纳米SiO_2对新拌水泥浆体流变性能的影响
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摘要
选用RHEOLAB QC型旋转黏度计,分别测试了内掺水泥质量分数0. 0%、1. 0%、2. 0%与3. 0%纳米SiO_2的水泥浆体在5℃、20℃、30℃时的稳态流变曲线、静态屈服应力、恒定速率剪切下的表观黏度与剪切应力,系统研究了不同环境温度时纳米SiO_2对新拌水泥浆体流变性能的影响。结果表明:随纳米SiO_2掺量增加,水泥浆体的动态屈服应力与稠度系数均显著增大;随温度升高,掺纳米SiO_2的水泥浆体的稠度系数均增大,纳米SiO_2掺量为0%与1. 0%的水泥浆体的动态屈服应力增大,而纳米SiO_2掺量为2. 0%、3. 0%的水泥浆体的动态屈服应力基本不变;随纳米SiO_2掺量增加,水泥浆体的静态屈服应力与其在10～120 min的增长速率均增大; 20℃、30℃时,随纳米SiO_2掺量增加,水泥浆体的剪切变稀程度增大; 5℃与30℃时,随纳米SiO_2掺量增加,水泥浆体的触变指数增大;当纳米SiO_2掺量为1. 0%时,水泥浆体的活化能低,温度敏感性弱,热稳定性好。
The RHEOLAB QC rotating viscometer was used to measure the steady-state rheological curves,static yield stress and apparent viscosity and shear stress at constant shear rate of fresh cement pastes with nano-SiO_2 dosage of 0%,1. 0%,2. 0% and 3. 0% at 5,20 and 30 ℃,the effect of nano-SiO_2 on rheological properties of fresh cement pastes were investigated. The results show that: Dynamic yield stress and consistency coefficient increase with the increase of nano-SiO_2 dosage; When temperatures rise,consistency coefficients of the pastes increase,the dynamic yield stresses of pastes with nano-SiO_2 dosage of 0. 0% and 1. 0% increase,while the dynamic yield stresses of pastes with nano-SiO_2 dosage of 2. 0% and 3. 0% are basically the same; The static yield stress and the overall growth rate in the period of 10-120 min increase with the incorporation of nano-SiO_2; At 20 and 30 ℃,the degree of shear-thinning of cement pastes increase with the nano-SiO_2 dosage; At 5 and 30 ℃,the thixotropic indexes of cement pastes increase with the nano-SiO_2 dosage; When the nano-SiO_2 dosage is 1. 0% of cement,the activation energy is relatively low,revealing its low temperature sensitivity and good thermal stability.
The RHEOLAB QC rotating viscometer was used to measure the steady-state rheological curves,static yield stress and apparent viscosity and shear stress at constant shear rate of fresh cement pastes with nano-SiO_2 dosage of 0%,1. 0%,2. 0% and 3. 0% at 5,20 and 30 ℃,the effect of nano-SiO_2 on rheological properties of fresh cement pastes were investigated. The results show that: Dynamic yield stress and consistency coefficient increase with the increase of nano-SiO_2 dosage; When temperatures rise,consistency coefficients of the pastes increase,the dynamic yield stresses of pastes with nano-SiO_2 dosage of 0. 0% and 1. 0% increase,while the dynamic yield stresses of pastes with nano-SiO_2 dosage of 2. 0% and 3. 0% are basically the same; The static yield stress and the overall growth rate in the period of 10-120 min increase with the incorporation of nano-SiO_2; At 20 and 30 ℃,the degree of shear-thinning of cement pastes increase with the nano-SiO_2 dosage; At 5 and 30 ℃,the thixotropic indexes of cement pastes increase with the nano-SiO_2 dosage; When the nano-SiO_2 dosage is 1. 0% of cement,the activation energy is relatively low,revealing its low temperature sensitivity and good thermal stability.
引文
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[2]Ye Q,Zhang Z,Kong D,et al.Influence of nano-SiO2addition on properties of hardened cement paste as compared with silica fume[J].Construction and Building Materials,2007,21(3):539-545.
[3]Rong Z,Sun W,Xiao H,et al.Effects of nano-SiO2particles on the mechanical and microstructural properties of ultra-high performance cementitious composites[J].Cement and Concrete Composites,2015,56:25-31.
[4]Senff L,Labrincha J A,Ferreira V M,et al.Effect of nano-silica on rheology and fresh properties of cement pastes and mortars[J].Construction and Building Materials,2009,23(7):2487-2491.
[5]Khayat K H.Viscosity-enhancing admixtures for cement-based materials-An overview[J].Cement and Concrete Composites,1998,20(2-3):171-188.
[6]Jalal M,Pouladkhan A R,Ramezanianpour A A,et al.Comparative study on effects of class F fly ash,nano silica and silica fume on properties of high perfermance self-compacting concrete[J].Construction and Building Materials,2015,94:90-104.
[7]Senff L,Hotza D,Repette W L,et al.Mortars with nano-SiO2and micro-SiO2investigated by experimental design[J].Construction and Building Materials,2010,24(8):1432-1437.
[8]Yuan Q,Zhou D,Li B,et al.Effect of mineral admixtures on the structural build-up of cement paste[J].Construction and Building Materials,2018,160:117-126
[9]Berra M,Carassiti F,Mangialardi T,et al.Effects of nanosilica addition on workability and compressive strength of Portland cement pastes[J].Construction and Building Materials,2012,35:666-675.
[10]肖佳,申闯,李允,等.纳米SiO2对聚羧酸减水剂的吸附作用研究[J].硅酸盐通报,2018,37(2):391-397.
[11]Li Q,Gao X,Xu S.Multiple effects of nano-SiO2and hybrid fibers on properties of high toughness fiber reinforced cementitious composites with high-volume fly ash[J].Cement and Concrete Composites,2016,72:201-212.
[12]Singh L P,Karade S R,Bhattacharyya S K,et al.Beneficial role of nano silica in cement based materials-review[J].Construction and Building Materials,2013:1069-1077
[13]Wu Z,Shi C,Khayat K H,et al.Effects of different nanomaterials on hardening and performance of ultra-high strength concrete(UHSC)[J].Cement and Concrete Composites,2016,70:24-34.
[14]Park J B.Characteristics of cement mortar with nano-SiO2particles[J].2007,21(6):1351-1355
[15]Lu J X,Chi S P.Improvement of early-age properties for glass-cement mortar by adding nanosilica[J].Cement and Concrete Composites,2018,89:18-30
[16]Wang Y,Wang L J,Li D,et al.Effects of drying methods on rheological properties of flaxseed gum[J].Carbohydrate Polymers,2009,78(2):213-219.
[17]Wang B,Li D,Wang L J,et al.Anti-thixotropic properties of waxy maize starch dispersions with different pasting conditions[J].Carbohydrate Polymers,2010,79(4):1130-1139.