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Across the UK, the jointing of modular paving causes delays in project completion, and premature failure of otherwise well-constructed paved surfaces. These problems can affect all forms of bound modular paving— whether on domestic patios and driveways, commercial and retail environments, or in heavily trafficked public realm schemes such as pavements, highways, town squares and market areas. While surface specification and sub-base design usually receive close professional attention, the performance of the paving joints remains a critical but often underestimated determinant of long-term durability.
Weather-related delays to jointing- The most familiar paving jointing issues for owners, designers, and contractors alike, are delays caused by unsuitable weather for applying cement-based pointing materials on site, even the wet-slurry types. This is because they cannot be applied in the rain, when residual water is present in the joints, or when rainfall is expected within the next 24 hours. As the paving jointing is generally one of the final construction steps before handover, these constraints frequently postpone completion and delay opening the new or refurbished paved areas to service. However, under commercial pressure, these environmental limitations are sometimes overlooked, and contractors may be pressured to maintain programme deadlines and budgets. While this may be expedient at the time, it introduces significant issues and risks that will only become evident later.
Premature joint deterioration, breakdown and failure – Cementbased paving jointing materials rely on a controlled water-to-cement( w: c) ratio to achieve their designed performance and durability. Any residual water within the joints, or additional water from rainfall during or shortly after installation, strongly disrupts and compromises this ratio. The result is then a material with increased porosity, reduced strengths, and shrinkage cracking. Crucially, these defects are not immediately visible, and all may continue to appear to be well for completion and handover, including the retained samples on larger projects, which are cast into moulds on site i. e., they are under controlled
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