Road performance of new modified filter mudcake filling by composite curing agent

Filter mudcakes are produced by filtering and dewatering waste slurries from engineering construction and river dredging. The poor mechanical properties of filter mudcakes make them unsuitable for subgrade filling, but converting them into subgrade filling that meets road engineering requirements solves disposal problems. In this work, the performance of modified filter mudcakes (MFMs) was assessed through the optimisation of curing agents, assessment of engineering characteristics and centrifuge modelling. The solidification effect was found to be greatest when 8% ground granulated blast-furnace slag, 4% quicklime and 1% gypsum were added to the filter mudcake. For this mix, the compressive strength was 2730 kPa after 7 days and the water stability coefficient was 85%. The California bearing ratio of these filter mudcakes was 33.7% at 7 days, and the compression coefficient (<0.1 MPa−1) and the permeability coefficient (5.39 × 10−8 cm/s) both met the specification requirements at a dosage of 4%. As the degree of compaction was increased from 88% to 97%, the final settlement of the new MFM subgrade at the centre decreased from 50.9 mm to 35.4 mm, and that of the shoulder decreased from 42.3 mm to 29.6 mm, meeting specification requirements (<100 mm). The results support the excellent long-term stability and application potential of MFMs as subgrade materials.