Quality Assurance

Raw Materials Quality Control

Cement - Ordinary Portland Cement (Type-1) is mainly used in concrete production. Each delivery of cement is subjected to regular mortar testing at internal laboratory to ensure compliance with specifications. And, chemical characteristics are documented in the manufacturer’s test certificate and are available for verification. 

Aggregates - Physical properties of each incoming batch of aggregates are tested at the internal laboratory following standard test methods and procedures, at an external third-party laboratory at specified intervals. Coarse aggregates with nominal maximum size of 9.5mm and 19 mm are commonly used for general concrete mix designs, and nominal maximum size of 25mm may be applied where required by project specifications. 

Water - Water used for concrete production shall conform to the quality requirements specified in relevant standards. Water analysis tests are performed by an external laboratory at intervals of six months. Water supply is consistently maintained in a hygienic state and ensured to be free from objectionable particular matter, as well as harmful concentrations of sewage, oil, acids, and any other deleterious contaminants. 

Cool Water - Cool Water may be supplied to achieve the required concrete temperature in accordance with the special requirements of construction projects. 

Admixture   - Superplasticizer 

​ ​        ​Retarder 

​ ​        ​Slump Retention Admixture 

​ ​        ​Air-Entrained Admixture 

​ ​       ​Water-Proofing Admixture 

​ ​       ​High Range Water Reducing Admixture (PCE Base) 

The primary suppliers of admixture are SIKA, Aung Pyi Tan and BASF. Quality Assurance Certificates for each batch are obtained from admixture suppliers and as part of internal quality control procedures, include measuring Specific Gravity (SG) tests on all incoming admixtures.

Laboratory Testing and Verification

Testing of Fresh Concrete 

- Slump Test / Workability Test 

- Unit Weight Test 

- Air Content Test by Pressure 

- Temperature Test 

- Setting Time Test 

- Concrete specimens sampling, making and curing 

Testing of Hardened Concrete - To ensure effective quality control, in house concrete specimens are subjected to compressive strength testing at specified curing ages -3days, 7days and 28days or at additional ages required by project specification. 

Concrete Acceptance Criteria (ACI 318) - Every arithmetic average of any three consecutive compressive strength tests shall be equal or exceed specified compressive strength F’c. No individual strength test shall fall below specified compressive strength F’c 3.5 MPa or the equivalent reduction permitted by ACI 318.

Mix Design and Documentation 

Perform laboratory trial mixes for each proposed mix. Secure approval of the concrete mix design prior to production. Approve the mix based on compressive strength, slump, durability and workability. Record and maintain complete documentation for all concrete grades in accordance with project requirements.

Calibration

All batching load cells and testing equipments shall undergo regular calibration at specified intervals, performed by external laboratories or in-house laboratories as applicable.