NATIONAL CERTIFICATE (VOCATIONAL) NQF LEVEL

Transcription

1 MARKING GUIDELINES NATIONAL CERTIFICATE (VOCATIONAL) NQF LEVEL 3 NOVEMBER 2009 S This marking guideline consists of 7 pages.

2 (MARKING GUIDELINES) -2- NC420(E)(N27)V QUESTION 1 APPLICATION OF SABS/SANS SPECIFICATION 1.1 The wall must be placed in the centre of the foundation. The supporting soil of the foundation must not be made of shrinkable clay or a collapsible material. A foundation must be constructed of concrete with a compressive strength of no less than 10MPa at 28 days, or be mixed in proportions by volume 1:4:5 one part cement, four parts sand and five parts course aggregate. Any continuous strip foundation must have a minimum thickness of 200mm. Where any strip foundation has more than one level, the higher portion must extend over the lower portion for a distance at least equal to the thickness of the foundation. where any concrete floor slab is thickened to form a foundation the thickness, including that of the floor slab, must not be less than that required for a continuous strip foundation. and the width of the thickened portion below the floor slab must not be less than that required for a continuous strip foundation. The width of any continuous strip foundations must not be less than 600 mm for a load bearing or free standing masonry wall or 400 mm for a nonload bearing internal masonry wall. ANY FIVE (5) 1.2 Agreement certificate confirms the fitness-for-purpose of a non-standard product, material or component issued by the Board of Agreement of South Africa. (2) 1.3 The reinforcement in each member. The various grades of concrete to be used. The type of reinforcement or pre-stressing tendon. The amount of concrete cover to be provided to the reinforcement. The details of all joints between members. The details of anchorage of pre-stressing steel. ANY FIVE (5) 1.4 Standards are guidelines set out by the SABS/SANS to make sure that quality product and services are produced safely. Specifications are a set of instruments published by the SABS that make sure that a product or service is safe to use and that it does what it is supposed to. Also it is the regulations of the codes as well as the deemed to satisfy rules which must be applied. In South Africa Standards enhance competitiveness and provide the basis for consumer protection, health and safety (4)

3 (MARKING GUIDELINES) -3- NC420(E)(N27)V 1.5 Purpose to provide a continuous access on a specific gradient from one level to the next. Use by motor vehicles must have a gradient of not more than 1:25 within a distance of 5m from any street boundary crossed by the ramp or drive way. Ramp or drive way used by pedestrians must have a gradient of not more than 1:8 (2) 1.6 A parapet is a low protective wall along the edge of a structure such as a balcony to prevent a person from falling of it. (2) AO Access opening B Bath BT Bidet CI Cast iron CE Cleaning eye 1.8 Provides local authority and clients a reference to know what standard of work they can expect. Products, methods and services are more suitable for their use. Less raw materials is wasted. Fewer sub-standard products are produced. Consumer do not use unsafe products. Trading with other countries may improve as the countries have more confidence in South African products. Less time is wasted as a result of faulty products and bad service. ANY THREE (3) 1.9 A person who is qualified by virtue of his/her experience and training to make a determination regarding the performance of a building or part thereof in relation to a functional regulation. (2) [30] QUESTION 2: APPLY FINISHING MATERIALS TO CONCRETE CEILLINGS/ SOFFITS. 2.1 Epoxy paint, P VA or any other suitable paint 2.2 (Rolling) starts painting in one corner room and paints the edges of the ceiling, working towards the middle. Paints the ceiling in bands across the width of the room. When applying the second coat, paint the bands in the opposite direction. (Spraying) you can either use an airless sprayer or an air compression sprayer. The airless sprayer is easier to control and better to use when painting a large surface Make sure that you cover all the surface that you do not want sprayed with paint, and wear the right protective equipment for the job: a hat, goggles, mask and overalls are all necessary. ANY THREE (3)

