Experimental study on the development of strength and modulus of elasticity of cement-treated aggregate base (CTAB) materials was undertaken. Unconfined uniaxial compression tests were conducted with 189 samples for 16 CTAB mixtures at different ages. Two different aggregates, conventional crushed limestone base and recycled concrete materials, were used in the test program. Using the test results, equations were proposed to estimate the development of compressive strength and modulus of elasticity of CTAB materials with time. Test results indicated that the relationship between the compressive strength and elastic modulus of CTAB materials could be expressed in a single equation regardless of aggregate type and mixture proportions.

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The need for faster, less traffic-disruptive rehabilitation for aging highway infrastructure is an emerging concern for many state highway agencies. In response to this concern, the California Department of Transportation (Caltrans) launched the Long-Life Pavement Rehabilitation Strategies (LLPRS) program in 1998 to rebuild 2,800 lane kilometers of high-volume urban freeway with premium pavements that will last 30+ years and require minimal maintenance over their service life. This paper presents innovative strategies and technologies for achieving faster project completion with less traffic disruption as applied on three experimental LLPRS projects. The research team and the Caltrans project team used Construction Analysis for Pavement Rehabilitation Strategies (CA4PRS) software from the initial planning and design stages to implement the most economical rehabilitation strategies for the projects. The postconstruction analysis of all three LLPRS projects, made with data collected during construction, revealed a close match with the preconstruction schedule estimate generated by CA4PRS, validating the software's scheduling reliability. Incentive-disincentive contractual provisions proved effective for shortening project duration on all three LLPRS projects, which were time critical because of their heavy traffic volume. Resultant traffic data demonstrate the importance of a public outreach campaign that convinced motorists to use alternative routes or to adjust their commuting modes, resulting in significantly lower traffic demand in the construction work zone. The strategies and lessons addressed in this paper will help state highway agencies and contractors maximize construction productivity for early project completion and minimize inconvenience to the traveling public.

Different mathematical models have been developed to represent the relationship between strength and maturity of concrete. The linear relationship between double logarithmic strength and logarithmic maturity can be implemented in practice to monitor the in-place strength gain and time of opening under variable temperature conditions. Moisture of concrete was considered within the context of existing maturity concepts as a means for improving the predictability of concrete strength. A moisture modification factor developed by Bazant on the basis of Powers' work was modified and included in an existing temperature-based maturity model. An improved relationship between relative strength and maturity was established by using the corrected moisture modification factor.

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