Quality Control Procedure

1. Purpose
1.1 The purpose of this procedure is to ensure and maintain an acceptable standard for the raw materials, batching process, delivery and final product before its placement.The Quality Management System of Over Seas Cement Industries (OCI) is based on ISO 9001:2000.
2. Responsibility
1 The Technical Manger and the Quality Control Engineer will be responsible for the preparation and implementation of the Quality Control Procedure.They will be assisted by the competent professionals working within the QC department.
2 Any non-conformance encountered will be immediately addressed and a copy will be sent to the Management Representative for Quality Records (MRQ) to take appropriate preventive measures.
3 The periodic verification and calibration of the batching plant and all the connected equipments are the responsibility of the QC Engineer. Relevant records for the same will be sent to the (MRQ).
4 Whenever required, the Technical Manager will provide an appropriate project related Quality Plan to the Main Contractor.
5 The Technical Manager will review the required product conformance records from the raw materials suppliers to ensure the products comply with the requirements of the specification.
3. Laboratory
OSCI has a well equipped laboratory to conduct routine tests on raw materials and concrete.The laboratory is managed by the Technical Manager with the assistance of experienced Laboratory Engineers, QC Engineer, Laboratory Technicians, Laboratory assistants and site supervisors who are trained and qualified to handle any situation.
4. Qualification and Training
1 The qualification of the Personal working at the QC department will be as required by the normal practice. Outstanding Experiences in the same field is also considered as the selection criteria.
2 All employees working in the QC department will have proper experience in the field of quality control.
3 Periodic training will be conducted to introduce codes, standards and practices.
5. Standards and Equipments
1 Copies of the latest International Standards, Codes of practices etc. and periodicals on the latest developments about concrete are available for ready reference.
2 The laboratory has enough modern equipments to conduct in-house tests, according to the attached frequency, on raw materials and the final product.
6. Raw Material Receival
1 Only high quality raw materials will be utilized in the concrete.All Materials received by OCI will go through a comprehensive testing program to maintain an acceptable level of the production quality.
2 After identification of a potential source, samples will be collected by qualified and experienced personnel and a full range of tests will be carried out according to the attached schedule.
3 If the test results on the raw materials are satisfactory, the raw materials will be accepted.
4 Raw material received is controlled by qualified technicians appointed specifically for receiving raw materials according to the following criteria:-
a. All deliveries must be accompanied by a delivery note; the delivery notes will be checked for type, source and quantity of materials.The materials will be immediately rejected if they are not from the approved sources or correct type.
b. Aggregates are also inspected in the trucks before unloading, for cleanliness, size, color and other contamination. If the quality of the aggregate is in doubt, it will be unloaded in an isolated area and samples will be collected for extensive testing.The material will be accepted if it complies with the minimum requirements, otherwise it will be rejected and removed.
c. Admixture samples will be collected from each new delivery and solid content and specific gravity tests will be conducted to check compliance.
d. Cement samples will be collected from each new delivery and kept in the laboratory for one to two months. If the concrete strength at 28/56 days (Made with the same batch of cement) is satisfactory the cement samples will be discarded, otherwise the samples will be tested to check compliance.
e. Water is accepted on the basis of delivery notes and samples are randomly collected according to the test schedule and tested to check compliance.
f. Ice is accepted only from approved manufacturers and ice samples are randomly collected according to the test schedule and tested to check compliance.
7. Stocking of Raw Materials
a.Aggregates
Aggregates will be stock piled in shaded bays. Each bay is separated by concrete walls to prevent intermingling and cross contamination of aggregates. In addition, the aggregates will be stored on solid concrete flooring. Stock piles are built up by horizontal layers to avoid segregation and all bays will be clearly identified.
b. Cementitious Materials
OCI has a sufficient number of upright cement silos to store various types of cementitious materials.All silos are clearly identified. Keeping in line with the company policy to give the highest consideration to the environmental protection, each silo is fitted with dust filters to reduce air pollution.
Ice is brought in bags from the ice factory and stored in a purpose built insulated storage room

c. Chemical Admixtures
Chemical admixtures are stored in bulk liquid storage tanks of white color to reduce heat absorption and each tank is fitted with a cleaning outlet and circulation pumps to prevent segregation of chemical components.
d.Water
Incoming water from ADWEA is initially stored in large storage tanks and then passed through a chiller.The chilled water is then stored in suitable insulated tanks.
e. Ice
Ice is brought in bags from the ice factory and stored in a purpose built insulated storage room.
8. Quality Control Tests on Raw Materials
Regular tests are carried out on raw materials and on each concrete mix to check compliance with the project specification or the minimum requirement specified by the purchaser.All samples are collected and tested in OCI Laboratory or in an independent laboratory as shown in the testing schedule.The routine tests such as sieve analysis, moisture contents, specific gravity and water absorption etc. are conducted in OCI Laboratory (in-house testing)
and the other tests which cannot be done in OCI Laboratory, will be conducted in an approved independent laboratory (independent testing).
