermiculite is a good replacement
of coarse and fine aggregate.
Aluminum powder as an air entraining agent,
steel fibre is used to increase its strength and Super plasticizers conplastsp 430 is used to
increase it workability.
12 Floating Concrete by using Light Weight
Aggregates and Air Entraining Agent Mukesh D. Ghadge Vaibhav D. Kamble Investigation showed that aggregate size and proportion
influenced the unit weight and compressive strength of
concrete.
13 Experimental Investigation of Floating slab with
Incorporated Pumice stone and Vermiculite Gowthama prasanth.U, Jeyaraj.C, Sivaperumal.B, Thirumurugan.S Preethiwini.B
Moreover, the result showed that it is possible to
produce a Floating and satisfied strength concrete by using
pumice as aggregate.
14 Experimental Study on Light Weight Concrete by
Partial Replacement of Cement and Fine
Aggregate with Fly Ash and Thermocol Nagaswaram Roopa
K. Supriya
Strength is increased by partial replacement of cement with fly ash and fine aggregate with Thermocol.
For 3 days of curing period ,it is observed that the strength of concrete at partial replacement of fly ash and Thermocol
is increased when compared to the normal compressive strength of concrete.
Chapter-3 AIM and OBJECTIVES
“Some Experimental Analysis of Floating Concrete by Cementitious Material and Thermocole”
Objectives of Work
• To study rheological properties of fresh concrete through compacting factor test or Slump Test.
• To study mechanical properties of hardened concrete through following test for 7, 28 days.
1. Compression strength (IS 516-1959)
2. Splitting tensile strength(IS 5816-1999)