{"id":4660,"date":"2026-06-23T17:51:42","date_gmt":"2026-06-23T09:51:42","guid":{"rendered":"https:\/\/www.nlscientific.com\/cbr-test-astm-d1883-bs-1377-4\/"},"modified":"2026-06-23T17:52:48","modified_gmt":"2026-06-23T09:52:48","slug":"cbr-test-astm-d1883-bs-1377-4","status":"publish","type":"post","link":"https:\/\/www.nlscientific.com\/en_ph\/cbr-test-astm-d1883-bs-1377-4\/","title":{"rendered":"CBR Test (ASTM D1883 \/ BS 1377-4): Method, Apparatus &#038; Values"},"content":{"rendered":"<p>The <strong>California Bearing Ratio (CBR) test<\/strong> rates the strength of subgrade, sub-base and base materials and is a primary input to flexible pavement thickness design.<\/p>\n<h2>What the Test Measures<\/h2>\n<p>CBR compares the load needed to push a standard plunger into the compacted soil against the load for the same penetration into a standard crushed-stone reference. It is expressed as a percentage; higher CBR means a stronger, stiffer layer.<\/p>\n<h2>Apparatus Required<\/h2>\n<ul>\n<li>CBR loading frame with plunger and load\/penetration measurement<\/li>\n<li>CBR moulds, surcharge weights and soaking tank<\/li>\n<li>Compaction rammer and density equipment<\/li>\n<li>Dial gauges or transducers for penetration<\/li>\n<\/ul>\n<p>NL Scientific manufactures the <a href=\"https:\/\/www.nlscientific.com\/en_ph\/product\/eco-smartz-advance-cbr-marshall-loading-frame-50-kn\/\">ECO-SMARTZ Advance CBR \/ Marshall Loading Frame 50 kN<\/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>Compact the soil into the CBR mould at the required density and moisture.<\/li>\n<li>Apply surcharge weights and, where specified, soak the specimen (commonly 4 days) recording swell.<\/li>\n<li>Place the mould in the loading frame and seat the plunger.<\/li>\n<li>Penetrate at 1.27 mm\/min, recording load at standard penetrations.<\/li>\n<li>Read the loads at 2.5 mm and 5.0 mm penetration.<\/li>\n<\/ol>\n<h2>Calculation &amp; Reporting<\/h2>\n<p><strong>CBR (%) = (Test load &divide; Standard load) &times; 100<\/strong> at 2.5 mm and 5.0 mm; report the higher value. Standard loads are 13.24 kN (2.5 mm) and 19.96 kN (5.0 mm).<\/p>\n<h2>Acceptance Criteria<\/h2>\n<p>Subgrade CBR often ranges from 2\u201310% for clays up to 30%+ for granular sub-base, with minimums set by the pavement design method. Soaked CBR is normally specified to represent worst-case moisture.<\/p>\n<h2>Frequently Asked Questions<\/h2>\n<h3>Why is the specimen soaked?<\/h3>\n<p>Soaking simulates the weakest in-service moisture condition, giving a conservative design value and a measure of swell potential.<\/p>\n<h3>Can the same frame run Marshall tests?<\/h3>\n<p>Yes \u2014 a combined CBR\/Marshall loading frame runs both at their required rates, which is efficient for combined soil and asphalt laboratories.<\/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>The California Bearing Ratio (CBR) test to ASTM D1883 \/ BS 1377-4: apparatus, procedure, calculation and typical subgrade values.<\/p>","protected":false},"author":1,"featured_media":1836,"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-4660","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\/4660","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=4660"}],"version-history":[{"count":1,"href":"https:\/\/www.nlscientific.com\/en_ph\/wp-json\/wp\/v2\/posts\/4660\/revisions"}],"predecessor-version":[{"id":4665,"href":"https:\/\/www.nlscientific.com\/en_ph\/wp-json\/wp\/v2\/posts\/4660\/revisions\/4665"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.nlscientific.com\/en_ph\/wp-json\/wp\/v2\/media\/1836"}],"wp:attachment":[{"href":"https:\/\/www.nlscientific.com\/en_ph\/wp-json\/wp\/v2\/media?parent=4660"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.nlscientific.com\/en_ph\/wp-json\/wp\/v2\/categories?post=4660"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.nlscientific.com\/en_ph\/wp-json\/wp\/v2\/tags?post=4660"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}