Preparation And Study On The Dry-mixed Mortar Incorporating Large Volume Of Low-activity Fly Ash And Coal Gangue

The production and application of dry-mixed mortar is a new technological revolution of construction industry and building materials industry, and a major direction in the development of future building material.The dry-mixed martar has not only got over lots of shortages such as inaccurate measurement of mixture,environment pollution,excessive cement volume etc,but also could meet the requirements of new wall materials ,if mixing in different chemistry admixture to improve and optimize the product performance.In our country the research,production and application of martar still in initial stages of development,and regardless of technology, equipment or services,are all lagging behind foreign countries.Because of higher cost of dry-mixed mortar,it is difficult to popularization and application widely in big or middle city of our country.At present ,in the power stations there are a great deal of low-activity or low- activity fly ash which has not widely been utilized or studied. It is also a problem that has troubled power plants and researchers of domestic and overseas. In addition,the studies of mortar which has mixed in lots of calcined coal gangue to replace cement have also not been reported.This paper primary studied the influences of mixing in different kinds of mixture(no-grade fly ash and coal gangue) and mixed design on properties of mortar,then analyzed the reactive activity of lime,gypsum and chemistry activators when added in mixture ,more over studied the influences of different kinds of addition agents on the performance of dry-mixed mortar.The experimental results demonstrate that: (1) low-activity fly ash has low activity because of poorly CaO,low fineness,less density,high ignition loss,and large water demanded. The coal gangue has higher fineness and density, low loss, and preferable activity when it has been calcined.(2)The temperature of calcination has influence on coal gangue's activity, it has the optimum reaction activity when the best stitering temperature during 700 to750℃.(3)The performances of moatar would reduces significantly when mixed in low-activity fly ash;and mixing content of lime has some influence on mortar with fly ash;if coal gangue is added into mortar ,workability of the mortar would be improved and the compressive strength and flexural strength would be sharply enhanced.And gypsum's mixing content and the proportion of FA:M have greatly influence on mortar.(4)Different lime, gypsum and activator types have different influence on the activity of fly ash and coal gangue. And the analyse of orthogonal experiment indicated that lime and activators have obvious influence on the properties of mortar incorporating large volume of low-activity fly ash and coal gangue than gypsum. (5)When water reducer is added into mortar ,water-cement ratio has reduced,the compressive strength and shear strength have improved,but shrinkage rate of 28 days has increased.(6)When redispersible polymer or wood-fiber is added into mortar incorporating large volume of low-activity fly ash and coal gangue, mortar's adhesive performance has remarkably improved;When water retaining agent is added into mortar,workability and water-retentive performance have improve.