建筑用粉煤灰再生混凝土的力学性能和抗冻性能研究  

Study on mechanical properties and frost resistance ofrecycled fly ash concrete for construction

作　　者：卜娜蕊 刘睿 方炜 赵慧斌 白润山 BU Narui;LIU Rui;FANG Wei;ZHAO HuiBin;BAI Runshan(School of Civil Engineering,Hebei University of Architecture Civil Engineering,Zhanjiakou 075000,China;Jingdezhen Construction Engineering Quality Testing Center,Jingdezhen 333000,China)

机构地区：[1]河北建筑工程学院土木工程学院,河北张家口075000 [2]景德镇市建设工程质量检测中心,江西景德镇333000

出　　处：《功能材料》2023年第5期5223-5229,共7页Journal of Functional Materials

基　　金：国家自然科学基金项目(51968046);河北省张家口市科技局“科技奥运专项”项目(20110015D)。

摘　　要：以再生混凝土为研究对象,选择粉煤灰来取代水泥,通过调整粉煤灰的占比,制备了不同取代率(0%,10%,30%,50%和70%)的高性能粉煤灰再生混凝土。研究了不同粉煤灰取代率对再生混凝土的微观形貌、力学性能、弯曲韧性和抗冻性能的影响。结果表明,掺入粉煤灰后没有产生新的水化产物,但水化反应速率加快,Ca(OH)_(2)的衍射峰强度增大,且粉煤灰颗粒与水化产物凝胶结合更为紧密,使再生混凝土的致密性加强,当粉煤灰取代率为50%时,再生混凝土的结构最为致密。随着粉煤灰取代率的增加,再生混凝土的抗压强度和抗折强度均先增大后减小,当粉煤灰取代率为50%时,28 d的抗压强度和抗折强度均达到最大值,分别为44.2和5.96 MPa,且挠度达到最大值为7.7 mm,抗变形能力最强。随着冻融循环次数的增加,再生混凝土的表面脱落剥离现象加剧,随着粉煤灰取代率的增加,再生混凝土的质量损失率先减小后增大,相对动弹性模量先增大后减小。当冻融循环100次、粉煤灰取代率为50%时,再生混凝土的质量损失率最低为-0.09%,相对动弹性模量最大为94.52%,抗冻性能最佳。Taking recycled concrete as the research object,fly ash was selected to replace cement.By adjusting the proportion of fly ash,high performance fly ash recycled concrete with different replacement rates(0,10%,30%,50%and 70%)was prepared.The effects of different replacement rates of fly ash on the micro morphology,mechanical properties,flexural toughness and frost resistance of recycled concrete were studied.The results showed that there wasn t new hydration product after adding fly ash,but the hydration reaction rate was accelerated,the diffraction peak strength of Ca(OH)_(2)was increased,and the fly ash particles were more closely combined with the hydration product gel,which enhanced the compactness of recycled concrete.When the replacement rate of fly ash was 50%,the structure of recycled concrete was the most dense.With the increase of replacement rate of fly ash,the compressive strength and flexural strength of recycled concrete increased first and then decreased.When the replacement rate of fly ash was 50%,the compressive strength and flexural strength at 28 d reached the maximum value,44.2 and 5.96 MPa,respectively,and the deflection reached the maximum value of 7.7 mm,with the strongest deformation resistance.With the increase of freeze-thaw cycles,the surface peeling phenomenon of recycled concrete intensified.With the increase of replacement rate of fly ash,the mass loss of recycled concrete decreased first and then increased,and the relative dynamic elastic modulus increased first and then decreased.When the freeze-thaw cycle was 100 times and the replacement rate of fly ash was 50%,the minimum mass loss rate of recycled concrete was-0.09%,the maximum relative dynamic modulus of elasticity was 94.52%,and the frost resistance was the best.

关 键 词：粉煤灰 再生混凝土 取代率 力学性能 抗冻性能 

分 类 号：TU560.2[建筑科学—建筑技术科学]