Non-dispersible underwater concrete(NDC)provides erosion resistance for the construction of wading projects.In order to improve the performance of NDC,the optimization design of anti-dis-persant and the regulation of setting time were investigated.Polyacrylamide(PAM)and hydroxyprop-yl methyl cellulose(HPM C)were selected as the main anti-dispersants,and polycarboxylic acid water-reducing agent,silicone and polyether defoamer were selected as the auxiliary agents to optimize the design of NDC anti-dispersant from the perspective of anti-dispersion and flowability.Lithium carbon-ate and aluminum sulfate were selected as setting agents to regulate the setting time of NDC.The re-sults show that the NDC anti-dispersant,which was prepared with HPMC as the main agent,polycar-boxylic acid water-reducing agent and polyether defoamer as auxiliary agents,displays superior anti-dispersion and flowability.The fresh cement mortar(water-to-cement mass ratio is 0.5 and cement-to-sand mass ratio is 2)containing 0.45%HPMC and 1%poly carboxylic acid water-reducing agent by mass of cement shows excellent anti-dispersion and good flowability with a pH value of 9 and an ex-tension of 150 mm.In this system,aluminum sulfate is more effective and economical in regulating the setting time,but the dosage should be less than 2%.This paper provides reference for experimen-tal research related to NDC by optimizing the design of anti-dispersant and regulating the setting time.
non-dispersible underwater concrete(NDC)anti-dispersantwater-reducing agentsetting time