| Sulphoaluminate cement (SAC) is used increasingly in concrete structures constructed inwinter, especially in hydraulic engineering and structure remedial engineering because of itsmany engineering advantages such as higher strength at early ages, lower heat of hydration,anti-permeability, and so on. Although SAC has many excellent performance, is suitable forapplication in the field of waterproof, but only with common preparation ofSulphoaluminate cement waterproof mortar (SACWM) has some disadvantages, for instancethe late strength descend, low flexural strength and permeability resistivity will not be able tomeet the hydraulic engineering, so this thesis has made some improvement study, and it is thegoal of this work to develop a SACWM with strength qualified and high permeabilityresistivity.(1) Orthogonal design was preformed to study the water reducing agent of naphthalene,aliphate type and silicone water-repellent agent on effect of mechanical properties andpermeability resistivity through range analysis. Results showed that silicone water-repellentagent has a bigger impact than the water reducing agent of naphthalene and aliphate.Furthermore silicone water-repellent agent reasonable dosage was0.2％, if content more than0.2％will reduce the strength and permeability resistivity.(2) By the compound test of fly ash with slag powder or silica fune, the effect of thecompound mineral admixture on the strength, water–absorption rate (WAR), permeabilityresistivity and microstructure of SACWM are discussed. It is demonstrated that the mineraladmixture can significantly reduce SACWM early strength, but little effect on the long-termstrength. The impermeability of SACWM was worst when fly ash, slag power is3:2. Whilethe impermeability of SACM was best when fly ash, silica fune is3:2, but considercomprehensive performance, we select slag, silica fume4:1is optimal proportion.(3) Respectively studied to redispersible powder and cellulose ether effect on thestrength, WAR, permeability resistivity and microstructure of SACWM. It showed that thoughthese two kinds of polymers will reduce the early strength, but didn’t have much effect on thelate strength, and these two kinds of polymer can obviously decrease the WAR. In terms of impermeability, the cellulose ether is obviously better than redispersible powders, especiallywhen the content of cellulose ether is more than1.5‰, the permeability pressure of SACWMwould reach more than2.2MPa. The optimal proportion cement, slag, silica fune, aggregatewere17.5％,4.5％,3.0％and75％, respectively. Whereas water-reducing agent,water-repellent agent, lime, cellulose ether were1.0％,0.2％,1.0％and2.0％by mass ofthe total cementitious materials. The performance of the mortar meet the requirements in theJC/T984-2005.(4) Artificial sand grain size matching has great influence on the consistency, strength,WAR, and permeability resistivity of SACWM. Reasonable grain size matching not only canimprove the strength, reduce WAR of SACWM, but also can improve the consistency andimpermeability of SACWM. Based on the principle of water-proof mortar, optimal schemeselection A2B3C2is relatively reasonable, the coarse sand, medium sand, fine sand ratio is0:1:1. That amount of mineral admixture is15％, cellulose ether is1.75‰.The performanceof SACWM were of the following property: the1d flexural strength5.6MPa, compressivestrength22.8MPa,28d flexural strength6.7MPa, compressive strength34.1MPa,7dimpermeability pressure is only11mm on2.2MPa constant pressure1h. |
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