海水海砂火山渣混凝土断裂性能试验研究

Experimental Study on Fracture Properties of Seawater Sea Sand Volcanic Slag Concrete

海洋岛礁工程建设面临着取材困难、运输与材料成本昂贵等问题。为此,开发了新型海水海砂火山渣混凝土(SSAC),以推动海工建设的发展。通过混凝土三点弯曲梁断裂试验,探讨了不同缝高比(0.2、0.3、0.4)和组料类型对SSAC断裂力学性能的影响,获取了双K断裂韧度、断裂能与软化曲线等断裂参数的变化规律。结果表明,受粗骨料的影响,采用火山渣的混凝土的荷载-裂缝口张开位移曲线(P-CMOD)与普通混凝土相似,但其下降段更为陡峭。SSAC断裂韧度小于普通混凝土,且均不受缝高比影响。受海水海砂的影响,SSAC的断裂韧度和断裂能较淡水河砂火山渣试件分别提高14.30%和6.77%。基于试验数据,推导得出考虑组料影响的双K断裂韧度与软化关系计算公式,计算结果与试验结果吻合良好。

There are many problems in the construction of ocean islands and reefs,including the shortage of materials,high cost of transportation and materials.Therefore,a new type of seawater sea sand volcanic slag concrete(SSAC)was developed to promote the development of marine construction.Through the notched three-point bending beam test,the influences of different initial notch-to-depth ratio(0.2,0.3 and 0.4)and concrete mix component types on the fracture mechanical properties of SSAC were analyzed.The variations of fracture parameters,such as double K fracture toughness,fracture energy and softening curve were also obtained.The results indicate that the load-crack mouth opening displacement(P-CMOD)curve of concrete with volcanic slag coarse aggregate is similar to that of ordinary concrete,but the descending section of volcanic slag concrete P-CMOD curve becomes steep due to the effects of coarse aggregates.The fracture toughness of SSAC is smaller than that of ordinary concrete,and it is not affected by the initial notch-to-depth ratio.Under the influence of seawater and sea sand,the fracture toughness and fracture energy of SSAC are 14.30%and 6.77%higher than that of fresh water river sand volcanic slag concrete.Based on experimental data,the analytical expressions of double K fracture toughness and softening considering the influence of concrete mix component are established.The calculation results are in line with the test ones.