Soil cement yard paving works well for Arizona firm

I UMBERYARDS require extra Ldurability in their pavement surface. Forklift loads may not be unusually heavy, but since forklift tires are quite small and operate under very high tire pressure, the loads transmitted are concentrated. This, together with the tremendous twisting stress created throughout the workday, transmit unusual stresses to the pavement.

The result can be expensive to the yard owner, if not in initial cost of surfacing, then in the hazard and nui sance-and eventual cost of repair-of potholes and chuckholes.

Phoenix-based O'Malley's Building Materials, one of the largest lumber and building materials dealers in the Southwest,has tried a newway of combatting these problems and now, after more than a year of activity on the new surface, the company remains pleased with its decision-

It was to use a sub-base of soil cement for the lumberyard at a new Building Materials Center retail outlet in Buckeye, an agricultural center and suburban community located 36 miles west of Phoenix.

Needed was a high-quality, water impervious durable base for pavement of the two-acre yard. Drainage of heavy rainfall was a major consideration, the object being to avoid minor dish-shaped sections that can hold water even though overall grade is adequate for runoff.

If this retained water penetrates the asphaltic-concrete wearing level on top, and is held in the granular base or sub- grade soil, the base fails resulting in potholes or chuckholes.

Constant application of heavy loads on the area aan aggravate this situation, creating a pumping action that actually draws more water to the deteriorated area.

In this case, the use of soil cement, which is a simple, compacted mixture of in-place native soil, Portland cement and water, provided the desired waterimpervious, slab-like qualities, and also resulted in considerable savings over a conventional granular base.

The savings were realized in construction costs by'eliminating the hauling out of native soil followed by replacement and processing of granular base material. Instead, everything is done in place.

"We are very pleased with the results," says Roberto Sanchez, assistant general manager for O'Malley's.

'We feel soil cement is the thing of the future for lumberyards, because of the cost, and its ability to stand up

Story at a Glance

Proper attention to yard paving initially can save owner lots of money, prevent maintenance headaches later use of soil cement process by Arizona firm proves a winner.

under the kind of twisting and turning stresses that are generated in the yard."

"The next one we build will have soil cement as a base, too," asserts Sanchez.

The first step in application was a simple lab test which determined the exact cement content necessary to provide the required strength and dur' ability for the particular soil conditions.

Next, the contractor (National App' licators, Inc., Phoenix) dispensed the cement in blanket form on the soil using a self-propelled, self-calibrated cement spreading machine.

A self-propelled mixing machine worked the next step, passing over the project area and integrally mixing the soil, cement and water in place. Compaction of soil and cement forces the soil particles together. As the cement hydrates, it fuses them in a spot' welding action, resulting in an extremely hard, durable material.

After final trimming to reach the desired grade of the yard, the soil cement is cured either through repeated applications of moisture for seven days or the application of a bituminous cure seal.

Finally, the wearing level is applied on top. Most frequently used over soil cement is a 2" thickness of asphaltic concrete. However, if initial wear is not expected to be as strong as it will be eventually then further cost savings can be made, as O'Malley's did, by applying a thinner "chip seal" surface which later can be resurfaced to a greater thickness when activity warrants.