Transportation
Construction requires transportation! And there is a direct correlation between transportation, weight and environmental impact. Transportation costs are directly related to the weight of concrete products, demonstrating a significant economic advantage when using ESCS lightweight aggregate. The ranges of products that benefit from lower weight include large structural members (girders, beams, walls, hollow-core panels, double tees) to smaller consumer products (precast stair steps, fireplace logs, wall board, and adhered manufactured stone masonry veneer). The following Table includes two trucking studies conducted at a U.S. precast plant. These studies demonstrated that the transportation cost savings were seven times greater than the additional cost of lightweight aggregate used to reduce the concrete density.
Transportation cost savings varies depending on the size and mass of the concrete elements and the distance to transport. However one manufacturer of lightweight concrete wallboard found it economical to ship product to all 48-mainland states from one manufacturing facility.
Fewer trucks in congested cities are not only an environmental necessity but will also generate fewer public complaints. The potential for lower costs may be possible when shipping by rail or barge but is most often realized in trucking where highway loadings are posted.
With ready-mix concrete up to 25% more, lightweight concrete can be delivered to the job site per truckload than with conventional concrete. This also translates into fewer trucks on the roads and around congested construction sites.
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Table 13.1 Analysis of Shipping Costs of Concrete Products * |
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Project Example Number 1 |
Project Example Number 2 |
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Shipping Cost per Truck Load |
$ 1,100 |
$ 1,339 |
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Number of Loads Required Normalweight Lightweight |
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Reduction in Truck Loads: |
431 |
87 |
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Transportation Savings |
287 |
66 |
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Shipping Cost per Load |
144 |
21 |
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Reduction in Truck Loads |
$ 1,100 |
$ 1,339 |
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Transportation Savings: |
x 144 |
x 21 |
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Profit Impact |
$158,400 |
$ 28,119 |
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Less: Premium Cost of lightweight concrete |
$ 158,400 |
$ 28,119 |
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Transportation Cost Savings |
– 17,245 |
– 3,799 |
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by using lightweight concrete |
$ 141,155 |
$ 24,320 |
*Courtesy of Big River Industries, Inc.
Sustainability of the Workforce – Ergonomics
Less weight makes concrete more labor friendly. The best example of lightweight concrete and ergonomics is with concrete masonry. The Center for Infrastructure Research, University of Nebraska at Lincoln reported that long-term problems stem from heavy concrete masonry units. “Some masons must retire early due to the heavy lifting, and many masons experience crippling back and shoulder injuries before retirement”. This continual loss of skilled labor is expensive to replace and can hardly be considered “sustainable or green”.
By reducing the weight of concrete masonry and other concrete products that must be physically handled by labor we enhance the sustainability of our workforce. It is common knowledge that lighter components have a positive effect on constructability. At the same strength, lightweight concrete products are up to 40% lighter than traditional concrete products. Less weight minimizes the physical demands on labor and equipment, resulting in fewer injuries and worker’ compensation claims. Repeatedly lifting less weight extends a worker’s career, and allows women and men to work efficiently.
For example, concrete masonry units that weigh less will increase mason productivity up to 21% on 8x8x16″ units, and 55% on 12x8x16″ units. Increase productivity means earlier completion and lower overhead costs. Even though a mason will lay approximately 20% more wall area in a year, the mason still lifts 15% less weight (about 94 less tons per year). To a similar degree this example applies to most concrete products that must be handled by labor.
Less weight extends equipment life because lighter loads mean less wear and tear and helps insure safer scaffolding and worker platforms. Less weight means it is easier to meet OSHA weight requirements.
ESCS Aggregate/Cement Interface