Repair Crumbling Concrete
Concrete is simply artificial rock. If it's mixed, placed, finished and cured correctly it can last 100 or more years. If your concrete steps, walkways, patios, etc. are crumbling, you may be able to repair them with traditional products and methods or you can choose from some modern materials.
Often concrete deterioration is just a surface blemish. The concrete just below the surface is still sound. If this is what's wrong at your home, then you can patch the concrete and the patch will stay in place for many years if you just do a few simple things.
To add a thin patch of concrete that wouldn't exceed 3/8-inch in thickness, all you do is mix coarse clean sand with Portland cement. The mixture should resemble bricklayer's mortar. Mix two parts sand to one part cement to get a super-strong mixture.
The secret trick to get this material to permanently bond to your existing concrete is to apply a coat of cement paint to the rough concrete just a moment before you apply the patching mixture.
You make cement paint by just adding clean water to pure Portland cement and stirring it until it's the consistency of regular latex paint. Make sure the rough concrete is free of all dust and lightly spritz it with water before applying on the cement paint.
Once the patching mixture starts to stiffen up, you can use a wood trowel or magnesium or steel float to match the texture of the surrounding concrete.
Be sure to cover the patch with plastic for at least three days after you pour it. Try to keep the patch wet for the three days by spritzing it with water and covering it once again with the plastic so the concrete patch stays damp.
To repair deeper concrete defects or to replace chunks of missing concrete, just add small stones to your mix. The ratio should be three parts stone, two parts sand and 1.5 parts Portland cement for a strong mix. Always use the cement paint to bond your new concrete to your old.
Modern epoxies are available that also make great repairs. Simply purchase epoxies that are clearly labeled as concrete patching materials and follow the directions on the label for amazing results.