Landscape blockwork

BLOCK PAVING

Concrete block paving units are manufactured to a wide range of designs as illustrated inFig. 2.14. Blocks may be of standard brick form (200×100 mm) to thicknesses of 60, 80 or 100 mm depending on the anticipated loading. Alternative designs include tum- bled blocks, which emulate granite setts, and various interlocking forms giving designs based on polygo- nal and curvilinear forms. Colours range from red, brindle, buff, brown, charcoal and grey through to silver and white, with smooth, textured or simulated stone finishes. For most designs, a range of kerb blocks, drainage channels, edging and other accessory units are available. Concrete paving blocks are usually laid on a compacted sub-base with 50 mm of sharp sand. Blocks are frequently nibbed to create a nar- row joint to be filled with kiln-dried sand. For the wider joints that occur between the simulated stone setts a coarser grit can be used to prevent loss by wind erosion.

Physical properties, including water absorption, freeze/thaw resistance, abrasion resistance and toler- ances on size, are categorised in BS EN 1338: 2003.

Guidance on the design and construction of pavements for a range of applications is given in BS 7533 Parts 1–13 inclusive. The types of tactile paving surfaces – blister, rib and groove – are defined and coded in the standard DD CEN/TS 15209: 2008.

Sustainable urban drainage systems (SUDS) are designed to reduce the environmental impact of imper- meable hard landscaping surfaces which create rapid rainwater run-off. With permeable surfaces, including nibbed blocks, the rainwater permeates through the spacing and is dispersed by natural drainage into the underlying soil, or may be collected through rainwater harvesting systems for further use.

Where the appearance of grass is required, but with the traffic-bearing properties of a concrete block pave- ment, a selection of porous (hollow) blocks is available which can be filled with soil and seeded to give the required effect. Different block depths and sub-bases can be specified according to the anticipated traffic

loading. Sulphate-resisting blocks are available if dic- tated by the soil conditions.

EARTH-RETAINING BLOCKWORK

A range of precast-cellular concrete-interlocking blocks is manufactured for the construction of dry- bed retaining walls. Soil is placed in the pockets of each successive course to allow for planting. The rear is backfilled with granular material to allow for drainage.

The size of the block determines the maximum con- struction height, but over 20 m can be achieved with very deep units. A face angle of 15^◦to 22^◦is typical to ensure stability, but other gradients are possible with the appropriate block systems. Limited wall curvature is possible without cutting the standard blocks. The systems are used both for earth retention and to form acoustic barriers.

References

FURTHER READING

British Cement Association. 2005:BCA guide to mate- rials for masonry mortar.Camberley: BCA.

Concrete Block Association. 2006:Aggregate concrete blocks. Part L. Thermal insulation from April 2006.

Guidance for designers and users. Leicester: CBA.

Concrete Block Association. 2007:Aggregate concrete blocks. Aggregate block sustainability. Data Sheet 16.

Leicester: CBA.

Concrete Society. 2007: External in-situ concrete paving.Technical Report No. 66. Camberley: The Con- crete Society.

Hugues, T., Greilich, K. and Peter, C. 2004:Building with large clay blocks. Details, products, built examples.

Basel: Birkh¨auser.

Robust Details. 2007:Robust details handbook. 3rd ed.

Milton Keynes: Robust Details Ltd.

STANDARDS

BS 743: 1970 Materials for damp-proof courses.

BS 5628 Code of practice for use of masonry:

Part 1: 2005 Structural use of unreinforced masonry.

Part 2: 2005 Structural use of reinforced and pre- stressed masonry.

Part 3: 2005 Materials and components, design and workmanship.

B L O C K S A N D B L O C K W O R K 5 3 BS 5977 Lintels:

Part 1: 1981 Method for assessment of load.

BS 6073 Precast concrete masonry units:

Part 2: 2008 Guide for specifying precast concrete masonry units.

BS 6100 Glossary of building and civil engineering terms:

Part 0: 2002 Introduction.

Part 1: 2004 General terms.

Part 6: 2008 Construction parts.

BS 6398: 1983 Specification for bitumen damp-proof courses for masonry.

BS 6515: 1984 Specification for polyethylene damp- proof courses for masonry.

BS 7533 Pavements constructed with clay, natural stone or concrete pavers:

Part 3: 2005 Code of practice for laying precast concrete paving blocks and clay pavers for flexible pavements.

Part 4: 2006 Code of practice for the construction of pavements of precast concrete flags or natural stone slabs.

Part 6: 1999 Code of practice for laying natural stone, precast concrete and clay kerb units.

BS 8000 Workmanship on building sites:

Part 3: 2001 Code of practice for masonry.

BS 8103 Structural design of low-rise buildings:

Part 2: 2005 Code of practice for masonry walls for housing.

BS 8215: 1991 Code of practice for design and instal- lation of damp-proof courses in masonry construc- tion.

BS EN 413-1: 2004 Masonry cement. Composition, specifications and conformity criteria.

BS EN 771 Specification for masonry units:

Part 1: 2003 Clay masonry units.

Part 3: 2003 Aggregate concrete masonry units.

Part 4: 2003 Autoclaved aerated concrete masonry units.

Part 5: 2003 Manufactured stone masonry units.

