NSP - Center of Soil and Pavements

Structures of Center of Soil and Pavement

Center of Soil and Pavement (NSP) is a service unit under  Geotechnical Department (DG), we offer testing analysis of soils  and pavement material, inspection of (airport) pavement and  underground utilities for the customer of Macau and a growing  international client base, to provide them an accurate and timely  reports to meet the unique requirement of civil engineering,  geotechnical engineering and (airport) pavement engineering 

Soil Classifi cation

Soil classifi cation is fundamentally important to any geotechnical  engineer. It provides a common language to concisely express  the general characteristics of soils, which are infinitely varied,  without detailed descriptions. Currently, two more elaborate  classification systems are commonly used by the engineers. They  are the American Association of State Highway and Transportation  Officials (AASHTO) classification system and the Unified Soil  Classification (Unified system) System. Both systems take into  consideration the results of particle size analysis, Atterberg limits  etc. LECM provides particle size analysis, moisture content,  Atterberg Limit, void ratio, specifi c gravity of soil etc. 

Quality of Soil Engineering

The quality of civil engineering construction such as foundation,  retaining walls, dams, (airport) pavement and improvement of  backfilling etc. afterward must be assessed by verification test,  to know such as the density, settlement characteristic, bearing  capacity etc. LECM has participate those reception tests for  Macau government, and provide soil compaction test, soil relative  density test, fi eld density test, interior/fi eld CBR test, interior soil  permeability test to the public etc. In future, more advanced, quickly  and portable types of test will be introduced in evaluation of soil  compaction / soil bearing capacity depending on their feasibility and  applicability in Macau Civil Construction. Such as non-nuclear fi eld  density gauge, dynamic cone penetrometer test to evaluate the CBR  of subgrade soil portable, quickly and non-destructively 

Soil Mechanic

Geotechnical engineering was necessary to investigate the physical  properties of different types of soils, just as it was necessary in  structural engineering to investigate the properties of steel and  concrete, etc. However, unlike steel and concrete, practical problems  involving soils may require the consideration of a variety of soil  properties, such as the permeability, the resistance against shear, and  the stress-deformation relationships, etc. LECM has involved those  kinds of test in site investigation for Macau government project.  In field and laboratory test, LECM provides direct shear tests,  laboratory / fi eld vane shear test, unconfi ned compressive strength  test, soil permeability test, etc. Besides that, LECM provides the  advanced test such as, triaxial compressive strength tests, 1-D  consolidation test etc. In future, more advanced and automatic data  logging system will be involved in testing the physical properties of  soil. 

Bearing Capacity of Soil

In foundation engineering, the soil must be capable of carrying the  loads from any engineered structure placed upon it without a shear  failure and with the resulting settlements being tolerable for that  structure. It is necessary to investigate both base shear resistance  and settlements from any structure. Beside soil laboratory test to  evaluate the mechanical properties of soil as described in previous section, it is obviously that the most reliable method for obtaining  the ultimate bearing capacity at a site is to perform a fi eld load test.  This would directly give a bearing capacity if the load test is on a  full-size footing. LECM provides fi eld plate load test, lightweight  dynamic penetrometer test to investigate the bearing capacity of  shallow foundations, airport / road pavement etc. In future, dynamic  plate load test, automatic data logging would be introduced to  monitor the long term stress-deformation relationships of soil  depending on the depending on their feasibility and applicability. 

Quality of Bituminous Material

The quality of bituminous material is important to producing  qualified bituminous concrete mixture for (airport) pavement.  Using the correct grade of bitumen insures that the pavement  will perform as expected under the conditions encountered in the  field. Therefore, other than the grading of mixture, the grade of  bitumen characterizes the performance quantitatively, in order to  comply with the requirement of climate, traffic and construction serves etc. to fulfill the performance and durability in pavement  construction. Traditionally, penetration, softening point, ductility,  fl ash and fi re point of bitumen are the major parameters to describe  the characteristic of bituminous material. LECM provides all of  the services to the Macau government. In coming future, with the  application of different design methodology of bituminous concrete  mixture with application of different grade of bitumen, further  comprehensive and advanced grading test would be introduced, such  as penetration index, viscosity to optimize pavement construction. 

