Red Devil 0641 Concrete Repair Patch, Cement Crack Filler, Pre-Mixed, 1 Gallon, Pack of 1, Gray, Made in USA

Why I reached for this patch

A few freeze–thaw cycles left my driveway, a couple of foundation blocks, and the edge of a patio step looking tired—hairline cracks here, a shallow spall there, and one wider, irregular gap that had been slowly raveling. I wanted an easy, water-cleanup repair that wouldn’t turn a Saturday into a cement-mixing project. The Red Devil concrete patch checked the right boxes: premixed, 1‑gallon size, interior/exterior rated, and a claimed flexible, crack‑resistant cure. I put it to work across a handful of repairs to see how it handles prep, application, finish, and weather.

What it is

This is a premixed, water‑based concrete repair compound in a 1‑gallon pail. It’s a smooth, paste‑like patch that spreads with a putty knife or trowel, adheres to clean masonry, and dries to a light-to-medium gray. Cleanup is soap-and-water simple, which immediately puts it in a different category than cementitious mixes or two‑part epoxies that demand dedicated mixing gear and solvent cleanup.

Prep matters more than the pail

Success with any patch starts with a clean, sound substrate. I:

• Chased out loose material with a cold chisel and wire brush.
• Vacuumed dust and blew out the cracks.
• Washed oily spots and let everything dry. Slightly damp concrete is fine; wet surfaces are not.
• For a couple of wider joints (approaching 3/8–1/2 inch deep), I added foam backer rod to control depth. That reduces waste and helps the patch flex rather than debond.

Stirring the pail is worth the minute it takes. The compound can separate slightly in storage; a quick mix brings it back to a uniform consistency.

Application and workability

Workability is the standout here. The patch loads on a putty knife cleanly, spreads without tearing, and feathers nicely at the edges. It has enough body to stay put on vertical surfaces—useful on block foundations and stair risers—yet it still levels well under a trowel.

• Hairline cracks: I used a flexible putty knife to press material in and then skimmed over with a thin layer. No sagging, no pinholes.
• Narrow-to-medium cracks and small spalls: A margin trowel made quick work of filling and shaping. For deeper voids, I built the repair in two lifts to minimize shrinkage.
• Vertical repairs: On a basement window well with block, it held its shape and didn’t slump, which saved me from babysitting it.

It skins over in a couple of hours in mild weather. I waited 24 hours before light foot traffic and 48 hours before any risk of standing water. Dry times will stretch in cool or humid conditions and shorten in warm, dry sun. If you’re patching outdoors, avoid the hottest midday window to prevent too-fast surface drying.

Adhesion and durability

Adhesion to properly prepared concrete and block has been solid. After months of rain, sun, and a few freeze–thaw swings, the patches haven’t lifted, curled, or telegraphed new cracks. On the step edge that sees daily foot traffic, the repair remains intact with no edge crumbling.

That said, this is a repair patch, not a structural mortar. For very large spalls, dynamic control joints, or structural cracks that move seasonally, a specialty product (like a two‑part epoxy, polyurethane crack sealant, or a polymer‑modified repair mortar) is a better fit. For cosmetic cracks, small breaks, and non‑structural gaps, the flexibility here helps it resist the hairline shrink‑cracks you sometimes see with rigid cement‑only mixes.

On the deeper fill I mentioned earlier, there was slight settling after the first pass—expected with any paste laid thick. A quick second skim the next day brought it flush, and it stayed put after that.

Finish and color

The cured color is a medium gray—lighter than “battleship,” darker than many weathered slabs. On my driveway (aged, light gray), the patch is visible up close but not jarringly so. On newer or very light concrete, expect contrast. On rough, broom‑finished surfaces, the patch’s fine, smooth texture may stand out unless you texture it while green. A stiff brush rolled across the fresh surface can mimic a light broom finish reasonably well.

If color uniformity matters, plan to paint the patch with a masonry coating once fully cured. It takes paint well. Stains are trickier; color penetration on a polymer‑modified patch rarely matches bare concrete. I wouldn’t bank on post‑staining for a perfect blend.

Weather resistance

I put some of the repaired areas to the test before the warm season ended: light vehicle traffic over the driveway cracks, a couple of gully-washer rains, and a cold snap. The patch stayed bonded and didn’t spider‑crack. Because it’s water‑based and flexible when cured, it tolerates minor movement and the expansion/contraction cycle better than a brittle cement-only repair.

I still wouldn’t apply it immediately before rain. Give it a full day or two to set up, longer if temperatures dip below 50°F. And like any patch, avoid trapping water behind it—fix drainage issues first, or you’ll chase failures no compound can solve.

Cleanup and storage

Soap and water cleanup is as easy as advertised. Tools cleaned up in minutes, and there’s almost no odor. That makes it suitable for interior use without throwing the house into a solvent cloud.

For storage, reseal the lid tightly and set a piece of plastic wrap directly on the surface of the remaining compound before closing the pail; that helps prevent skinning. If a thin skin forms later, peel it off and stir. Keep it from freezing.

Where it fits—and where it doesn’t

Use it for:
- Hairline to moderate cracks in slabs, steps, and block
- Small spalls, chips at slab edges or stair noses
- Cosmetic repairs you plan to paint or where a medium gray is acceptable
- Interior or exterior touchups where fast, clean application matters

Skip it for:
- Structural cracks or actively moving joints
- Large, deep rebuilds needing aggregate-rich mortar
- High-abuse industrial floors or heavy vehicle ruts

Practical tips

• Undercut edges slightly for better mechanical lock on spalls.
• Wipe the trowel with a damp rag for cleaner feathering.
• Texture while it’s still workable if you’re matching a broom finish.
• For deep voids, use backer rod or build in lifts to control shrinkage.
• Shade outdoor patches from direct hot sun for the first few hours.

Value

A 1‑gallon pail is a practical size for homeowners and pros tackling multiple small repairs. Coverage varies wildly with crack width and depth, but I handled a handful of driveway cracks, a couple of block joints, and a step repair with plenty left in the bucket. Compared to buying cement, sand, admix, and mixing tools for a small job—or timing out a fast‑setting repair mortar—this premixed approach saves setup and cleanup time without feeling like a compromise.

Pros and cons

Pros:
- Ready to use; no mixing or special tools required
- Excellent workability and edge feathering
- Strong adhesion on clean, sound concrete and block
- Flexible, crack‑resistant cure suitable for interior/exterior
- Easy water cleanup and low odor

Cons:
- Medium‑gray color can contrast on light or stained concrete
- Slight settling on thicker fills may need a second pass
- Not intended for structural repairs or high‑movement joints

Recommendation

I recommend the Red Devil concrete patch for small to medium non‑structural repairs where ease of use, clean application, and reliable bonding matter more than a perfect color match. It excels at everyday fixes—driveway and patio cracks, chipped steps, and cosmetic block repairs—delivering a durable, flexible patch with minimal fuss. If your slab is very light and you’re a stickler for invisible repairs, plan on painting the area after curing. For large structural issues, reach for a different class of product. For the kinds of maintenance most of us face each season, this patch is a straightforward, effective solution.