NEM - Center of Materials Testing

Providing physical  and mechanical testing services on construction materials  including concrete, cement, aggregates, steel reinforcement,  prestressed steel reinforcement, structural steel, geosynthetics,  gullies, manhole covers, aluminium, coatings and many  others. Provide outdoor environmental monitoring, such as  noise, air quality (dust), etc. 

Quality Control of Concrete

Concrete is the main material for civil engineering. Selecting  concrete with appropriate workability, mechanical properties and  durability could be the foundation for assuring the engineering  quality. The method of quality control for concrete in Macao is  including: certifi cation of concrete for concrete batching plant and  quality supervision for specifi c concrete of engineering project.   

• Certification of Concrete for Commercial Concrete Batching Plant

Certifi cation of concrete is jointly participated by DMC and DQN.  Factories, which have obtained certifi cation, comply with the quality  management system and technical requirements specified in the  Rules of Scheme for Certifi cation. The purpose of certifi cation is to  verify whether factories have the ability to manufacture products that  comply with the requirements of “Macao Standard for Concrete”,  “Approval & Reception Procedure for Ready Mixed Concrete”  and “Rules of Scheme for Certification”. Now, the certified  manufacturers is including Macao local concrete plants, concrete  batching plants for Hong Kong-Zhuhai-Macao Bridge project and  light rail projects precast segment. 

• Quality Supervision for Specific Concrete of Engineering Project 

The quality of specifi c concrete which did not be certifi ed should be  supervised in accordance with “Approval & Reception Procedure for  Ready Mixed Concrete” and requirements of project. 

Every engineering project should implement trail mix test for the  specifi c concrete mix design and testing for raw materials of concrete  before using it. During the construction, it is also necessary to  monitor mechanical properties, durability and hazardous substances  of the concrete through regular sampling and testing.  

-Trial Mix Verifi cation of Concrete

After the approval of the mix design of concrete, it is required to  implement three trail mixes in three dates and take samples within  the batch to prove the concrete mixture and harden concrete are all  meet the relative requirements for the quality assurance purpose. In  addition, it is necessary to verify the applicability of the production  process and facilities. 

Despite of the verifi cation of the concrete strength, the permeability  and resistance of chloride ions should be also verifi ed according to  the engineering requirement.  

-Quality Control of Constitute Materials of Concrete

For ensuring the quality of concrete, the fi rst matter is importance  to control the quality of component materials of concrete, such as  cement and other cementitious materials, aggregate, admixtures and  mixing water.  

Cement and Other Cementitious Materials

The performance of cement and other cementitious materials should  be tested according to Macao Standard for Cement and Macao  Standard for Concrete. 

Aggregate

According to Macao Standard of Concrete for testing.

Mixing Water 

Mixing water from the public supply can be used without any need for testing.

Admixture

According to Macao Standard of Concrete for testing.

-Hardened concrete strength test

Normally, the main consideration of the mix design is compressive  strength which is one of the characteristics to sustain the construction  safety and applicability. According to the Macao concrete standard,  it is required to take cubic sample of concrete for each casting for  verifying the compressive strength.  

The coring method is using to take sample for evaluation of in situ  concrete strength or the acceptance for the compressive strength of  PHC pile and concrete kerb. 

• Durability of concrete- impermeability

Waterproof concrete is used for preventing the leakage of the  rooftop, water tank and basement structure. Hardened concrete  which is under water pressure could be tested for the waterproof  ability by the impermeability test.  

• Durability of concrete-Resistance of the penetration chlorideion

The corrosion of the steel reinforcing bar is the major factor that  shorten the service life of concrete structure. The free chloride ion is  strongly associated with the corrosion speed of steel reinforcing bar.  Macao is a place surrounded by sea, so the permeability of chloride  could be used for evaluating the durability of reinforced concrete  structure when it is directly expose in the air and sea water.  