9. Mix Designs and Trial Mixes
a. Each mix design will pass through many stages prior to reaching final approval.The first stage is studying and analyzing the contract specifications in order to determine the particular requirements such as :-
1. Source and characteristics of the concrete raw materials.
2. Characteristics of concrete (Strength, Durability etc.).
3. Minimum and maximum cementitious ratio.
4. Any other special admixtures and or requirements.
b. The second stage is to verify the characteristics of raw materials to be used in the specified mix, in order to fall within the limits of the project specifications or acceptable standards. Some of the tests carried out to determine the properties of the aggregates are as follows :-
1. Sieve analysis.
2. Clay silt and dust content.
3. Flakiness and Elongation indices.
4. Specific Gravity and Water Absorption.
5. Aggregate Impact Value.
6. Sulphate and Chloride content.
7. Any other special tests, if required.
c. The third stage is the calculation of the target mean strength and the material quantities for one cubic meter of concrete which will satisfy the workability requirements and the specified characteristics for each type of job.
d. The fourth stage is to conduct laboratory trials (by the laboratory engineer) on the proposed mix design to determine the actual characteristics of the concrete.The Technical Manager will review the test results and if the results are satisfactory he will approve the mix propor tions. If the results are unsatisfactory, the mix proportions will be adjusted and further trials will be conducted until satisfactory results are obtained.
e. The fifth stage is to conduct a plant trial on the mix
proportions obtained in the laboratory, under full scale site conditions, to ensure that the mix is cohesive, workable, pump able and complies with the respective contract specification.Any fine tuning to the laboratory mix proportions may be done during the plant trial and the mix proportions may be revised.
f. The sixth stage is submitting the final mix design to the consultant/purchaser for their approval. If required further trials will be conducted in their presence and all the required tests will again be repeated until the mix is approved by the concerned authorities.
10. Mix Design Loading to the Plant
Prior to receiving orders from the site, a mix identification number will be allotted to each approved mix and the corresponding proportions will be loaded into the batching plant computer which is controlled by password to prevent alterations.
11. Order Receivable
All orders for concrete will be taken by the dispatcher (either by telephone or by fax) with essential details in order to allow ample delivery time between trucks to meet the contractors program.The dispatcher will also provide
the plant manager with a weekly schedule for the required quantity of concrete to allow the plant manager to procure sufficient raw materials and reserve a sufficient number of agitators and pumps for the pour.
12. Maintenance and Calibration of the Plant
OCI has tow Concrete Batching Plants at one location (Al mafraq).The total production capacity from all plants is about 240 Tones per hour.All batching equipments are properly maintained and measuring devices are regularly calibrated. Scales for all devices are zeroed on a daily basis. Everyday before starting the plant, the plant operator will check the level of hydraulic oils, electrical breakers, cleanliness of the mixer etc. If any discrepancy is found the operator will record it and inform Workshop Manager for appropriate action. Concrete production will start only after getting clearance from the Workshop Manager.The mixer is washed at least twice per day to avoid any contami nation and accumulation of hardened concrete in the mixer.To avoid any breakdown during the time of production,
monthly checking on all equipments and systems for all batching plants is conducted by the maintenance section with the help of the plant operator.
The weighing system of the plant is calibrated according to the attached frequency or after any major repair work is carried out.
13. Batching and delivery
Everyday before starting the production and at least two times during the day, the moisture content of all aggregates will be ascertained and entered into the computer system to automatically maintain the free water to cementitious ratio of the concrete.
Upon receiving order from the client, the dispatcher will send trucks to the batching plant for loading the designated mix.The plant helper will visually inspect the agitator and make sure that there is no wash water inside the drum.
After getting the clearance from the plant helper, the operator will key-in the necessary information into the computer and produce concrete in coordination with the dispatcher.The drum of the agitator will be rotated about 1-2 revolutions per minute during transit and on site except while discharging concrete.
The plant operator is not allowed to produce any type of concrete, unless he has an approved mix design from the Technical Manager. To prevent any cancellation, the dispatcher will verbally confirm each concrete order at least one hour prior to the batching. If OCI cannot supply concrete in time due to any unforeseen reason, then the dispatcher will inform the contractor about the problems encountered in the plant and he will reschedule the delivery program

in coordination with the contractor.
The QC Engineer will always liaison with the dispatcher and plant operator to oversee all batching operations.
The batched concrete will then be sent to the laboratory along with the delivery note containing at least the following the information :-
1 Delivery note number.
2 Date of batching.
3 Mix identification number.
4 Customer details.
5 Time of batching.
6 Concrete grade.
7 Cementitious content.
8 Water to cementitious ratio.
9 Maximum size of aggregates.
10 Target slump.
11 Quantity ordered.
12 Quantity delivered.
13 Truck number.
The plastic concrete in each agitator will be checked by a qualified and experienced technician for consistency, temperature etc. If the plastic concrete is in acceptable condition, it will be delivered to the respective site, if not it will be disposed in a designated area.To check the quality of the hardened concrete, cubes will be cast randomly from each concrete grade before delivering to the site.The quality of the hardened concrete is checked depending on
the requirements of the project specification and according to the frequency indicated on the attached schedule.
