Study On Basic Properties Of Alkali Activated-Blended Portland Cement

With the rapid development of large-scale infrastructure construction in China,the demand for cement performance had gradually increased.The goal of cement plant was to meet the basic performance requirements for the use of mixed materials,seldom considered the actual engineering demands,and not made full use of all kinds of mixed materials,also affected the addition of mineral admixtures to the mixing station.At the same time,cement production produced huge energy and resource consumption.In addition,a large number of solid waste materials had not been effectively utilized.Alkali activated-Blended Portland cement was made of less cement clinker(less than50%)and reasonably mixed with more mineral admixtures and activators,which met the performance requirements of cement and concrete.Compared with blended portland cement,the system could guarantee higher early strength,reduced dependence on steam curing conditions,maximize the activity effect and micro-aggregate effect.Therefore,Alkali activated-Blended Portland cement was easier to be popularized and applied in engineering.Sodium silicate,potassium silicate,sodium hydroxide and potassium hydroxide were used as activators in order to produce alkali activated-blended portland cement.On this basis,fly ash was used to replace slag,gold slag was used to replace fly ash.The fluidity,mechanical properties and composition of hardened paste were studied.The conclusions were as follows:(1)To verify the effects of different kinds of activators on the properties of mortar.The influence of addition of hydroxide on the fluidity was less than that of potassium(sodium)sodium silicate.Excessive excitant would affect the fluidity of mortar.The addition of potassium silicate had a good effect on early and late strength,and hydroxide mainly acts on early strength.Potassium silicate was an excellent activator,and 1%was a suitable dosage;(2)The action mechanism of different excitant was obtained through the analysis of hydration products.The hydration products were mainly hydrotalcite and C-S-H gel,and sodium silicate and potassium silicate had some inhibition on early hydration of cement,but promoted the later stage of hydration.The role of sodium hydroxide and potassium hydroxide was mainly due to the contribution of OH~-,while sodium silicate and potassium silicate are attributed to the interaction of OH~-and the silicate formed by hydrolysis;(3)The industrial design of alkali activated cement mixed with different mixtures was discussed.The effective mixture of different mixtures could be obtained by mixing 32.5 and42.5 grade alkali activated cement with suitable activator.The application of low strength concrete construction could make up for the gaps in Chinese cement industry in terms of low strength grades,and also met the needs of heterosexual differentiation,so as to reduce pollution and carbon emissions in cement clinker production.