改性铁尾矿微粉对中高强混凝土性能的影响研究

Influence of Modified Iron Tailings Powder on the Properties of Medium and High Strength Concrete

将不同掺量的改性铁尾矿微粉完全替代粉煤灰做矿物掺合料制备C50混凝土,并设置与铁尾矿微粉等掺量的粉煤灰组为对照,研究改性铁尾矿微粉对中高强混凝土抗压强度、工作性能和耐久性能的影响。结果表明:改性铁尾矿微粉混凝土具有较好的工作性能;抗压强度随改性铁尾矿微粉掺量的增加而降低,各组较对应的粉煤灰对照组强度略低,相差范围在3.7~4.6 MPa内,在改性铁尾矿微粉的掺量为矿物掺合料总量的30%~60%时,均满足C50混凝土的抗压强度要求。在改性铁尾矿微粉的掺量为矿物掺合料总量的40%~60%时,抗碳化性能随改性铁尾矿粉掺量的增加先增强后减弱,与粉煤灰对照组基本持平;抗渗透性能随铁尾矿粉掺量增加而减弱,但抗渗等级均能与粉煤灰对照组一致,为“非常低”;抗硫酸盐侵蚀性能、抗冻性能均随改性铁尾矿粉掺量增加而增强,抗硫酸盐等级可以达到KS180,抗冻等级均可达到F300,且均优于粉煤灰对照组。综合看来,改性铁尾矿微粉在其掺量为矿物掺合料总量的40%~60%时可替代粉煤灰应用于中高强混凝土中。

In order to study the effect of modified iron tailings powder on the compressive strength,working performance and durability of medium and high strength concrete,the C50 concrete were produced by different amounts of modified iron tailings powder,which completely replacing fly ash as the mineral admixture.The fly ash group with the same amount of iron tailings powder was set as a control group.The results show that the modified iron tailings powder concrete has a better working performance,and the compressive strength of modified iron tailings powder concrete decreases with the increase of modified iron tailings powder content.The strength of each group is slightly lower than that of the corresponding fly ash control group,and the difference is within 3.7-4.6 MPa.When the amount of tailing powder in total mineral admixture is 30%-60%,it can meet the compressive strength requirements of C50 concrete.When the content of modified iron tailings powder is 40%-60%,the anti-carbonation performance first increases and then weakens with the increase of tailings powder content,which is basically the same as that of the fly ash control group.The anti-permeability performance weakens with the increase of tailing powder content,but the anti-permeability grades can be consistent with the fly ash control group,which is very low.The anti-sulfate erosion performance and anti-freezing performance are enhanced with the increase of tailings powder content.The anti-sulfate grade can reach KS180,the anti-freezing grade can reach F300,and all are better than the fly ash control group.In general,the modified iron tailing powder can be used in medium and high strength concrete instead of fly ash when the dosage of total mineral admixture is 40%-60%.