Experimental Research On TBM Tunnel Excavation Materials Used As Concrete Aggregate And Cemented Sand Gravel Aggregate

TBM tunnel excavation is the engineering waste from construction,and is still discarded as construction waste.A large number of tunnel excavation occupy land resources,and can lead to environmental pollution,which becomes an urgent engineering problem to be solved.On the other hand,due to the large-scale exploitation of natural sand and gravel aggregates over the years,the available resources have gradually decreased,therefore,the price of natural sand and gravel has become higher and higher.At the same time,human beings’awareness of ecological and environmental protection is gradually increasing,so the continued exploitation of natural sand and gravel aggregates will become unsustainable.Therefore,based on the above problems,The feasibility of TBM excavated material as aggregate was studied contents are as following:(1)TBM tunnel excavation materials are used as aggregates,and the quality of raw materials has been inspected.In accordance with the test methods and data processing methods listed in"Test Rules for Hydraulic Concrete"SL352-2006,Eight indexes including apparent density,clay content and lump content were tested.Among them,the content of needle flake is 0,The concern that TBM tunnel excavation can not be used as aggregate is eliminated.Through the particle screening test of TBM tunnelled material,the proportion of tunnelled material at different particle sizes was observed and used to make the mix ratio scheme.(2)The compressive strength test of TBM tunnel excavated material as concrete aggregate was carried out.The test sets five water-cement ratios(0.55,0.60,0.65,0.70,0.75),three substitution rates(25%,50%,100%),and two ages(7d,28d),with a side length of 150mm,The cube specimens were subjected to a compressive strength test after the set age under standard curing conditions.The test results can reach the expected C10-C25 strength range,And by separately controlling the two variables of water-cement ratio and substitution rate,the change trend of compressive strength under different variables is compared,and the influence of the two factors on compressive strength is further explored.(3)The compressive strength test of TBM tunnel excavated material as cemented sand gravel aggregate was carried out.The test is divided into the direct use of the tunnel excavation materials and the use of the tunnel excavation materials mixed with 8%fine particles.The test has formed three sets of cementitious materials with a side length of450mm cube full-graded specimens.After curing under the same conditions for 180 days The compressive strength test showed that the overall trend of the strength of the tunnel excavated material with 8%fine-grained material was greater than the strength of the direct use of the tunnel excavated material;the minimum value of the compressive strength result was greater than 0.75 times the strength design standard value.Finally,the results of this test were compared with the results of the production test of Datong Shoukoubao Reservoir.The two glue materials were cement 50 kg/m~3 and fly ash 40kg/m~3 and cement 40 kg/m~3 and fly ash 40 kg/m~3.Under the ratio,the compressive strength of the cemented sand and gravel specimens with TBM tunnel excavation materials as aggregates is greater than the production test results of Datong Shoukoubao Reservoir.