Toward Fit-for-Purpose Certification of Road Additives

Abstract

Chemical stabilizers and dust palliatives are widely used in road construction and maintenance to improve the characteristics and performance of available materials for lower dust levels, improved riding quality, reduced gravel loss, and improved all-weather passability. Numerous products are available to the road industry. However, the level of research and the usefulness of the findings differ from product category to product category. In many instances, no effort has been made to quantify the benefits and cost-effectiveness of additives over longer periods of time (e.g., 5 years), and little attempt has been made to compare the performance of treated roads with the performance of untreated roads for reduced gravel loss and reduced maintenance, the two most important factors in unsealed road management. Only limited information on material requirements and application techniques is available, whereas there is minimal information on rejuvenation. This lack of understanding has culminated in general skepticism in the road industry regarding chemical dust control and stabilization with so-called alternative stabilizers. The situation is aggravated by poor marketing, with many sales representatives having no engineering background, little understanding of the road industry, and insufficient information to provide adequate technical backup. Discussions with road authorities and consulting engineers indicated that a “fitfor-purpose” certificate for each product issued by an independent certification body would contribute to confidence in the use of the products. A certification system would also encourage suppliers to conduct appropriate product research. An internationally recognized certification body in South Africa was therefore approached about developing such a certification system, under the guidance of a steering committee with representation from road authorities, consulting engineers, product suppliers, and academia. Unsealed road additive certification is introduced, the development of control tests for certification is detailed, and a procedure for certification is proposed.