<p><p><strong>Reference(s):</strong></p><p><em>Army and Air Force (1994)<br>Austroads (1998)<br>TRB (1985)</em></p><p><strong>Method Summary</strong></p><p>Phenolphthalein is a color-sensitive indicator and is sprayed on soil to determine the presence of lime or cement in the field or laboratory (Army and Air Force 1994). A reddish-pink color will develop when a stabilizer is presented (pH is equal to or greater than 10) and the presence of the stabilizer and uniformity of the mixing can be verified.</p><p><strong>Accuracy and Precision</strong></p><p>This method provides only an estimate of lime and cement content for depth of treatment.</p><p><strong>Adequacy of Coverage</strong></p><p>It is only used for checking soil locally.</p><p><strong>Implementation Requirements </strong></p><p>Visualizing a reddish‑pink color in soil is a straightforward process requiring minimal training or experience.</p><p><strong>General Comments</strong></p><p>Phenolphthalein indicator solution is useful in distinguishing areas that have been properly treated and untreated areas. It also helps aid in identifying areas where density test samples should be taken.</p></p>