Driveway cracks are one of the most frustrating defects a Melbourne homeowner can experience. In Victoria, geology is often the culprit. Much of Greater Melbourne sits on reactive clay soils classified as Class M (moderately reactive), Class H1/H2 (highly reactive), or Class E (extremely reactive).
During dry summer months, reactive clay dehydrates and shrinks away beneath the concrete slab. During winter downpours, the clay swells aggressively with tremendous upward pressure. If a concrete driveway is poured without proper civil engineering, cracking is practically guaranteed.
Pouring concrete directly onto scraped clay is the leading cause of slab failure. We excavate a full 200–225mm below finished level, install a heavy non-woven geotextile membrane to prevent clay migration, and place a minimum 100mm layer of Class-3 Fine Crushed Rock (FCR). This is compacted in 50mm lifts with heavy vibrating plates to achieve 98% dry density.
Cheap contractors use flimsy SL62 mesh or allow reinforcing steel to rest directly on the ground during the pour. Concrete has enormous compressive strength but poor tensile strength. We specify heavy-duty SL82 mesh (8mm deformed steel bars at 200mm centers) elevated continuously on rigid plastic bar chairs so the steel is locked into the center-third of the concrete slab.
All concrete shrinks as water evaporates during curing. To prevent random, jagged hairline cracks, we perform machine diamond saw cuts within 18–24 hours of pouring. These cuts relieve tensile stresses at predetermined, laser-straight lines, ensuring the slab expands and contracts cleanly across decades.
Our civil concreting team provides full site inspection, council crossover permits, aggregate stone sample presentation, and fixed-price quotation.
View physical aggregate sample trays in your own driveway lighting.
