4562 Expansive soils are divided into four categories based on the swelling

4562 expansive soils are divided into four categories

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4.5.6.2 Expansive soils are divided into four categories based on the swelling potential, as follows: a) Low <1% ; b) Medium 1-2 %; c) High >2 % and up to 5 %; and d) Very high > 5 % Professional guidance should be sought for the determination of detailed properties of expansive soils. 4.5.6.3 The effects of expansive soils on buildings include: a) lifting of lightly loaded columns; b) jammed or out-of-plumb doors and windows; c) tilting of walls ; d) lifting of floor slabs; and e) cracking of walls . 4.5.6.4 The following measures shall be adopted to minimize the effect of heave on structures: a) the use of piled foundations; b) the use of tapered or pointed beam soffits; c) suspending of the floor slab ; and d) adequate drainage of surface water away from the foundation and floor slab .
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PCTTS 599: 20XX 75 4.5.7 Pavements 4.5.7.1 The pavements dealt in this section are those suitable for use as driveways and parking areas for private cars and light goods vehicles only. Driveways shall be not less than 3 m wide. 4.5.7.2 The choice of flexible (asphalt) or rigid (concrete) pavement is largely influenced by the cost of construction and the soil conditions at the site. Pavements with gravel topping are acceptable if the gravel or crushed rock is reasonably hard, free from clay, and would not be easily crushed by the light traffic. Adequate provision for drainage shall be made. 4.5.7.3 Where firm soils or rocks are present, any type of pavement mentioned in 4.5.7.2 may be used. Where soft soils are present, gravel or a flexible paving is recommended. 4.5.7.4 For all kinds of pavements, the topsoil shall be removed and replaced by a minimum of 150 mm of compacted, granular material. 4.5.7.5 For rigid pavements, the concrete slab shall have a minimum thickness of 100 mm. The slab shall be reinforced with welded wire mesh of minimum 100 mm 2 per metre in both directions and placed 25 mm below the top surface of the slab. Construction joints shall be created every 5 m. NOTE A98, A142 and 150x150X4.5 welded wire fabric are acceptable. 4.5.7.6 For flexible pavements, a minimum thickness of 50 mm of asphalt (cold or hot mix) shall be applied on an adequate sub base and compacted by roller.
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PCTTS 599: 20XX 76 5 Foundations 5.1 General 5.1.1 All load bearing walls and columns shall be supported on reinforced concrete foundations. The following foundation types are commonly used: a) Pad footing; b) Strip footing; c) Piled foundation; and d) Raft foundation. Figure 5-1 illustrates the above foundation types and Figure 5-2 shows details of a ground floor slab on grade typically used in single storey buildings. 5.1.2 Pad or strip footings shall be located on a layer of soil or rock with good bearing characteristics. Such soils include dense sands, marl, other granular materials and stiff clays. Piled and raft foundations require a more sophisticated level of design and should have some engineering input.
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