Elements and Performance Criteria

Context
This competency unit includes -
operation of concrete mixers
measuring of ingredients and additives
interpretation of formulae/mixing specifications
matching concrete to specification
finishing concrete to match samples
spraying concrete to make exposed aggregate
applying sealers and curing compounds to wet concrete.
Surface finishes applied to green concrete as cast may include, but are not limited to -
fine wood float
rough wood float
hand steel float
broomed
helicopter steel float
raked finish.
These surface finishes may be applied before or after veneering.
The surface finish after veneering may then also require further finish after curing.
Typical problems include -
off colour batches
bleeding between concrete mixes
consistency of veneer and cover
consistency of spray pattern
adequacy and consistency of surface finish
wet patching of surface finish.
This competency includes the operation of all ancillary equipment and the operation of plant using PLCs where appropriate.
All operations are performed in accordance with standard procedures and work instructions.

OHS
All operations are subject to stringent OHS requirements and these must not be compromised at any time. Where there is an apparent conflict between performance criteria and OHS requirements, the OHS requirements take precedence.

Assessment context and methods
Competence in this unit may be assessed by observation over time on an operating plant. Where this is done, the timeframe must allow for adequate assessment of operation under all normal and a range of abnormal conditions. Where this is not practical, additional assessment techniques must be used.
Competence may also be assessed by use of a suitable simulation and/or a range of case studies/scenarios. A combination of these techniques should be used to ensure the competency is adequately assessed.
In all cases it is expected that the practical assessment will be supported by targeted questioning to assess the underpinning knowledge. Questioning will be undertaken in such a manner as is appropriate to the language and literacy levels of the operator and reflecting the requirements of the competency.
Competence is not required in all possible finishing methods, but is required in at least two different finishing methods.

Resource implications
Resources required include suitable access to an operating plant or equipment which allows for appropriate and realistic simulation. A bank of case studies/scenarios will also be required where these form part of the assessment method. Questioning may take place either in the workplace, or in an adjacent, quiet facility such as an office or lunch room. No other special resources are required.

Essential knowledge and enterprise requirements
Knowledge and understanding of concrete and of the veneering and finishing process sufficient to recognise problems and take appropriate action.
Knowledge of the enterprise's standard procedures and work instructions and relevant regulatory requirements along with the ability to implement them within appropriate time constraints and in a manner relevant to the mixing and application of coloured cement and special aggregates.

Competence includes the ability to:


apply and/or describe:

principles of concrete mixing (if mixed by operator)
principles of veneer adhesion
principles of concrete finishing

distinguish between causes of faults such as:

material
mixing
application
finishing
as is relevant to the practical operation of the equipment/process/system.

Critical aspects
It is essential that the process be understood and that the importance of critical material properties, mixing variables and surface finishing techniques is known. Competence must be demonstrated in the ability to recognise and analyse potential situations requiring action and then in implementing appropriate corrective action.

Consistent performance should be demonstrated. In particular look to see that:

surface finish matches specification and is consistent
coverage is adequate and consistent
sealer coverage is adequate and consistent.
Competence must be demonstrated in the operation of all ancillary equipment to the level required for this competency unit.

Communicating ideas and information
(1)

Collecting analysing and organising information
(1)

Planning and organising activities
(1)

Working with others and in teams
(1)

Using mathematical ideas and techniques
(1)

Solving problems
(1)

Using technology
(1)