14. Introduction of Ice
Ice will be brought in bags from the nominated supplier and stored in the storage room.Whenever necessary the required quantity of crushed ice will be weighted and added to the conveyor belt along with the aggregates (the quantity of ice depends on the temperature requirements of the concrete, ambient temperature etc.). Ice along with other constituents will be fed into the mixer at the batching plant.The weight of water added into the mixer will
be reduced with an equal quantity of ice added into the mixer.All materials including ice will be mixed in the mixer prior to discharging concrete into the agitator.
15. Sampling and testing procedure on site
On site it is the responsibility of the purchaser to collect and test the samples according to the standard procedures. However, if requested by the purchaser, OCI may provide experienced technicians to the site for collecting and testing samples.The sampling and testing procedure on site should be as follows:-
1.0. Common Sampling practice
When a truck arrives on the site, the concrete technician will collect the delivery ticket and check the temperature (if applicable) and slump as follows. Rotate the drum of the truck for about 2 minutes at high speed and discharge the concrete into a clean wheel barrow at slow speed, discard a small quantity (about 1 wheel barrow) before collecting the sample. Cover the sample with a polythene sheet and transport it to the testing location immediately (the quantity of the sample shall be at least 2 times the amount required for the tests).
2.0.Temperature measurement
Collect samples as describe above. Insert the thermometer into the concrete near the center of the wheel barrow and gently press the surface of the concrete all around the stem.After two minutes, record the temperature to the nearest 1ºC and remove the thermometer. Complete the test within five minutes after obtaining the sample.
3.0. Slump test
Collect the samples as described above and remix the sample preferably with a square mouthed shovel. Dampen
the base plate and cone and place the base plate on a sturdy level surface. Hold the cone firmly against the base plate

by standing on the foot pieces. Fill the cone in three layers (each layer should be approximately one-third of the height of the cone after tamping).Tamp each layer with a standard tamping rod by uniformly distributing 25 strokes over the cross section of each layer.
For the bottom layers, incline the rod slightly and make approximately half of the strokes near the perimeter and then progress with vertical strokes spirally towards the center.While tamping the bottom layer, the tamping rod should just touch the base plate. Rod the second and top layer through its entire depth, so that the strokes just penetrate into the previously placed layer.When tamping the top layer, heap the concrete above the cone before tamping is started and keep an excess of concrete above the cone at all times during tamping.After the top layer has been tamped, strike off the surface of the concrete with the tamping rod by means of a combined sawing and rolling motion.After cleaning the spilled concrete from the base plate, raise the slump cone in 5 to 10 seconds in a careful vertical motion with a steady upward lift. Immediately after removing the cone, place it adjacent to the slumped concrete. Lay the steel rod across the cone and measure the slump by determining the difference between the height of the cone and the highest point of the slumped specimen. Report the result to the nearest 5 mm. If
shear slump is obtained take another sample from the truck and repeat the test.The slump test should be completed within 150 seconds without interruption from the start of the filling to the removal of the mould.
4.0. Making test cubes and initial curing
Collect the concrete as described above. Place the previously assembled moulds on a rigid horizontal surface. Fill the mould with concrete in three relatively equal layers. Compact each layer with at least 35 strokes with a standard compacting bar. Distribute strokes evenly over the entire cross section of the mould and ensure that the compacting bar does not penetrate significantly into the previous layer nor forcibly strike the bottom of the mould when compacting the first layer.After the top layer has been tamped smooth, strike it level with a trowel and wipe clean the outside of the mould.After the concrete in the mould has hardened enough, wrap it with wet hessian and polythene sheet.The following day check whether the concrete has hardened enough for removing it from the
cube moulds (the concrete should be in the mould between 16 to 24 hours). If the concrete has not hardened enough, delay the de-moulding of the cubes for another 24 hours or as required.
16. Slump Adjustment on site
If the slump of the concrete in the agitator (Concrete Mixer) is low, a suitable super plasticizer may be added to the concrete on the site with the permission of the purchaser/consultant. If approved by the concerned authority the plasticizer shall be added as follows:-
1.0 The drum of the truck shall be reversed slightly and super plasticizer is added directly on to the concrete.After adding super plasticizer the drum shall be rotated for about 3 minutes at a high speed in the normal direction. Samples should be collected again and if the test results are acceptable the concrete shall be poured in the final location. If the slump of the concrete is high, the drum should be rotated at a high speed for about 10 minutes or to a reasonable time to achieve the correct slump. Samples should be collected again and concrete shall be poured in the final location, if the results are within the acceptable range.
17. Concrete Placement
OCI has a fleet of concrete pumps and agitators (concrete mixers) and has supplied concrete to bridges, towers etc. including raft foundations as large as 3500 m3 in 23 hours.
OCI will ensure sufficient manpower, equipment and coordination between site and plant staff to maintain uninterrupted supply of concrete. However, for night time and early morning concreting, it is the responsibility of the main contractor to provide proper access and adequate lighting at all work areas, whenever required. Concrete pouring may be achieved by pump or direct delivery from the agitator.