中文摘要：

为准确测定建筑材料抗折强度,以P·O42.5普通硅酸盐水泥28 d抗折强度为研究对象,考察了水泥胶砂从试件制备到抗折强度测定中的影响因素,通过实验和公式计算得到对水泥胶砂28 d抗折强度有影响的因素从大到小依次为：密实方式不同2.10%,养护温度偏差2.07%,取样重复性读数偏差1.50%,荷载速度偏差1.33%,养护时间偏差1.03%,测试条件偏差1.01%,计算机数据偏差0.20%,试验过程中抗折强度的扩展不确定度为7.70%。

英文摘要：

For building materials bending strength accuracy,P·O42.5 cement is chosen to study the impact factors of bending strength.The different uncertainties of impact factors on bending strength are obtained by experiment and calculation.The deviation rate from the greatest to the least is：thick method 2.10%,curing temperature 2.07%,repeatability indications 1.50%,load speeds 1.33%,curing time 1.03%,test conditions 1.01% and computer data 0.20%,and expanded uncertainty is 7.70%.