“弱环”,是西德沼气专家组近年来在非洲部分国家推广的水压式沼气池中施工新技术。其具体方法为:在拱盖与锥底交界处或拱盖的其它适当部位(如φ=50°),采用水泥:石灰:砂=1:3:15的石灰水泥砂浆砌筑一层厚为5～7cm的石灰水泥砂浆层。施工时,应将“弱环”上表抹光,24小时后,在其上砌筑一层比例为水泥:砂:卵石=1:3:6的混凝土层。 “Weak-ring” is a new technology in the construction of hydraulically activated biogas digesters promoted by West German biogas experts in some countries in Africa in recent years. The concrete method is as follows: lime-cement mortar of cement: lime: sand = 1: 3: 15 is used to build a layer of concrete with the thickness of 5 ~ 7cm lime cement mortar layer. During construction, the table of “weak ring” should be wiped lightly. After 24 hours, a layer of concrete layer with the ratio of cement: sand: pebble = 1: 3: 6 should be masked.