Subgrade stabilization in Santa Ana parking lot with MIRAFI RSi

Overview

Rancho Santiago Community College District undertook a parking lot expansion in the spring of 2014 at Santa Ana College in Santa Ana, California. The improvement projects, which included upgrades to parking lot and fire lane pavements, incorporated MIRAFI® RS380i. The high-performance geotextile was used to reduce pavement thickness and prevent conflicts between over-excavation, grading, and existing underground utilities.

Challenge

The Geotechnical Engineer, Geo-Advantec of San Dimas, California, designed the pavement sections for both the parking lots and fire lanes. Each section included concrete pavers underlain by bedding sand and a geotextile layer. One paver section was installed over Asphalt Concrete (AC), while the other was constructed on Portland Cement Concrete (PCC).

The on-site native subgrade consisted primarily of slightly sandy silty clays and clays. Due to the high moisture content of these clayey soils, soil pumping during the required compaction process was anticipated. To address this, Geo-Advantec recommended the use of a Subgrade Enhancement Geotextile (SEG).

MIRAFI^® RS380i was selected and placed beneath the Class II base layer in both the AC and PCC pavement sections. Its purpose was to stabilize the subgrade, provide separation between the soft subgrade fines and the base material, and reduce the overall thickness of the pavement structure. This solution allowed the project team to maintain the required pavement performance while minimizing excavation depth. By using MIRAFI RS380i, the district avoided costly utility relocations and accelerated construction timelines – delivering a cost-effective and technically sound pavement solution.

Solution

The inclusion of the MIRAFI RS380i high-strength woven geotextile in the parking lot improvements resulted in significant cost savings for the Rancho Santiago Community College District. These savings were linked to reduced aggregate base requirements, which in turn helped avoid the need to relocate shallow utilities and enabled faster compaction – ultimately expediting construction.

Additionally, the improved pavement structure is expected to require less maintenance over time. This is due to the enhanced performance characteristics provided by MIRAFI RS380i, including subgrade reinforcement, separation, confinement, and filtration. Together, these properties contribute to reduced susceptibility to cracking and pavement failures, delivering a more durable, long-lasting solution.

MIRAFI® RS380i allowed for reduced base thickness, improving compaction and accelerating the construction timeline.

The geotextile layer was placed to avoid over-excavation and protect existing underground utilities during pavement construction.

MIRAFI® RS380i was installed beneath the Class II base layers in both AC and PCC pavement sections to reinforce subgrade and provide separation

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