耐碱玻纤混凝土抗折强度测定及不确定度评定

为了测定耐碱玻璃纤维混凝土的抗折强度并分析其不确定度及纤维体积率对混凝土抗折强度的影响,选择耐碱玻璃纤维体积率为0%0,.6%,0.8%,1.0%的100 mm×100 mm×400 mm混凝土抗折试件进行试验。试验在MTS810材料试验机上进行,通过三分点加载测定其抗折强度,分析混凝土抗折强度试验中影响试验结果不确定的因素和来源,并按照JJF 1059-1999标准的要求,对合理玻璃纤维掺量试件的抗折强度的不确定度进行分析和评定。结果表明:耐碱玻璃纤维的掺入改变了混凝土抗折破坏形式,不同纤维体积率的混凝土抗折强度较普通混凝土依次提高了18.87%,21.64%,23.24%。综合考虑各方面因素确定耐碱玻璃纤维混凝土合理玻璃纤维掺量为0.6%;通过对试件抗折强度测定的不确定度评定,表明数学模型中自由度及测量的重复性是引入测量结果不确定度的主要因素;建议在进行同类试验时,试件尺寸应尽量大,从而可增大跨距,以减小剪力对测量结果的影响。

An Evaluation of Measurement Uncertainty on Flexural Strength of Alkali-resistance Glass Fiber Concrete

The concrete flexural strength of the alkali-resistance glass fiber was measured and the influence of the fiber volume rate to the concrete flexural strength and the uncertainty was analyzed,and the concrete flexural contents of the 100 mm×100 mm×400 mm of the alkali-resistance glass fiber volume rate for 0%,0.6%,0.8%,1.0% were measured.The test was conducted on a MTS 810 material test system.The flexural strength was measured through the three point bending load test and the affecting factors of measurement uncertainty of the concrete flexural strength test were analyzed.Besides,the uncertainty of the flexural strength of the equitable glass fiber content was analyzed and evaluated according to JJF 1059-1999.The analysis results show that the form of the flexural failure was changed due to alkali-resistance glass fiber,the concrete flexural strength of the different fiber volume rate was improved 18.87%,21.64%,23.24% than ordinary concretes,and the equitable glass fiber content of the alkali-resistance glass fiber concrete was 0.6% through accounting of various factors;the degree of freedom and the repeatability of measuring in mathematical model were the main influencing factors of measurement uncertainty through evaluated to the measurement uncertainty of the flexural strength;in order to reduce the influence of shear on the result of the measurement,the specimen size should be big enough to increase the span in the similar test.