<p><p><figure id='attachment_856' style='max-width:869px' class='caption aligncenter'><img class="wp-image-856 " style="border: 2px solid #696969;" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Diagram showing a tunnel protection scheme using injected grout under the tunnel to improve the soils underlying the tunnel." width="869" height="869" /><figcaption class='caption-text'> Tunnel Protection Scheme (Illustration courtesy of Munfakh, G.A., 1991. Deep Chemical Injection for Protection of an Old Tunnel, Deep Foundation Improvements: Design, Construction, and Testing, ASTM STP 1089, ASTM International, West Conshohocken, PA)</figcaption></figure></p><p>Chemical grouts are a mixture of materials where all the elements of the grout are a pure solution with no suspended particles. These grouts are used in highly specialized applications such as sealing water intrusions into tunnels or deep excavations to pretreat coarse soils. This technique is applicable to new embankment and roadway construction over unstable soils and stabilization of the pavement working platform.</p><p>