Research On The Effect Of Admixtures Of Modified Alkamines On Cement Performance

In view of the high price of the traditional grinding aid alkamine and the components ofthe early strength of concrete admixtures on the poor effect of durability, this paper, based onthe effect of ethanolamines and commercially available alkamines on performance of Portlandcement, aims to develop the new type of modified alkamine by modification of ethanolaminesuse in cement or concrete and achieve saving energy and reducing consumption and improvecement and concrete performance.The common alkamines are first choosed and studied on cement properties,the fourmodified alkamines were synthesized with four different modifiers, and got the optimumsynthetic process, its effect on cement properties was studied, through the macro-detectionmethods of mechanical properties, particle distribution, physical properties, as well asmicro-test technology of FTIR, XRD, SEM and heat of hydration rate, to analyze its effect andenhanced mechanism, the results show that:1. Influence regularity of MEA and DEA on cement setting time is similar with TEA,with the increase of dosage, cement setting time was initially accelerated and then wasretarded, the content continues to increase will cause accelerator, when MEA and DEA are atthe addition rate of0.04%, the initial setting and the final setting are accelerated by24.3%,25.7%and10.1%,14.3%, respectively; When they are at the addition rate of0.08%,3dcompressive strength of cement pastes are increased by27.2%and17.6%, specific surfacearea increased by44.6%and57.5%, respectively, the results indicate that MEA and DEA canimpove the early shrength and the grinding effect.2. EDIPA, DEIPA, THEED and HEDTA are at the addition rate of0.01%,0.02%,0.02%and0.02%, respectively,3d and28d compressive strength of cement pastes increased by7.1%,16.8%,18.9%,20.2%and6.9%,18.7%,11.5%,9.8%, it shows HEDTA and DEIPA cansignificantly improve the strength at3d and28d, under the above content, the setting time issignificantly accelerated with THEED, the initial setting and the final setting are acceleratedby24.3%and25.7%, the setting time is significantly retarded with DEIPA, the initial settingand the final setting are retarded by14.5%and13.8%, and the grinding effect of DEIPA is themost evident, sieved particles of45μm, angle of repose reduce47.8%and13.5%, and specific surface area increased by15.0%.3. The optimum synthesis process for acid A-modified alkamine and acid B-modifiedalkamine were: reaction temperature115℃, amount of catalyst1.6%, reaction time4h andreaction temperature105℃, amount of catalyst1.6%, reaction time4.5h, respectively; Thedifferent molar ratio of raw materials have different products, the optimal molar ratio ofC-modified alkamine and acid D-modified alkamine were1:1and2:1, respectively.4. The optimal content of acid A-modified alkamine, acid B-modified alkamine, acidC-modified alkamine and acid D-modified alkamine is0.01%、0.02%、0.01%and0.02%,respectively,3d and28d compressive strength of cement pastes increased by18.2%、15.2%、16.8%、18.0%and31.5%、9.7%、14.1%�'�18.8%, it shows acid A-modified alkamine cansignificantly improve the strength, the content of chemical combined water and the hydrationexothermic quantity, and3d age mineral composition and micromorphology analysis，Diffraction peak of AFt phases and CH is sharp in early stage, and hydration products is moreand more dense in late stage, it shows four types of modified alkamine can also accelerate thehydration of C3A and C3S; Under the above content, acid C-modified alkamine and acidD-modified alkamine has significant effects on the setting time and specific surface area,respectively, the initial setting and the final setting are accelerated by10.5%and6.9%, andspecific surface area is increased by17.7%; The role of acid B-modified alkamine is goodgrinding and optimization of grain size distribution, sieved particles of45μm, angle of reposereduce39.1%and13.5%, and cement particle content of3~32μm is highest.5. The compatibility of between cement mixed with four types of modified alkamine andsuperplasticizer, it shows cement with modified alkamine can adapt admixtures well.