Mark J. Farrow, P.E¹ & Nasir H. Syed²

Water injection stabilization has been used effectively to pre-swell the expansive subgrade soils prior to construction of new aircraft pavement sections and prior to re-construction of widened roadways. This technique has been used beneath new runways, taxiways, holding aprons and shoulders to reduce post-construction differential upward pavement movements. It has also been used beneath the extended limits of widened roadways to prevent excessive differential deflections across the widened sections.

Due to the depth of the expansive soils within the Metroplex, injection stabilization was performed to depths of seven (7) to ten (10) feet. Pre-swell movements (prior to construction) of up to six (6) to eight (8) inches have been achieved by means of injection stabilization.

Due to the variable nature of the subgrade soils along typical roadway, runway and taxiway alignments and the need for rapid acceptance evaluations, the injection process was controlled on the basis of penetrometer values correlated with moisture contents and absorption-pressure-swell rests. This paper presents an overview of the injection stabilization operation and the acceptance criteria used for various projects.