In building construction work there are some inherent dangers. The very nature of the work means that for a large percentage of the time, the structure is in a partially completed state. Openings to the exterior and interior have to be kept clear of obstructions to permit free passage of material and equipment.
Loose materials have to be kept on hand ready for installation and heavy loads have to be hoisted or manoeuvred into place. All manner of cutting and penetrating tools, implements and projections abound, and relatively large quantities of potentially dangerous waste materials are generated. Each of these presents a particular hazard to the safety of construction personnel and to the general public - where the construction is close to public access areas.
The legal responsibilities of the principal and the contractor for the safety of site personnel and the public are set out in the Health and Safety in Employment Act 1992, while general guidance on this subject is provided in Occupational Safety and Health (OSH) Guidelines for the Construction Industry. The basis of safe working practices is an attitude to safety by all site personnel. Creating a safe working environment requires that in addition to any formal rules of conduct, all personnel should be continually aware of the potential dangers of their surroundings and the particular activities in which they are involved. Safety is not someone else's problem; it is everyone's responsibility.
The following briefly outlines some of the potential hazards and/or the practices which should be instituted to provide general safety for those involved directly and indirectly with concrete construction.
Properly guarded walkways should be provided around formed areas of suspended work, so that the various tradespeople will have safe access to them while carrying out their tasks before concreting commences, and a safe means of retreat as concreting progresses. Where ladders are being used, one person at a time is the safety rule.
When heavy loads, such as formwork, reinforcement or concrete are being hoisted by crane, the path over which the load travels should be kept clear of all personnel. Adequate warning should be given to persons working in these areas so that they can get clear before lifting of the load commences. Clear areas should also be maintained around the anchorages of prestressing tendons while stressing is in progress, in case failure of an anchorage occurs.
Unfixed materials and hand tools should be kept well away from unguarded edges of suspended formwork or openings through it, or otherwise should be kept entirely within the forms to prevent them from falling onto people below.
Forms should be maintained in a clean condition at all times. This is important not only for safety and good-housekeeping reasons but it is also an essential requisite for producing good concrete. Offcuts of timber, steel, electrical wiring and conduits, plumbing pipes and other debris should be removed at regular intervals (not longer than daily), as they are all potential causes of people tripping, falling or otherwise injuring themselves.
The cut ends of starter bars or fabric which project from construction joints in columns, walls and slabs can be a source of serious injury to persons falling on or against them. Proprietary plastic caps or other simple forms of guarding should be used until the joining or lapping reinforcement is being placed.
Lightweight rigid sheet materials should not be left lying around loose, but should be tied or weighted down, particularly overnight. Such material can easily become airborne in the strong wind gusts which are common in many parts of New Zealand. In this condition, they become lethal missiles.
Safe practices for temporary electrical installations are set out in the Electricity Act and Regulations and should be followed. Adequate safeguards are important where overhead powerlines cross or are close to the work area, particularly where cranes are being used.
Most minor injuries to people working on construction sites can be prevented or minimised by the wearing of appropriate clothing and personal-protection devices. While this applies to all construction personnel, it applies particularly to those engaged in concrete construction, as the injuries they are designed to protect against are common in the various stages of concrete construction.
Overalls or tough trousers and a heavy-duty, long-sleeved shirt or jacket, offer reasonable protection from scratches by nails, tie wire, cut timber edges and cut reinforcement ends. They also give protection from harmful ultraviolet radiation from the sun. Shorts and T-shirts provide little or no protection from any of these sources of injury.
An approved type of 'hard hat' is required by industrial regulations in New Zealand. Common sense should dictate that this is an essential device in areas where there is a constant risk of objects falling from above and where headroom is likely to be restricted by temporary construction, such as formwork and falsework.
Safety boots with heavy-duty soles and protective toecaps minimise the chance of pierced feet from protruding nails or crushed toes from dropped timber or steel props. Like helmets, these are required by law.
All concrete construction work involves some degree of manual labour. Appropriate work gloves should therefore be used when handling undressed timber, reinforcing bars, cut fabric sheets, or formwork props. They should also be worn for all activities involving the handling of fresh concrete, because it is strongly alkaline and can cause corrosive burns on bare skin, or strong allergic reaction in some instances. The 'slurry' of cement, water and sand, in which the coarse aggregate is suspended, is also very abrasive and will rapidly damage the outer layers of skin when rubbed against it.
Safety goggles should always be used when cutting or grinding with power tools. It would also be prudent to wear them whenever there is a chance of eye damage from airborne grit, cement dust, or splashed concrete slurry.
Sunglasses & Sunscreens
Glare from sheet metal formwork and smooth, Iight-coloured concrete can be hazardous in the short term (by obscuring a potentially dangerous situation) and in the long term by causing permanent damage to the eyes. Sunglasses are therefore recommended in these situations. Publicity of the dangers associated with long-term exposure to harsh New Zealand sunlight should provide sufficient reasons for using sunscreens on those parts of the body which cannot be otherwise protected.