Discussion on the factors affecting the water absorption and permeability of permeable bricks
The experiment was suspended with the planned porosity, water-binder ratio, volumetric sand ratio, and slag powder content as the four elements, and the compressive strength and water permeability coefficient were tested. The test results indicate: within a certain range, as the planned porosity and volumetric sand rate increase, the water permeability coefficient increases; as the water-to-gel ratio increases, the water permeability coefficient decreases; the water permeability coefficient increases first with the increase in the amount of mineral powder. After the trend of decreasing. Keywords: water-binder ratio; porosity; volumetric sand ratio; mineral powder content; water permeability coefficient doi: 10.3969 / j. 1006－8554.2016.09.0820 Introduction Permeable concrete is a new type of environmentally friendly green building material, which has an outstanding role in maintaining ecological balance . This article intends to advance the permeable function of permeable concrete on the basis of ensuring a certain strength function, and investigates the influence of multiple factors on the permeable concrete function to select the best combination plan. 1 Test 1.1 Non-essential test Raw material crushed stone: natural crushed stone, particle size 5mm ～ 10mm. Water-reducing agent: Polycarboxylic acid-based high-efficiency water-reducing agent consumed by Shandong Huadi Construction Technology Co., Ltd., mineral powder: Jinan Luxin New Building Material Company S95 mineral powder. 1.2 Test piece forming and maintenance Firstly, put all coarse aggregate and 10% water into the mixer for pre-mixing. Participate in the mixing of cement ore powder and sand, stir for 2min, and start to participate in the remaining water and water reducing agent to stir evenly . First insert the test mold manually, and then place the test mold on the shaking table for 30 seconds. Maintenance: Cover the test piece with a plastic cloth to prevent water from transpiration. 1.3 Determination of water permeability coefficient The "fixed water volume method" was selected for this test. The permeation coefficient is measured by a self-made permeation meter. The device is a transparent glass rectangular cylinder with upper and lower teeth opening, and its dimensions are 5cm × 5cm × 20cm. In this test, the vertical seepage velocity of the test piece under the condition of variable water column height is used to weigh the water permeability function of the test piece.  2 Measurement of water permeability coefficient The water permeability function of the concrete is expressed by the water permeability coefficient. The test method is based on the practice of Darcy's law. However, this test method still has no real standard in China. This article is based on the Japan Concrete Engineering Association The recommended test method for the permeability of large-pore concrete refers to the test method for soil water permeability in accordance with JISA1218, and a test device combining a fixed water level and a variable water head is selected. 2.1 Test instrument In this water permeability test, a common instrument for measuring the permeability coefficient of permeable concrete was selected in Japan, and the international research on the permeability function of permeable concrete is a cheap instrument, so the results of the water permeability test are highly credible. 1) Water tank with floating ball: Select the water tank that can make the feed water level fluctuate, but also make the drainage water level difference persist. 2) Pressure gauge: Select a pressure gauge that can indicate water supply and drainage levels, a transparent tube with a fixed length of 1m, and a scale or a ruler. 3) Permeable drum: Select a drum whose inner diameter and length are larger than the maximum size of the coarse aggregate in the test sample. 2.2 Test method This test directly introduces Japan's test method for measuring the permeability coefficient. A method combining a fixed water level and a variable water head is used. The specific test process is as follows. 2) Wrap a layer of electrical tape on the outer surface of the cylindrical test piece, and then put a layer of rubber sleeve on it. Start to wrap the test piece with electrical tape to prevent water from flowing out of the front of the test piece to be tested. 3) Dispatching a water tank with a floating ball valve to shake the water level on the water supply side so that the water level difference on the water supply side persists and the water overflows from the overflow port. 4) After the flow rate of the water flowing out of the overflow port is generally shaken, use a balance to measure the amount of water permeation at a certain water level difference between time t1 and t2, and measure twice. 5) The pressure difference between the water supply side and the water supply side is measured by a pressure gauge. 3 Test results and analysis Test cooperation plan is shown in Table 1. The final consequence of the test: The compressive strength of groups 1 to 9 was identified as 32.49MPa, 32.42MPa, 35.34MPa, 15.82MPa, 13.23MPa, 25.32MPa, 11.01MPa, 13.64MPa, 12.81MPa. The compressive strength of groups 1 to 9 was 1.87mm / s, 2.48mm / s, 0.51mm / s, 9.26mm / s, 17.34mm / s, 13.9mm / s, 32.51mm / s, 21.44mm / s , 23.91mm / s. 2.2 Data analysis and discussion In order to further analyze the significance of the influence of each factor on the permeability coefficient, the analysis of variance was discontinued for the consequences . Consequence: the primary and secondary relationship is A> C> D> B, and the optimal combination is A3B1C3D2. 