Research on the Setting Retarder Available for Alkali Activated-carbonatites-slag Grouting Material

摘要

The effect of some chemical reagents often used in alkali-activated cement, such as Pb (NO_3)_2, Zn (NO_3)_2, and NaCl, etc., on the gelation time of alkali-activated carbonatite-slag grouting material (AACSGM for short) was investigated. The results are as follows: Pb (NO_3)_2 or Zn (NO_3)_2 has retarding effect when its addition is not less than 3% of ground blast-furnace slag by mass, when NaCl or Na_2B_7O_4 is to be used its addition should not be less than 8%; chemical reagent BaCl_2 can effectively retard the gelation of AACSGM paste and keep its fluidity constant for at least 3 hours. Besides, the strength of AACSGM mortars is improved. The retarding effect of BaCl_2 is mainly attributed to: (1) the formation of a protective layer on the surface of slag grain due to the reaction between BaCl_2 and sodium silicate solution, and (2) the increase of the amount of single silicate species in the sodium silicate solution.