The surface of concrete is porous and riddled with small cracks and fissures. When ice melters are applied to sidewalks, driveways and other concrete surfaces, the water created by the melting ice finds its way into these cracks. Because water expands as it freezes, the melted ice in the concrete causes problems when it refreezes, creating cracks and bubbles in the concrete. Fortunately there are ways to protect your concrete from this damage.
To protect your concrete, avoid ice melters that contain sodium chloride (rock salt) and potassium chloride. These chemicals work only at temperatures of 20 degrees Fahrenheit or higher. Instead, use melters that contain calcium chloride or magnesium chloride. These ice melters prevent the refreezing that damages concrete by keeping the ice melted in temperatures as cold as 25 degrees below zero and 13 degrees below zero, respectively.
Even if you use a high-quality ice melt product free of sodium chloride and potassium chloride, other people and businesses you visit during winter might not. Sealing your concrete creates a physical barrier between your concrete and ice melters, preventing you from unknowingly dropping on your concrete any harmful chemicals picked up on your snow boots or car tires.