Keeping Projects on Schedule in Winter
When winter hits, construction sites are susceptible to rain delays that cost both time and money. Project Managers turn to the only proven method for site winterization -- the process of chemically treating the surface soils with lime and/or cement-based reagent. This process is commonly used to provide access to construction sites during the rainy season by making native soils impervious to water.
This type of treatment ensures immediate access to construction sites after a storm event. By reducing the permeability of the soil, treatment reduces the susceptibility of the subgrade to water saturation and soil rutting. An added benefit of this type of soil modification is the vast improvement of the subgrade through increasing the soil strength and decreasing the shrink/swell potential of any clayey material.
Winterization is the changing of soil behavior, principally through the reduction of excess moisture, in order to expedite construction. Winterization is commonly performed on subgrade and sub-base materials in order to expedite compaction and subsequent paving. A wide range of problem soils can be modified with various treatment products to improve behavior. Included in this category are soils with high silt content where reduction of moisture sensitivity can be achieved. Also included are clayey soils, where in addition to reducing excess moisture, the soil texture can be modified using a small percentage of lime and flocculating the clays into a sand-like material that can be easily worked. Unstable, fine-grained sands can also be cemented to form a stable platform. Winterization may involve drying up construction sites and access roads regardless of the in-situ soil types. The common denominator for soil winterization is the improvement of soil behavior. Lime/cement treatment is not only effective, it is also a very efficient winterization approach, permitting other work to proceed without delay.
If drying is required for only a shallow depth (6"-12"), the subgrade soils can be treated and worked in place. Caution should be exercised, however, in areas where water may have collected at greater depths. Such areas may require more treatment product mixed to greater depths (18") for effective bridging. The depth of modification needed to bridge a soft subgrade is generally equivalent to the depth required to stabilize the subgrade by excavation, placement of a geofabric, and backfilling with an aggregate material.
When water is encountered, an evaluation should be made to determine if water is infiltrating from an outside source. If the flow of water is continuous, then dewatering will be required prior to any treatment. Dewatering should be to at least 6 inches below the bottom of treatment to allow for "wicking". If it is determined that the water is only perched, then areas containing any standing water should be pumped prior to treatment.
Contractor ingenuity and experience can usually be relied upon for the appropriate techniques to solve most job site variations. The services of a Geotechnical Engineer may be required, however, on the more complex projects and are recommended on “first time” applications.
Soil modification is an effective and economical technique that expedites construction with generally modest engineering requirements. In most instances, soil modification with various treatment products will correct adverse conditions immediately and permit construction activities to proceed on schedule.
For small projects or isolated areas consider a Dry-Sac - One-ton sack of 50/50 lime and cement mix; User friendly handling; on-the-spot use; immediate availability and will provide a timely and cost-effective solution to constructability problems.