BS EN 772 Methods of test for masonry units:

Part 1: 2000 Determination of compressive strength.

BS EN 845 Specification for ancillary components for masonry:

Part 1: 2003 Ties, tension straps, hangers and brackets.

Part 2: 2003 Lintels.

Part 3: 2003 Bed joint reinforcement of steel mesh- work.

BS EN 934 Admixtures for concrete, mortar and grout:

Part 1: 2008 Common requirements.

Part 2: 2001 Concrete admixtures. Definitions, requirements, conformity, marking and labelling.

BS EN 998-2: 2003 Specification for mortar for masonry. Masonry mortar.

BS EN 1338: 2003 Concrete paving blocks. Require- ments and test methods.

BS EN 1745: 2002 Masonry and masonry products.

Methods for determining design thermal values.

BS EN 1806: 2006 Chimneys. Clay/ceramic flue blocks for single wall chimneys.

BS EN 1858: 2003 Chimneys. Components. Con- crete flue blocks.

BS EN 1996 Eurocode 6: Design of masonry struc- tures:

Part 1.1: 2005 General rules for reinforced and unreinforced masonry.

Part 1.2: 2005 Structural fire design.

Part 2: 2006 Design considerations, selection of materials and execution of masonry.

Part 3: 2006 Simplified calculation methods for unreinforced masonry structures.

BS EN 12859: 2008 Gypsum blocks. Definitions, requirements and test methods.

BS EN 12860: 2001 Gypsum based adhesives for gyp- sum blocks. Definitions.

BS EN 13139: 2002 Aggregates for mortar.

BS EN ISO 14683: 2007 Thermal bridges in building construction. Linear thermal transmittance. Simpli- fied methods and default values.

BS EN 14909: 2006 Flexible sheets for waterproofing.

Plastic and rubber damp proof courses. Definitions and characteristics.

BS EN 15037 Precast concrete products. Beam-and- block floor systems:

Part 1: 2008 Beams.

Part 2: 2009 Concrete blocks.

Part 3: 2009 Clay blocks.

DD CEN/TS 15209: 2008 Tactile paving surface indi- cators produced from concrete, clay and stone.

BS EN 15254 Extended application of results from fire resistance tests. Nonloadbearing walls:

Part 2: 2009 Masonry and gypsum blocks.

BS EN 15318: 2007 Design and application of gyp- sum blocks.

BS EN 15435: 2008 Precast concrete products. Nor- mal weight and lightweight concrete shuttering blocks.

Product properties and performance.

PD CEN/TR 15728: 2008 Design and use of in- serts for lifting and handling of precast concrete ele- ments.

DD 140-2: 1987 Wall ties. Recommendations for design of wall ties.

BUILDING RESEARCH ESTABLISHMENT PUBLICATIONS

BRE Special digests

BRE SD1: 2005 Concrete in aggressive ground.

BRE SD4: 2007 Masonry walls and beam and block floors. U-values and building regulations.

BRE Digests

BRE Digest 432: 1998 Aircrete: thin joint mortar sys- tem.

BRE Digest 460: 2001 Bricks, blocks and masonry made from aggregate concrete (Parts 1 and 2).

BRE Digest 461: 2001 Corrosion of metal compo- nents in walls.

BRE Digest 468: 2002 AAC ‘aircrete’ blocks and masonry.

BRE Digest 487: 2004 Structural fire engineering design. Part 4. Materials behaviour: Masonry.

BRE Good building guides

BRE GBG 44: 2000 Insulating masonry cavity walls (Parts 1 and 2).

BRE GBG 50: 2002 Insulating solid masonry walls.

BRE GBG 54: 2003 Construction site communica- tion. Part 2. Masonry.

BRE GBG 58: 2003 Thin layer masonry mortar.

BRE GBG 62: 2004 Retro-installation of bed joint reinforcement in masonry.

BRE GBG 66: 2005 Building masonry with lime- based bedding mortars.

BRE GBG 67: 2006 Achieving airtightness (Parts 1, 2, and 3).

BRE GBG 68: 2006 Installing thermal insulation (Parts 1 and 2).

BRE Information papers

BRE IP 14/98 Blocks with recycled aggregate. Beam- and-block floors.

BRE IP 1/99 Untied cavity party walls. Structural performance when using AAC blockwork.

BRE IP 7/05 Aircrete tongue and grooved block masonry.

BRE IP 1/06 Assessing the effects of thermal bridging at junctions and around openings.

BRE IP 8/08 Determining the minimal thermal resis- tance of cavity closers.

ADVISORY ORGANISATIONS

Aircrete Products Association, 4th floor, 60 Charles Street, Leicester LE1 1FB, UK (0116 253 6161).

British Concrete Masonry Association, Grove Crescent House, 18 Grove Place, Bedford MK40 3JJ, UK (01234 353745).

Concrete Block Association, 60 Charles Street, Leices- ter LE1 1FB, UK (0116 253 6161).

Concrete Society, Riverside House, 4 Meadows Busi- ness Park, Station Approach, Blackwater, Camberley, Surrey GU14 9AB, UK (01276 607140).

Mortar Industry Association, Gillingham House, 38- 44 Gillingham Street, London SW1V 1HU, UK (020 7963 8000).

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