Danish Ali Bhatti
(Fa17-BAR-032)
TERRAZO CONCRETE
Terrazzo is a composite material, poured in place or precast, which is used for floor and wall
treatments. It consists of marble, quartz, granite, glass, or other suitable chips, sprinkled or
unsprinkled, and poured with a binder that is cementations, chemical, or a combination of
both. Terrazzo is special prepared concrete surface containing cement and marble chips in
proportion to 1:2. The marble chippings can be selected from a wide range of colors and
sizes and set in practically any color of cement matrix to create an unlimited range of shades
and effects. Terrazzo is cured and then ground and polished to a smooth surface or
otherwise finished to produce a uniformly textured surface.
Characteristics of Terrazzo
•Terrazzo has been described as a decorative form of concrete. Random sized marble chips
are mixed in a binder, toweled, ground and polished. •Good terrazzo has a smooth surface
that is a mixture of 70% or more coarse marble aggregate and 30% or less Portland cement
matrix. •Terrazzo combines the durability of marble with the strength and economy of
concrete. •Ease of maintenance - is one of the principal reasons why terrazzo is found in so
many buildings where traffic is heavy.
TYPE OF TERRAZZO
EPOXY TERRAZZO: A nominal 1/4″ or 3/8″ thick resin matrix veneer placed upon a level
concrete slab; Also can be specified with glass, synthetic, or granite aggregates in lieu of
marble to provide brilliant colors or chemical resistance; The best “thin-set” system.
Advantages: Unlimited matrix colors, color control, resiliency, chemical resistance and
tensile- compressive strengths not found in cement based systems. Excellent for multi-
colored patterns and designs. Light weight and flexibility make it ideal for multi-story use. It
has the lowest maintenance cost due to non-absorbancy. In sanitary areas can be installed
with minimal dividers providing seamless characteristics. When used in conjunction with a
flexible membrane as a specified extra, it can absorb some horizontal concrete crack or
control joint movement. It also has the quickest pour to grind installation time. Can also be
used over properly installed and prepared plywood. Glass and other decorative aggregates
increased costs.
RUSTIC BONDED TERRAZZO: Terrazzo with a non-ground, textured surface, for exterior
use. This system is available with Bonded and Monolithic Terrazzo.
Advantages: Infinitely variable textures, colors and patterns may be created in a weather-
resistant, skid-resistant deck surface.
SAND CUSHION TERRAZZO : A cement matrix topping underbed with wire reinforcing,
isolation sheet, and sand layer system for interior floor use. This is the best cement system.
Advantages: Due to the underbed’s depth, wire mesh reinforcing, isolation sheeting and
sand layer it will absorb minor substrate defects and prevent mirroring to the surface.
BONDED TERRAZZO : A cement matrix and underbed system for interior and exterior
areas where conditions require 1.25″ to 1.75″ inches of recessed depth to be filled in
addition to the .5″ terrazzo topping.
Advantages: With sand-cement underbed it has less dependence on the concrete slab for
flatness when compared to monolithic.
MONOLITHIC TERRAZZO : This 1/2″ thick cement matrix veneer placed upon a provided
concrete slab is dependent on the concrete quality for flatness and crack prevention. On
grade or below grade only.
Advantages: Fast installation and the most economical price make it ideal where time and
budget are critical but where the beauty, low maintenance and the performance of terrazzo
is desired.
POLYACRYLATE TERRAZZO : A nominal 3/8″ think polymer modified cement matrix
veneer placed upon a provided level concrete slab. Polymer provides strength to allow for
thinner applications of cementitious systems.
Advantages: Fast installation and moderate price range make it ideal to replace vinyl or
carpet without depth transition difficulties; also good to use in areas subject to moisture
vapor transmission where Epoxy terrazzo or other non-breathing floors will not adhere.
USAGE
In terms of volume, the biggest use by far is for floor tiles. The most common size of tile is
300 x 300 x 28mm which in the UK alone covers over 20 million sq.m. of floors. Other sizes
are available. Complementary features such as skirtings, staircases, upstands, partitions and
other architectural characteristics can also be made from pre-cast terrazzo units or cast in
situ.
