An exposed aggregate driveway a couple of streets back from the beach at Mount Maunganui had gone pale and chalky within about four summers, the surface sealer worn off entirely and a scatter of the smaller aggregate stones starting to work loose at one edge where the sun hit hardest through the afternoon. The concrete underneath was fine. What had failed was everything sitting on top of it, and on a section this exposed to sun and salt air, that is the part that decides how long a driveway finish actually lasts.
Why coastal sun is harder on a driveway than inland heat
Mount Maunganui gets some of the highest UV exposure in the country through summer, on top of a near-constant onshore breeze carrying fine salt spray off the harbour and the open coast. That combination breaks down an unprotected acrylic sealer faster than the same product would last on an inland driveway, and once the sealer goes, the cement paste binding the exposed stones starts to erode from UV and wind-driven grit rather than from foot or vehicle traffic. A driveway here without a resealing routine can lose its surface finish in under half the time you would expect a few hours inland.
What actually holds up in exposed aggregate
The aggregate itself matters less than people assume; river gravel, basalt chip and the local scoria-toned stone all perform reasonably well underfoot. What matters more is the binder and the sealer. A penetrating, UV-stable sealer, reapplied roughly every two to three years on a coastal section rather than the five to seven years that would suit an inland driveway, keeps the cement matrix from chalking and keeps the stones locked in rather than gradually working loose as the surface erodes around them. Skipping resealing on a driveway like this is not a cosmetic shortcut; it is what causes the stone to start popping out under a tyre within a handful of summers.
The sand underneath changes the base as much as the finish
Much of Mount Maunganui sits on free-draining sandy ground, which is good news for water not sitting under the slab but means the base course has to be compacted properly rather than relying on the sand’s natural drainage to make up for a thin or poorly compacted layer. A base of at least 100 to 150 mm of well-compacted metal over the sand gives the slab something firm and even to sit on; skip that and a driveway can develop soft spots or slight undulation within a few years as the sand shifts under load, particularly near the boundary where a fence or retaining edge holds moisture against one side.
Salt, steel and why reinforcing choices matter here
Ordinary black steel reinforcing mesh, if it is set too close to the surface or the concrete cover is thin, can start corroding faster near the coast as salt-laden moisture works through the slab, eventually showing as rust staining or hairline cracking along the mesh lines. Galvanised mesh, or simply making sure normal mesh sits with adequate cover of at least 40 mm below the surface, avoids most of that risk on a driveway this close to the water.
Matching the sealer, the aggregate and the base to what a coastal Tauranga section actually throws at a driveway is worth discussing directly with whoever is pricing the pour, and a Tauranga concrete contractor specialists who work this stretch of coast regularly are the ones who will know the resealing interval that actually holds up here rather than the standard one printed on a tin.
Frequently asked questions
How often does an exposed aggregate driveway need resealing near the coast? Roughly every two to three years on an exposed coastal section, compared with five to seven years inland, because UV and salt spray break down the sealer faster.
Why do aggregate stones start popping out of a driveway over time? Once the sealer wears away, the cement binder around the stones erodes from UV and windborne grit, loosening the aggregate at the surface.
Does sandy ground need a different driveway base near Mount Maunganui? Yes, a well-compacted metal base of 100 to 150 mm over the sand is still needed, since natural drainage does not replace proper compaction under the slab.