Sustainable use of natural stone as paving material
2011 (engelsk)Inngår i: Geophysical Research Abstracts, European Geosciences Union (EGU), 2011, Vol. 13, artikkel-id EGU2011-9358Konferansepaper, Oral presentation with published abstract (Fagfellevurdert)
Abstract [en]
Sustainability is not only a matter of choosing durable stone types for a specific application. It is also about theenergy consumed during the production, transportation and placing of the stone. It is also about dimensioningand shaping of the stone properly for the actual construction and the stone together with other materials in theconstruction. This contribution deals with the latter and is a case study on a failed paving construction.Stone paving is the collective expression for the use of stone slabs, setts and kerbs for exterior paving purposes.There are three European product standards in force; EN 1341, 1342 and 1343 respectively. These standardsdescribe e.g. how to denominate the products, the allowed dimensional tolerances and which technical propertiesto validate. There is little or no information on the actual usage of these products. Such information has generallyto be elaborated by each country.The standard way of construction for pavements is non-bonded laying of elements in crushed sand/splitmixtures. Under special loads and cleaning requirements this traditional, unbound construction method easily failsand a bound construction is needed. The structural integrity of an unbound pavement construction is maintainedon the basis of friction and mechanical interlock. Energy from traffic loading enters the structure via the surfacecourse, some of this energy is dissipated within the surface course itself and some is transmitted into the beddingcourse and thereafter the supporting base layers beneath. There are two structural elements in the surface course,the setts and the jointing medium. The jointing medium has physical properties which are important to consider,such as stiffness modulus, resistance to shear et al, which crucially affect the manner in which the pavementresponds to applied loads.Sufficient friction between the various components is crucial but is not generated and mechanical interlock notexercised without movement of the component parts of the structural model. The unbound paving is not a rigidconstruction and the various parts of this structural model must be mobilised in order that friction is generated.The paving is therefore also heavily dependant upon the unseen surface finishing of the setts (and slabs). In orderto adequately generate friction between the paving element and both bedding and jointing materials the unseensurfaces have to be rough, preferably a cleft or riven surface, to function properly.There are two distinct categories of setts, shallow setts and full setts, each requiring a different approach:Shallow setts are those having depth less than width.Specifying shallow setts makes a more economical use of the raw material used in their manufacture but thepavement construction requires to designed more carefully and there is an upper limit to the level of traffic whichcan be carried. A concrete base must be provided when specifying shallow setts.Full setts are those having depth not less than width.For many centuries the "golden rule" was that setts must be at least as deep as they are wide. The heavier thetraffic loading, the deeper the sett in relation to its width. Before the advent of concrete and mortar, when jointing,bedding and supporting base were all unbound, this rule was very necessary. Even with the development of highperformance mortars and reinforced concrete for a base, we need to use full setts when the traffic loading exceedsa given maximum.The deeper the sett in relation to its width, the more the strength of the pavement is taken by the joints between thesetts. So, with deep, full setts we can sometimes lay over an unbound or a bituminous base, even for heavy traffic.As can be seen, these simple rules given above depend on proper definition of the traffic loads. i.e. numberof vehicles per day and the weight of them. When the general rules are not followed the stones start to move inan uncontrolled manner. Some cases and one in particular will be detailed in this presentation. The case studiesdemonstrate the importance of the necessary knowledge needed to build a paving that can cope with the dynamicand static traffic loads. In addition, it shows the problem that may arise due to a poorly defined border betweensetts and slabs.
sted, utgiver, år, opplag, sider
European Geosciences Union (EGU), 2011. Vol. 13, artikkel-id EGU2011-9358
Serie
Geophysical Research Abstracts, ISSN 1607-7962
HSV kategori
Identifikatorer
URN: urn:nbn:se:ri:diva-339OAI: oai:DiVA.org:ri-339DiVA, id: diva2:1051053
Konferanse
EGU 2011, ERE 5.3: Sustainability of traditional construction materials in modern society, EGU European Geosciences Union, General Assembly 2011, Vienna, Austria , April 3-8, 2011.
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