Terrazzo is mainly used internally. It can be found in supermarkets, shopping centers,
railway stations, airports, reception areas, bakeries, showrooms and hospitals. A high
quality, durable product which is hygienic and easy to maintain, terrazzo can be used in
most heavy duty internal areas.
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Colored Concrete
From translucent to opaque, the color choices for concrete are endless, thereby allowing you
to achieve different looks with colored concrete. Colored concrete can be made to look like
different materials such as brick, slate or even tile and colors can range from earth tones to
vibrant hues. Colored concrete with finishing techniques like stamping and troweling may
also be used to create a decorative pattern, is an affordable technique that provides
consistent color and may be used in many design applications, from driveways, outdoor
counters, fire pits and built-in outdoor furniture.
Typologies
Powder Pigments:Colored concrete can be achieved through mix-added powder pigments
before pouring concrete. Powder pigments which are available in liquid or mix-ready bags
and are often made from recycled material, are added directly to the concrete mixer prior to
pouring. Coloring concrete with powder pigments easily provides uniform color since most
bags contain a precise measurement of pigments. Colors for pigments range from earth
tones of browns, tans, warm grays, blues and greens.
Staining : Staining concrete is a method of coloring after the concrete has cured. This can be
done by acid staining or by water-based staining. Acid staining uses a mixture of acid stain
and water which controls the depth of color. The chemical reaction of the stain on the
concrete which is applied using a broom or walk-behind scrubber and then finished with a
sealer, creates a unique marbled effect. Water-based stain may even be mixed to create
custom colors and is free of solvents and harmful acid, making application safer. The range
of colors for acid staining consists of subtle tones of tans, browns and blue-green. Water-
based stain is available in a variety of colors, as well as black, white and metallic tints.
Pros and Cons: Concrete is a great material because it is durable and not easily damaged.
Colored concrete is an inexpensive look to achieve as it may be done by do-it-yourselfers.
Many types of colored concrete powder and stains are available that do not have harmful
ingredients, thereby making colored concrete environmentally friendly. However, cement is
susceptible to moisture, so if you want the color to last, it's important to keep pigmented
concrete well sealed at all times and to periodically inspect the surface for defects. Likewise,
reapplying a coat of sealer must be done on a regular basis, especially on outdoor colored
concrete, not only to prevent color from fading, but to protect it from UV exposure and other
environmental factors. Moreover, you can't change the color of concrete once it is chosen, so
it is important that the right color is used the first time.
Methodologies
1. Integral coloring : Colorant added to concrete during mixing produces uniform color
throughout the slab.The colorant may be liquid or powder. Integral color is for new
installations only, and usually only for large monochrome areas, since the main application
device is a ready mix truck. Integral colors are expensive because you are coloring the
entire depth of the slab.
2. Shake-on colors: Shake-on color consists of finely-ground pigments and dry cement that
is “broadcast” onto freshly placed concrete. The powder gets worked into the concrete
during bullfloating.
Bleed water from the plastic concrete wets the cement powder, causing it and the pigments
to bond to the exposed surface. Because the pigments are concentrated in the top layer,
grinding and polishing will remove the color. Since shake-on colors rely on water from
freshly placed concrete, they are only suitable for use on freshly placed concrete.
3. Acid Stains: Acid stains are formulas of acid, metallic salts and water. The acid chemically
reacts with minerals in the concrete, creating a unique, mottled color effect that’s as durable
as the wear zone of the concrete it’s applied to. Acid stains are hazardous materials and
require all the safety precautions common to acidic products.
Concrete floors that have been acid stained must be neutralized and rinsed thoroughly to
remove any excess acid. You must be careful when handling acid stains, also, because spills,
sloshes and drips instantly create permanent “features” in the floor. Acid stains can be used
for retrofits or new installations.
4. Acetone dyes : The benefits of fast-drying solvent-based dyes are often overshadowed by
the risks inherent with using highly flammable reduction solvents. Acetone – one of the
most common reduction solvents, has a flash point of 4 degrees F and an odor and toxicity
that makes it impractical to use in most occupied spaces. The color usually is applied after
the floor has been polished with a 400-grit resin.