• Concrete workability-Creep Strain Test

Creep strain, the deformation level of concrete keep increasing  by time to time during a long period loading of concrete. Creep  strain could cause the enlargement of deformation (deflection) for  the structure (component). In addition, it could affect the normal  function of the structure and cause the loss of the pre-stressing force  of the pre-stressed structure. 

• Hazardous substances control – Chloride ion content

When the raw material has chosen improperly, could lead to  concrete contain high level of chloride ion. High chloride ions will  destroy the passivation layer of the rebar surface, which can cause  damages to the rebar’s seal protection. Long-term effects will lead  to reinforcement corrosion and concrete cover broken. Hence the  chloride ion content is needed for concrete.  

Quality Assurance of precast segments

Precast segments are the most important structural element of viaduct  for Macao LRT project. It should not only bear the stress from the  upper structure but also meet the requirements of appearance quality,  and the service life of structure for Macao LRT project requirement  is required to achieve 100 years. Therefore, the best quality of  inherent performance, appearance and durability are required for  precast segments. The precast segments are mainly prefabricated  in professional manufacturer or the precast yard which is specially  established for Macao LRT project. 

 For ensuring the quality of precast segments, DMC and CA jointly  perform the quality control for production process, to ensure that  the all precast segments which will be delivered for establishing in  Macao shall strictly meet the quality standards. 

• Expressly permitted production basic conditions

The all concrete batching plant of precast yard must be certifi ed  according to Ready-mixed Concrete Certifi cation of Macao, and  ensuring that the quality of constitute materials and concrete  comply with the requirement of Macao code. 

• Strictly verify the application of raw materials

All the raw materials to be used shall be tested and fulfill the  specification. The aggregate for concrete must be separated  from others and stored independently, to achieve the target as  “specifi ed material to be specifi cally used”. The consumption for  raw materials will be regularly traced to avoid the unqualified  materials such as marine sand is to be used in the project. 

• Strictly supervise the quality with detection method during construction 

The raw materials, concrete and products shall be took samples  for test according to the Rule of Concrete Certifi cation, project  requirements and the relevant Macao code not only by DMC but  also by the approved independent 3rd party Lab. The quality for  precast segments shall be comprehensive, timely and effective  controlled with the double testing supervision mechanism. 

• Strictly control the quality of production process

For ensuring the quality of precast segments, the reinforcing cage,  the formwork, the topographic survey and the fresh concrete must  be performed acceptance procedures, irregular spot checks will  be performed to monitor the quality by DMC. Especially pointed  out that the temperature of concrete pouring into formwork is  required not more than 30 o C, this requirement is stricter than the  relevant Macao code, it could prevent temperature crack from  occurring to effect on the durability of the structure. 

• Specifi ed detection method for 100 years durable concrete

Test methods and acceptance criteria for durability performance  of concrete are be defined according to the exposed external  environment condition in Macao and 100 years service life of the  structure. It can be quantitative evaluation for concrete durability  with the chloride ion migration index or electric flux, and  facilitate to uniformly supervise the quality of the project. 

• Perform “First Mechanism”— strictly control the appearance quality

“First Mechanism” mean that the first precast segment must  be inspected and accepted by supervisor and LECM during  production in accordance with the relevant requirements.  The purpose is that according to the project requirements of  appearance quality and the relevant code, the fi rst precast segment  is inspected for appearance, meanwhile the acceptance criteria  and the allowed treatment scope for appearance will be defi ned.  At last the fi rst qualifi ed precast segment should be as a model of  appearance acceptance when mass production.  

• Perform product test — strictly control the quality of segments before delivery

A batch of precast segments is every accumulated 50, took sample  from finished segments to perform rebound test, chloride ion  content test and cover thickness test. By passing the product test,  the batch of precast segments can be allowed to deliver to Macao  site for establishing, ensuring to comply with the requirements of  in-situ quality. 

Quality Control of Steel Materials

Quality Control of Steel Materials is daily major testing for DMC.  The purpose of quality control is to verify products comply with  NORMA DE AÇOS PARA ARMADURAS ORDINÁRIAS  and REGULAMENTO DE ESTRUTURAS DE AÇO PARA  EDIFÍCIOS.  

