Special concrete

Presentation
on
Special Concretes
(Concrete Technology)
by
Dnyaneshwar. D. More
(Assistant Professor)(Assistant Professor)
DEPARTMENT OF CIVIL ENGINEERING
Sanjivani Rural Education Society’s
SANJIVANI COLLEGE OF ENGINEERING, KOPARGAON – 423 603
SAVITRIBAI PHULE PUNE UNIVERSITY, PUNE

CONTENTS
 Polymer concrete composite
 Necessity of Polymer concrete composite
 Light weight concrete
 Thermal Conductivity of concrete
 Heavy weight concrete
 Recycled aggregate concrete
 High Volume Fly ash Concrete

Polymer concrete composite
Definition: Polymer concrete composite is a part of
group of concretes that use polymers to supplement or
replace cement as a binder.
The composites using polymer can be:
1. Polymer concrete (PC)1. Polymer concrete (PC)
2. Polymer modified concrete (PMC)/ Polymer Cement
concrete (PCC)
3. Polymer impregnated concrete (PIC)
4. Partially Impregnated and Surface coated polymer
concrete.

Necessity of Polymer Concrete
 The porosity due to air-voids, water voids or due to
the inherent porosity of gel structure itself.
 on account of the porosity, the strength of concrete
is naturally reduced.
 reduction of porosity results in increase of strength
of concrete.
 All the methods used to reduce porosity have been
found to be helpful to a certain extent only, but
could not really help to reduce the water voids and
the inherent porosity of gel, which is estimated to
be about 28%-30%.

Advantages of Polymer Concrete
 High tensile and flexural strengths.
 Excellent adhesion, good resistance to attack by
chemicals.
 Very low water absorption, high water resistance. Very low water absorption, high water resistance.
 Good resistance to abrasion.
 Good freeze–thaw stability.
 Greater strength.

Disadvantages of Polymer Concrete
 low Young’s modulus,
 high creep values,
 shrinkage varying with the polymer used,
 sensitivity to high temperature, sensitivity to high temperature,
 high cost involved in preparation.

Applications of Polymer Concrete:
 In making facade plates, sanitary products, panels,
floor tiles, pipes, and industrial flooring.
 It is used in various precast and cast-in applications in
construction work, skid-resistant overlays in
highways, plaster for exterior walls, and resurfacinghighways, plaster for exterior walls, and resurfacing
of deteriorated structures.
 In addition, PC is also widely used as repair material,
in particular for concrete carriageways, around the
world Nowadays.

1. Polymer concrete (PC)
 It is an aggregate bound with a polymer binder
instead of Portland cement.
 The main technique in producing PC is to minimize
void volume in the aggregate mass so as to reduce
the quantity of polymer needed for binding the
aggregates.
 This is achieved by properly grading and mixing the
aggregates to attain the maximum density and
minimum void volume.

 The graded aggregates are prepacked and
vibrated in a moulds.
 Monomer is then diffused up through the
aggregates and polymerization is initiated by
radiation or chemical means.
 A Silone coupling agent is added to the monomer
to improve the bond strength between the
polymer and the aggregate.
 In case polyester resins are used no
polymerization is required. Polymer Concrete (PC)

2. Polymer Modified Concrete (Polymer Cement
Concrete)
 more popular because of its ease of handling,
economy and satisfactory results when compared
with its counterparts.
 It has high chemical resistance, Low water absorption It has high chemical resistance, Low water absorption
and low permeability make it an effective material for
use in hydraulic structures as well.
 It has the property of setting quickly.

Preparation
 It is made by mixing cement,aggregates,water and
polymer
 mixture is cast in moulds, cured dried and then
polymerized
 The polymers that are used in this process are: The polymers that are used in this process are:
• Poly butadiene styrene
• Epoxy styrene
• Furans
• Polyester-styrene.
• Vinylidene Chloride

 epoxy resin is mostly used because of the superior
characteristic as the addition of latex provides a large
quantity of the needed mixing water in concrete.
 Epoxy resin is a better binder than cement.
 PMC is made with as low as possible addition of extra
mixing water as possiblemixing water as possible
 Typically, water-cement ratios are in the range 0.40
to 0.45.
 The hardening of a latex takes place by drying or loss
of water.
 Dry curing is mandatory for LMC

Epoxy Resins
 Epoxy resins are the bi-components reacting in
ambient temperature .
 Chemically are poly-ethers formed by reaction
between poly-epoxy (base) & hardener
(polyamines) comprising of active hydrogen atom.
 Products is highly cross-linked & reaction is
exothermic; high mechanical properties, chemical
resistance, strong bonding to usual material, good
dimensional stability

 Latex is an ultra-fine emulsion, after coagulation
the material behaves like rubber.
 The concrete is stronger & can be made flow-able
micro-concrete.
 Processing is similar to ordinary concrete.