Though solvent-based dyes can impart vivid colors, they aren’t UV-stable. Sunlight, through
a window or skylight can fade the colors. Most require a topical protective treatment to lock
the color in. Respirators and explosion-proof ventilation are required when installing
solvent based dyes on new or existing concrete floors.
5. Water-based dyes : Water-based stains and dyes have several advantages. They are
odorless, safe and easy to apply, and dry quickly. Different colors can be easily mixed and
matched, creating striking patterns and effects in areas large or small. Combined with
hardening, densifying and polishing, water-based stains can create a translucent, gemlike
effect. However, water-based stains must be used with protective coatings to lock in the
color. Like acetone dyes, they are not UV-stable and will fade in direct sunlight. Water-based
dyes can be used for new installations or retrofits. Water-based colors are easily applied
with pump-up or airless sprayer, followed by spreading with a microfiber pad. The color
usually goes on before the floor has been hardened and densified.
6. Color hardener/densifiers : Color hardener/densifiers are a recent innovation in which
fine pigments suspended in water are blended by the applicator with a lithium-silicate
hardener/densifier. This lets you harden/densify and color in one step. Apply color
hardener/densifiers to concrete floors ground no finer than with a 200-grit resin pad.The
pigments in these products are similar to shake-on colors in that they are surface
treatments, so polishing after application removes the color. Also like shake-on colors, most
are UV stable and suitable for exterior application. While a protective treatment to “lock in”
the color isn’t needed, strictly speaking, protective treatments are always a good idea for
horizontal concrete, inside or out.
APPLICATION
If it’s a new installation, any of these products will work. If it’s a refit or restoration, you’re
limited to acid-stains, water-based dyes, acetone dyes or colored hardener/densifiers.If it’s
polished concrete and uniform color you’re after, acetone or water-based dyes are your best
bet. The difference? For safety and environmental concerns, choose water-based dyes. For
slightly more vivid colors, acetone may be the product you want.For the mottled, antique
look without polishing, consider acid-staining.Shake-ons are best for small, simple jobs,
when there’s not going to be any grinding. Since shake-ons are surface treatments, grinding
will take the color off. Consider integral color for large areas where you want uniform
color.You can grind these installations aggressively if, for example, you want to expose
aggregatee
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HAMMERED CONCRETE
Concrete having an exposed aggregate finish, usually obtained with a power-operated
hammer which removes the sand-cement matrix around the aggregate particles to a depth
of one-quarter inch.The amount of removal can vary significantly, depending on the
application. Think of bushhammering as more aggressive than sandblasting and usually less
severe than scabbling. Hand tools or bits for electric and pneumatic hammers are used,
depending on the desired surface texture, the amount of surface to be tooled, and the
location of the work. A special tool for bushhammering has several conical or pyramidal
points, and resembles a meat tenderizer. Similar effects can be achieved by using pointed or
chisel bits or needle scalers. Bushhammering is done for various purposes. It can produce
pleasing surface textures varying from a light scaling to a deep reveal of coarse aggregates.
Other applications include removing fins, protrusions, or drips that can form on concrete
during construction, or mineral deposits that can build up on concrete over time. Because it
increases roughness, bushhammering also can be used to prepare concrete surfaces before
patching. Marble, calcite, and limestone aggregates are well-suited for concrete to be
bushhammered for architectural purposes. Natural gravel can shatter or break out of the
cement paste, while hard granite and quartz aggregates can break erratically or into the
paste, rather than across the intended surface. Most structural concretes can be
bushhammered. Use air-entrained low-slump mixes, properly placed and vibrated. Gap-
graded and low-sand-content mixes are recommended for best appearance. Concrete can be
bushhammered after it reaches a strength of about 4000 psi and is at least two to three
weeks old and surface dry. Be careful when working close to an edge or corner. It's a good
idea to do a sample area for acceptance by the owner and specifier before beginning work.
This can minimize misunderstandings about the intent or quality of the work.
