PROCEDURE
FOR MASONRY DAM GROUTING
USING
SPG-1A, ADMGP-1, ACC-2025 AS GROUT ADDITIVES
Grouting
of masonry dam involves, water & cement slurry grouting with a pressure of
around 2 kgs per square cms. To 3 kgs per square cms. (max).
Cement
& water is mixed in proportion starting with 1:10 to 1:15 and this cement
slurry is pushed at 0.5-1.00 kgs per square cms pressure initially.
As grouting progresses, the pressure increases and water content is
reduced till maximum pressure of 2 kgs per square cm to 3 Kgs per sq. cms. is
achieved and in this way the grouting is continued till no more slurry can be
pumped implying all voids are filled and plugged with cement during this
grouting operation.
In
this type of operations certain inherent disadvantages lead to excessive cement
consumption, large delays and inefficient plugging, i.e. :-
(1) The
algae, fungus or slime on the cavities substrate do not allow immediate bonding
to
(2)
`Big to small cavities' or `small to big' lead to unplugging at the
``neck' due to increase
(3)
Water
is used as carrier.
However, due to high water content and due to segregation,
(4)
The
use of high water contents and lower solids in the grouting slurry renders the
grout
Our
grouting system comprising of combination of SPG – 1A, ADMGP – 1 and
ACC-2025
SPG-1A
enables higher solid content in the grout without loss of fluidity
hence ensuring higher packing efficiency, higher sealing capacity of
the grout and better plugging. It is possible to reach higher impermeability
coefficient faster by using SPG-1A in the cement slurry.
ADMGP-1
enhances
bonding properties between slurry and substrate, irrespective of the presence of
slime, algae etc.
Accelerator
2025
is a very fast acting, fast plugging formulation which enhances the efficiency
of slurry in plugging and sealing all openings to ensure most efficient grouting
Establish
setting time of cement, if the I.S.T is beyond 45 minutes, use 2 kgs to 4 kgs of
ADMGP-1 per bag of cement being grouted. Reduce water by 33%-50% using SPG-1A
200ml to 400 ml per bag of cement. SPG-1A will ensure same slurry flow at
elevated solid content. Grout as usual.
At first sign of resistance to slurry flow, incorporate ACC 2025 200ml to
400 ml into the system and continue grouting till pressure higher than 2.00-3.00
kgs per square cm is achieved or till slurry ceases to flow. Whichever earlier.
COLGROUT
ADMIXTURE CG-101S
In
Colgrout, cement, synthetic sand and water is used. Colloidal solution is made
by high speed stirring and this colloidal solution is pressure grouted in
cavities of stacked metal.
In using Colgrout, following disadvantages are generally observed:-
The
impellers of stirrer wear rapidly, and with time the colloidal quality of
Colgrout suffers.
The
water cement ratio is in the range of around 0.8 - 0.9, the high water
cement ratio is supposed to give high fluidity to Colgrout, but accompanying
disadvantages are very high setting time. During this period the water
slurry system moves down by gravity yielding high segregation and in
some
instances complete separation of cement and sand.
During
pressure grouting in many instances water slurry which is capable of
travelling faster moves ahead leaving behind dry mix.
Hence aggravating segregation problem.
The
cohesiveness is merely due to high impeller rotation, uniform distribution of
cement particle in matrix which is easily disturbed during pressure grouting
and high setting time.
Since
the water cement ratio is high of the order of 0.85 and the aggregate size
is
small the shrinkage is high.
Colgrout
Admixture CG-101S is specially formulated for Colgrout application.
It ensures cohesiveness in Colgrout, eliminates separation, reduces
setting time of Colgrout, arresting further separation and segregation. The
polymer nature of Colgrout ensures uniform cement distribution in matrix.
Following
physical attributes of CG-101S ensure its value at Colgrout additive:-
(1)
High cube strength.
(2)
High flow metre reading.
(3)
High ultimate strength in absence of curing.
(4)
Reduction in setting time by 15-20% reduces the segregation and separation of
cement and sand.
(5)
Very high improvement in cohesiveness of the colgrout.
(6)
The impermeability of the Colgrout is enhanced so also the impermeability
characteristics of the entire matrix is enhanced considerably.
(7)
Anti-washout properties ensures water & solid particles move at same
rate under pressure grouting.
(8)
Colgrout Admixture CG 101S reduces shrinkage, hence enhancing Colgrout
masonry quality.
(9)
In impeller slurry the colloidal solution obtained is easily disrupted
due to high water content, long
Higher
ultimate strength make possible large cement savings & improved Colgrout
cost/economy.
