KEC Polished Concrete Floors

This project has a polished concrete slab as the floor finish in many of the rooms including the classrooms and hallways.  Since the polished concrete slab is the finished flooring, it can not be patched later so it is very more important to make sure the work is fully coordinated prior to placing the slabs.  It is also important to pre-plan the slab pour with the structural engineer and the concrete subcontractors along with the subcontractors that have work installed below the slab.  When concrete cures it is subject to many many variables and therefore no two concrete pours are quite the same.  Concrete is also subject to cracking due to many many variables.  While it is impossible to prevent slab cracks, there are lots of ways to minimize and control cracks.  Polished concrete floors look really great when they are done right, but even the best slabs will crack, that is a nature of the product and part of the look.

Polished concrete floors are a sustainable floor option for the following reasons:

1. A concrete slab is a required element for almost all construction projects and polishing the slab as the finished floor does not require the harvest, manufacture, and transport of additional materials such as wood flooring, carpet, or vinyl tiles. 
2. There is no finished flooring like carpet, wood, or vinyl on the slab that will need to be replaced in 5 to 10 years.  So you are avoiding the manufacturing and transportation of the new material and removal to a landfill of the existing material.
3. The polished slab is a smooth hard surface that does not trap dust or allergens like a carpet can so a polished concrete floor provides less opportunities for these indoor air quality issues to build up.
4. The reflective nature of polished concrete can assist with added ambient lighting which can reduce the amount of artificial illumination needed. This will help to maximize the natural and artificial lighting and imrpove energy efficiency.
5. Use of passive solar design benefits from exposed concrete slabs which help retain the internal temperature of the building. Using thermal mass as a design element will moderate the daily temperature fluctuations, and reduce the load on HVAC systems.
6. The mix design for this slab on grade includes Ground Granulated Blast Furnace Slag (GGBFS).  This is a by-product of energy plants that used to be sent to landfills but is now used in concrete mixes to supplement the cement.  This increases the amount of recycled content in the concrete mix, diverts materials from landfills, and reduces the amount of cement and therefore embodied energy in the concrete mix.

Source International Polished Concrete Institute

Below is a mock-up that was prepared for the KEC showing the look of this polished slab.  This slab was first ground down to expose the aggregate in the concrete mix.  The surface is then polished using a multi-step polishing process to give it a glossy finished look.

Here is a sample video demonstration of the concrete grinding and polishing process.  Note this demonstration was not performed at the KEC or by the company doing the KEC, it is simply for reference of the typical process.