High water content in dredged silt leads to elevated costs for drying and solidification. By fully utilizing the porous water absorption of Expanded Perlite (EP), we can locally separate free water from the silt, resulting in an uneven water distribution and creating a silt-water separation solidification environment. Experimental results indicate that incorporating EP with silt can effectively enhance the unconfined compressive strength (UCS) of the solidified silt, but the method of incorporation affects the rate of strength increase and pore distribution. The stewing method, which involves pre-mixing EP into the silt and then adding cement after 24 hours, proves most favorable for promoting the solidification effect. After 28 days of curing, the strength of the stewing sample is 1.56 times that of the sample directly solidified with cement after EP incorporation, and 2.15 times that of the sample solidified with cement only. This indicates that the local silt-water separation effect facilitated by EP can effectively enhance the strength of the solidified silt. Meanwhile, hydration heat test results show that EP promotes cement hydration. According to the pore distribution curve and surface morphology images of EP-silt-solidified soil, while EP introduces porosity, it also provides growth space for hydration products, resulting in an embedded bond that forms a solidified soil skeleton between the interface of silt and EP. The method of regulating water content using EP is a physical one, which is convenient and efficient, differing from energy-intensive methods like machinery. Additionally, as a high-silica lightweight aggregate, EP exhibits good compatibility with silt and is environmentally friendly.

Perlite is a volcanic glass that, under thermal treatment, expands, producing a highly porous and lightweight granular material which finds application in the construction, horticulture, insulation and other industrial sectors. Proper control of the feed properties and the expansion conditions allows the production of purpose-oriented grades, while the primary evaluation of its appropriateness for use in each sector is performed by the proper characterization of relevant physical, thermal or/and mechanical properties. However, due to its extreme fineness, low density, and friability, most of the available characterization methods either fail in testing or provide erroneous results, while for certain properties of interest, a method is still missing. As a consequence, the way towards the evaluation of the material is rife with uncertainties, while a well-defined methodology for the characterization of the critical properties is of practical importance towards the establishment of a pathway for its proper analysis and assessment. This article presents the available methodology for determining the main properties of interest, i.e., the size and density, water repellency/absorption and oil absorption, the microstructural composition, crushing and abrasion resistance and isostatic crushing strength, and also sampling and size reduction processes. The issues raised by the application of existing methods are analyzed and discussed, ending up to a proper methodology for the characterization of each property, based on the long-term experience of the Perlite Institute. The study is supplemented by updated insights on ore genesis, physicochemical properties, mineralogical composition and the expansion mechanism, as background information for the sufficient comprehension of the nature and properties of perlite.