Study On Synthesis Of Liquid State Alkali-free Setting Accelerator For Portland Cement

The effect of some kinds of inorganic salts and polymerized aluminum sulfate on the setting behavior of ordinary Portland cement was discussed in laboratory under the prerequisite of alkali-free and liquid. The basic composition of liquid state alkali-free setting accelerator was elected according to results of the tests. The stability and property of liquid state alkali-free accelerator were investigated, along with microstructure of hardened cement pastes and setting-accelerating mechanism of liquid state alkali-free accelerator.Test results on preparation of Inorganic salts setting accelerator showed that the ordinary Portland cement was obviously accelerate either aluminum sulfate or aluminum nitrate was added into individually, or introduced simultaneously. But solubility of aluminum sulfate and aluminum nitrate is so less that their solution addition is too much meeting require of the setting property. Then they are not used as liquid state alkali-free setting accelerator. Polymerized aluminum sulfate has got better rapid setting effect than inorganic salts. Compared with inorganic salts saturated solution, solid content of polymerized aluminum is still high. The best preparation of polymerized aluminum sulfate is aluminum sulfate: aluminum hydroxide colloid =1.71: 1.26.Polymerized aluminum sulfate isn't steady. Test results on polymerized aluminum sulfate stability proved that polymerized aluminum sulfate could be made whose stabilization time is up to over 150d when triethanolamine and lactic acid was added into simultaneously. When preparation of polymerized aluminum sulfate is aluminum sulfate : aluminum hydroxide colloid =1.71 : 1.26, addition of triethanolamine and lactic acid is 3% and 7% respectively, aluminum sulfate concentration is 27.3%, poly-reaction temperature is 99°C, and reaction holding time is 30min, resultant polymerized aluminum is transparent whose stabilization time is over 150d, and solid content of polymerized aluminum is up to over 35.7%, and density of polymerized aluminum is 1.47g/ml. When solid addition of polymerized...