Large scale repair work involves the disturbance and removal of large sections of existing concrete. These tasks generate high levels of airborne crystalline silica dust. Typically crews working on highway repair projects spend about half their shift performing tasks that create dust such as operating jackhammers and sawing concrete and the remainder of their shift doing relatively dust-free patch work.
Preparing the Site
Site preparation is the work done on land prior to construction, including gaining access and finalizing the site location, soil testing, demolitions, excavations, land clearing, leveling, and other land preparation projects. Whether you are constructing a new building or just repairing a damaged structure, proper site prep is essential to your project’s success. Here are a few ways it can make your job easier and improve the results of your building project:
A comprehensive site preparation process will help you identify any complications before they become a problem. It will also allow you to address them before your 大規模修繕工事 project begins, ensuring the best possible outcome for your investment.
The size and location of your project will dictate how extensive your site preparation needs to be. For instance, a small residential project will have very different site preparation requirements than a large commercial building. In addition, the type of soil on the property will influence how much site prep is needed.
For example, open fields with light sand soil may only need minimal mowing to prepare them for planting. On the other hand, recently-harvested sites with slash piles and thickets of undesirable brambles and trees may require more intensive preparation.
Site preparation will also help you minimize the risk of accidents and injuries by removing obstructions from the construction area. For example, mud can be very dangerous for crew members, as it is slippery and difficult to walk on. Furthermore, if it is tracked onto concrete floors and materials, it can damage them. In addition, a muddy site will make it harder to maneuver equipment and trucks, and it can also cause water infiltration within your building, which can lead to problems down the line.
Installing the Formwork
The formwork is the temporary support system in which concrete is poured to take on its shape and gain initial strength. Its construction is usually done on-site using a range of different materials. It is critical that it is sound and able to be reused for future projects, as the cost of new forms can add up quickly.
When selecting a formwork system, the contractor should look at the structural and architectural drawings of the project. They should then consider the form material that will be used, such as boards, plywood or timber girders. Ideally, the boards should be new to avoid rot and ensure that they can support the load. If plywood is used, it should be moisture resistant. It is also important that the formwork is erected to the correct measurements.
Once the formwork has been erected, it must be treated with a release agent to ensure that it does not stick to the concrete when it is poured. A chemical that is typically made from wax, oil or plastic should be applied to the surface of the formwork. Once it has been treated, the formwork should be inspected and certified before it is used to ensure that it will not fail or collapse under its design load.
Modular systems are often lighter weight and require less physical effort to erect than traditional systems. This can reduce the risk of injury to workers erecting, using and dismantling the system. However, they can be susceptible to falling over if they are not properly braced during their erection. It is recommended that a competent designated observer monitor the erection of modular systems and that no one should be underneath them during concrete placement.
Pouring the Repair Material
Even the best designed facilities do not last forever and 大規模修繕 work is a necessity. Unfortunately, we often see repairs implemented that do not meet code requirements for structural loadings and exposures as well as do not address the harsh operational demands that transfer stations are subjected to.
The selection of repair materials is one of the most critical components in any large-scale concrete repairs project. The material used must be compatible with the existing concrete and have excellent bond strength, dimensional stability, freeze-thaw resistance, and abrasion resistance. There are many repair products available, each with their own advantages and disadvantages. Generally, the most appropriate repair product is one that is both Portland cement based and contains various polymers that enhance its durability and bond strength to the existing concrete structure.
A very good primer or bonding agent should be used prior to pouring the repair material. Sto’s Full-Depth Plus, with integral corrosion inhibitor, is a single-component cement-based repair material for structurally repairing or overlaying deteriorated concrete. It can be utilized in both form & pump and form & pour applications. It can be used at up to a 4-in. depth and is suitable for use on both horizontal or vertical/overhead concrete repairs.
When pouring the concrete, it is important to use a good quality ready-mix truck or mobile batch vehicle and properly mix the repair material per manufacturer specifications. This is necessary to ensure that the water-to-cement ratio falls within acceptable limits. It is also important to achieve proper concrete consolidation around the dowel bars and along the patch perimeter. This will reduce honeycombing that can decrease concrete strength and durability.
Pumping
The pump is a mechanical device used to move liquids, or sometimes slurries, by mechanical action converted into hydraulic energy. The Freyssinet group can offer its services as a general contractor or subcontractor, executing large scale repair works on tunnels or other civil structures such as bridges and flyovers. The large-scale renovations are usually carried out based on urgency rather than the complete inventory of the deteriorated surfaces; a program such as RMI (Remodeling Index) helps to determine which areas need urgent repair.
Many facilities implement short term or patch style repairs to keep operational, maintain environmental containment requirements and to keep customers happy. These type of repairs may work for the code prescribed loads and exposures, but if the underlying problem is not addressed they will expand and create much larger problems and costs down the road.
Developing long-term maintenance and repair plans and building in sufficient funding to cover these renovations is the best way to maintain the value and durability of a complex or apartment complex. This will allow the owner to keep up with renovations, preventing damage and premature aging. This also allows owners to have a reserve fund that can be used for larger renovations when the time comes.
