Manufactured sand is a substitute for natural river sand and has attracted widespread attention in the construction industry.However,the polyacrylamide(PAM)introduced during the production process has a great impact on the performance of concrete,limiting the promotion and application of manufactured sand in projects.Eleven common PAMs on the market are used to explore the effects of different molecular weights and concentrations on the working performance and mechanical properties of cement mortar.Research shows that the interference of concentration on the fluidity of mortar is significantly greater than the impact of molecular weight and ion type.Among them,anionic polyacrylamide(APAM)degrades the fluidity of mortar the most(-10.7％)at a concentration of 0.005％.In terms of strength,research shows that adding PAM can slightly improve the 28-day strength of mortar.Among them,cationic polyacrylamide(CP AM)has a greater improvement in strength.The 28-day strength improvement at the dosage of CP AM 6 million and 0.005％is the highest by 14.3％,and APAM 8 million.The strength increased by 9.3％at a dosage of 0.005％.In addition,research shows that PAM will significantly reduce the effectiveness of polycarboxylic acid superplasticizer(PCE),with a minimum reduction of 15％in fluidity and a minimum reduction of 11.6％in strength.PCE and PAM have a competitive relationship,and it is necessary to find solutions to the adverse effects of PAM for subsequent scientific research.The program provides new perspectives for thinking.At the same time,the test blocks mixed with PAM are extremely sensitive to moisture conditions in terms of shrinkage.When selecting machine-made sand,special attention must be paid to the maintenance humidity.
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