Little piles of sand on a brick patio mean that ants are building homes. Unfortunately, the ants are digging that sand out from beneath pavers that were carefully levelled and settled, eventually resulting in tipped pavers and an uneven surface.
Water-based, polyurethane and acrylic sealants protect existing patios. The sealants coat or impregnate pavers and the sand between them. Sealants often darken pavers. A variety of finishes is available, from invisible to glossy.
Polymeric sand combines joint sand with a water-soluble polymer. Poly sand is worked between pavers just like sand. The surface is then covered with water to activate the polymer. The result is a flexible grout-like sealant between bricks impervious to ant homebuilding.
The ultimate solution to excavations by ants is to lay the brick patio on a bed of concrete. Once the bricks are laid, joints can be filled with mortar or polysand. Local building codes may dictate specific materials.
If ants are the only problem, ant traps, a surface sealant or alternative filler may solve the problem. For new patios or where winter or freeze-thaw cycles and flooding have caused upheaval, cement foundations are the most economical long-term solution.