4 (MARKING GUIDELINES) -4- NC420(E)(N27)V 2.3 Area of kitchen = 6m x4m = 24m 2 /0,5M 2 = 48 boxes + 5% =50.4 boxes or = 50½ boxes (3) 2.4 Erect the scaffold platform in order to reach the ceiling. The scaffold must cover the area you need to No scaffolding must be left unsafe. The framework must be of one type of material. Work areas must be safe. Scaffolding may not be over loaded Safety shields, glasses, boots and belts, must be worn. Scaffolding must be erected by a specially trained person. Make sure the scaffold standards are properly secured. Ensure it is securely and effectively braced to ensure stability in all directions ANY SIX (½ 2) (3) [10] QUESTION 3: FIXING REINFORCING STEEL 3.1 Bending schedule is a list of all reinforcements needed for a structure showing the bar mark, cutting length, number of bars needed and different sizes and shapes 3.2 Plain round mild steel High yield tensile steel (2) 3.3 (5) (5)

5 (MARKING GUIDELINES) -5- NC420(E)(N27)V 3.4 Must have good tensile strength to withstand the stress to which the concrete will be subjected. Must be a material that can be bent to any required shape The surface of the reinforcement must be able to bond with the concrete. The reinforcement materials must be clean and free of rust. There must be no oil or grease on the reinforcement materials. (5) 3.5 Reinforcement must be accurately fixed. Bars intended to be in contact at passing points must be securely wired together at all such points with 16 to 18 gauge annealed binding wire. If butt jointing of reinforced bars by electric arc welding is needed, then an engineer must approve this. The welding must be done by a skilled welder. In order to obtain good adhesion between concrete and the steel bars, the bars must be overlapped where they join by about 40 times their diameter. The reinforcement bars should be tied together and well supported so that they do not move when concrete is poured and compacted. ANY THREE (3) 3.6 CUTTING Once the steel has been made, it is delivered to the place where it is going to be cut and bent. Sometimes happens on the construction site, but it is usually done in a steel yard. A steel yard is a place where people work specifically on steel, cutting and bending it to requirements. If the steel is going to be cut on the construction site, you need to get permission from the engineer to do this. BENDING We need to tell the steel yard how the bars need to be bent. Most bending is done according to SANS 282:2004 (SABS 82) shape codes. Must be according to the bending schedule for a particular project or job. Give at least one mark for cutting and one mark for bending (3) Tendons that cannot de-stress in an accident More effective design as tendons can be easily woven Bonded post-tensioned concrete is very strong because of the bond created between the wire and the concrete. (3) 3.8 Pre-tensioned concrete: The embedded steel bars or cable are stretched before the concrete hardens Post-tensioned concrete: The embedded steel bars or cables are stretched after the concrete has set. (3) [25]

6 (MARKING GUIDELINES) -6- NC420(E)(N27)V QUESTION 4: REINFORCED CONCRETE 4.1 Substructure is that part of the structure that is below ground level, usually called the foundation or the part of the building you cannot see. 4.2 Superstructure is the part of the structure that is above ground level, in other words, the part of the building or structure which is visible. (2) Labels: Correct sketch: TOTAL: = = 5 3 (8) 4.3 Tensional stress when stress forces concrete to pull apart. Compressional stress when stress forces the concrete to press together. Shear stress when stress forces concrete to move parallel to each other in different directions. (5) 4.4 Shrinkage due to incorrect pouring Drying shrinkage cracks. Elastic deformation, later creep. Differential deformation. Interference settlement. (5) 4.5 Can be completely recycled. Have excellent light reflection and greater visibility. Have long lasting skid resistance and traction for safer driving. Can be grooved to improve run-off. Have integral rumble strips and speed bumps. Can have varied textures to worn motorists of hazards. Do not rut Uses local material (5) [25]

7 (MARKING GUIDELINES) -7- NC420(E)(N27)V QUESTION 5: CONCRETE PIPES 5.1 Storm-water culvert (SC) pipes SC they are used for storm-water and culver applications where there is no internal pressure. (2) Sewer irrigation (SI) pipes these are used in sewer and irrigation applications where there could be internal pressure, such as when blockages occur. (2) 5.2 The moulds are less expensive centrifugally spun moulds. Because of the dry mix, the process tends to be a lot cleaner than the centrifugally spun method. It is less labour intensive. (3) 5.3 Industrials gloves. Ear protectors Eye protector (goggles) Rubber safety boots. Safety shoes. Overalls Safety helmet. ANY THREE (3) [10] TOTAL: 100