• Steel bar test

• Wires-strand for prestressing

• Material for Steelwork

Quality Control of Metallic Coating and Painting

For ensuring the durability of structures, coating and painting on  the surface of metal and concrete generally shall be inspected in  accordance with the requirements of the relevant code, in order to  achieve the purpose of quality control for coating and painting. 

• Coating Thickness test

• Adhesion force test for coating

• Uniformity of Galvanizing Coating

Quality Control of Geosynthetics

Geosynthetics used in civil engineering, physical properties and  mechanical properties should be tested in accordance with the  requirements of the relevant code, in order to achieve the purpose of  quality control for the materials. 

Quality Control of Manhole Top and Gully Top

Manhole top and gully top used in road or sidewalk, dimension and  mechanical properties should be inspected in accordance with the  requirements of the relevant code, in order to achieve the purpose of  quality control for the materials. 

Test of Rock Core

Test of rock — test results are one the basic reference for pile foundation design

Environmental Monitoring

As everyone is concerning about the environment nowadays,  however people can only describe the level of environmental  pollution with their own sensation. For this reason, there have  to be one independent and professional crew for conducting  environmental monitoring, which will statistically refl ect the level of  pollution. Therefore, DMC has started the project of environmental  monitoring since May 2013, which the environmental monitoring  includes both Air quality/Dust (Total Suspended Particulates – TSP)  level and Environmental Noise level measurement. It is believe that  the environmental monitoring will be widely implemented in other  constructions in the future. 

Environmental noise level measurement

Acoustic calibration for sound level meter prior to and following each noise measurement

AAR Research Project

Due to the coastal area that the construction situated in Macao, the  durability of concrete could be a critical issue of the construction  engineering. LECM have implemented the research for the river  sand material used in different Macao concrete manufacturers since  2012. The selected test methods of AAR are mortar-bar and concrete  prism methods. Besides, LECM have devoted itself to studying the  feasible approaches to alleviate the AAR reactivity of river sand as  well. The following are the photo examples of this job. 

Certification of Cement

Certification of cement product and factory is responsible and  conducted by both DMC and DQN. The purpose of this certifi cation  is to provide quality assurance for the cement product used in Macao.  The criterion of the certification are <Macao Cement Standard>  and<LECM’s Rule of Scheme for Certification of Cement>. The  certification can be divided into verification of cement factory  quality system, initial type test, analysis of factory auto-control test  result, verifi cation of conformity cement-regular surveillance, regular  sampling of cement product and issue of certifi cation. The following  are the photo examples of this job. 

Certification of PHC-pile

Certification of PHC-pile is jointly participated by DMC and DQN.  Factories, which have obtained certifi cation, comply with the quality  management system and technical requirements specified in the  Rules of Scheme for Certifi cation. The purpose of certifi cation is to  verify whether factories have the ability to manufacture products that  comply with Macao Concrete Standard and the Reception Procedure  of PHC-pile. 

Certification of Concrete Pipe

Certification of concrete pipe is jointly participated by DMC and  DQN. Factories, which have obtained certifi cation, comply with the  quality management system and technical requirements specifi ed in  the Rules of Scheme for Certifi cation. The purpose of certifi cation is  to verify whether factories have the ability to manufacture products  that comply with specifi ed standards. 

Database for Test Data

To increase efficiency in the production report, to improve the  accuracy and confidentiality, DMC has established a database test  data for linking it with testing operation, test report preparation  and data processing. The main process is the sample administrator  receiving samples, the technician entering sample data, the  technicians operating test, then test data is automatically imported  into the database and test report is being prepared. During this  process, the personnel will be controlled by access rights. Currently,  the data base is being used for handling tests of concrete cubes, concrete prisms, steel bar, etc. The application of this data base will  subsequently be extended to other tests, such as steel bolt test, steel  article test, coating testing, geotextile test, drain cover test, concrete  trial mix verifi cation.