Using alternative subgrade conserves aggregate resources
California is one of the largest users of aggregate for all types of growth and construction in the United States. An example is the 2.5-mi. Santa Monica Boulevard Transit Parkway, between Interstate 405 and Moreno Drive at the Beverly Hills city limits. To execute the $68.5 million paving project, the largest in the City of Los Angeles in a decade, the state mandated that the construction both conserve aggregate commodities as well as reduce the negative impact on traffic flow in the area. Contech Construction Products, Inc., West Chester, OH, provided the answer to the States concerns with Tensar BX1200 Biaxial Geogrid. One layer of the polypropylene reinforcement grid used throughout the entire project allowed reductions in base course thickness and aggregate fill materials over conventionally designed pavement. It enabled project engineers to bridge shallow utilities that otherwise would have required expensive relocation to minimize disturbance of potentially contaminated subgrades from an old rail line. The Tensar reinforced alternative also enabled faster construction time and reduced the impact of traffic disruption on area commuters and businesses. In those areas of poor subgrades, where the contractor was unable to achieve the projects required 95 percent modified proctor on the subgrade, another layer of Tensar created a firm construction platform that mitigated the soft subgrade and reduced over-excavation and recompaction efforts by 50 percent. The new boulevard features three lanes going both east and west, with additional access roads being considered for construction in the north and south.