Study On Hydration Character Of Alkali-Activated Slag Cement

Alkali activated slag cement （AASC） with better physical mechanics and durabilityproperty is a new kind of low-carbon cement material, which has environmentalbenefits and economical benefits; To promote its research and application suit with thesocial economic strategy of sustainable development. The correlative theory of AASChas been getting mature day after day since was invented, However, the problem of lackof its basic theory, which prevent AASC used widely, is not solved satisfactionally.From the essence of hydration reaction, the physical and chemical characters andmechanism should be investigated, in order to provide theroy foundation to solove thekey problem of AASC’s development.With the help of EDS, FT-IR, TG-DSC, SEM and any other micro-test, the activity,hydration degree, hydration heat evolution and pore solution are investigated, in orderto promote the use of cementitious materials to make some basic theoretical work. Themain conclusion is as followes:There is a relation between the daosage and type of alkali and the finess of slagwith the activity of AASC. While the dosage of alkali is constant, the activity of AASCwith water glass is the best, the activity of AASC with Na₂SO₄is the worst; While themodul of water glass is1.0².42, with the improvement of modul, the activity of AASCfirstly increased, and then decreased, the AASC with WG2.0is the best; While thedosage of alkali is3%⁶%, the improvement of the dosage of alkali and theincreasement of finess of slag is beneficial for the activity of AASC.The hydration degree of AASC depends on the dosage and type of alkali and thefiness of slag. The hydration degree of AASC with NaOH is the strongest,90dhydration degree of it is42.5%, the weakest is Na₂SO₄; While the modul of water glassis1.0².42, the improvement of modul delays the hydration degree of AASC; While thedosage of alkali is3%⁶%, the improvement of the dosage of alkali and theincreasement of finess of slag is good at the activity of AASC.The dosage and type of alkali and the finess of slag have effects on the hydrationheat of AASC. The cumulation heat of hydration of AASC with NaOH is higher thanthe other type of AASC; While the modul of water glass is1.0².42, the improvementof modul is bad for the rate of hydration heat evolution and the cumulation of hydrationheat of AASC; While the dosage of alkali is3%⁶%, the enhasement of modul is favourable for the rate of hydration heat evolution and the cumulation heat of hydrationheat of AASC.Compared with OPC, AASC belongs to the category of low heat cement, and theheat of hydration of it has a relation with the dosage and type of alkali. The chemicaladditive YP3and PN can change the heat of hydration of AASC significantly.The pH value and the Al, Si, Na and Ca iron concentration of pore solution ofAASC is discreased with the time prolonged, and this is different from OPC; While thedosage of alkali and the hydration time is current, the pH value and Al, K ironconcentration of pore solution of AASC with NaOH is the biggest, but the Si ironconcentration o it is the smallest; The pH value and Al, K, Na iron concentration ofAASC with water glass increased, but the Si iron concentration disceased, with themodul of water glass increasing.The C/S ratio of C-S-H is0.9¹.4, the main hydration of AASC, which belongs tothe type Ⅰ C-S-H, and the hydrate of AASC doesn’t contain the CH.