Concrete is used to repair sidewalk and in many different ways, including sidewalks, driveways, patios, concrete floors, and slabs. Concrete is a mixture of cement, sand, water, and aggregates. Aggregates include stone, gravel, crushed brick, and other materials. In New York City, concrete is typically poured using forms called “slab forms.” Slab forms consist of two side rails, a top rail, and a bottom rail. When concrete is poured into these slab forms, it sets into perfectly flat surfaces. These types of concrete are commonly referred to as “ready-mix concrete,” because they already have cement mixed into the mixture.
Sand is a critical ingredient in repair sidewalk concrete. Without sand, concrete would not be set properly. Most concrete contains between 10% and 20% sand. Sand is used throughout the construction industry, and is often included in building products (e.g., bricks). Sand is commonly mined from riverbeds. Riverbeds are formed from rivers over time, which causes the sand and rock to sink into the riverbed and become buried under layers of silt and clay. Over time, this gradual sinking creates a layer of sedimentary rock, which eventually becomes exposed at the surface. A number of companies produce sand for use in concrete, asphalt, and other applications. One company, RediMiner, produces sand specifically made for the concrete industry.
Repair Sidewalk Cement
Cement is a type of material that makes repair sidewalk concrete hard and strong. Cement is a combination of limestone, iron oxide, silica, alumina, and gypsum, among other ingredients. Limestone is responsible for binding all of the other ingredients together. If any of the ingredients were missing, the concrete would not be set correctly.
Water Water is an important ingredient in concrete. Concrete cannot be set without water. Water is added to the mix to keep the ingredients separate and helps create concrete with the correct consistency. Too much water may cause the concrete to slump or flow before setting, while too little water could make the concrete dry out and crack.
Aggregates are the particles that makeup concrete. There are three basic categories of aggregate: natural, recycled, and artificial. Natural aggregates include things like pebbles, marbles, shells, and sand. Recycled aggregates include items like glass, plastic, rubber, metal, wood, cardboard, paper, and even some food scraps. Artificial aggregates include things like steel shot, polystyrene beads, and expanded shale. Each category has its own advantages and disadvantages. Natural aggregates are the least expensive. However, they tend to break down easily and require additional maintenance. Recycled aggregates can be reused indefinitely, and they are less likely to crumble than their natural counterparts. Artificial aggregates are generally stronger and more durable than either natural or recycled aggregates.
Admixtures are substances that improve certain characteristics of concrete, such as making it harder or more porous. Common admixtures include accelerators, retarders, stabilizers, and air entrainment agents. The amount of each additive varies depending on the type of concrete being produced.
Repair Sidewalk Sealers
Sealers help protect newly poured concrete from water damage. Sealer manufacturers include Dow Corning, Wacker Silicone, and Rhinoplasty.