lime as building material.pptx

1. LIME IS A GENERAL TERM FOR CALCIUM-CONTAINING INORGANIC MATERIALS, IN
WHICH CARBONATES, OXIDES AND HYDROXIDES PREDOMINATE.
LIME IS CALCIUM OXIDE OR CALCIUM HYDROXIDE.

2. LIMESTONE QUARRY IN BRONNOY, NORWAY.

4. The rocks and minerals from which these materials are derived, typically limestone
or chalk, are composed primarily ofcalcium carbonate. They may be cut, crushed or
pulverized and chemically altered. "Burning" (calcination) converts them into the
highly caustic and, through subsequent addition of water, into the less caustic (but still
strongly alkaline) slaked lime or hydrated lime (calcium hydroxide, Ca(OH)2), the process
of which is called slaking of lime.
Slaked lime (calcium hydroxide) is mixed into a thick slurry with sand and water to
form various kinds of mortar and render for building purposes. Lime mortar was
traditionally used in the joints between bricks or stones in masonry building
construction. Now cement is usually added to the mixture to form a harder mortar.
Hydraulic lime is a variety of lime, a slaked lime used to make lime
mortar. Hydraulicity is the ability of lime to set under water.

7. 1.01 LIME
One of the oldest manufactured building materials used
as a mortar and plaster by all the early civilizations:
1. CEMENTING MATERIALS
• Egyptians used lime plaster before 2600 B.C.
• Greeks used it extensively for mortars and plasters
• Romans developed a mixture of lime putty and volcanic
ash for the first real cement.
Manufactured by the
calcination of limestone
(carbonates of calcium
and magnesium).

8. Before quicklime can be
used, it must first be mixed
with water in the process
called slaking or hydration.
The lime has now become
calcium hydroxide
(Ca(OH)2), known as slaked
lime or hydrated lime.
The carbonates decompose
into carbon dioxide, which is
expelled, and calcium oxide
(CaO) called quicklime.
Quicklime
1.01 LIME
1. CEMENTING MATERIALS

9. Hydrated lime mixed with water to make lime putty, is used
as an ingredient of hard-finish coat for two-and three-coat
Portland cement plasters. It is also used for mixing with
cement mortar or concrete to:
• increase its workability
• decrease its permeability
to water
• reduce cracking due to
shrinkage
A type of lime which will
set under water is
hydraulic lime, used only
where slow underwater
setting is required.
1.01 LIME
1. CEMENTING MATERIALS

10. Gypsum, like lime, was used
as a plaster by the Egyptians,
Greeks and Romans.
“Plaster” from the Greek
word for both the raw
material and calcined
product. In architectural
terminology the words
“Plaster” and “gypsum” are
often used interchangeably.
1.02 GYPSUM
Gypsum rock is ground fine and heated (calcined) to between
325 F. to 340 F. when it loses about three-fourths of its
combined water.
The remaining product is Plaster of Paris if pure gypsum is
used, or hard wall plaster if 39.5 % impurities are present or
added to retard the set and improve the setting qualities. Hard
wall plaster is harder than lime plaster, sets more quickly and
thoroughly.
1. CEMENTING MATERIALS

11. Gypsum plaster is rendered
more plastic by the addition of
hydrated lime.
Fiber or hair is also sometimes
added for greater cohesiveness.
The fiber may be hemp, sisal or
jute; the hair is generally
cleaned goat or cattle hair.
1.02 GYPSUM
1. CEMENTING MATERIALS