Stydy On The Properties Of Non-sintered High Strength Aggregate From Dredged Sediments

In recent years,with the rapid development of economy,the amount of dredged sediment increases every year,and the accumulation of dredged sediment will cause secondary environmental pollution.In the environment of energy saving,energy conservation and emission reduction and sustainable development,the recycling utilization of dredged sediment and solid wastes has become an urgent problem to be solved.In China,excessive mountain mining,quarrying and soil sampling have made many mountains cut into cliffs,resulting in different degrees of damage to the mountain,which seriously affected the ecological environment.The research group is devoted to the study of the utilization of dredged sediment resources and the development of new building materials,which can effectively solve the series of problems caused by dredged sediment.Dredged sediments non-sintered high strength aggregate,which utilized the dredged sediments and composite cementitious material as raw material were manufactured in an un-sintered process.The new technology of preparing single core aggregate,multi core aggregate and more multi-core aggregates was explored.The strength,durability and microstructure of the aggregates with different core shell structures were characterized and the strength mechanism was analyzed.Specific research contents and results are as follows:(1)Determination of physical and chemical properties of dredged sediment.Physical and chemical properties of dredged sediment with different water content were measured.The physical and chemical properties of dredged sediment containing cementing material and sediment containing no cementing material were determined respectively.The results showed that the pH value,density value,bulk density and salt content of the dredged sediment containing the cementitious material increased,the porosity decreased,and the content of organic matter was almost unchanged.With the increase of the moisture content of dredged sediment,its bulk density gradually decreases,and the porosity increases gradually.(2)The optimum ratio of raw materials for preparing un-sintered aggregate from dredged sediment was determined:The adding amount of core cementing material is 10%,the addition amount of shell cementing material is 30%,the type and amount of core adhesive is additive A,the addition amount is 5%,and the shell additive A:C=9:0.5 is the best formula.The obtained aggregate properties were as follows:the bulk density was 859 kg/cm3,the water absorption rate was 8.13%,the cylinder strength was 8.78 MPa,and the mass loss rate after the freeze-thaw cycle was 15.48%.And meet the requirements of GBT17431.1-2010.(3)The preparation process of single core aggregate,multi core aggregate and more multi core aggregate were studied,and its performance was characterized.The particle size of single core aggregate is between 2.36mm-9.5mm,and the diameter of multi core aggregate is between 4.75mm-26.5mm.The maximum particle size of more multi core aggregate can reach 31.5mm.The aggregate strength of the three kinds of aggregates were 6.28 Mpa,7.64 MPa and 8.54 MPa,respectively,and all exceeded the national standard requirements of 6.0 MPa.After 30 freeze-thaw cycles,the mass loss rate of the organic content of the three kinds of aggregates accorded with the national standard.Core aggregate is the lowest,and the mass loss rate is 15.05%.The organic content of the three kinds of aggregates accorded with the national standard.(4)The effects of core shell structure,particle size distribution and particle size on aggregate strength were studied.The results show that the compressive strength of the aggregate decreases with the increase of the size range of aggregate,and the maximum particle size of the aggregate is 16mm,regardless of the continuous grain size or the single particle size.(5)Study on mud reaction of aggregate.The mud reaction mechanism of dredged sediment ball and crushed aggregate was compared,and the mud reaction mechanism was discussed.When the mud ball is soaked in 1h,its spherical structure disappears and is reduced to mud.When the crushed aggregate is soaked for 24h,the soil particles falling from the broken aggregate do not form slurry,and the hydration degree is low.