Soil

Industry professionals from throughout the U.S. recently attended a workshop in Arlington, Texas to learn more about the rapidly expanding area of full-depth reclamation (FDR) with cement and soil-cement pavements. The attendees included contractors, equipment and material suppliers, and professional regional cement and pavement promoters.

The program provided an opportunity for discussion on expanding the market for FDR and soil-cement pavements, as well as their construction, short presentations from local promoters on “What Works” in their area, interactive training of a recently developed pavement thickness design program, and a field trip to observe an innovative cement slurry process.

The two-day workshop was sponsored by the Portland Cement Association with the cooperation of the Cement Council of Texas.

The extended drought across the Southeast is causing home foundations to sag and crack, sometimes causing loud pops that the homeowners can hear.

Clay soils that have sustained homes for decades are drying and shrinking, causing sinking foundations, cracking walls and sticking doors. Other effects from excessive drought include collapsed concrete slabs and chimneys that have pulled away from houses.

Contractors are reporting their call volumes up 200 percent. "We have people reporting right now that they are literally hearing the brick crack," said Mark Beckham, owner of foundation repair service Ram Jack of Charlotte. "It holds on as long as it can, then lets go."

The problem can occur anywhere there is a layer of clay beneath a home’s footing. Contractors say they are seeing problems with dwellings of all ages, and that houses on slabs as well as those built over crawl spaces are at risk.

The Portland Cement Association has outlined industry goals to reduce carbon emissions by adopting a three-part approach by 2020. The information is part of PCA’s 2007 Summary Report on Sustainable Manufacturing.

According to the report, the cement industry aims to reduce CO2 emissions by 10 percent below 1990 baseline levels by a) upgrading plants with state-of-the-art equipment; b) improving product formulation to reduce energy of production and minimize the use of natural resources; and c) conducting research and developing new applications for cement and concrete that improve energy efficiency and durability.

A major element of the effort is the recycling of cement kiln dust, or CKD, which is created during the third stage of manufacturing when clinker is formed. Electrostatic and bag filters capture the dust for recycling. The industry recycles more than 75 percent of cement kiln dust — nearly eight million tons each year — directly back into the cement kiln as raw material. Recycling this byproduct also reduces the need for limestone and other raw materials and helps conserve energy. Other uses for CKD include agricultural soil beneficiation and soil stabilization.