How to Fix Cracked Polymeric Sand Joints That Last

If you are searching for how to fix cracked polymeric sand joints, the honest answer is that patching over the cracks rarely lasts. Alliance Gator's instructions for an existing paver surface call for removing the old joint material, letting the pavers dry completely, and installing fresh polymeric sand to the full required depth.

Cracks and washouts are almost always a symptom. The joint was too shallow, never fully compacted or activated, got rained on too soon, or is sitting on a base that moves. Fix the cause, then re-sand, and the new joints have a real chance of holding.

This guide explains why joints fail, how to tell a failed joint from a normal one, and how to redo them step by step using the published instructions from Alliance Gator, Techniseal and SEK Surebond.

Why polymeric sand joints crack or wash out

Each of these causes comes straight from the manufacturer data sheets:

• Joints too shallow. The data sheets for Gator Maxx G2, HP NextGel, NOCO and PolySweep each list a minimum joint depth of 1 1/2 in. A thin skin of sand on top of old material or bedding sand will not hold.
• Sand left flush with the surface. The Gator Maxx G2 data sheet says the sand must sit at least 1/8 in below the top of the paver or below the chamfer "or erosion may occur," and that cured joints should never be in direct contact with foot traffic or tires. Techniseal warns that failing to recess the joint could lead to premature joint degradation.
• No compaction. Techniseal calls mechanical compaction mandatory for HP NextGel. Alliance recommends compacting in several directions so there are no air gaps or voids.
• Too little or too much water. SEK says the entire PolySweep joint must be fully saturated during activation, but not flooded. Alliance says not to let Gator Maxx G2 wash out of the joint.
• Damp pavers or joints at install. Alliance notes that damp joints stop the sand from sliding in and packing densely, which is critical to performance.
• Rain or cold too soon. Every sand has its own dry weather and temperature window (see the table below).
• A base that moves or holds water. Techniseal says the bedding layer must drain so the joint can dry, and its warranty excludes cracking due to structural movement and deflection from heavy machinery or trucks.
• Harsh pressure washing. Techniseal restricts high pressure washers on HP NextGel joints for the first 30 days and warns that direct, violent jets can damage them.

Is the joint actually failed?

Not every soft joint needs replacing. Techniseal's HP NextGel data sheet notes that joints become soft when humid but harden again when dry, so check your joints on a dry day before you decide.

• Cracked but tight: hairline cracks with the sand still bonded to the paver edges. Watch it through a few dry spells.
• Loose, crumbling or missing: sand you can scrape out with a fingernail, or joints that have dropped well below the paver edge. These need to be redone.
• Pavers rocking, sunk or spread apart: the problem is below the joint. Reset the pavers and fix the base first.

Why topping off old sand does not work

It is tempting to sweep a fresh bag over the cracks and wet it down. The data sheets rule that out. Alliance says not to use Gator Maxx G2 with other materials in the joints. Techniseal says not to mix HP NextGel with cement, sand or any other material. SEK says not to mix or dilute PolySweep with any other product. A thin top layer also cannot reach the 1 1/2 in minimum depth these products require, so it has nothing solid to bond to and tends to flake off.

How to fix cracked polymeric sand joints, step by step

This sequence follows the Gator Maxx G2 instructions for an existing paver surface, with product-specific details from the Techniseal and SEK data sheets. Always follow the instructions on your bag and your product's data sheet.

1. Find the cause. Check slope, drainage, sunken pavers and any heavy loads before you start.
2. Remove the old joint material. Use a joint scraper or narrow hand tool, a stiff brush and a leaf blower. Get down to at least the depth your new sand requires, and be careful not to disturb the bedding material under the pavers.
3. Reset loose or sunken pavers. Re-level the bedding, reset the pavers and make sure they are tight and interlocked. Alliance requires pavers to be completely interlocked.
4. Let everything dry completely. Alliance says pavers must be completely dry before installing, and neither the surface nor the joints should be damp. If you used water to flush out old sand, wait until the joints are dry all the way down.
5. Check the forecast and temperature against your product's data sheet.
6. Sweep in new sand and compact. Fill the joints, run a plate compactor (a rubber pad is recommended) or use the method your data sheet specifies, then refill and repeat. Finish at least 1/8 in below the top of the paver or the chamfer.
7. Clean the surface. Sweep with a hard bristle broom, then a soft one, and blow off remaining dust while keeping the leaf blower low so it does not pull sand out of the joints.
8. Activate with water exactly as your data sheet describes. For Gator Maxx G2, Alliance says to shower 30 sq ft for at least 30 seconds, starting at the lowest point, or until the sand repels water. Techniseal has you check that activation reaches 75% of the joint depth for HP NextGel and NOCO.
9. Protect the new joints. Keep off pressure washers early and follow the waiting time before cleaning or sealing. Techniseal's typical wait before cleaning and sealing HP NextGel is at least 7 days and may take up to 30 days.

Choosing a replacement polymeric sand

Part of learning how to fix cracked polymeric sand joints is picking a sand rated for your joint width and conditions. The figures below come from each product's own data sheet; do not apply one brand's numbers to another.

Sources: Gator Maxx G2 data sheet, HP NextGel data sheet, NOCO data sheet, PolySweep data sheet. For other products, check the data sheet in our TDS and SDS library.

Where ConSandtrate and concrete crack fillers fit

We carry ConSandtrate Concrete Crack Filler, sold in a 3 lb container in 5 colors and marketed as a concrete crack filler. We do not have a manufacturer data sheet for it in our library, so we cannot publish crack widths, cure times or weather limits for it. Read its label before use, and do not treat it as a replacement for the polymeric sand products above unless its label covers paver joints.

If the crack is in a concrete slab or walk rather than between pavers, you need a concrete repair product instead. For example, the Quikrete Concrete Repair No. 8620 data sheet rates it for cracks up to 1/2 in wide in concrete, sidewalks, patios and driveways, and says not to use it in control or expansion joints. See our concrete repair and mixes for options.

How to keep new joints from cracking again

• Keep water moving off the surface. The Gator Maxx G2 data sheet calls for a minimum slope of 1/8 in per linear foot away from pools and structures.
• Clean gently. Alliance recommends washing with Gator Shampoo and rinsing with a hose and watering gun set to shower at normal building water pressure.
• Remove organic debris. Both Alliance and Techniseal note that excess moisture, shade, and soil or organic matter left on the surface contribute to moss, mold and mildew.
• Keep heavy equipment off patios and walkways that were not built for it.

Frequently asked questions

Can new polymeric sand go on top of old cracked joints?

No. Alliance, Techniseal and SEK all say not to mix their polymeric sand with other materials, and each requires a minimum joint depth of 1 1/2 in. Remove the old material first.

How deep should the old sand be removed?

At least to the minimum depth on your new product's data sheet. For Gator Maxx G2, HP NextGel, NOCO and PolySweep that is 1 1/2 in. Do not disturb the bedding sand below.

Why do polymeric sand joints feel soft after rain?

Techniseal notes that HP NextGel joints become soft when humid and harden again when dry. Check them on a dry day before deciding they have failed.

How much polymeric sand does it take to redo the joints?

It depends on the product, paver size, joint width and depth. Use our polymeric sand calculator, which uses the manufacturer coverage figures for each sand.

Is ConSandtrate a polymeric sand for paver joints?

It is sold as a concrete crack filler. We do not have its manufacturer data sheet, so follow its label for where and how to use it.