UNIT CODE

DCMSST612

UNIT TITLE

Use soil stabilisation techniques

APPLICATION

This unit describes the performance outcomes, skills and knowledge required in soil stabilisation techniques to improve engineering characteristics that may otherwise disqualify a particular site for specific projects.

The unit of competency is applied by technicians involved with pavement design and other civil projects and who use techniques to assess the application of different soil stabilisation methods.

No licensing, legislative, regulatory or certification requirements apply to this unit at the time of publication.

ELEMENT

Elements describe the essential outcomes.

PERFORMANCE CRITERIA

Performance criteria describe the performance needed to demonstrate achievement of the element.

1.    Explain the principles of soil stabilisation

1.1.      Explain how soil properties can be improved with soil stabilisation methods:

1.2.      Explain the considerations for stabilisation when recycling materials from pavements

1.3.      Summarise the benefits of soil stabilisation

1.4       Evaluate soil stabilisation techniques

1.5       Justify the importance of soil stabilisation for given site characteristics

2.    Differentiate techniques and materials applied for soil stabilisation

2.1.      Identify and outline soil binders and their applications

2.2.      Explain mechanisms of stabilisation and associated chemical reactions

2.3.      Compare the advantages and disadvantages of calciumbased additives and/or binders.

2.4.      Summarise environmental risks and benefits with soil stabilisation

2.5.      Explain potential issues of sulfate soils that are stabilised with lime or cement.

FOUNDATION SKILLS

Foundation skills essential to performance are explicit in the performance criteria of this unit of competency.

UNIT MAPPING INFORMATION

No equivalent unit.

TITLE

Assessment requirements for DCMSST612 Use soil stabilisation techniques

PERFORMANCE EVIDENCE

To achieve competency in this unit a person must demonstrate knowledge of:

• Explain how at least four of the following soil properties can be improved with soil stabilisation methods:
  • Increase in dry unit weight
  • Volume changes
  • Bearing capacity
  • Soil in situ performance
  • Durability
  • Reduce entrance cracking in clay
• Provide at least one example to illustrate the use of stabilisation to address an issue with soil properties
• Summarise the benefits of soil stabilisation for these specific soils:
  • Cohesive materials
  • Wet soils
• Select stabilisation techniques for a given sample site for based on at least three of the following site characteristics:
  • Construction conditions and loading
  • Geographic site conditions
  • Sub-grade and existing pavement material
  • Size of area to be treated
  • Binder content and CBR strength
• Identify at least 3 examples to illustrate practical applications of soil stabilisation techniques
• Identify and outline at least four of the following different types of binders and their applications
  • Quicklime
  • Cement
  • Fly ash
  • Fibres
  • Cementitious pozzolans
  • Bitumen
  • Chemical and synthetic polymers
• Explain the at least two of the following mechanisms of stabilisation and chemical reactions involved in each:
  • Cation exchange
  • Flocculation and agglomeration
  • Pozzolanic reaction
  • Carbonate cementation

Note: If a specific volume or frequency is not stated, then evidence must be provided at least once for each criterion

KNOWLEDGE EVIDENCE

To achieve competency in this unit, a person must demonstrate knowledge of key principles of stabilisation, including:

• How stabilisation methods are performed
• Soil properties and their consideration for effective stabilisation
• Site characteristics that influence selection of stabilisation methods
• Binders and their chemical properties when used in stabilisation
• Justification for selection of soil stabilisation methods for specific site conditions
• Environmental costs and benefits of stabilisation

ASSESSMENT CONDITIONS

Assessment conditions:

All assessment must be completed in accordance with work health and safety standards.

When assessments are conducted remotely, invigilation software must be used to ensure authenticity of work completed.

Model answers or marking guides must be provided for all assessments to ensure reliability of assessment judgements when marking is undertaken by different assessors.

The candidate must have access to all tools, equipment, materials and documentation required.

Assessor Requirements:

Assessors must satisfy the assessor requirements in the standards for registered training organisation (RTOs) current at the time of assessment.

Assessors must also hold a tertiary qualification in engineering or related field.

Assessors must have worked for at least 3 years in industry where they have applied the skills and knowledge covered in this unit of competency.

The RTO must also ensure that trainers and assessors keep their industry knowledge up to date through ongoing professional development.

The RTO must take appropriate steps, as an ongoing procedure, to verify information about trainer and assessor’s qualifications, vocational competencies and current industry skills