{"id":4817,"date":"2026-07-11T09:14:46","date_gmt":"2026-07-11T01:14:46","guid":{"rendered":"https:\/\/www.nlscientific.com\/flakiness-elongation-index-test-bs-812-105\/"},"modified":"2026-07-11T09:20:06","modified_gmt":"2026-07-11T01:20:06","slug":"flakiness-elongation-index-test-bs-812-105","status":"publish","type":"post","link":"https:\/\/www.nlscientific.com\/en_ph\/flakiness-elongation-index-test-bs-812-105\/","title":{"rendered":"Flakiness &#038; Elongation Index Test (BS 812-105): Method &#038; Apparatus"},"content":{"rendered":"<p><!-- nleeat --><\/p>\n<div class=\"nl-guide-meta\" style=\"border-left:4px solid #10243e;background:#f4f7fb;padding:12px 16px;margin:0 0 20px;font-size:14px;color:#3d4c60\">Written by the <strong>NL Scientific Engineering Team<\/strong> &middot; Reviewed by our <a href=\"https:\/\/www.nlscientific.com\/en_ph\/certifications\/\">ISO\/IEC 17025 (SAMM 835) accredited<\/a> calibration laboratory &middot; Last updated <strong>11 July 2026<\/strong><\/div>\n<p>The <strong>flakiness and elongation index tests<\/strong> quantify particle shape of coarse aggregate. Flaky (thin) and elongated (long) particles pack poorly, break under compaction and weaken both concrete and asphalt skeletons.<\/p>\n<h2>What the Test Measures<\/h2>\n<p>Flakiness index (FI) is the percentage by mass of particles whose least dimension is less than 0.6 of their nominal size, measured with a slotted thickness gauge. Elongation index (EI) is the percentage whose greatest dimension exceeds 1.8 of nominal size, measured on a length gauge.<\/p>\n<h2>Apparatus Required<\/h2>\n<ul>\n<li>Metal flakiness (thickness) gauge with standard slots, or matching bar sieves<\/li>\n<li>Elongation (length) gauge with fixed pegs<\/li>\n<li>Test sieves to split the sample into size fractions (63&ndash;6.3 mm range)<\/li>\n<li>Balance readable to 0.1% of sample mass<\/li>\n<\/ul>\n<h2>Test Procedure<\/h2>\n<ol>\n<li>Sieve the dried sample into individual size fractions; discard fractions below 6.3 mm and any fraction under 5% of the sample.<\/li>\n<li>For each fraction, attempt to pass every particle through the corresponding gauge slot \u2014 particles passing are flaky.<\/li>\n<li>For elongation, test each particle against the corresponding peg gap \u2014 particles that cannot pass between pegs are elongated.<\/li>\n<li>Weigh flaky and elongated portions per fraction.<\/li>\n<\/ol>\n<h2>Calculation &amp; Reporting<\/h2>\n<p>FI = total mass of flaky particles \/ total sample mass &times; 100; EI likewise. Report per-fraction and combined indices with the fractions tested. (Note: EN 933-3 flakiness uses bar sieves and gives slightly different values \u2014 state the standard.)<\/p>\n<h2>Acceptance Criteria<\/h2>\n<p>Common limits: FI &le; 35 for concrete aggregate, &le; 25&ndash;30 for asphalt wearing courses and &le; 20 for surface dressing chippings; elongation limits typically mirror flakiness. Crushed granite from well-set cone crushers normally achieves FI 15&ndash;25.<\/p>\n<h2>Frequently Asked Questions<\/h2>\n<h3>Why do flaky particles matter in asphalt?<\/h3>\n<p>They orient flat under rollers, block aggregate interlock, and snap under traffic \u2014 raising binder demand and rutting risk. Wearing-course specs therefore carry the tightest shape limits.<\/p>\n<h3>Can flakiness be improved at the quarry?<\/h3>\n<p>Yes \u2014 choke-feeding cone crushers, correct closed-side settings and vertical-shaft impactors in the final stage all reduce flaky output substantially.<\/p>\n<h2>Recommended Apparatus<\/h2>\n<p>NL Scientific manufactures the <a href=\"https:\/\/www.nlscientific.com\/en_ph\/product\/flakiness-thickness-gauge\/\">Flakiness \/ Thickness Gauge<\/a> for this method. Browse the full <a href=\"https:\/\/www.nlscientific.com\/en_ph\/product-category\/aggregate-rock\/\">Aggregate &#038; Rock Testing Equipment<\/a> range or <a href=\"https:\/\/www.nlscientific.com\/en_ph\/contact-us\/\">request a quotation<\/a> from our engineers.<\/p>\n<p><!-- nlfaq --><br \/>\n<script type=\"application\/ld+json\">{\"@context\": \"https:\/\/schema.org\", \"@type\": \"FAQPage\", \"mainEntity\": [{\"@type\": \"Question\", \"name\": \"Why do flaky particles matter in asphalt?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"They orient flat under rollers, block aggregate interlock, and snap under traffic \u2014 raising binder demand and rutting risk. Wearing-course specs therefore carry the tightest shape limits.\"}}, {\"@type\": \"Question\", \"name\": \"Can flakiness be improved at the quarry?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Yes \u2014 choke-feeding cone crushers, correct closed-side settings and vertical-shaft impactors in the final stage all reduce flaky output substantially.\"}}]}<\/script><\/p>","protected":false},"excerpt":{"rendered":"<p>Written by the NL Scientific Engineering Team &middot; Reviewed by our ISO\/IEC 17025 (SAMM 835) accredited calibration laboratory &middot; Last updated 11 July 2026 The flakiness and elongation index tests&hellip;<\/p>","protected":false},"author":1,"featured_media":3745,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[178,164],"tags":[],"class_list":["post-4817","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-aggregate-rock-testing","category-blog"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.nlscientific.com\/en_ph\/wp-json\/wp\/v2\/posts\/4817","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=4817"}],"version-history":[{"count":1,"href":"https:\/\/www.nlscientific.com\/en_ph\/wp-json\/wp\/v2\/posts\/4817\/revisions"}],"predecessor-version":[{"id":4842,"href":"https:\/\/www.nlscientific.com\/en_ph\/wp-json\/wp\/v2\/posts\/4817\/revisions\/4842"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.nlscientific.com\/en_ph\/wp-json\/wp\/v2\/media\/3745"}],"wp:attachment":[{"href":"https:\/\/www.nlscientific.com\/en_ph\/wp-json\/wp\/v2\/media?parent=4817"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.nlscientific.com\/en_ph\/wp-json\/wp\/v2\/categories?post=4817"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.nlscientific.com\/en_ph\/wp-json\/wp\/v2\/tags?post=4817"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}