(2) Can the material contain high moisture?
To judge whether this condition is satisfied or not, the liquefaction potential test (LPT) introduced in paragraph 3 should be carried out. Based on the results of the LPT, the material is judged as not liable to liquefy in case that the degree of saturation of the sample after drainage is less than 70%. This test is not applicable for coals or other materials having solid density not higher than 2,000kg/m3.
3 Liquefaction Potential Test (LPD)
3.1 Outline of the test procedure
The principle of the LPT is based on the Proctor/Fagerberg test procedure presented in D.1.3 of the BC Code, by which the TML is determined by assuming that the material having moisture lower than that corresponding to 70% degree of saturation is not liable to liquefy. Based on the same principle, it can be said that the material is not liable to liquefy when it cannot contain moisture corresponding to 70% degree of saturation. In the LPT, the material is made saturated at first and the characteristics of natural drainage is tested to confirm whether the degree of saturation of the material may reach to 70% or not.
To make a sample saturated, water is supplied into the sample in the vessel after vacuuming the air in the void of the sample for 15 minutes. After that, water is drained through the hole having 3.1mm in diameter on the bottom of the vessel for 30 minutes and the degree of saturation is measured. In the case that the degree of saturation is less than 70%, it is judged that the sample is not liable to liquefy.
3.2 Apparatus
The vessel for the LPT consists of three main parts, i.e. the lower vessel, the upper cylinder and the lid, as illustrated in figure 2.
The vessel should be airtight for vacuuming. The plug for the drain hole is designed for preventing blockade of the hole by particles of the sample.
The recommended capacity of the vacuum pump is not less than 100 litres/minute - 300W. For compaction, the compaction hammer for the Proctor/Fagerberg test procedure is used. A set of apparatus for measuring density of solid material and the moisture content, and a suitable weighing instrument are needed (refer to D.1.3.2 of the BC Code).
3.3 Detailed procedure
The procedure can be sequentially grouped into the following steps：
(A) Measurement of the capacity of the lower vessel and density of the solid material.
(B) Preparation of saturated sample and measurement of its weight.
(C) Drainage and measurement of the weight of the sample after drainage.
(D) Measurement of moisture content of the sample after drainage.
