Exposed aggregate concrete will look attractive on driveways, patios and walkways. Pouring finishing and placement starts with spraying the surface with acid to completely wear the concrete. Proper placement methods is required to follow especially in exposed seeding methods if you want to have a long lasting and perfectly designed exposed aggregate concrete in your yard. Moreover, checking the screeds and forms must be done before placement along with the sub grade for its firmness and compactness. It is only after proper seeding of the aggregate the fresh concrete paste is made. Time is the essence in this crucial step.
• Screed checking is done in the same way as for any normal concrete. It must be 1/8 to 3/8 inches low in the seeding. This is because the exposed aggregate concrete will raise the thickness of the final surface. Bull floats are used to smoothen up the concrete however wood is recommended for the initial finish.
• The forms must be set precisely so that the final slab is at proper level and have easy draining ability. Broadcasting or seeding usually begins immediately after the final initial bull float application.
• Broadcasting the aggregate uniformly onto the concrete surface it is then worked out by a sawing motion to ensure proper screed.
Tamping tools and bull floats are usually used but there are modern roller screeds available that are very effective. A final pass is then made using a bull float to ensure complete paste coverage on the embedded aggregate.
Pouring the Concrete
The pouring of concrete must be perfect. Therefore, make sure everything is ready before the truck arrives, the forms are completed, all tools are ready, safety gears are on and the water hose is ready and not dripping.
• When you start pouring, make sure it is consistent. Also, ensure that you lay down the cement uniformly and properly. This will help in easy exposing and the best finish on the exposed aggregate concrete.
• While the concrete is poured properly, you must “rod” the concrete. That means you will have to level it using a screed rod. This will push down the gravels near the top and will raise the “cream” and “fines.”
In the entire process, consistency is the key factor that will ensure a good finish to the exposed aggregate concrete. Therefore, you will need to rod it the same way throughout, bull-float it in the same direction, use the same number of passes and same amount of pressure. Once it is done, apply the releasing agent.
Exposing the Aggregate
After placing the concrete it is time to focus on revealing the decorative aggregate. Care must be taken to expose the top layer only and the rest to remain embedded in the concrete permanently. The rule of thumb is followed and only one-third the diameter of the aggregate material is removed. Contractors may use several exposure methods depending on the size of the project and the look desired in the exposed aggregate concrete.
• Brushing and washing is the oldest and simplest method and does not require special tools or chemical retarders. Spraying water and scrubbing with a broom will wash away the thin layer from the surface mortar.
• Chemical surface retarder is also used by most contractors to expose aggregate slab surface instantly after placing and finishing. This method delays the set to provide flexibility and to remove the cement paste a day after. Scrubbing or pressure washing method may be applied for this purpose.
Abrasive blasting is another process followed to give the proper finish to the exposed aggregate concrete. This method is usually followed after the concrete has hardened and set. Sandblasting or shot blasting process is used for that matter. However, care must be taken not to fracture the surface and this method must be avoided strictly if you want to preserve the shape and color intensity of the aggregate.
About the author: Jessica Curry is a professional writer to share my blogs and ideas about Home improvement, Health, Business and Automotive that will be informative for readers who loves to gain knowledge. ideas. Follow her on social media at Twitter, Google+ and Facebook.