Cold mix bituminous plant

1. Cold Mix Bituminous Plant
Prepared By : Rahul Pitroda
Guide by : Prof. Manish Jain

2. Introduction
• Cold placed asphalt pavement mixtures are generally mixes made with emulsified or cutback
asphalt. Emulsified asphalts may be anionic or cationic. Cutback asphalts may be MC
(medium curing) or SC (slow curing)grades.
• Aggregate material may be anything from a dense-graded crushed aggregate to a granular
soil having a relatively high percentage of dust. The aggregate at the time of mixing may be
either damp, air-dry, or artificially heated and dried.
• Mixing methods may be performed either in the roadway, along the roadway, or in a
stationary mixing facility

3. Asphalt
• The type and grade of asphalt selected for use in cold-laid pavement construction depends a great
deal upon the aggregate, mixing method, and climatic conditions.
• Mixtures prepared at a stationary mixing facility generally permit a more viscous grade of asphalt
than used in the road-mixing method. Cool weather conditions require a lower viscosity grade and
permit a faster curing or setting type of asphalt to be selected than for warmer or hot weather
mixing conditions.
• Mixtures prepared with emulsified asphalt do not require aggregates as dry as those prepared with
cutback asphalts

4. Cold mix asphalt & hot mix asphalt
• Cold mix is a mixture of unheated aggregate and emulsion or cutback and filler. The main
difference between cold mix and hot mix asphalt is that aggregates and emulsion or cutbacks
are mixed at ambient temperature (10°C-30°C) in case of cold mix and aggregates and binder
are mixed at high temperature (138°C-160°C) in case of HMA. Dense graded cold mixtures
far lower permeability and good resistance to deformation. Open graded mixtures are
and semi dense mixtures have good adhesion and lower permeability.

5. ADVANTAGES
• It eliminates heating of aggregate and binder.
• It is environmental friendly and conserves energy. Cold mix pavement can provide energy savings
over 50% compared with hot mix . So it can be considered as green bituminous mix for rural road
construction.
• It can be easily prepared using small set up on site. It can be produced manually for small scale
Laying of HMA for rural road construction sometimes is not economical because setting up of a
mix plant for small scale job increases the project cost.

6. Aggregates Selection
• In India aggregates should conform the physical requirement laid by MoRTH(Ministry of Road
Transport and Highways)
• specification (2001). Testing of aggregate like sieve analysis, specific gravity, aggregate impact
value and soundness is necessary.

7. Emulsion Selection
• Selection of emulsion depends on aggregate type and aggregate gradation
and ability of emulsion to coat the aggregate. According IS 8887:2004
specifications, five grade of emulsion; RS-1, RS-2, MS, SS-1 and SS-2 are
to prepare cold mix. Quality tests should be carried out on the selected
emulsion according to IS 8887:2004

8. Mix Composition
• A wide variety of aggregates and soil-aggregate combinations can be processed. There are many
cases where material from road cuts, pits, or nearby quarry sites may be economically crushed or
used.
• Often the entire output below a certain maximum size from a rock crusher is used. Suitable local
materials also include granular soils having up to 20 percent passing the 75 um (No. 200) sieve, as
well as clean sands and gravels. Granular materials that are mostly fine aggregate and have
relatively high percentage mineral dust may cause mixing, aeration, and compaction problems.
• Well-graded aggregates are always desirable for any course of the asphalt pavement structure, but
many poorly graded and gap-graded aggregates are adequate for base courses when properly
prepared by road mixing methods and procedures.

9. Formulas may be used for approximating the asphalt content for initial mixing.
For estimating the approximate emulsified asphalt content in dense-graded mixes the following
empirical formula may be used:
P = (0.05A + 0.1B + 0.5C) x (0.7)
where:
P = percent of total emulsified asphalt by weight of dry aggregate,
A = percent of aggregate retained on the 2.36 mm (No. 8) sieve,
B = percent of aggregate passing 2.36 mm (No. 8) and retained on 75 um (No. 200) and
C = percent of aggregate passing 75 um (No. 200).
(All above percentages should be expressed as whole numbers.)

10. Mix component Percentage on aggregate
Granite aggregate 20mm 26
14 mm 15
10 mm 9
6 mm 15
Dust 35
OPC 0 1 2 3 4
Pre-wet water 2.5 2.5 3 3.5 4
Bitumen Emulsion 8.06

11. USE OF ADDITIVES IN COLD MIX
• Additives are used to accelerate curing rate imparting initial strength to mix in early life. Portland
cement and lime are the common additives used in emulsion mixes. These additives are typically used
by 1 to 3 percent of total weight of dry aggregate. Additive imparts some charges to emulsion which
help emulsion to break quickly and bitumen droplets come out from emulsion and stick to aggregate
giving binding properties

12. Suitability for Pavement Construction
• Cold-laid asphalt mixes may be used for surface, base, or subbase courses if the pavement
structure is properly designed. Cold-laid surface courses are suitable for light and medium traffic.
• When used in the base or subbase, they may be suitable for all types of traffic. Cold-laid
pavements have special advantages in outlying areas where economic problems exist in getting
the necessary improved mileage. Also used on large jobs, cold-laid paving mixtures reduce
construction costs, but not necessarily the strength or
quality of the pavement structure.
• Asphalt pavements made by cold-laid methods can be designed and built to meet current
traffic requirements.
• They can also be increased in thickness, as may be dictated for subsequent traffic, by adding
additional pavement courses.

13. Cutback Cold Mix Asphalt Manufacture
• Cold-mix asphalt is not a sophisticated preparation. Generally, placing and compacting do
not normally call for equipment as sophisticated as that required for hot-mix asphalt.
• This type of pavement construction, however, is no less important since a large percentage of the
nation's roadways have cold-mix asphalt bases and even surfaces.
• Less control is required for cold-mix preparation with a distributor and motor-grader operation. But
possibilities for as great a control as for hot-mix asphalt are present
in a plant-mix operation. However, many plants used for producing cold mixes do not use or have all
the means for maintaining close uniformity of control. Wherever suitable materials are available, such
plant mixing procedures are employed for high production and low cost.
• Cold-mix recycling or reworking of existing asphalt pavement or aggregate structures is another
important pavement construction alternative.

14. Cold - mix asphalt with bitumen foam
• Water is sprayed through nozzles into the hot bitumen under pressure. The water
expands explosively when the pressure is released, resulting in a fine bitumen
foam that can easily be used to coat the cold aggregate substances. The quality of
the cold mix can be influenced as desired by adding cement.

18. http://www.e-asphalt.com/ingles/cutbackcoldmix/index.htm
www.ammann-group.com/en/home/asphalt-mixing-
plant/continuous-asphalt-mixing-plant/coldmix-130-400-th/

19. THANK YOU