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Precast Concrete Bollards Balance Security and Design 07-23-15 | News

Precast Concrete Bollards Balance Security and Design

Concrete bollards restrict vehicle access to public areas

When it comes to outdoor site furnishings, precast concrete products offer a high degree of quality and custom aesthetics to suit any building or landscape design. Precast products use molds, which make for exceptional consistency across a range of individual items"?uand help in planning accurate concrete mixes and volumes. Casting facilities also have the benefit of a clean manufacturing environment to minimize impurities.

Smooth Surfaces
One of the principle benefits of precast concrete is that it can be manipulated to present a range of premium aesthetics. Using different concrete mixes, aggregate selections and processing methods, precast concrete can achieve a range of colors, textures and finishes that would otherwise be difficult, or costly, to achieve through onsite casting.

Concrete is well-known for smooth concrete surfaces, which can be achieved simply by pulling concrete from its form or by applying a light sandblast to further smooth surfaces. Smooth concrete is ideal of utility areas, as it requires minimal additional processing and is conducive to painting. It's also worth noting, however, that smooth finishes are never free from small air voids, or bug eyes, which naturally rise to concrete surfaces during curing.

Pedestrian spaces can be protected by concrete bollards in urban environments.

Depending on the application, these imperfections can be undesirable"?uespecially when they'll be viewed up close. Voids can be removed with additional concrete sacking, but this can be an expensive added process. Light sandblasting will further reveal voids and other imperfections, making them more noticeable.

Exposed aggregate
An alternative to presenting smooth concrete is to remove the layer of binding cement to expose integral aggregate. Exposed aggregate finishes tend to be more uniform and consistent than smooth finishes"?uvirtually eliminating the appearance of voids and other imperfections"?uboth up close and from a distance.

Aggregate materials typically comprise about 60 to70 percent of a concrete mix. They can have a significant effect on the color, appearance and texture of concrete when exposed. A multitude of different aggregate-types can be used to make concrete, offering a range of different colors and textures.

Aggregates can be exposed to different degrees to achieve a range of textures and appearances"?uand to preserve the appearance of binding concrete mix. Light exposure involves sandblasting a concrete surface until aggregates are just visible through the concrete mix, which still maintains a significant presence in the overall appearance of the surface.

Medium exposure removes more of the surface concrete, creating a more balanced aesthetic between aggregate and cement. Deep exposure aims to expose as much aggregate as possible"?uabout a third of each stone or half of the smallest stone size"?uto make it the dominant feature. Aggregates are typically exposed though sandblasting, but chemicals are sometimes used in forms to limit curing of surfaces for easier removal.

A range of Reliance Foundry concrete bollards suit any architectural design

In addition to sandblasting, a range of other processes are available to alter concrete surfaces: acid etching (similar to sandblasting but allows more preservation of color and detail); form liners, which involves modifying forms with additional materials to achieve unique textures; and additional tooling, which is often used to achieve a broken stone aesthetic. Molds can also be modified to incorporate decorative reveals and other textured effects to enhance the overall appearance and uniformity between products.

Depending on the final application, controlling surface finishes can be difficult and costly when implemented onsite. Precast concrete facilities offer more controlled environments for planning and implementing desired finishes"?umany of which would be nearly impossible to achieve otherwise.

Concrete reinforcement
On its own, concrete has exceptional compressive strength but is weak in tension and shear strength"?uespecially when subject to significant forces over time.

Steel is an excellent material for reinforcing concrete. It offers high tension and shear strength"?uespecially when bound within concrete during curing"?uand behaves in a similar manner when exposed to environmental variations such as temperature and humidity.

Steel is economical and readily available to manufacturers across North America. It can also be bent, cut or bound into different shapes to accommodate the range of desired concrete structures"?uand assembled rapidly into formwork and molds. Together, concrete and steel can be used to build structures with incredible strength and durability.

Once installed, integral steel requires minimal maintenance, as the high PH levels of most concrete is sufficient to prevent corrosion. In installations subject to high salt exposure"?ufrom de-icing salts or along coastal waterfronts"?uor where concrete contains low PH levels, a number of alloys and coatings are available to ensure minimal corrosion. Galvanized and stainless steel are highly resistant to rust, and epoxy coatings can isolate materials from oxidation.

Concrete bollards and outdoor site furnishings
Using precast concrete for outdoor site furnishings is an ideal means to creating consistent and unique aesthetics across a building or landscape. Site furnishings typically serve dual purposes"?uproviding functional value while also enhancing visual elements of surrounding areas.

Reliance Foundry specializes in outdoor bollard designs that provide a high degree of security and decorative appeal. Reinforced concrete is an optimal material for bollards, as it offers a high degree of protective strength as well as visual appeal.

The company's bollards have been designed with steel pipe reinforcement for high-impact protection. Pipe lengths are cast directly into bollards and are then embedded deep into ground for maximum strength and to ensure they won't be dislodged in the event of a collision. Pipes are made from structural grade steel to provide exceptional tension and shear strength to withstand vehicle impacts.

Bollards are also manufactured with an exposed aggregate finish suitable for withstanding wear and pollutants of high-traffic urban environments. Aggregates are collected from British Columbia's Fraser Valley"?uemblematic of the Pacific Northwest and suitable for any landscape or architectural style.