Hardscapes - Segmental Concrete Blocks
About Segmental Concrete Blocks
Segmental Concrete Blocks on the Rise
| It was not until the mid-1980s when constructing retaining walls took a turn. Commercial and institutional site developments traditionally constructed retaining walls using stone, poured-in-place reinforced concrete, H-pile walls with wood lagging, regular mortared concrete block, and new or used timber railroad ties. For decades the most popular of these was definitely the poured-in-place reinforced concrete wall. However, since the mid-1980’s, a different kind of method has been rapidly on the rise. Owners are now increasingly choosing the segmental concrete block approach. Estimates show that because of cost and aesthetic advantages, the use of segmental concrete blocks has grown 20-30% per year in the past several years. |
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Segmental Blocks
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Segmental concrete blocks are designed to readily interlock with adjacent blocks, with no need for a mason to mortar the blocks together. All blocks are made of concrete and have a standardized shape, are effortlessly stackable, easy to interconnect, come in a variety of textures and colors, and are also quiet attractive. Normally a segmental concrete block is about 6-10 inches high, 16-18 inches wide, 10-24 inches deep and weighs around 68-120 pounds, light enough for one person to lift it into position unaided. |
The appearance of a segmental retaining wall is appealing. Rather than a plain, homogeneous poured-in-place wall, the architect or engineer can have a variety of block shapes, sizes, colors and surface textures to choose from. Manufacturers can add dye to the cement used in making blocks to give colors like charcoal, gray or different shades of reds and earthy browns. Green and blue blocks can also be created, but are less common. Colors increase the cost of the block by around 10-20%.
| There are a variety of segmental concrete block surface textures. The straight-face block has a coarse, attractive texture. The tri face or beveled-face block has a piece of the block beveled off at each corner of the face, making for a deeply textured, shadowed wall. Then there’s the striated segmental block, which has a sequence of deep, vertical parallel lines on its surface. Manufacturers are continuing the trend of creating aesthetically pleasing, nicer-looking block faces. |
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Stacking the blocks is simply placing one block on top of the formerly laid course of blocks, then inserting a sturdy pin into the prefabricated holes on the top and bottom surfaces of the interfacing blocks. While some blocks need pins to connect adjacent blocks together, others rely on a lip or on the blocks weight to stay firm in position. Segmental concrete blocks can be purchased from a local concrete-block manufacturer in order to keep transportation costs to a minimum. |
Dramatic Cost Savings
| The reason why segmental concrete blocks are quickly developing and gaining popularity is because they are faster to build for less than half the cost. The truth is, a lot less concrete is used as opposed to the cast-in-place wall where concrete accounts for 50% of the total cost. Also, reinforcing steel is eliminated, less labor is required and it’s less expensive since there is no need for costly carpenters to construct and remove from work, nor for iron workers to place reinforcing steel. |
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The other advantage is that using segmental concrete blocks is faster since workers don’t have to wait seven days for concrete curing, and then return to the job site to strip off from work and backfill. The fact that these walls last up to 75 years is rather encouraging too.
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