You swept, watered and waited, and the joints still feel soft under a thumb. Before you dig anything out, know that “soft” can mean two very different things. It can mean the sand is simply still damp, which fixes itself. Or it can mean the sand never bonded, which does not. The makers’ own pages draw that line clearly.
This guide uses the Alliance Gator blog and FAQ and the Sika Evolution Pro data sheet to sort what you are seeing into “wait”, “re-wet” or “redo”, with a timeline of how long to give it at each step. I did not test any product. Everything below comes from those documents, and I say where they stop.
First, is it actually broken?
Alliance Gator’s answer to a contractor who reported joints that felt soft is blunt: polymeric sand cures by drying, and to set fully it has to dry out completely. If it did not harden, there is most likely a moisture problem, and joints that stay wet stay soft until they dry. Its FAQ puts it in one line: hard means the area is dry, soft means it is still damp or wet.
The same FAQ adds a point that changes how you should think about the whole product. Polymeric sand is not a mortar. It is designed to go from hard and dry to soft when wet, and that is how it self-heals. Sika’s data sheet says something similar for wet spots: joints may soften when saturated but will harden after drying. So a joint that is soft the morning after rain is not evidence of failure. A joint that is still soft after a good dry spell is.
Match what you see to what to do
| What you see | Most likely meaning | What the makers say to do |
|---|---|---|
| Soft in patches, firm elsewhere, no sand washed out | The soft patches drain more slowly than the rest and are still damp | Wait. Alliance Gator says some areas stay wet because they are not draining as fast as the dry ones. Fix the cause of the slow drainage if it keeps happening |
| Hard crust on top, loose or powdery underneath | Under-watered. Water did not reach the bottom of the joint | Alliance Gator: if it was activated recently, run a sprinkler over it for about an hour, and if a crust formed, poke small holes in the joint so water can seep in. If it has not hardened after a few days of good weather, remove it and redo it |
| Soft everywhere, days after the last rain | The joints cannot dry: shade, a sprinkler hitting them, poor pitch, a stone dust bed, or no drainage under the pavers | Find the water source first (see the next section). Sika says do not install pavers over a concrete slab without a drainage base, because joints stay saturated |
| Joints low, gappy or sand washed out | Rain or heavy watering hit before it set, or the sand was over-watered and displaced | Not a hardening problem. Sika says heavy rain can wash away or displace the sand and that you should not over-water. Remove and refill as in our guide to reapplying polymeric sand |
| Bag was lumpy or already hard when you opened it | Moisture got in before use | Sika: moisture can cause premature gelling of the product. Do not use sand from a bag that has gone solid |
Why joints stay wet
Alliance Gator lists the common reasons joints fail to dry, and it notes that the weather is not the only culprit:
- A concrete overlay done improperly, or pavers set directly on a slab with no way for water to leave
- Stone dust used as the bedding layer
- The north side of a house or deep shade
- Sprinkler systems that spray the joints
- Improper patio pitch, including depressions in the crushed stone base that act as puddles and wick water up through the joints in patterns that look random from above
- Fall and early spring conditions, with short days, cool temperatures and wet weather
- Poor compaction, which leaves the sand fluffy and able to hold more water
The cool-weather point has numbers on Sika’s sheet. It lists a setting time of 220 minutes and then notes that longer drying times may be needed when temperatures are below 21 C (70 F) for the first 24 to 72 hours. It also asks for air and surface temperatures to stay above 5 C (41 F) for at least 48 hours after installation, and it says curing is longer in cold or damp conditions. A November install in a shaded corner is slower on every count.
How long to wait before you call it failed
The makers give different clocks for different questions. Put side by side, they make a usable timeline:
| Time after watering | What the maker says | Source |
|---|---|---|
| First 24 hours | Keep rain off. 48 hours if joints are wider than 1/2 in | Sika Evolution Pro data sheet |
| 24 hours | Foot traffic is fine if the sand is dry | Sika data sheet and Alliance Gator FAQ |
| 48 hours | Air and surface temperature must have stayed above 41 F | Sika data sheet |
| 72 hours | Sprinklers stay off. Vehicles allowed from here, dry weather permitting | Sika data sheet |
| A few days of good weather | If an under-watered joint has not hardened by then, remove it and redo it | Alliance Gator FAQ |
| About the first two weeks | If joints have not dried out in this window, the odds are the sand was compromised, even if it dries later | Alliance Gator blog |
| 30 days | Earliest point to apply sealers or cleaners | Sika data sheet |
Two rows matter most for a “won’t harden” decision: the few days of good weather and the first two weeks. A few dry days is the point where a re-wetting attempt has failed. Two weeks is the point where Alliance Gator says the sand has probably lost its long-term performance even if it eventually firms up. If you are inside those windows and the weather has been wet, the right move is usually to wait, not to dig.
If you decide to redo it
Both makers want old sand removed before new sand goes in. Sika says remove all existing sand to full joint depth, or at least 38 mm (1.5 in), and not to partially fill joints with any other material. Alliance Gator’s FAQ gives the same 1.5 inch minimum for a repair and adds a warning: partly filling a joint with regular sand will make the surface peel and flake and voids the warranty. So the fix for a bad batch is not a top-up. Our reapplying guide has the depth comparison and the sand volumes for a typical patio, and the removal guide covers getting set sand out.
Before you refill, fix what kept it wet, or it will happen again. For the new sand, both makers also give the same installation checks that prevent a repeat:
- Install only when no rain is expected for 24 hours, or 48 hours with joints wider than 1/2 in.
- Start with joints that are completely dry, compacted, clean and filled to about 1/8 in below the paver chamfer.
- Remove every trace of sand from the surface with a stiff broom, a soft broom and a leaf blower.
- Water in sections of about 50 square feet, from the lowest point up, with a shower setting for about 1 minute per section, so water reaches at least 1 in into the joint. Stop when the sand will not take more water.
- Keep sprinklers off for 72 hours and cover the area with a tarp if rain surprises you.
For the refill, a product I have read the listing for is Alliance Gator G2 Maxx in slate gray. It is in stock, rated 4.3 stars from 74 ratings with 500 or more bought in the past month, and sold by a third-party seller. Check price on Amazon: Alliance Gator G2 Maxx Polymeric Sand. This is an affiliate link (see our disclosure for details). If the old sand failed because of water, the product choice matters less than the drainage.
When the problem is the base, not the sand
If the joints stay wet because pavers were laid straight over a concrete slab, because the base has puddling depressions, or because the pitch is wrong, no joint sand will cure reliably. Sika says outright that its sand is not for pavers installed directly over a slab without a drainage base, and Alliance Gator’s FAQ points to ICPI’s overlay guidance, which calls for drainage holes at the lowest points of the slab. That is a job for a hardscape contractor. You can find one near you through Angi. This is an affiliate link (see our disclosure for details).
Two related guides: how long polymeric sand takes to set for rain and traffic times by product, and our haze guide if the problem is a white film rather than soft joints.
Sources: Alliance Gator blog post “Why Your Polymeric Sand Did Not Harden” and the Alliance Gator FAQ for Gator Jointing Material (both read on 10 November 2026), and the Sika Evolution Pro Polymeric Sand product data sheet, version 01.03, December 2025. Other brands have their own sheets and limits, so check yours. I did not test any product.
Etienne Basson maintains and repairs his own home, and writes practical guides on choosing the right materials and products for repair and finishing jobs: fillers, sealants, adhesives, and similar. He focuses on what actually works for a specific job, not just a spec sheet.