【作者】 高杨；

【导师】 杨长辉；

【作者基本信息】 重庆大学 ， 材料科学与工程， 2021， 硕士

【摘要】 水泥混凝土的强度发展和水化过程密切相关,其水化速率会因为温度的降低而减缓,提升胶结材低温水化硬化速率对保证低温条件下的施工和应用至关重要。碱激发矿渣胶结材在常温下凝结硬化快、早期强度高,又因为碱液的存在而具备低温水化硬化的潜力。目前,国内外关于碱矿渣胶结材低温水化行为的研究较少,难以指导工程应用。本文通过正交试验,研究了低温养护（0℃）条件下水胶比、碱当量、水玻璃模数对碱矿渣砂浆早期强度的影响。在此基础上,探究了拌合物入模温度、氢氧化钠掺入方式、矿渣细度对碱矿渣凝结时间、抗压强度、内部温度的影响,结合XRD、TG、SEM等测试结果分析了养护温度对其水化硬化行为的影响。试验研究了早强型矿物对低温下AAS砂浆强度发展的作用效率。揭示的基本规律如下:（1）0 ℃养护条件下,配合比参数对碱矿渣砂浆4 h抗压强度的影响程度从大到小依次为碱当量、水胶比、水玻璃模数,对碱矿渣砂浆1 d抗压强度的影响程度从大到小依次为水胶比、碱当量、水玻璃模数。（2）拌合物入模温度、氢氧化钠掺入方式、矿渣细度影响了AAS的早期硬化性能。在0℃养护,碱当量=8%,W/C=0.35,Ms=1.2的条件下,入模温度在12～19℃范围内时,温度的下降会延长AAS净浆的凝结时间,降低砂浆的早期抗压强度;Na OH以片状或粉状的形式直接掺入到AAS体系中时,可提高入模温度,缩短AAS净浆的凝结时间,提高砂浆1h、2 h龄期的抗压强度;矿渣细度由450 m²/kg提高到790 m²/kg后,低温下的水化反应速率变快,净浆凝结时间缩短,砂浆6h龄期内的抗压强度的提升效果明显,4 h和6 h抗压强度均提升了50%以上。（3）负温下,碱矿渣胶结材初期强度发展随温度降低幅度显著提高,本研究条件下,矿渣细度为450 m²/kg,-10℃养护时,碱矿渣砂浆的1 d抗压强度低于3 MPa,仅为同龄期20℃养护的8.3%;矿渣细度为790 m²/kg,-10℃养护时,碱矿渣砂浆的1 d抗压强度低于8 MPa,仅为同龄期20℃养护的13.5%。（4）CaO/Ca（OH）₂、水泥熟料、碱矿渣水泥石粉、高强硫铝酸盐水泥均能提高AAS胶结材的低温硬化性能。比较而言,CaO的效果最好,在固相温度为0℃时,可以将AAS净浆的凝结时间控制在15 min～39 min;在0℃养护时,可以获得最优的早期强度,砂浆2 h、4 h、6 h、1 d抗压强度分别能达到9.5MPa、13.4MPa、15.3MPa、24.6MPa。（5）CaO-熟料、CH-熟料、CSA-熟料三种复合矿物对AAS低温硬化性能的提升效果要优于单掺组。比较而言,CaO-熟料的效果最好,在固相温度为0℃时,初凝时间控制在19 min,终凝时间控制在23min;在0℃养护时,砂浆2 h抗压强度为8.5 MPa,4 h抗压强度为14.3MPa,6 h抗压强度15.5MPa,1 d抗压强度为32.3 MPa。更多还原

