Validating the Effectiveness of Concentrated Liquid Stabilizers
I. Research Problem Statement:
When roadways are to be maintained or reconstructed, but poorer materials are encountered where there is higher clay content and higher plasticity index, a more intensive approach is often required. Current approaches are to subexcavate the poor material and replace it with better material, integrate gravel or stone into the base, use geosynthetic materials to provide stability, stabilize with enzymes, or to chemically treat the poor material with cementitious materials. Another method, when the poorer material is comprised specifically of clay, is to permanently stabilize it with ionic stabilizers called Concentrated Liquid Stabilizers (CLS). Formerly called Sulphonated Petroleum Products, CLSs have been used since the early 1960's, but have been only recently been reintroduced into the United States. Manufacturer and vendor marketing claims are that CLSs have the ability to permanently stabilize poorer clay roads for up to 20 years. Although this product category was initially developed in the United States, most investigations of this product category have been done is South Africa. These studies have been structured as best as they could, but they predominantly have been ad hoc in nature with limited oversight, funding, and quality control. The results therefore are mixed and reflect this confusion, which leads to improper use or refusal to use CLSs because of questionable results. Therefore, claims of the manufacturer and vendor marketing remain unverified. A carefully controlled study is needed to verify and validate the effectiveness of the available CLS products.
II. Research Objective:
This research need statement proposes a carefully controlled application of at least five CLSs on unsurfaced roads with five different soil conditions of varying levels of clay and plasticity. Each site should also have an untreated control section. These roadway sections should be regraded, reshaped, and recompacted following the proper gravel road construction practices but should incorporate the CLSs into the roadway material. A final thin aggregate surface layer should also be placed to provide for adequate traction. The study is proposed to be done in cooperation with potentially the Federal Highway Administration, the Bureau of Indian Affairs, the Tribal Technical Assistance Program, the Navajo Nation, and Apache County, Arizona. While initial contacts have been made over the past several years as this has been discussed and developed, new contacts, commitments, and agreements will probably be needed as personnel have changed. The process should include the following steps: (1) Identification of five locations that cover a range of poorer material quality, but that each has a uniform soil type for a minimum of three miles (5 products plus 1 control at 1/2 mile each). (2) Obtain agency agreement for each location to cooperate for a minimum period of five years. These agencies will provide needed equipment of road graders, water trucks, compactors, personnel and supervision to execute the work using good engineering and construction practices. (3) Incorporation of five different CLSs each on a minimum of one-half mile of unpaved roads according to each manufacture's recommendation. (4) Provide soil samples and their analysis of each of the test sites prior to performing any work. Soils at each site should be tested for california bearing ration (CBR) prior to any work being performed, prior to the application of the products, after the application of the products, and at three months, six months, nine months, twelve months, eighteen months, twenty-four months, thirty-six months, forty-eight months and sixty months after the product is applied. The lead agency will provide soil test reports and conduct dynamic cone penetrometer (DCP)/CBR measurements. (5) Summarize the results of the tests after twelve months to document the short-term results that will give direction to agencies as to which products work best in each of the soils. A final report should be prepared after the sixtieth month. The final report should document the effectiveness of the CLS products, show the process to use to identify which material is best suited to CLS treatment, what material attribute results are needed, what CLS works best for each type of poorer clay material, how to design or specify the proper application, how to measure the success of the application, document each product's cost-effectiveness, and how to best use SPPS in the overall management and maintenance program.
III. Potential Benefits:
This work is expected to benefit all low-volume unsurfaced road owner agencies by providing specific options to treat high clay content and high plasticity index soils. These options would be available for county engineers, maintenance professionals, planners, designers, and managers to employ in providing a cost-effective, durable, long lasting, quality road where poor quality materials exist to benefit the traveling public.
IV. RELATIONSHIPS TO THE EXISTING BODY OF KNOWLEDGE:
Little scientific work exists to support the claims of the manufacturers. Three studies are identified as follows: (1) Bolander, Peter, ed. Dust Palliative Application and Selection Guide. Project Report. 9977-1207-SDTDC. US Department of Agriculture, Forest Service, San Dimas Technology and Development Center, San Dimas, CA: 28 p. November 1999. (2) Evaluation of Sulphonated Petroleum Products as Soil Stabilisers and Compaction Aids, P. A. K. Greening (TRL) and P. Page-Green (CSIR Transportek), Project Report T PR/INT/267/03. (3) A Comparative Study of the Performance of the Soil Stabilizers in Secondary Unsurfaced Roads in Paraguay, World Bank, March 2002.
V. FOLLOW-ON AND IMPLEMENTATION ACTIVITIES:
This research supports the mission of the Road Dust Institute to advance the State-of-the-Practice in dust control and soil stabilization.
VI. ESTIMATED FUNDING REQUIREMENTS:
The estimated cost will be about $400,000 over a five-year period.