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Chiseled concrete
Demolishing concrete is a heavy-duty task that calls for heavy-duty tools. Most concrete
demolition projects call for the use of a jack hammer or hammer drill. Occasionally, very
small areas of concrete must be removed from a larger project, or you may simply need to
clean up the ragged edges left by a larger tool. These situations call for the use of a cold
chisel. This small, pointed piece of metal can make precision cuts in concrete when used
properly. It is also used for manual engraving on concrete surface for aesthetical purposes
which can be quite labor intensive.
APPLICATION
1- Grasp the cold chisel loosely in your fist placing the tip of the chisel against the concrete
you intend to break. Lean the chisel so that only one point of the tip is resting on the
concrete.
2- Grasp the bottom end of the handle of a small sledge hammer tightly. Tap the head of the
chisel with a half-swing and immediately strike it again with a full swing. Continue digging a
hole in the concrete with only one point of the cold chisel using a half-strike/full-strike
double tap of your sledge.
3- Lean the chisel perpendicular to the angle of the first angle so that the full width of the
blade rests against the concrete and the bevel is parallel to the surface of the concrete.
4- Strike the head of the chisel with your hammer with the same half strike/full strike
maneuver to remove larger chunks of concrete.
5- Reposition the chisel with the width of the tip resting flat and the bevel parallel to the
surface of the concrete and remove another small chunk with the double tap maneuver.
Continue moving the cold chisel and removing small chunks until the job is complete.
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Fare-Faced Concrete
Fair-faced concrete is also called decorative concrete by pouring-forming one time. It uses
the natural texture of concrete itself and the nature state formed by carefully designed
apparent seam,zen seam and split bolt hole as the manifestation of decorative surface. As its
surface is smooth,profile clear, color uniform, transition natural, it owes much beauty when
used in the building facade decoration.By using fair-faced concrete, there is no decoration
process as plastering, putty and coating after concrete formed. It uses the natural texture of
concrete surface as decorative surface compared with traditional concrete project. So it has
advantages such as reducing the construction process,shortening the construction period
and reducing the occurrence of quality problems, the dangers and project cost. fair-faced
concrete can avoid the common quality faults of traditional external wall decoration, reduce
the waste of resources.
Normal concrete catters to only strength and durablity (due to environmental factors)
requirements of the designer. Usage of fare-faced concrete comes into play when additional
aesthetic design constraints are imposed in terms of surface finishing,edges details and
color pigmentation , by designer. It provides required tecture through usage of specialised
formwork molds for (made up of wood,plastic or metals) pouring and curing of concrete.
Concrete Pouring : Before the placement of concrete, the base should be wetted with
right amount of water, 50mm thick cement mortar should be poured. Its parameters such as
materials, water cement ratio and admixture should be the same with the mix proportion
ratio of fair-faced concrete. Fair-faced concrete walls are poured every layer with height of
500-1000mm, it is required that the thickness of every layer is the same. If pouring height is
too high, the internal air of concrete can not be released, there will be defects such as
bubbles which influence the visual quality of concrete. Inserted vibration bars are used in
concrete vibrating, the bars should stretch into concrete layer no more than 200mm,
vibrating is closed till there are laitance appearing in the surface, no subsidence of concrete
and no bubbles. Vibration bars should be quickly stretched into and slowly pulled out to
avoid leaked vibration, owed vibration and over vibration.
Formwork Dismantling : At normal state ( room temperature 18-20℃), split bolts can
be loosened 6-8 hours after concrete poured in order to dismantle formworks. The
dismantling time is strictly controlled according to the temperature and the strength of
concrete samples to ensure the surface, edges and corners of concrete not be damaged in
dismantling process.After dismantling, concrete should be covered with thick qualitative
plastic (usually transparent plastic) which can avoid color pollution. The plastic can also be
used in product protection. During summer watering, the quality of water is controlled in
case color pollution exits; when winter maintenance, plastic cloth and burlap bags are used
for insulation. In winter construction period, the temperature of the internal and surface of
concrete should be measured every day, concreteconstruction is not allowed when the
temperature is below 0℃ in principle.
