Minor damage in concrete like pitting or spalling is often purely aesthetic, but it can also indicate a deeper problem. Minor surface defects are an easy fix, but larger issues like widespread delamination or major voids will require very different approaches. Your first step is to assess the state of the slab.
The easiest way to assess a slab is to tap it with a hammer or – for larger areas – drag a heavy chain across the surface.
A sound slab will “ring” with an even sound no matter where you tap.
A bad slab will “thud” or sound hollow – this can happen in a localized area or across the entire slab if there are major issues, and will generally require demolition, sub-grade remediation and re-pouring to properly fix.
Assuming the slab is sound and surface damage is under 1/2″ deep, you’ve got an easy job on your hands!
As an easy rule of thumb, 10# will cover 4.5 ft2, 20# will cover 9 ft2 and 40# will cover 18 ft2 at a 1/4″ depth, which is common for these types of repairs.
Sweep the repair area to remove any dirt or debris that act as bond breakers. Consider using a pressure washer for large or heavily soiled areas.
Bring the repair area to saturated surface dry (SSD) to ensure a good bond. At SSD, the concrete will appear wet but will be mostly dry to the touch – there should be no standing water.
Project Tip: Use the Sakrete App to measure, estimate and purchase materials for the job straight from your phone.
Repair materials have a wider range of acceptable consistencies than standard concrete and are often mixed by ratio rather than volume. The most common ratio is 4:1 – 4 parts mix to 1 part water, but 3:1 is also acceptable when a thinner consistency is desired.
Wearing respiratory protection and gloves, add pre-measured water to your mixing pail, followed by the dry mix. Start at a 4:1 ratio – 4 parts mix to 1 part water and adjust from there.
Mix for two minutes to achieve complete consolidation of the mix.
Adjust water slowly to reach desired consistency, but do not exceed 3:1.
Project Tip: Mixing by hand is sometimes most convenient for small patches. Be sure to wear gloves!
ApplyingTop ‘N Bond is an extremely forgiving product to work with, providing a smooth finish and plenty of working time to achieve a perfect finish.
Apply mix to damaged area using a margin trowel.
Rod the material to eliminate air bubbles and ensure a good bond.
Use a flat trowel to smooth the patch – two or three passes should be sufficient. Be sure not to over-work!
Top ‘N Bondcan be spread to a “feather edge,” which means that there is no minimum depth restriction – the product can be spread in a thin coat to deliver a smooth transition from the repaired area to sound concrete.
Because Top ‘N Bond is a feather edge material, it can also be spread across a large surface area very easily. Consider mixing to a looser 3:1 consistency for easier spreading.
Project Tip: Top ‘N Bond is heavily polymer modified to deliver excellent bond strength. Be sure not to add Bonding Agent to this mix – it can actually act as a bond breaker!
Put the finishing touches on the job.
Wait a few minutes to allow the mix to cure slightly, then make a pass over the repair using a paint brush (for small areas) or broom (for larger areas) to make the patch match the existing concrete.
Make sure to only pull the broom in one direction – and only make a single pass to avoid over-working the patch.
For large areas, consider immediately applying Sakrete Cure ‘N Sealto ensure proper cure. Otherwise, cover with plastic after the material has set and regularly mist to ensure a good cure.
Allow to cure for 24 hours before opening to foot traffic and 72 hours for vehicular traffic.