Modified graphene cement-based composite material, and preparation and application of material

[0036] Example 1: Cement-based material without modified graphene

[0037] Add 202.5g of water to 450g of cement, use a mortar mixer to stir slowly until uniform, slowly add 1350g of standard sand and continue to stir evenly, pour into the mold, vibrate gently until it is dense, and cure for 28 days.

[0038] The compressive strength of the modified graphene cement-based composite material is 55 MPa, and the flexural strength is 8.2 MPa.

[0039] In size 80×40×40mm 3 Four electrodes are embedded in the graphene cement-based composite material test block to obtain a pressure-sensitive sensor, and the four electrodes are sequentially distributed on the same surface of the test block from left to right, and are distributed symmetrically about the central axis of the test block surface, forming Two inner electrodes and two outer electrodes, the distance between the two inner electrodes is 40 mm, and the distance between the two outer electrodes is 60 mm.

[0040] Apply a DC voltage of 10V to the two external electrodes, use the electronic universal testing machine to load and unload the cyclic compressive stress of the sensor, use the electrochemical workstation to collect the voltage signal of the two internal electrodes, and use the digital collector to collect the strain The loading and unloading speeds of the cyclic compressive stress are both 50N/s, the maximum compressive stress is 5MPa, and the minimum compressive stress is 0MPa.

[0041] The method of using an electrochemical workstation to collect voltage signals for the two inner electrodes is: collecting data every 0.1s, the voltage adjustment range is from -10V to 10V, and the total time is 4000s.

[0042] The method for collecting strain using a digital collector is: collecting data once every 1s.

[0043] The blank cement-based material does not have pressure sensitivity.

[0044] Example 2: Graphene cement-based sensor with graphene content 0.5% of cement mass

[0045] A modified graphene cement-based composite material is composed of water, cement, graphene, naphthalene-based water reducing agent (provided by Nanjing Subote New Material Co., Ltd.), and standard sand. The particle size of the graphene is 7-8μm , The thickness is less than 10nm, the specific surface area is not less than 120m 2 /g. First weigh 1.575g of naphthalene-based water-reducing agent powder, mix it with 162g of water, add 0.225g (0.05% of cement mass) graphene powder to the naphthalene-based water-reducing agent solution, and use a 360W ultrasonic cell pulverizer ultrasonic 10min; Repeat the above steps 4 times; then add 0.225g of graphene powder to the above graphene dispersion, use an ultrasonic cell crusher with a power of 720W to sonicate for 10min; repeat the above steps 4 times until the graphene content is 2.25g . Finally, an ultrasonic cell crusher with a power of 1200W was used to sonicate for 10 minutes to obtain a uniformly dispersed modified graphene suspension. Add the above modified graphene suspension to 450g of dry cement powder, and at the same time add 40.5g of water, use a mortar mixer to slowly stir until it is uniform, slowly add 1350g of standard sand to it, continue to stir evenly, inject it into the mold, gently shake it until it is compact After curing for 28 days at a temperature of 20°C and a relative humidity of 95% or more, the modified graphene cement-based composite material is obtained.

[0046] The 28d compressive strength of the modified graphene cement-based composite material is 65.5MPa, and the flexural strength is 9MPa.

[0047] In size 80×40×40mm 3 The pressure-sensitive sensor is obtained by embedding 4 electrodes in the ink-based cement-based composite material test block, and the four electrodes are sequentially distributed on the same surface of the test block from left to right, and are distributed symmetrically about the central axis of the test block surface, forming Two inner electrodes and two outer electrodes, the distance between the two inner electrodes is 40 mm, and the distance between the two outer electrodes is 60 mm.

[0048] Apply a DC voltage of 10V to the two external electrodes, use the electronic universal testing machine to load and unload the cyclic compressive stress of the sensor, use the electrochemical workstation to collect the voltage signal of the two internal electrodes, and use the digital collector to collect the strain The loading and unloading speeds of the cyclic compressive stress are both 50N/s, the maximum compressive stress is 5MPa, and the minimum compressive stress is 0MPa.

[0049] The method of using an electrochemical workstation to collect voltage signals for the two inner electrodes is: collecting data every 0.1s, the voltage adjustment range is from -10V to 10V, and the total time is 4000s.

[0050] The method for collecting strain using a digital collector is: collecting data once every 1s.

[0051] The pressure sensitive sensor has strong pressure sensitivity, with strain sensitivity and stress sensitivity of 95 and 0.75%/MPa respectively.

[0052] Example 3: Graphene cement-based sensor with graphene content of 1% of cement mass

[0053] A modified graphene cement-based composite material is composed of water, cement, graphene, naphthalene-based water reducing agent (provided by Nanjing Subote New Material Co., Ltd.), and standard sand. The particle size of the graphene is 7-8μm , The thickness is less than 10nm, the specific surface area is not less than 120m 2 /g. Weigh 2.25g naphthalene water-reducing agent powder, mix it with 162g water, add 0.45g (cement mass 0.1%) graphene powder to the naphthalene-based water-reducing agent solution, and use a 360W ultrasonic cell pulverizer ultrasonic 15min; Repeat the above steps 4 times; then add 0.45g of graphene powder to the above graphene dispersion, use an ultrasonic cell pulverizer with a power of 720W to sonicate for 30min; repeat the above steps 4 times until the graphene content is 4.5g . Finally, an ultrasonic cell crusher with a power of 1200W was used to sonicate for 30 minutes to obtain a uniformly dispersed modified graphene suspension. Add the above modified graphene suspension to 450g of dry cement powder, and at the same time add 40.5g of water, use a mortar mixer to slowly stir until it is uniform, slowly add 1350g of standard sand to it, continue to stir evenly, inject it into the mold, gently shake it until it is compact After curing for 28 days at a temperature of 20°C and a relative humidity of 95% or more, the modified graphene cement-based composite material is obtained.

[0054] The 28d compressive strength of the modified graphene cement-based composite material is 68 MPa, and the flexural strength is 10 MPa.

[0055] In size 80×40×40mm 3 The pressure-sensitive sensor is obtained by embedding 4 electrodes in the ink-based cement-based composite material test block, and the four electrodes are sequentially distributed on the same surface of the test block from left to right, and are distributed symmetrically about the central axis of the test block surface, forming Two inner electrodes and two outer electrodes, the distance between the two inner electrodes is 40 mm, and the distance between the two outer electrodes is 60 mm.

[0056] Apply a DC voltage of 10V to the two external electrodes, use the electronic universal testing machine to load and unload the cyclic compressive stress of the sensor, use the electrochemical workstation to collect the voltage signal of the two internal electrodes, and use the digital collector to collect the strain The loading and unloading speeds of the cyclic compressive stress are both 50N/s, the maximum compressive stress is 5MPa, and the minimum compressive stress is 0MPa.

[0057] The method of using an electrochemical workstation to collect voltage signals for the two inner electrodes is: collecting data every 0.1s, the voltage adjustment range is from -10V to 10V, and the total time is 4000s.

[0058] The method for collecting strain using a digital collector is: collecting data once every 1s.

[0059] The pressure sensitive sensor has strong pressure sensitivity, with strain sensitivity and stress sensitivity of 300 and 2.9%/MPa respectively.