CONCRETE & STONEWORK
not so relevant as the static load is taken by the stone on to the bedding and substructure .
A useful personification to help understand the need to always fully consider the jointing requirements , and take the right decisions to select , specify and install the most appropriate joint pointing materials , and especially for repointing , can be :
Larger Format Paving Is More Bedding Dependent
The natural stone setts used in the UK were and are predominantly granite , as well as other hard types of stone , including slate , basalt , gneiss , quartzite , and limestone . Historically these have long been used for paved highways , public and commercial areas , where they provide the top wearing course throughout our town centres , and this has been the case since before Roman times . The other key difference other than plan from larger format paving , is their much greater thickness , with the traditional stone sett thicknesses used in the UK ’ s town centres and market squares being from minimum 100mm , up to more than 200mm deep , according to area , exposure , and local conditions , as well as availability and cost of course . Stone sett paved surfacing was very successful for hundreds of years , with pointing and any repointing being done with lime mortars , when weather conditions allowed , pitch and bitumen could also be used for more watertightness where required .
However , this was all before the arrival of the motor car and heavier delivery vehicles , which combined with increased time pressures on any area closures or waiting times in paving works , soon led to the demise of lime mortars for paving , and the widespread adoption of cement mortars based on OPC ( Ordinary Portland Cement ) as the new wonder material for pointing and repointing . This change was made to try and meet increasingly onerous installation time pressures , plus service demands with increasingly aggressive exposure conditions throughout the 20th Century . Today in the 21st Century the demands are even higher , which is due to the increased frequency of traffic , plus larger and heavier cars with powersteering , especially new EV ’ s , the trend to more stress-inducing SUV style with 4 x 4 / AWD family cars , plus the increases in commercial vehicle size and capacity up to 40-tonne articulated delivery trucks in the modern world . today ’ s far higher traffic loads and other exposures , which are all much greater than ever before .
It is important to ensure the right substructure and level of structural support for the intended loading in accordance with BS 5750 , plus the right bedding and bonding materials , as well as the right jointing materials to provide an attractive , serviceable , and durable finish . It is also important to consider that because of the size differences , larger format paving can be said to be more ‘ Bedding Dependent ’, and smaller format paving can be regarded as more ‘ Joint Dependent ’, which is quite logical if you think about it . This means that the pointing material in the joints is important and integral to allowing and accommodating lateral movement and stress transfer to the substrate with small format paving . This is also why the tensile / flexural strengths and elastic e-modulus of the jointing material is more important than just the compressive strength , which is
BUT
Smaller Format Paving Is More Joint Dependent
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