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本文正文为英文版，中文译文正在准备中。
Before the finishing phase of an office block, control building or ancillary block starts, World Steel prepares five things at the same time: drawings and programme, handover of the structural shell, incoming materials, storage areas and tools. Doing this well lets the masonry, plastering, screeding and tiling that follow get it right the first time.
1. Drawings, programme and labour
- Prepare shop drawings and method drawings showing positions, survey lines, typical sections, levels, mix designs and other notes. Shop drawings are approved by the supervision consultant and the project management consultant before work starts.
- Prepare a programme showing the sequence of work, durations and resources (labour, materials, plant) for each item. The programme is agreed by all parties and depends largely on the owner's finishing schedule.
- Plan the labour to meet the programme, and provide PPE, signs, guardrails and debris nets for work at height.
2. Handover of the structural shell
| Area | Condition for handover |
|---|---|
| Floor slabs | Clean, with no unrelated materials; defects at column and wall bases and at recessed slabs already repaired. |
| Soffits | Formwork fully removed (nails, fins, foam, plastic sheet); bulging beam concrete chipped back to size. |
| Columns and walls | Formwork fully removed and tie sleeves broken out; bulging concrete chipped back to size. |
3. Incoming materials
- Sand: checked truck by truck by the materials officer and the storekeeper, who measure the load and record the quantity. Sand of the wrong type or with too many impurities is sent back. Samples are tested for aggregate properties.
- Bricks: counted and broken ones rejected; sizes spot-checked and the delivery refused if many are off size. Samples are taken from each batch of the same type for compressive and flexural strength and water absorption.
- Cement: delivered on dry, covered truck beds; stored in a dry, walled and roofed store; bags raised off the floor, at least 20 cm from the walls, no more than 10 bags per stack, stacked by batch.
4. Storage and mixing areas
- Laydown areas are planned for the conditions of each project, for easy receiving, handling and control. Mortar is preferably mixed at ground level and carried up to the work area.
- The mixing area has walls on three sides so sand does not spread over the slab, and a roof so work continues in any weather.
- Mortar is machine-mixed and kept in troughs; the mix proportions are posted at the mixer; gauge boxes for sand, cement and stone are made in advance (usually 40×40×25 cm or 40×20×20 cm).
- Masonry mortar is used within the shift; mortar mixed more than 2 hours earlier is not used.
- Bricks are stacked near the hoist: on pallets moved by forklift where there is space, in tidy piles moved by barrow where space is tight.
5. Tools
Mortar mixer, diesel and hand pallet trucks, wheelbarrows, timber, steel and cage pallets, trowels, wooden floats, aluminium straightedges, tape measures, spirit levels, plumb lines, laser levels, survey instruments and waste bins in every area.
Common mistakes
| Mistake | Consequence | Prevention |
|---|---|---|
| Mixing mortar directly on the slab | Dirty slab, poorer mortar | Use a mixer, troughs and mortar boards |
| Bricks and sand dumped anywhere | Untidy site, material waste | Contain the sand; stack bricks on pallets or in tidy piles 1.5–2 m from the wall line |
| Cement left on the floor | Cement absorbs moisture and lumps | Raise, cover and stack by batch |
| Accepting the shell before bulging concrete is chipped back | Thick plaster, extra quantities | Record a list of defects to be fixed in the handover minutes |
Reference standards
The edition in force when the contract is signed applies.
- TCVN 7570:2006 Aggregates for concrete and mortar – Specifications
- TCVN 7572:2006 Aggregates for concrete and mortar – Test methods
- TCVN 1450:2009 Hollow clay bricks
- TCVN 1451:1998 Solid clay bricks
- TCVN 9202:2012 Masonry cement
