Lightweight Cellular Concrete as a Subbase Alternative in Pavements: Instrumentation plan, Installation and Preliminary results

The use of Lightweight Cellular Concrete (LCC) in the pavement structure is a potential solution to reducing the burden of the pavement on the roadbed, especially over weak soils, hence alleviating potential rutting and other forms of distress. Evaluating the performance feasibility of such materials is necessary, especially in comparison to traditional materials. This will involve both field and laboratory evaluation to provide relevant information for its application. As part of the field evaluation, a design that incorporated LCC as a subbase alternative in the pavement structure was developed and constructed. A shoulder bus stop which experienced severe rutting and cracking was selected as a trial location. The design of the trial included one control section constituting Granular B as subbase material and two LCC sections with LCC thicknesses of 250mm and 350mm as subbase material. Subsurface instrumentation was installed in each layer of the three sections including strain gauges, pressure cells, moisture probes, maturity sensors, and temperature strings. A weather station consisting of a rain gauge and solar radiation shield was also installed at the location of the trial section to monitor weather events. The instrumentation has been monitored to obtain information about the trial section with LCC and compare with the traditional Granular B material. Readings from the maturity sensors indicated that the concrete hydration process peaked at about twelve hours for both LCC sections and depicted a 28-day compressive strength of 1.67MPa and an ultimate strength estimated to reach 2.20MPa and 2.02MPa for the LCC 350 and 250 sections respectively. Temperature profiles indicated higher temperatures within and below the LCC layers compared to the control section, portraying LCC insulation properties. Moisture conditions were generally found to be saturated for all layers in all section during the preliminary study period. In general, data from all installed sensors including pressure cells and strain gauges, in addition to results already discussed are presented in this paper.