Quality of Bituminous Mixture

Quality control of bituminous concrete mixture is to provide the  traveling public with an adequate and economical pavement on  which vehicles can move easily and safety from point to point. The control process of hot-mix bituminous concrete mixture becomes  important to ensure their quality. For continuously improvement  of bituminous concrete pavement of Macau, LECM always works  with Macau government in quality control of bituminous concrete  mixture with field sampling, interior and field reception test to  study the both the mechanical and fi eld performance of mixture. To  qualify the high-temperature performance of bituminous concrete  mixture, rutting susceptibility of bituminous concrete mixtures  is introduced and would be serving to the public soon. In future,  more test items would be introduced in the Macau such that the  more comprehensive performance of bituminous mixture can be  evaluated, such as indirect tension test for resilient modulus of  bituminous mixtures, resistance of compacted asphalt mixtures  to moisture-induced damage, quick non-destructive non-nuclear  density gauge for bituminous mixture in fi eld. 

Rutting Susceptibility of Bituminous concrete mixtures

Airport Pavement

Pavement Classifi cation Index

The PCI is a numerical indicator that rates the surface condition of the airport pavement. The PCI provides a measure of the present  condition of the pavement based on the distress observed on the  surface of the pavement which also indicates the structural integrity  and surface operational condition (localized roughness and safety).  Continuous monitoring of the PCI is used to establish the rate of  pavement deterioration, which permits early identifi cation of major  rehabilitation needs. The PCI provides feedback on pavement  performance for validation or improvement of current pavement  design and maintenance procedures.  

Underground Utility Survey

In Macau, spaces are limited in nature for underground facility  construction such as electricity distribution, natural gas, water  mains, storm drains, wastewater pipes, cable television, fi ber optics  etc., so that the qualifi ed construction works are always challenges  in either of planning and construction. Nevertheless, the destruction  of underground facilities is happened in sometime who affect  the public, safety of the workers, even in stability of existing’s  or neighborhoods. Therefore, locating specific pipes or cables in  large underground networks is becoming increasingly client base.  Geophysical surveying techniques become the first priority to  provide a toolbox of rapid, discrete and cost-effective methods for  locating and identifying subsurface features. LECM has involved  the work of geophysical surveying by GPR since 2008 with the  Macau government. It provides a non-intrusive and non-destructive  method of surveying the subsurface and concrete imaging. Not only  is ground radar a highly cost effective non-disruptive technique, it  is also a rapid means of obtaining subsurface information, such as  concrete imaging and re-bar mapping, geo-profiling, identifying  the voids, etc. In coming future, cable and pipe locator would be  introduced to locate specific pipes and cables in even large and  complicate underground networks more quickly and accurately.  

Research of Science and Technology Development Fund of Macau

The research mainly through theoretical calculations (mechanical  model of finite element analysis), indoor model test (Automatic  Asphalt Pavement Analyzer, AAPA to evaluate the fatigue  performance of bituminous concrete mixture, Multi Rounds  Rutting Tester, RLWT to investigate the behavior of Marshall  specimens / pavement core specimens on high temperature  conditions (60 o С), Multi Rounds Loaded Rotating Wheel Rut  instrument, RLWT, Immersion Marshall test, Freeze-thaw Splitting  test, Low Temperature Bending test) and demonstration projects,  to deeply study of the engineering technology to minimize the  reflective cracking overlay. Furthermore, this research is to  improve bituminous concrete overlay fatigue performance (crack  resistance) and high resistance to deformation against the climate,  environment and traffi c characteristics of Macau, and to balance the  contradiction between other properties, and to optimize the overlay  structures and materials. Through this research analysis, the overlay  technology under the formation of the old cement concrete was  completed. In July 2012, the application of these fi ndings is applied  in demonstration projects in Macau, so far, inspection show that the  pavement performance is excellent, early disease phenomenon was  not found.