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

The use of lightweight materials in the pavement structure could be a potential solution to reduce the burden of the pavement on the roadbed, especially over weak soils, hence alleviating potential rutting and other forms of distresses. Evaluating the feasibility of such materials to perform compared with traditional materials is necessary. This will involve both field and laboratory testing to provide relevant information for its application. As part of the field evaluation, a design that incorporated the use of Lightweight Cellular Concrete (LCC) as a subbase alternative in the pavement structure was developed and constructed. A shoulder, also serving as a bus stop which experienced severe rutting and cracking was selected as a potential location. The design of the shoulder included three sections with one control section constituting Granular B as subbase material and two LCC sections with different LCC thickness of 250mm and 350mm respectively 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 1.55Mpa and 1.60Mpa for the 250mm and 350mm sections respectively. Temperature profile depicted higher temperatures within and below the LCC sections compared with the controlled sections, portraying LCC insulation properties. Higher moisture conditions were generally found underneath the control section than the LCC sections. In general, data from all installed sensors including pressure cells and strain gauges, in addition to results already discussed will also to be presented in this paper.