Use
CG-101S 200ml per bag of cement, reduce cement by 15-20%, reduce water by 5-10%,
Use this Colgrout as usual.
| PRODUCT & APPLICATION | METHOD | COST ANALYSIS |
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1.For
mass concreting and dams where highly
plasticized
mortar, with high impermeability coefficient
is required, we recommend our
Entrair RET-1025, ERE-1025 is mixed in the proportion of 200 ml per bag of cement in high speed mixer to ensure optimum air entrapment. |
Mix
cement, coarse aggregates and fix aggregate as usual. Add water in the proportion of W:C 43 to 50. Use 200 ml RET-1025 200ml per bag of cement.
|
Considering
15% cement mix, per meter cube amount
of REC 1025 is 1.50 litres. Cost of REC
@ Rs.90/- per litre dosage of 1.50 Lts. REC
1025 works out to Rs.135/- per metre cube of concrete.
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2.For
masonary portion, use Super Plasticizer
1156 @ 200 ml per bag of cement. This mortar
highly plastic mortar at low water cement
ratio high workability, and high strength
mortar. It is possible to save cement upto
30 – 40% wit increased strength.
For earth grouting Rapid Grout ensures rapid slurry plugging and high plugging efficiency. It also saves cement tremendously. |
Mix
cement sand in the proportion 1:4
or 1:6. Use SPRET 1156 @ 200
ml per bag of cement.
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Considering 1:6 cement aggregate mortar, per metre cube quantity of SPRET 1156 required will be 1.43 litre. Cost of SPRET 1156 @ Rs.110 per litre. Cost of dosage per metre cube of cement mortar Rs.157.30.
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4.The
down stream portion of the dam
is gunniting using 20-25% cement and sand Force
under presurre.
During gunniting operation if the throw back is high the cement consumption is high. If the gunniting is porous, high volume of cement slurry is consumed in grouting. To reduce cement consumption in grouting Anchorex ensure impervious & dense gunniting with minimum cement consumption, Anchorex is used as gunniting aid.
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Add one litre Anchorex per bag of cement in gunniting mix & complete gunniting. Cement saving upto 30%-40% is possible without loss of quality if anchorex is used.
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Cost of Anchorex is 101 in 200 ltrs barrel Rs,150\-. dosage of 1 ltr per bag of cement ie.Rs.150\-per bag of cement.
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5.Lower
discharge gate is practically always
submerged. The gate guides are imbeded in the
surrounding concrete using suitable anchoring.
However due to constant hydrostatic pressure these gate guides tend to loosen and weaken allowing constant water discharge. The gate guides can be butteressed and reinforced with our P.A. Mortar TH –4. |
Epoxy
Mortar R2 EM-105 is factory prepared mortar comprising of Resin
& Hardner. These two components are
mixed together at site to obtain a
fast setting mortar of compressive strength
1200 Kg/Sq.cm. It requires no
curing.
|
Cost
of Epoxy Mortar R2 EM-105 is Rs.205 per kg the spacific gravity of this
product is 1.40.
|
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6.Discharge buckets, discharge to hidel power station, and areas subject to high pressure water flow prone to rapid errosion are treated with a layer of P.A. Mortar-TH4 2mm thick, which has high abrasion resistance, high compressive strength protecting the underlying concrete from rapid degradation. |
Epoxy
Mortar R2 EM-106 is trowable mortar
& can be thowalled on vertical surface
upto thickness of 2mm.
|
Cost of RZ EM-106 is Rs.200 per kg for 2mm layer coverage is 2.5 sq ft. Cost per sq ft is Rs.80/-.
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7.Concrete Cure Coating For large construction the water curing is expensive & laborious. Concrete cure coating eliminates water curing, it ensures uniform concrete hydration. Useful for canal lining, |
Mix water to Concrete Cure Coating in proportion 1:2. Within 1 to 1\2 hour after placing of concrete or cement mortar, spray C.C.C over the entire gunnited surface, C.C.C forms a restraining water loss from the water in concrete allowing uniform hydration of cement mortar. |
Cost
of concrete cure coating Rs.80\-per ltr. Covering
after addition of 2 ltrs. of
water is 20 sq
mtre ie. Rs.4.00 per sq metre. (The cost of water curing @ Rs.300\- per 10 KL Water, labour cost of Rs.7.50 per man hour is Rs.2.75 per sq ft).
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8.Colgrout
Admixture for Colgoruting sand and cement
slurry. Improves strength, eliminates
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Mix
CG -101 to cement sand and water in Colgrout dispenser. Use 200ml CG –101 per bag
of cement.
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Cost of CG –101 is Rs. 40/-per kgs, dosage of 200ml Costs Rs. 11.20 [Sp. Gr. 1.4]
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