瓦斯隧道用气密性水泥混凝土致密性评价研究

Study on evaluation of air-tight concrete compactness in gas tunnel

气密性混凝土的制备与性能评估是瓦斯隧道建设的重要技术。研究了在不同掺量气密剂作用下C40混凝土的性能变化规律,采用含气量(A)、透气系数(K)、电通量(Q)、动弹性模量(E_(d))多指标评价C20、C30、C40混凝土的密实性,并利用灰色关联方法探究了K与其他测试指标的相关性。结果表明,气密剂可有效降低混凝土透气系数而不影响抗压强度;以K为母序列,A、Q、E_(d)关联度均高于0.67,表明A、Q、E_(d)与K的规律一致,均可较好地反映气密性混凝土密实性;随龄期延长,混凝土电通量逐渐降低,而动弹模量略有升高,证明气密剂对水泥混凝土致密性的改善是一个长期过程,且前期效果更明显。

The preparation and performance evaluation of air-tight concrete is an important technology in gas tunnel construction.The performance variety rule of C40 concrete under different dosage of air-tight agent was studied firstly.Secondly,multiple indexes including air content(A),air permeability coefficient(K),electric flux(Q)and dynamic elastic modulus(E_(d))were used to evaluate compactness of C20,C30 and C40 concrete,in addition,the correlation between air permeability coefficient and other test indexes was explored by grey correlation calculation.The results show that air-tight agent reduced permeability coefficient of concrete effectively without affecting compressive strength.Furthermore,the correlation degrees of gas content A,Q and E_(d) are all higher than 0.67,with the K as master sequence,which indicated that A,Q,E_(d) and K can reflect the tightness of air-tight concrete.Additionally,the electric flux of concrete decreases gradually,while the dynamic modulus increases slightly with the extension of age,which proves that the compactness improvement of air-tight concrete affected by air-tight agent is a long-term process,and it is more obvious in preliminary effect.