A typical rehabilitation alternative of roadways that have reached their serviceability level is the construction of asphalt concrete (ac) overlays on either rigid or flexible pavements. However, overlays constructed with conventional ac tend to reflect the cracking and jointing patterns of existing pavements a short time after their placement. Other typical distresses observed in conventional ac mixtures are fatigue cracking, stripping, and moisture damage. A manganese-based ac additive (cti-101, chemkrete) has been claimed to minimize some of these problems. The ohio chemkrete test section was builtat a location subjected to average climatic and traffic conditions.Whether the additive led to any beneficial performance gains or, atleast, to equal performance for the same cost of conventional ac overlays was studied. The study compared condition surveys (consistingof pavement condition rating and crack surveys), dynaflect deflection measurements, and laboratory testing of field-procured specimens that obtained values of resilient modulus, marshall stability, indirect tensile strength, fracture toughness, creep compliance, and fatigue. Results of laboratory tests performed on field-procured cores indicated better performance by conventional ac specimens than by thechemkrete-treated specimens. On the basis of results of core testing, vesys iii computer model rut depth calculations predicted that rut depths would be approximately twice the magnitude along the chemkrete-treated section than along the control section. Dynaflect deflection measurements indicated a slightly better performance on the control section than on the chemkrete-treated section. No significant gains in the engineering properties of ac mixtures are obtained with the addition of chemkrete. This paper appears in transportation research record no. 1269, Asphalt mix materials and mixtures 1990.
Samenvatting