delta ring meaning in English

护木卡环
三角形密封环

Test for filler aggregate used in bituminous mixtures - delta ring and ball test
沥青混合料用填充集料试验.三角环和球试验
Tests for filler aggregate used in bituminous mixtures - part 1 : delta ring and ball test
沥青混合料中用填充骨料的试验.第1部分:三角环和球试验
Tests for filler aggregate used in bituminous mixtures - part 1 : delta ring and ball test ; german version en 13179 - 1 : 2000
沥青混合物用填充集料的试验.第1部分:三角环和球试验