From the September 2016 issue of HealthCare Business News magazine
Types of concrete and methods of installation
Poured-in-place regular (conventional) weight concrete (147 pounds per cubic foot, pcf, density) is the most common type of concrete used for radiation shielding. It is relatively inexpensive and, like other forms of concrete, has high structural properties. It can, however, require a substantial amount of space, depending on the shielding requirements. Fortunately, there are other types of concrete and methods of installation that can offset this limitation. Heavy (high-density) concrete has superior shielding properties and requires significantly less space than regular weight concrete. Heavy concrete can achieve in-place densities ranging from 148 pcf to more than 330 pcf.
In addition to the traditional poured-in-place method, pre-manufactured modular concrete shield block units are available which can be stacked to create effective shielding systems. Modular concrete block is available as both conventional and heavy concrete formulations. With its wide array of product types and installation methods, it’s easy to understand why concrete is the most common and versatile radiation shielding material in use today.
Benefits of different concrete systems
There is no “one-type-fits-all” approach when it comes to selecting the best concrete shielding system for a project. Poured-in-place, regular-density concrete is a common approach, primarily due to its familiarity of use as a general building material. A treatment room (also referred to as a vault or bunker) is essentially a small building, and poured-in-place conventional concrete shielding is often selected due to availability and ease of construction. In many markets, regular density concrete offers a relatively low-cost shielding option. Finally, poured-in-place concrete is structural by design and can be readily adapted to a variety of seismic locations.
Heavy concrete has all the ease of construction and structural advantages of regular-density concrete and requires less space, which reduces excavation and foundation costs. The use of high-density concrete can effectively reduce the wall and/or ceiling thickness by up to 55 percent compared to regular concrete. This significantly reduces the footprint of the shielding barriers, thereby freeing up space for other profit-generating and/or patient enhancement uses.
In locations where space is limited or obstructions need to be worked around, high-density concrete can provide the appropriate amount of shielding in that limited space. Heavy concrete can be poured, pumped, conveyed or placed with concrete buckets for delivery where needed. While heavy concrete consists of select raw materials that are higher in cost compared to regular concrete, the batching and placement processes utilize the same methods and a lower overall volume of material is required. Therefore, the cost increase can be limited to the cost of the select materials.
