A Study On The Preparation Research Of One-part Alkali-activated Nickel Slag Cement

As a kind of industrial waste residue,nickel slag can pollute the environment and it's storage will occupy great amount of land.Since nickel slag contains the feature of activity,it can be used to produce high quality cement based on the alkali-activated method.Now the most alkali-activated cements are two-component,the setting time is very short and it is unsuitable to be widely used in practice.In this paper,a new one-part alkali-activated cement(SN)is produced using nickel slag.The SN can meet the requirement of practice with short setting time,and it can reduce the occupied land used to storage nickel slag.The nickel slag is the object of activation,there are four kinds of alkali activating system:A,B,C and D.The NaOH is the activator in system A,the Na2SO4 and t OPC are activators in the system B,the Na2CO3 and OPC are activators in the system C,the Na2SO4,NaOH and OPC are activators in the system D.In this paper,the influences of activator on the water requirement of normal consistency,setting time,soundness,flexural strength and compressive strength are studied.XRD,FSEM-EDS,IR,simultaneous thermal analyzer and pore size analyzer were used to analyze kinds and morphology of hydration products and pore structure.Furthmore,Then this paper did comparative research on the sulfate resistance of SN concrete and OPC concrete.The main conclusions are as follows:1.The main hydration products are C-S-H,C-A-H and calcite in the system C.When the content of OPC is 10%,the content of Na2CO3 increases from 2%to 8%,Meanwhile,there is a decline of the setting time and average pore size,and an increase of the mount of calcite,the proportion of harmless pore,little harmful pore,flexural strength and compressive strength.When the content of Na2CO3 is 6%and the content of OPC increases from 10%to 40%,it leads to a decrease of the setting time and average pore size,and increase of the amount of calcite,the proportion of harmless pore,flexural strength and compressive strength.Considering the cost,setting time,flexural strength and compressive strength,the optimum proportion is presented.For the ZY,the mass ratio of nickel slag,OPC and Na2CO3 is 80:20:6,flexural strength and compressive strength of cement mortar are 8.4 MPa and 45.3 MPa,respectively.ZY can meet the requirement of P.042.5,which also has a 16.4%cost saving and a good application prospect.2.When the content of NaOH is 8%in system A,nickel slag is replaced by OPC in system B,C and D(replacement ratio is 10%),and the content of Na2SO4 is 8%in system B,the content of Na2CO3 is 8%in system C,the content of Na2SO4 and NaOH are 4%in the system D.As a result,the activated effect of Na2SO4 is bad,and the flexural strength and compressive strength of 28d are worst.There are Aft and sodium calcium aluminosilicate.in the hydration products of system D,which can fill pores and lead to the greatest flexural strength and compressive strength of 28d.The calcite has filling effect in system C,so the flexural strength and compressive strength of 28d are slightly lower than in system D.3.When the dosage of cement,volume sand ratio and water-cement ratio are same,the workability of ZY concrete is better than that of OPC concrete,the compressive strength of ZY is slightly lower than that of OPC concrete.However the difference of elastic modulus between them is very small,and the sulfate attack resistance of the ZY concrete is better than that of OPC concrete.