Permeation Grouting using Polyurethane and Acrylate Resins in a Silty SAND (SM); Injection Methods, In-situ Verification Testing Methods and Laboratory Results.-Paper

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The study evaluated polyurethane and acrylate permeation grouting in a large-scale silty sand (SM) soil block designed to represent conditions in Vancouver, British Columbia. Grout was injected through probes in approximately 0.3 m lifts, with pressure, flow, and injected volumes recorded. Performance was assessed using in-situ dynamic cone penetrometer (DCP) testing, laboratory strength tests, and excavation observations.<br /><br />Polyurethane treatment consolidated about 85% of the target zone. Injecting 80 L of resin treated approximately 1.53 m³ of soil—a treatment factor of 4.73. Acrylate consolidated about 95% of its target zone; 57 L of resin (228 L mixed) treated approximately 1.71 m³, a treatment factor of 7.5. Increasing injection pressure modestly increased polyurethane flow but also increased the risk of pressure spikes and soil fracturing. Acrylate flow varied substantially between probes.<br /><br />DCP results showed that polyurethane-treated soil had roughly twice the penetration resistance of untreated soil. Correlations indicated increases of about 33% in SPT blow counts, 133% in California Bearing Ratio, and 80% in estimated bearing capacity. Laboratory unconfined compression and triaxial tests also showed increased strength and bearing capacity, with results suggesting substantial cementation cohesion. Strength varied among samples, partly in association with density and soil conditions. Acrylate treatment produced no measurable DCP resistance increase, and its direct simple shear results were inconclusive.<br /><br />Both treated soils remained unsupported at a face height exceeding 1.2 m after excavation. The authors conclude that the tested polyurethane method shows promise for increasing the bearing capacity of sandy soils, while further testing is needed to quantify its strength characteristics and determine acrylate’s shear performance.

Keywords

polyurethane grouting

acrylate permeation

silty sand

dynamic cone penetrometer

bearing capacity

soil stabilization

in-situ testing

large-scale soil block

Vancouver British Columbia

permeation grout