{"id":4661,"date":"2026-06-23T17:51:48","date_gmt":"2026-06-23T09:51:48","guid":{"rendered":"https:\/\/www.nlscientific.com\/proctor-compaction-test-astm-d698-d1557\/"},"modified":"2026-06-23T17:51:48","modified_gmt":"2026-06-23T09:51:48","slug":"proctor-compaction-test-astm-d698-d1557","status":"publish","type":"post","link":"https:\/\/www.nlscientific.com\/en_ph\/proctor-compaction-test-astm-d698-d1557\/","title":{"rendered":"Proctor Compaction Test (ASTM D698 \/ D1557): Method &#038; Apparatus"},"content":{"rendered":"<p>The <strong>Proctor compaction test<\/strong> establishes the relationship between a soil&#8217;s moisture content and its dry density, defining the maximum dry density (MDD) and optimum moisture content (OMC) used to control earthworks compaction.<\/p>\n<h2>What the Test Measures<\/h2>\n<p>By compacting soil at several moisture contents with a standard energy, the test produces a moisture-density curve whose peak is the MDD at the OMC. Field compaction is then specified as a percentage of this MDD.<\/p>\n<h2>Apparatus Required<\/h2>\n<ul>\n<li>Compaction mould (1000 cm\u00b3 or CBR mould) and collar<\/li>\n<li>Standard rammer (2.5 kg for D698) or Modified rammer (4.5 kg for D1557)<\/li>\n<li>Balance, drying oven and moisture tins<\/li>\n<li>Straightedge and extruder<\/li>\n<\/ul>\n<p>NL Scientific manufactures the <a href=\"https:\/\/www.nlscientific.com\/en_ph\/product\/proctor-test-apparatus\/\">Proctor Test Apparatus<\/a> and the full <a href=\"https:\/\/www.nlscientific.com\/en_ph\/product-category\/soil\/\">soil testing range<\/a>, built to ASTM, EN, BS and AASHTO requirements with ISO\/IEC 17025 accredited calibration.<\/p>\n<h2>Test Procedure<\/h2>\n<ol>\n<li>Prepare soil at several target moisture contents.<\/li>\n<li>Compact each in the mould in the specified number of layers and blows (3 layers\/Standard, 5 layers\/Modified).<\/li>\n<li>Trim level, weigh the mould to obtain bulk density.<\/li>\n<li>Take samples to determine moisture content.<\/li>\n<li>Plot dry density against moisture content for all points.<\/li>\n<\/ol>\n<h2>Calculation &amp; Reporting<\/h2>\n<p>Compute dry density for each point and plot the curve. The peak gives <strong>maximum dry density (MDD)<\/strong> and the corresponding <strong>optimum moisture content (OMC)<\/strong>.<\/p>\n<h2>Acceptance Criteria<\/h2>\n<p>Earthworks specifications require field density to reach a percentage of MDD (commonly 90\u201398% depending on layer and standard). Modified Proctor gives higher MDD than Standard and is used for heavily loaded layers.<\/p>\n<h2>Frequently Asked Questions<\/h2>\n<h3>Standard vs Modified Proctor \u2014 which to use?<\/h3>\n<p>Modified Proctor (D1557) applies higher compaction energy and suits pavements and heavily loaded fills; Standard (D698) suits general earthworks. The specification dictates which applies.<\/p>\n<h3>Why does dry density fall after the optimum?<\/h3>\n<p>Beyond the OMC, excess pore water carries part of the compaction effort and prevents further densification, so dry density decreases.<\/p>\n<p><em>Need the right equipment for your laboratory?<\/em> <a href=\"https:\/\/www.nlscientific.com\/en_ph\/contact-us\/\">Contact NL Scientific for a quotation<\/a> &mdash; Asia&#8217;s leading manufacturer of civil engineering and material testing equipment, shipping worldwide.<\/p>","protected":false},"excerpt":{"rendered":"<p>Standard and Modified Proctor compaction (ASTM D698 \/ D1557): apparatus, procedure and how to find maximum dry density and optimum moisture content.<\/p>","protected":false},"author":1,"featured_media":3938,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"rank_math_lock_modified_date":false,"footnotes":""},"categories":[164],"tags":[],"class_list":["post-4661","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.nlscientific.com\/en_ph\/wp-json\/wp\/v2\/posts\/4661","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.nlscientific.com\/en_ph\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.nlscientific.com\/en_ph\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.nlscientific.com\/en_ph\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.nlscientific.com\/en_ph\/wp-json\/wp\/v2\/comments?post=4661"}],"version-history":[{"count":0,"href":"https:\/\/www.nlscientific.com\/en_ph\/wp-json\/wp\/v2\/posts\/4661\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.nlscientific.com\/en_ph\/wp-json\/wp\/v2\/media\/3938"}],"wp:attachment":[{"href":"https:\/\/www.nlscientific.com\/en_ph\/wp-json\/wp\/v2\/media?parent=4661"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.nlscientific.com\/en_ph\/wp-json\/wp\/v2\/categories?post=4661"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.nlscientific.com\/en_ph\/wp-json\/wp\/v2\/tags?post=4661"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}