3. Polymer impregnated concrete (PIC)
 widely used polymer composite.
 It is nothing but a precast conventional concrete,
cured and dried in oven, or by dielectric heating from
which the air in the open cell is removed by vacuum.
 Then a low viscosity monomer is diffused through the Then a low viscosity monomer is diffused through the
open cell and polymerized by using radiation,
application of heat or by chemical initiation Polymer
Impregnated Concrete (PIC)
 monomer used are 1. Methylmethacrylate 2. Styrene
3. Acrylonitrile 4. T-Butyl styrene Monomers

 commonly used Monomers are methyl methacrylate
(MMA) and styrene for penetration because of
relatively low viscosity, high boiling point (less loss
due to volatilization), and low cost.
 After penetration, the monomer has to be
polymerized insitu.polymerized insitu.
 Three Ways of insitu polymerization:-
1. A combination of promoter chemical and catalysts
can be used for room-temperature polymerization;
but it is not favored because the process is slow
and less controllable.

2. Gamma radiation can also induce polymerization at
room temperature, but the health hazard associated
with it discourages the wide acceptance of this process
in filed practice.
3. using a monomer-catalyst mixture for penetration, and
subsequently polymerizing the monomer by heatingsubsequently polymerizing the monomer by heating
the concrete to 70o C with steam, hot water, or
infrared heaters e.g. Successfully used in bridge deck
wearing coat .

4. Partially Impregnated and Surface coated polymer
concrete.
 Provided where the major requirement is surface
resistance against chemical and mechanical attack in
addition to increase in its strength.
 Easily produced by initial soaking the dried specimens
in the liquid monomer like MMA, then sealing them byin the liquid monomer like MMA, then sealing them by
keeping them under hot water at 70c to prevent or
minimize loss due to evaporation.
 The polymerization can be done using thermal catalyst
method in which 3% by weight of benzoyl peroxide is
added to the monomer as catalyst.

 The depth of monomer penetration depends upon
1. Pore structure
2. Duration of soaking
3. Viscosity of the monomer
Advantages:
1. It reduces freeze thaw deterioration, corrosion
2. Increase in tensile strength2. Increase in tensile strength
3. Increase in compressive strength
4. Increase in modulus of elasticity
5. Resistance to acid attack
6. It improves the durability of concrete
7. Less pores  They are more or less similar to PIC

Light weight concrete:
Light weight Structural Aggregates:
 Rotary kiln expanded clays, shales, and slates
 Sintering grate expanded shales and slates Sintering grate expanded shales and slates
 Pelletized or extruded fly ash
 Expanded slags

Light weight concrete….
 Structural light weight concrete is similar to normal
weight concrete except that it has a lower density.
 Made with light weight aggregates.
 Air-dry density in the range of 1350 to 1850 kg/m3 Air-dry density in the range of 1350 to 1850 kg/m3
 28 days compressive strength in excess of 17 Mpa.
 Structural lightweight concrete is used primarily to
reduce the dead-load weight in concrete
members, such as floors in high-rise buildings.

Thermal Conductivity of concrete
 Thermal conductivity mainly depends on type of
aggregate, porosity, nature of pores and moisture
content.
 Conductivity can be modeled in terms of
Conductivity of solid and pores.
 Equivalent solid conductivity depend on
mineralogical composition of aggregates, can be
estimated.

Heavy weight concrete
 The major problem in a nuclear reactor is to
attenuate the gamma rays and neutrons emerging
from the core by means of Biological shield.
 To overcome this problem the cheapest and most To overcome this problem the cheapest and most
convenient shielding material chosen was the
heavy concrete.
 Aggregates used are manufacturing from rocks
like Hematite, Granite etc.

Recycled aggregate concrete
 Using waste in concrete. Pond ash Bottom ash as
fine aggregate.
 Recycled aggregate, demolition waste Construction
waste
 Problem of Original Interface
High Volume Fly ash ConcreteHigh Volume Fly ash Concrete
 Percentage of fly ash 50-60% of
 cementitious materials.
 Use of Super plasticizer.
 Low w/c (0.32 for 60%, or 0.45 for 50%).
 Low early strength.
 good long term strength and durability.

Special concrete

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