Mix Design
Admixture Addition at Site
Addition of Chemical Admixture at Jobsite
(Workability Adjustment)
Doc No: WI/TEC/034A
Revision: 00
Date: 15/January/2022
Work Instruction For Addition of Chemical Admixture at Jobsite
(Workability Adjustment)
“QCS 2014”
Prepared By
Technical Manager
Page 1 of 6
Addition of Chemical Admixture at Jobsite
(Workability Adjustment)
Doc No: WI/TEC/034A
Revision: 00
Date: 15/January/2022
( Design Target Slump Flow 500 & 550mm)
T olerance: (-60/+70mm)
Workability Adjustment:
Addition of admixture on site is totally controlled & coordinated by RMQ Quality Control
Supervisor, RMQ Technician on site, Approved third party technician & contractor QA/QC
Engineer complying fully with the QCS and CIRIA C577 recommendation.
Concrete Plastic Chemistry:
Concrete is an inherently variable material due to the physical nature and chemistry of its
constituents; ever-changing ambient conditions (temperature, humidity and wind speed) also
have their significant effects.
The practice of adding admixture on site is widely recommended and accepted within the
region as being an effective and efficient means of controlling workability to counter the
difficult environmental conditions and to prevent the uncontrolled addition of water on site.
CIRIA Guide to the construction of reinforced concrete in the Arabian Peninsula provides
recommendations on the design and control of workability within the region.
Quality Assurance:
Please be assured addition of admixture to adjust workability of batched concrete is totally
controlled exercise and documented complying fully within the range mentioned on our mix
design certificate and manufacture recommendation
Slump is very sensitive to minor changes in material properties and ambient conditions so some
variation in slump on arrival at site is to be expected. Lower slumps are quickly remedied by the
controlled addition of admixture on site provided proper addition and mixing techniques are
observed; this will include a measured dose which, when added to the original dose, does not
exceed the target range stated in the mix design. Mixing is at minimum 10 drum revolutions
per minute for 5 minutes to ensure homogeneity.
Mix:
C40/OPC/GGBS(65%)
A dmixture Dosage:
As per manufacturer recommendation dosage is maximum 2.5% by weight of total
cementitious content.
Reference Standards:
Q CS 2014, Section 5 Part 6 Property Requirements Page 27, clause 6.8.2.5 clearly states:
The adjustment for the slump of concrete to fit the job requirement can be conducted only one
time using a proper additive at jobsite provided that such addition does not increase the watercement ratio, setting time and above the maximum permitted by the
specifications/manufacture recommendation.
This will follow procedure below.
Page 2 of 6
Addition of Chemical Admixture at Jobsite
(Workability Adjustment)
Doc No: WI/TEC/034A
Revision: 00
Date: 15/January/2022
A ssessment
Initial slump flow is to be measured.
Slump flow at 500mm to 620mm is permitted to discharge.
If measured slump flow <500mm requires additional dosage of 0.5 L/m3.
Confirmation
RMQ Technician on site will check ticket and confirm with batch print out, how much
quantity/dosage of admixture is used while batching before re-dosing.
1. A calibrated measuring cylinder is used for all re-dosing. All technicians carry this
equipment whenever they visit sites for testing purposes.
2. All admixture addition is strictly carried in compliance with the manufacturer's
recommendations; any admixture on site will not exceed the maximum limit detailed
on our certificate of mix design F/TEC/025; which ensures compliance with the
recommendation of the manufacturer’s data sheet for the product concerned.
R e-dosing procedure
The required dosage shall be accurately measured out by RMQ technician on site.
The truck mixer shall bring the concrete as far back in the drum as possible without causing
discharge.
The measured dose of admixture shall be poured into the truck.
The truck mixer shall continue mixing the concrete and admixture for 5 minutes at a minimum of
10 revolutions per minute to achieve required workability and homogeneous concrete.
R e-assessment
Slump flow is to be re-measured.
Slump flow at 500mm to 620mm is permitted to discharge.
For slump flow above 620mm, load is to agitate and tested next 15 minutes till slump flow range
is achieved.
Note 1: BS EN 12390 - Method for determination of slump flow states that two operators
performing the test on the same sample of concrete will show an average difference of 40mm.
Note 2: The rejection of concrete without considering the above option indicates a
misunderstanding of concrete chemistry and admixture technology.