351 Skills Development Technology ANDMARKETVol. 9, 2016 Table 1 Permeable concrete cooperation ratio (amount per 1m3) Numbering plan Porosity% (Element A) Water-binder ratio (Element B) Volume sand ratio% (Element C) Mineral powder content% (Element D) Coarse aggregate (kg) Fine aggregate (kg) Cement (kg) Mineral powder (kg) Water (kg) 150.3221016009.40507.856.4170.4250.34520160022.78424.4106.1170.8350.36830160035.39349.1149.6170.64100.32530160020.32331.2141.9142.85100.34810160031.53399.944.4143.16100.362201600765. 591.9157.17150.32820160027.43309.377.3116.78150.3423016006.65279.5119.8128.69150.36510160016.14338.237.6128.5 For each element that affects the permeability function, the order of obviousness from strong to weak is planned porosity> volumetric sand rate> mineral powder content> water-to-gel ratio. Within a certain range, as the planned porosity and volumetric sand ratio increase, the water permeability coefficient increases; as the water-gel ratio increases, the water permeability coefficient decreases; the water permeability coefficient increases first and then increases Decreasing trend. The best cooperation ratio combination that is conducive to the function of permeable bricks is: planned porosity 15%, water-gel ratio 0.32, volume sand ratio 8%, and mineral powder content 20%. 4 Conclusion In practice engineering, there can be other factors that affect the permeability coefficient of permeable brick concrete. In addition, the research on the strength of permeable concrete and the permeable function should be combined with each other to obtain a more optimized cooperation ratio planning, and ultimately serve the engineering theory. . Environmentally hostile concrete- permeable brick concrete. When the reserved corrugated pipe breaks close to the end face of the beam, it is necessary to cut into the end face of the beam no less than 5cm to stop the corrugated pipe that is cut out. The anchorage at the fixed end with negative bending moment on the top plate is bm15p-5. The anchorage area is firstly equipped with spiral reinforcement in the notch at the fixed end, and then the steel head is fixed by the extrusion head outside the anchor plate. The equipment exhaust pipe is started and the bellows is delayed. , Satisfied with the requirements of grouting. The tension of the prestressed steel beam is selected by double-control, one-end and two-head, synchronous and symmetrical tensioning. When tensioning, each prestressed tendon in the prestressed bundle is stretched one by one, and the prestressed steel bundle at the same pier top is sequentially stretched symmetrically and uniformly from the side beam to the middle beam. When tensioning, it is necessary to ensure the straightness of the jack and the mission anchor. If the notch at the tension end is too shallow, it needs to be cut to the mission depth to prevent the anchor opening from losing too much or even the breakage of the steel beam. After the grouting is finished, the slot at the tensioned end is calibrated for general steel bars, and the opposite diameter steel bar is used for electric welding connection. After the connection is finished, the slot concrete pouring is stopped. After suspending the observation of the upper arch value of the box beam after tensioning the negative bending moment of the roof, it was found that the change was small (-0.1 to 0.2 mm), and it can be basically judged that the negative bending moment of the roof plate has little effect on the arch value of the box beam. . 4.3 The support withdrawal system is completed. The negative bending moment steel beams are converted into several pieces. After the tensioning, grouting and anchoring are completed, the remaining wet joints are poured from the span to the fulcrum. After the strength reaches the planning requirements, the beam can be dropped after the suspension. Abort the system change. The center of the cancellation of the support is to ensure that the beam is lowered uniformly and synchronously, and the support is stressed together. A pair of two-head spans are initially symmetrically dropped to the mid-span beam, and the two sides of each pier are stopped symmetrically. The falling method is to open the steel pipe reserved bolts on the outside of the sand box. Temporary support to complete the system change. 5 Conclusion At present, the Yizhang Expressway Bridge has been completed and opened to traffic, and its use is outstanding. The simple beam first and then continuous beam structure method is absolutely in the traditional sense for continuous beams, reducing the construction difficulty, and reaching the intention of continuous structure at a certain level together. The capacity of the forward structure is increased, and the expansion joint of the beam is increased. , And controlled the onset of lateral cracks on the bridge deck. With the advancement and improvement of construction methods from time to time, more and more bridge plans have chosen this type of bridge. However, the conversion process of this structural system is absolutely messy and requires high precision. During the conversion construction process, severe manipulation must be performed, so that the bridge with simple-to-continuous continuous structure system can reach a better application.