Excellent Methods to Break Up Absolutely One

When planning for the excavation and removal of old, in-place cement, two questions have to be asked. First, how much cement is there? Second, what kind of cement has to be removed?

Mass excavation and trenching operations typically deal with natural soil and rock. These can present their own difficulties depending on the hardness of the soil, the size of the rocks, the need to blast bedrock, etc. Cement is a man-made material that often can be more difficult to excavate than rock formations. The wide varieties of cement structures (pipe, slabs, footers, columns, beams, pavements, etc.) make planning for cement excavation a complicated exercise in estimating in-place quantities. They also have one operational characteristic in common; they have to be broken up before they can be excavated. This requires time-consuming and expensive demolition work with specialized tools and equipment prior to excavation. Once removed, however, the cement debris can be a cost-effective resource whose steel can be recycled as scrap metal and whose cement can be further crushed into usable aggregate. Cement that is not reused presents its own challenges for disposal in landfills specialized for construction-and-demolition (C&D) debris.

Cement and Cement Structures

Cement is a mixture of Portland cement, gravel and sand aggregates, water, and various admixtures depending on the type or classification of the cement. The main ingredient, Portland cement, is made by heating rock with clay, then grinding the resultant clinkers with gypsum. Aggregates such as sand, gravel, slag, and ash are added to make up the bulk of the cement’s mass and are held together by the cement. Use of cheap aggregates reduces the overall cost of the cement.

Water is added to hydrate the Portland cement, which then hardens when the water evaporates. The admixtures are added to increase strength, reduce weight, and preserve the material characteristics and quality of the cement during transportation. This is accomplished by entraining bubbles in the cement mix, thereby reducing the amount of water normally required in the cement mix, slowing the setting rate during hot temperatures, increasing the fluidity and workability of the cement, and inhibiting corrosion of the cement’s steel reinforcement. A typical cement mix consists of the following: 10%–15% cement, 60–75% aggregate, and 15–20% water. Entrained air bubbles may have a volume of 5% to 10%.

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