| With the continuous increase of urban construction scale in China,a large number of engineering residues(ER)are piled up,and the vigorous development of Mines leads to a large number of tailings,which are difficult to settle and manage.These bulk solid wastes lead to a series of problems such as resource waste and environmental pollution.Since there are many fine particles in their composition,it is difficult to dispose them as resource at large scale.In this paper,the high-efficiency binding materials for fine particles were used,namely the soil solidifying agent(SSA)for ER and tail solidifying agent(TSA)for iron ore tail(IOT),and they were made based on blast furnace slag(BFS).The ER and IOT were developed into non fired ceramicite(NFC)by both methods of high-pressure compaction forming(HPCF)and high-pressure roll forming(HPRF).The NFC prepared was aimed to replace the natural aggregates(such as sand and gravel)urgently needed in concrete processing.The performance of permeable concrete(PC)prepared by NFC of IOT was systematically investigated.Firstly,the SSA specimens was prepared using BFS powder,fly ash,as well as P.O 42.5cement and sulfate activator as raw materials,and the TSA specimens was prepared using BFS powder,fly ash,as well as P.O 42.5 cement and alkaline activator as raw materials.Then the NFC specimens of ER were prepared using shield sludge of Ningbo and SSA as raw materials,and The NFC specimens of IOT were prepared using IOT and TSA as raw materials.The NFC specimens were prepared by the method of HPCF.After the systematical characterization on the properties of the resulting specimens of NFC of ER,it was found that the compressive strength(CS)of the resulting specimens was increased with the increase of the content of SSA.As the binder-soil ratio(i.e.the mass ratio of SSA to ER)being 1:4 and the molding pressure being 10 MPa,the 28 d CS value of the resulting specimens of NFC of ER was 18.42 MPa,it was increased by 51.2%as compared with that using P.O 42.5 cement as binder and other conditions being same.The softening coefficient(0.72～0.90)of resulting specimens of NFS of ER was decreased with the decrease of binder-soil ratio(from1:4 to 1:8).The CS value of resulting specimens of NFC of IOT was increased with the increase of TSA content.As the binder-tail ratio(i.e.the mass ratio of TSA to IOT)being1:4 and the molding pressure being 10 MPa,the 28 d CS value of resulting specimen of NFC of IOT was 28.31 MPa,It was increased by 110.5%as compared with that using P.O 42.5cement as binder and other conditions being same.The softening coefficient(0.83～0.97)of resulting specimens of NFC of IOT was decreased with the decrease of binder-tail ratio(from1:4 to 1:8).Secondly,the specimens of NFC were prepared using the method of HPRF,and the resulting specimens of NFC of ER was using the SSA as binding materials,while that of IOT was using the TSA as binding materials.In the preparation of specimens of NFC of ER,it was found that the barrel pressure strength(BPS)of the resulting specimens with various curing age was increased with the increase of binder-soil ratio.It was increased by 108.1%for specimen of NFC of ER with binder-soil ratio being 1:4 as compared with that with binder-soil ratio being 1:10,and it was increased by 70.9%for that of IOT with binder-tail ratio being 1:4 as compared with that with binder-tail ratio being 1:10.The above mentioned specimens had the same curing age of 28 d.The increase of the curing temperature could accelerate the hydration reaction process of NFC specimen and shorten the curing time.However higher curing temperature could not improve the BPS of NFC specimens of longer curing age since the ettringite in NFC could dissolve as the curing temperature being higher than 65~oC.The water absorption rate of resulting specimens of NFC was decreased with the increase of binder-soil ratio(or binder-tail ratio),and they were 8.37%and 5.12%for specimen of ER and that of IOT with binder-soil ratio(or binder-tail ratio)being 1:4,respectively.The softening coefficient of resulting specimens of NFC was increased with the increase of binder-soil ratio(or binder-tail ratio),and they were 0.85 and 0.92 for specimen of ER and that of IOT with binder-soil ratio(or binder-tail ratio)being 1:4,respectively.Finally,the specimens of PC were prepared using NFC of IOT as aggregate.It was found that the CS value of PC specimens was firstly increased and then decreased with the increase of water-cement ratio.As the water-cement ratio being 0.31,the CS value of 28 d of resulting specimen of PC was 10.23 MPa.The effective porosity of PC specimens was decreased with the increase of water-cement ratio,and its reduction range was increased with the increase of water-cement ratio.As the water-cement ratio being increased from 0.31 to 0.34,the effective porosity of the resulting specimens of PC was decreased from 15.4%to 9.2%.As the water-cement ratio being 0.31,the crash-wear loss rate of the resulting specimen of PC was 14.8%,which was the minimum value among all specimens prepared with variation of water-cement ratio.As the sand was used to replace NFC,it is also found that the CS value of the resulting specimens was firstly increased and then decreased with the increase of sand replace proportion.As the sand replace proportion being 40%,the resulting specimen of PC had the highest value of CS at various curing age,which were 8.44 MPa(3 d),13.65 MPa(7 d)and 22.40 MPa(28 d),respectively.With the increase of the sand replace proportion,the value of crash-wear loss rate(CWLR)of resulting specimens of PC was firstly decreased and then increased.The specimen with sand replace proportion being 40%had the minimum CWLR of 7.6%,and that with the sand replace proportion being 0 had the maximum CWLR of 14.8%among all resulting specimens with various sand replace proportion.The CS value of resulting specimens of PC was firstly increased and then decreased with the increase of dry-wet cycles(DWC).The CS value of resulting specimen with DWC of 10 times was the highest one of 25.8 MPa among all specimens with DWC settlement,which was higher by15.2%than that without DWC.The mass loss rate was only 7.3%for specimen of PC after30 times of DWC settlement,which shows good resistance to DWC for PC with NFC of IOT as its aggregate. |
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