Note 3: It is the experience and expertise of the Readymix supplier to account for this type of
Page 3 of 6
Addition of Chemical Admixture at Jobsite
(Workability Adjustment)
Doc No: WI/TEC/034A
Revision: 00
Date: 15/January/2022
situation and ensure compliance, to maintain the quality of our concrete, at the level expected
from our valued clients/customers.
Note 4: The result of above practice ensures plastic and hardened properties complies fully with
the project/client requirements without compromising on quality, less disruption to supplies and
less waste to help the environment.
Reference notes extracted from ACT Books and CIRIA C557 notes are as follows:
CIRIA C577
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Addition of Chemical Admixture at Jobsite
(Workability Adjustment)
Readymix Qatar Ltd., Holcim
Page 5 of 6
Doc No: WI/TEC/034A
Revision: 00
Date: 15/January/2022
MPCE#4 Admixture
Hyperplast PC240SA-R
High performance concrete admixture based on polycarboxylic polymers
Description
Hyperplast PC240SA-R is a high performance super
plas cising admixture based on polycarboxylic polymers
with long chains specially designed to enable the water
content of the concrete to perform more effec vely.
This effect can be used in high strength concrete and
flowable concrete mixes, to achieve highest concrete
durability and performance.
Applications
 To produce high quality concrete of improved durability
and water ghtness.
 High strength and high performance concrete.
 Improved cohesion allow for use in mass concrete
pours and piling.
Advantages
 Op mises cement u liza on.
 High density and impermeable concrete through very
high water reduc on.
 Improves shrinkage and creep behaviors.
 Minimises segrega on and bleeding problems by
improving cohesion.
 Higher early and ul mate compressive strengths.
 Increases durability and resistance to aggressive
atmospheric
condi ons
thorough
reduced
permeability.
Compatibility
Hyperplast PC240SA-R is suitable to use with all types
of Portland cement and cement replacement materials.
Hyperplast PC240SA-R should not be used in conjunc on
with other admixtures unless DCP Technical Department
approval is obtained.
Standards
Hyperplast PC240SA-R complies with ASTM C494, Type G.
Technical Properties @ 250C:
Colour:
Yellowish to brownish liquid
Freezing point:
≈ -3°C
Specific gravity:
1.06 ± 0.02
Chloride content:
Nil
Method of Use
Hyperplast PC240SA-R should be added to the concrete
with the mixing water to achieve op mum performance.
An automa c dispenser should be used to dispense the
correct quan ty of Hyperplast PC240SA-R to the concrete
mix.
Dosage
The recommended dosage of Hyperplast PC240SA-R is
0.5 - 2.5 litre per 100 kg of cemen ous materials in the
mix, including GGBFS, PFA or microsilica.
Representa ve trials should be conducted to determine
the op mum dosage of Hyperplast PC240SA-R to meet
the performance requirements by using the materials
and condi ons in actual use.
Effects of Over Dosage
Overdosage of Hyperplast PC240SA-R will cause the
following:
 Significant increase in retarda on.
 Increase in workability.
Ul mate concrete strength will not be adversely affected
and will generally be increased provided that proper
concrete curing is maintained.
Cleaning
Clean Hyperplast PC240SA-R with fresh cold water.
Hyperplast PC240SA-R
Packaging
More from Don Construction Products
Hyperplast PC240SA-R is available in 25 litre pails, 210
litre drums and 1000 litre bulks supply.
A wide range of construc on chemical products are
manufactured by DCP which include:
Storage
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Hyperplast PC240SA-R has a shelf life of 12 months from
date of manufacture if stored at temperatures between
2°C and 50°C.
If these condi ons are exceeded, contact DCP Technical
Department for advice.
Cautions
Health and Safety
Concrete admixtures.
Surface treatments
Grouts and anchors.
Concrete repair.
Flooring systems.
Protec ve coa ngs.
Sealants.
Waterproofing.
Adhesives.
Tile adhesives and grouts.
Building products.
Structural strengthening.
Hyperplast PC240SA-R is not classified as a hazardous
material. Hyperplast PC240SA-R should not come into
contact with skin and eyes.
In case of contact with eyes, immediately flush with
plenty of water and seek medical a en on.
For further informa on, refer to the Material Safety Data
Sheet.
Fire
Hyperplast PC240SA-R is nonflammable.
01-0453-A-2021
Note:
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