为了研究混凝土在不同温度条件下的导热系数变化规律,利用单因素试验方法,以骨料体积分数、砂率、水胶比、饱和度粉煤灰掺量、矿渣掺量为因素,采用QTM-500导热仪测试混凝土在不同温度条件下(-30～20 ℃)的导热系数,并分析各影响因素对混凝土导热系数在不同温度条件下的变化规律,最终得出混凝土导热系数与各因素之间的预测方程。结果表明:混凝土导热系数与温度呈负相关性;混凝土导热系数随着骨料体积分数的增大而增大,随着砂率的增大而减小;干燥状态下,混凝土导热系数随着水胶比的增大而减小;饱和状态下,混凝土导热系数大于干燥状态下混凝土导热系数,随着温度的降低,尤其在0～-10 ℃时,混凝土导热系数骤增;混凝土导热系数随着粉煤灰、矿渣掺量的增加而减小;通过对试验结果进行多元回归,得到了混凝土导热系数与各因素之间的计算模型,该模型预测精度较高。研究结果可为混凝土结构内部温度场的精确计算、保温隔热性能以及表面裂缝的控制提供理论依据。
Abstract
The thermal conductivity of concrete was measured by QTM-500 thermal conductivity instrument at different temperatures (-30 ℃-20 ℃) with volume fraction of aggregate, sand ratio, water-binder ratio, fly ash content and slag content as variables. The prediction equation between thermal conductivity of concrete and the aforementioned factors was obtained by analyzing the changes of thermal conductivity affected by these factors at different temperatures. Results revealed that thermal conductivity of concrete was negatively correlated with temperature and sand ratio, while positively correlated with aggregate’s volume fraction; at dry state, thermal conductivity decreased with the increase of water-binder ratio, while at saturated state, thermal conductivity was greater than that under dry condition, and with the decline of temperature, especially at 0 ℃ -10 ℃, thermal conductivity increased dramatically. The thermal conductivity of concrete also reduced with the rise of fly ash and slag dosages. In addition, through multivariate regression analysis of the test results, a calculation model of high prediction accuracy between thermal conductivity of concrete and these factors was obtained. The research findings provide a more important theoretical basis for the accurate calculation of the temperature field in the concrete structure, the thermal insulation performance and the control of surface cracks.
关键词
混凝土 /
温度 /
导热系数 /
影响因素 /
多元回归
Key words
concrete /
temperature /
thermal conductivity /
influencing factors /
multiple regression
{{custom_sec.title}}
{{custom_sec.title}}
{{custom_sec.content}}
参考文献
[1] CAMPBELL A D, THORNE C P. The Thermal Conductivity of Concrete[J] . Magazine of Concrete Research, 1963, 15(43): 39-48.
[2] KHAN M I. Factors Affecting the Thermal Properties of Concrete and Applicability of Its Prediction Models[J] . Building and Environment, 2002, 37(6): 607-614.
[3] SHIN A H, KODIDE U. Thermal Conductivity of Ternary Mixtures for Concrete Pavement[J] . Cement and Concrete Composites, 2012, 34(4): 575-582.
[4] KIM K H. An Experimental Study on Thermal Conductivity of Concrete [J] . Concrete Research, 2003, 33(3): 363-271.
[5] LI S X, JONES B, THORPE R, et al. An Investigation into the Thermal Conductivity of Hydrating Sprayed Concrete[J] . Construction and Building Materials, 2016, 124: 363-372.
[6] DEMIRBOGA R, GÜL R. Thermal Conductivity and Compressive Strength of Expanded Perlite Aggregate Concrete with Mineral Admixtures[J] . Energy & Buildings, 2003, 35(11) :1155-1159.
[7] TANDIROGLU A. Temperature-Dependent Thermal Conductivity of High Strength Lightweight Raw Perlite Aggregate Concrete[J] . International Journal of Thermophysics, 2010, 31(6) :1195-1211.
[8] LIU L, WANG Z, JIN C, et al. An Experimental Study on Thermal Conductivity of Iron Ore Sand Cement Mortar[J] . Construction and Building Materials, 2015, 101(1): 932-941.
[9] 姚韦靖,庞建勇.新型隔热混凝土喷层支护技术研究与应用[J] .长江科学院院报,2017,34(1):124-128.
[10] 肖建庄, 宋志文, 张 枫. 混凝土导热系数试验与分析[J] . 建筑材料学报, 2010, 13(1): 17-21.
[11] 刘 凯,王 芳,王选仓. 水泥混凝土导热性能影响因素及预估模型研究[J] . 建筑材料学报,2012,15(6):771-777.
[12] 张伟平,童 菲,邢益善,等.混凝土导热系数的试验研究与预测模型[J] .建筑材料学报,2015,18(2):183-189.
[13] 杨华全,李文伟. 水工混凝土研究与应用[M] . 北京:中国水利水电出版社,2005.
[14] 张 楠, 张 涛. 利用差示扫描量热法研究孔溶液结冰对水饱和水泥基材料低温热形变的影响[J] . 硅酸盐学报, 2015, 43(5): 599-603.
[15] LEE C H, LEE K J, CHOI H S, et al. Characteristics of Thermally-enhanced Bentonite Grouts for Geothermal Heat Exchanger in South Korea[J] . Science in China Series E: Technological Sciences, 2010, 53(1): 123-128.
[16] PARK M S, MIN S H, LIM J H, et al. Applicability of Cement-based Grout for Ground Heat Exchanger Considering Heating-cooling Cycles[J] . Science China E: Technological Sciences, 2011, 54(7): 1661-1667.
[17] 白光照.两相复合体系热传导性能研究[D] . 上海: 中科院上海硅酸盐研究所, 2005.
[18] 姜自超. 基于瞬态平面热源法的磷酸镁水泥石导热系数研究[J] . 新型建筑材料, 2017, 44(2): 82-85.
基金
国家自然科学基金项目(51641906,51541909); 国家级大学生创新训练项目(201610758028)
PDF(3192 KB)
