CSG材料的冻融耐久性分析

Cement Sand and Gravel(简称CSG,胶凝砂砾石)材料是一种新的环保型筑坝材料。为了分析CSG材料在冻融循环状态下的耐久性及材料的单轴抗压强度与单位水泥含量的关系,通过对单位水泥含量不同的CSG材料试块冻融前后的自振频率、动弹性模量、相对动弹性模量、质量损失率及单轴抗压强度的测定及计算,得到随着单位水泥含量从40 kg/m~3到100 kg/m~3的增加,初始自振频率从4 812.21 Hz左右增加到6 597.86 Hz左右,10次冻融循环后的自振频率从1 492.96Hz左右增加到4 689.71 Hz左右;动弹性模量从5 587.30 MPa左右增加到14 521.27 MPa左右,10次冻融循环后从423.27 MPa左右增加到7 327.35 MPa左右;随着单位水泥含量从40 kg/m~3至100 kg/m~3的增加,CSG材料试块在10次循环后平均相对动弹性模量从9.88%增加到50.67%;质量损失率从27%下降至0.03%;单轴抗压强度从6.00 MPa左右增加至11.74 MPa左右,冻融后分别下降至1.61 MPa和7.87 MPa左右。从而得出结论:单位水泥含量高于80 kg/m~3时,耐久性指数显示为中等,材料耐久性得到保证;单轴抗压强度及其降低率随着单位水泥含量的增加而增加。

Analysis of freezing-thawing durability of CSG

In order to analyze the relationship between the durability and the uniaxial compressive strength of CSG ( cement sand and gravel) material under freezing-thawing state and the unit cement content，the self-vibration frequency，the dynamic elastic modulus，the relative dynamic elastic modulus，mass loss rate and the uniaxial compressive strength of the CSG materials with various unit cement contents are measured and calculated，from which the followings are obtained: along with the increase of the unit cement content from 40 kg /m3 to 100 kg /m3 ，the initial self-vibration frequency of the specimen of CSG material increases from about 4 812. 21 Hz to about 6 597. 86 Hz，which increases from about 1 492. 96 Hz to about 4 689. 71 Hz after 10 freezingthawing cycles，while the dynamic elastic modulus increases from about 5 587. 30 MPa to about 14 521. 27 MPa，which increases from about 423. 27 MPa to about 7 327. 35 MPa after 10 freezing-thawing cycles. Following with the increase of the unit cement content from 40 kg /m3 to 100 kg /m3 ，the mean relative dynamic elastic modulus of the CSG specimen increases from 9. 88% to 50. 67% and the mass loss rate decreases from 27% to 0. 03% after 10 freezing-thawing cycles，while the uniaxial compressive strength increases from about 6. 00 MPa to about 11. 74 MPa，which decrease to about 1. 61 MPa and 7. 87 MPa respectively after freezing-thawing cycle. Thus it is concluded that when the unit cement content is higher than 80 kg /m3 ，the durability index shows the medium and the durability of the material is guaranteed，while the uniaxial compressive strength and its decreasing rate increase along with the increase of the unit cement content.