【Abstract】 The strength development of cement concrete is closely related to the hydration process.The rate of hydration will slow down due to the decrease in temperature.Increasing the low-temperature hydration and hardening rate of cementitious materials is essential to ensure construction and application under low-temperature conditions.There is an urgent need to find a cementitious material that can harden and strengthen quickly in a low temperature environment.At room temperature,alkali-activated slag binder has mang excellent properties such as set quickly,fast hardening,high early strength,and has the potential of low-temperature hydration and hardening due to the presence of lye.At present,domestic and foreign literature reports on the low-temperature hydration behavior of alkali-activated slag cement are still lacking,and it is difficult to guide engineering applications.This paper studied the influence of water-binder ratio,alkali equivalent,and water glass modulus on the early strength of alkali-activated slag mortar under low temperature curing（0℃）by setting orthogonal experiments,and according to the early mechanical properties,the optimal mix ratio was determined.Basis on this,the influence of the mold entering temperature,sodium hydroxide incorporation method,and slag fineness on the setting time,low-temperature mechanical properties,and internal temperature of the alkali-activated slag cement was explored,the effect of curing temperature on its hydration and hardening behavior was analyzed by XRD,TG,SEM and other test techniques.The effects of early strength minerals on the strength development of AAS mortar at low temperature have been tested and studied.The basic laws revealed are as follows:（1）Under the curing condition of 0℃,it could be shown that the effect of the mixing ratio parameters on the 4 h compressive strength of alkali-activated slag mortar decreased in order of alkali equivalent,water-binder ratio,water glass modulus,and on the 1 d compressive strength of alkali-activated slag mortar decreased in order of water-binder ratio,alkali equivalent,water glass modulus.（2）The mold entering temperature,sodium hydroxide incorporation method,and slag fineness affect the early hardening performance of AAS.Cured at 0℃,alkali equivalent=8%,W/C=0.35,Ms=1.2,when the mold-in temperature was within the range of 12～19℃,the decrease in temperature would prolong the setting time of AAS paste and reduce the mortar.Early compressive strength the decrease of the mold entering temperature would prolong the setting time of the AAS paste and reduce the early compressive strength of the mortar;When Na OH was directly incorporated into the AAS system in the form of flakes or powder,it could shorten the setting time of the AAS paste and improve the 2 h compressive strength of the mortar due to the increase in the mold entering temperature;The slag fineness was increased from 450 m²/kg to 790 m²/kg,the hydration reaction rate at low temperature became faster,the setting time of the paste was shortened.The improvement effect of the compressive strength of the mortar in the first6 h was obvious.The 4 h and 6 h compressive strength increased by more than 50%.（3）Under negative temperature,the initial strength development of alkali-slag cementation material decreased significantly with the decrease in temperature.Under the conditions of this study,when curing at-10℃,the slag fineness was 450 m^2/kg,the 1 d compressive strength of the AAS mortar was less than 3 MPa,which was only 8.3%of the same age curing at 20℃;When curing at 10℃,the slag fineness was 790 m²/kg,the1 d compressive strength of alkali slag mortar was less than 8 MPa,which was only 13.5%of the same age curing at 20℃.（4）CaO/Ca（OH）₂,cement clinker,AAS powder,high-strength sulphoaluminate cement could all improve the low-temperature hardening performance of AAS binder.By comparison,CaO worked best,when the solid phase temperature was 0℃,the setting time of AAS paste could be controlled within 15 min～39 min;When curing at 0℃,the best early strength could be obtained.The 2 h,4 h,6 h,and 1 d compressive strength of AAS mortar could reach 9.5 MPa,13.4 MPa,15.3 MPa,and 24.6 MPa,respectively.（5）The three composite minerals of CaO-clinker,CH-clinker and CSA-clinker improved the low-temperature hardening performance of AAS better than the single-admixture group.By comparison,CaO-clinker worked best,when the solid phase temperature was 0℃,the initial setting time was controlled at 19 min,and the final setting time was controlled at 23 min.When curing at 0℃,the 2 h compressive strength of the mortar was 8.5 MPa,the 4 h compressive strength was 14.3 MPa,the 6 h compressive strength was 15.5 MPa,and the 1 d compressive strength was 32.3 MPa.更多还原