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Use of Hydrated lime in surface carpeting of modern highways is recognized practice all over the world.
Hydrated Lime is used as a filler in asphalt layer of roads. It is mixed with the
asphalt and increases the softening temperature of asphalt layer, In this way it prevents the surface deformation of the road. us of Hydrated Lime in
asphalt layer gives greater durability against rain water and damages due to the
changes in temperature. Moreover it is used as stabilizer in the lower layer of the road.
MAIN APPLICATION QUICK LIME AND HYDRATED LIME
A broad product line allows lime quality to meet the wide ranging and ever growing needs of customers in many
industries. For example in alkaline paper making, lime as raw material is used to produce a precipitated calcium
carbonate as filler for improving the brightness and opacity of fine paper. In environmental applications include
the scrubbing of combustion gasses, as well as the treatment of drinking water, industrial and municipal sewage
sludge and effluents. These are but a few of many specialized markets that lime quality supplies.
1.
PULP AND PAPER
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Fine papers - PCC
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Mineral fillers
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Coating pigments
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Kraft pulp
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Causticzing agent
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Effluent treatment
2.
STEEL
3.
MINES
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Alumina production
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Causticizing agent
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Filtering aid
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Ore floatation - Depressant
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PH regualtor
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Acidic waste water treatment
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Cyanidation of gold and silver ores
4.
CONSTRUCTION
5.
CHEMICAL PRODUCTS
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Absorbents
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Filtering aid
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Waste water treatment
6.
AGRICULTURE
7.
MUNICIPALITIES
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Water
Treatment
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Softening - pH regulator
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Purification - Corrosion control
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Sewage sludge
pasteurization and stabilization
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Sludge conditioning
Reports
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In hot climates harder, more viscous asphalt (grade 40 - 50) are normally recommended to obtain more stability
from asphalt as well as from aggregate interlock. If the mix is designed and constructed to maximum aggregate
to aggregate contact, then the properties of the asphalt cement are less important. Regard less asphalt content
on the low side of the acceptable range are recommended for these areas. Higher traffic areas would demand the
lower asphalt contents within the acceptable range. The strength and flexibility
of the mixture will be largely determined by the mechanical properties of the filler-binder mortar. The quality of filler present in the filler binder
mortar is very important, too much and voids are created in the mortar, too little and the mortar
develops the strength properties of the binder only.
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Strength of a mixture or perhaps more accurately, resistance to deformation under heavy load can be obtained
either by using high viscosity binders in the binder filler mortar or by using crushed tones with rough angular
surfaces of the aggregates or both at the same time.
-
Addition
of approximately 1.5% Hydrated lime filler is very much useful for improving properties of filler as regard
viscosity, ductility and grade penetration.
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The ratio of filler to the binder (asphalt) should range from 1-1.5. The optimum ratio is obtained whenever the
mix yields (Ring & Ball method) between 70-95oC,
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It has been observed that generally Filler - Asphalt mixtures are showing
59-62oC softening point. However,
with the addition of approximant 1/5 % hydrated lime in approved, well graded mixes softening point jumps to
more hydrated lime in approved, well graded mixes softening point jumps to more than
73oC which is reasonable
good against thermoplastic deformations during the summer season at Lahore. Hydrated lime can be used as
mineral filler which acts as an extender of the binder and performs two important functions. First it acts as a void
filling material to help produce a dense, durable mix. Second, it imparts stability and stiffen the mix. In order to
reduce the occurrence of rain water damage hydrated lime is added to the mix as mineral filler at a rate of
1-2%
by weight of aggregate. This material may be added as a dry powder. The performance of asphalt layers in
flexible pavements has been of considerable interest and importance to the transportation
infrastructure industry since asphalt paving became a common practice. A well designed, asphalt pavement should be able to support
traffic induced stresses and strains as well as damaging effects of climatic conditions during the entire designed
service life, while providing an adequate level of serviceability.
It is well known that the performance of asphalt layers depends on:
A)
The composition of the asphalt mix,
B) The engineering properties of the compacted asphalt mix,
C) Quality control exercised during the manufacture and construction,
D) Properties of the supporting pavement layer in
particulate their flexural stiffness, and the bond
between the layers.
E) The volume and type traffic and environmental and drainage conditions.
The main purpose of mix design is determining the optimum properties of the available aggregates including filler
and binder which will produce a mix that:
a.
Can be spreaded and compacted to a uniform surface of suitable texture;
b. Which has adequate resistance to deformations;
c. Will withstand, without cracking, repeated elastic deflections of the pavement.
d.
Will be impermeable to water and remain durable.
Climate Classifications and Temperature Computations.
The climatic regions may be classified as follows (Finn, Nair and Hilliard 1976):
a. Cold: Main. ambient Temperature of -
18o C.
b. Moderate: Normal maximum daily temperature of
32o C or less.
c. Hot: Normal maximum daily temperature of
32o or more.
Reference
"Asphalt Mix Design for Hot Climate Regions" paper by Mr. Livneh, M.Sc., D.Sc. Published in Australian Road
Research, June 1990. Mix Design Methods, MS-2, 1993 edition from Asphalt Institute. U.S.A.
Circular No. 2401 dated 21.5.1407 H (jan, 1987) from Ministry of Communication, kingdom of Saudi Arabia.
Civil Engineering Materials edited by N. jackson, published by English Language Book Society, U.K.
Filler in Asphalt Mixtures, Research Report No. 69-2 (RR-69-2) revised in April 1983.
Hot Mix Asphalt Paving, 31 July, 1991 by U.S. Army Corps. Of Engineers.
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