We often compare making concrete to making bread.  On the face of it, concrete is a very simple recipe – essentially a mix of sand, crushed rock, cement (the ‘glue’) and water. 

​However, as with bread, the devil is in the details, and the experience of the hands that make it.  There are a huge number of variables (aggregate properties, exact proportions, admixtures, cement:water ratios, reinforcement methods, curing conditions, finishing techniques etc.) that will affect the quality of a slab of concrete.  In the end, making concrete is part art, part science, and it is up to each ‘cook’ to fine tune their process until the end result is just right for their own needs.   

However, as with bread, the devil is in the details, and the experience of the hands that make it.  There are a huge number of variables (aggregate properties, exact proportions, admixtures, cement:water ratios, reinforcement methods, curing conditions, finishing techniques etc.) that will affect the quality of a slab of concrete.  In the end, making concrete is part art, part science, and it is up to each ‘cook’ to fine tune their process until the end result is just right for their own needs.   
​
Given the number of variables at play, we have been hesitant to repair concrete surfaces that we didn’t make.  However, when we were given the opportunity to refinish a pour-in-place concrete countertop that would otherwise have been thrown out after only a few years of use, we couldn’t pass it up.  We firmly stand by our belief that it is better to repair than to replace, so we decided to accept the challenge and put our claims about the repairability of concrete to the test. 

The main issues with the original countertop were a blotchy appearance and the fact that the surface layer was beginning to flake off – quite severely in places.  

We had several homeowners ask us about this latter problem at last year’s home show, mainly with respect to DIY projects.   When concrete is poured, a thin layer of fine materials forms on the surface, called the ‘cream’.  This is what gives that raw, natural concrete look that home décor shows and magazines love to show off.   It looks cool, but that surface is very delicate.  It’s possible to preserve it with the right combination of skill and sealing, but for the most part, there’s a good risk that the cream will start to wear off over time.  The problem will be worse if the concrete mix design and process weren’t designed for the application (a countertop is not a sidewalk!), or if there was too much water in the mix.  It is tempting – and sometimes necessary - to add extra water when finishing a pour-in-place project to make it easier to achieve a smooth surface, but too much extra water will result in a softer, less durable surface that is more prone to degradation over time. 
​
Our goal in repairing the countertop was to grind through the delicate cream in the hopes of finding a more durable base underneath that we could polish and seal for an attractive finish.  Our biggest fear?  That the concrete would be too soft throughout, and might disintegrate under the impact of our polishing machine.  

All in all, we’re pretty pleased with how it came out.  Well let’s be honest…really pleased!  It’s better than we hoped, and certainly better than it could have been.  And in the end, we saved a relatively new concrete countertop from being destroyed and replaced.  
​
The new surface isn’t perfect.  There were places where the concrete was softer, leading to small dips in the surface, and we decided not to do a major grind on the back edges where the concrete was particularly fragile for fear that we would undo all of our good work up to that point.  The edges stand out, as you can see below, but they also tell the story of the homeowners’ commitment to reducing waste (and saving money) by extending the life of their existing counters. 

To say that the repair was cheap would be misleading.  There are a number of costs that go into a good repair: job site preparations to minimize the amount of concrete dust that goes into the air and throughout the house; polishing pads and equipment; a high-quality sealer that will help preserve the new surface; labour; travel; and of course, the risk associated with embarking on an unpredictable project.  We can say, however, that the repair cost was less than half of what it would have cost to replace the old counters with new, high quality concrete countertops. 
​

The moral of the story?  If you’re looking for a hardy, durable surface that can stand up to life in the long run, consider concrete.  Invest in good quality concrete, designed for your application.  Care for your surfaces.  And don’t fret if something happens!  It can probably be repaired.