Coating standard: brief analysis of precautions and standards for construction and inspection of external wall facing brick

Core tip: Huang GuiQiang (Guangzhou Haizhu construction engineering quality supervision and testing office) Abstract: China is an ancient ceramic country with a long history and profound ceramic culture Since the reform and opening up, with the explosive growth of the real estate industry, the application scope and consumption of ceramic exterior wall brick have increased rapidly Ceramic exterior wall brick has become one of the first choice materials for building exterior wall decoration and plays an important role in protecting the wall because of its good decorative effect, long-lasting texture, low comprehensive cost, convenient later maintenance, acid and alkali resistance, durability, weather resistance, pollution resistance, high cost performance, easy construction and many other advantages But in construction Shenyang steel structure fireproof coating construction expert punde Building Fire Engineering Co., Ltd Recommended introduction: since its establishment, Shenyang punde Construction Fire Engineering Co., Ltd has cultivated a group of professional construction teams with excellent equipment, rich experience and serious responsibility with advanced and scientific management methods and strict engineering quality assurance and after-sales service system It has undertaken a number of fire system installation projects, which has been praised by customers Every idea and special requirement of you will be fully considered by us and fully realized in the construction technology, which will become the cornerstone of our successful long-term development We are looking forward to your invitation, to provide you with quality services and high-quality technical support! All construction coatings have passed ISO9001 Paint Home News: Huang GuiQiang (Guangzhou Haizhu District Construction Engineering Quality Supervision and testing office) Abstract: China is an ancient ceramic country with a long history and profound ceramic culture Since the reform and opening up, with the explosive growth of the real estate industry, the application scope and consumption of ceramic exterior wall brick have increased rapidly Ceramic exterior wall brick has become one of the first choice materials for building exterior wall decoration and plays an important role in protecting the wall because of its good decorative effect, long-lasting texture, low comprehensive cost, convenient later maintenance, acid and alkali resistance, durability, weather resistance, pollution resistance, high cost performance, easy construction and many other advantages However, in the construction, the base surface is not well treated before the facing brick is pasted, and the bonding strength between the leveling layer material (or the facing brick adhesive) and the base is too low, resulting in many quality problems such as falling off, cracking, hollowing, peeling, discoloration, etc., which are easy to cause the facing brick adhesive (plus the leveling material) and the facing brick to separate from the base wall or fall off the wall together, as well as the construction process of the facing brick of the external wall There are some hidden dangers in the process, construction time and maintenance reasons after construction Especially in the south of China, due to the impact of rainstorm and typhoon, the peeling and cracking of facing brick is more serious, which not only affects the urban landscape, but also endangers the safety of people's life and property, so we must pay full attention to it In this paper, the author has been engaged in the inspection experience of external wall facing bricks for a long time to explore some precautions in the construction and inspection of external wall tiles Key words: exterior wall facing; adhesive; decoration effect 1 Construction of facing brick 1 1 Process material selection → base treatment → wall pasting and setting up standard bar → plastering → snapping line → inlaying → caulking → maintenance and preparation of cement sand Cement with 32.5 grade or above should be selected Sand should be fine sand A layer of 1:0.3 cement fine mortar should be added between base and facing brick for water proofing Leveling layer (40-70 meshes for fine sand) shall be used to ensure the flatness of the base course and enhance the anti seepage effect 1:2 cement mortar is used for inlaying, and the thickness of mortar is 6-10 mm; the cement mortar used for inlaying can be mixed with a proper amount of lime paste to ensure the workability, enhance the adhesion between the base plastering and the facing brick, facilitate the adjustment of brick joints, and avoid hollowing In addition, φ 6 ~ φ 10 round iron is used to press the joint, so that the mortar joint is dense and uniform in thickness, and the anti seepage effect is further enhanced A horizontal expansion joint shall be set up every two floors along the height of the building to avoid hollowing and cracks caused by hot expansion and cold contraction of the facing bricks Adjust the width of brick joint, paste the whole brick as much as possible, enhance the visual effect, reduce the loss of cutting machine and the waste of labor and materials 1.2 process principle ⑴ due to the deviation of the flatness of the external wall, the thickness of the base plastering is different Thick place is easy to produce shrinkage cracks, thin place is easy to produce sand holes when coarse sand rolling, which has become the main hidden danger of external wall leakage When laying bricks on the outer wall, the flatness must be strictly controlled to reduce the micro cracks and sand holes in the base plastering (2) strictly control the size of the main structure, adjust the local size of the main structure according to the modulus of the face brick in the process of wall building, door and window frame installation, plastering, etc., and try to eliminate half brick sticking, so as to achieve the purpose of improving the appearance quality of the external wall (3) precautions ① the installation of facing brick shall be carried out after the quality acceptance of the base or base The matrix shall have sufficient strength, stability and rigidity, and its surface quality shall meet the requirements of the project quality acceptance specification ② Before construction, in order to avoid the serious loss caused by substandard bonding strength of facing bricks after large area of facing bricks are pasted, the supervision unit shall randomly select one person from the construction personnel who pastes the facing bricks, make sample pieces of each type of facing bricks on each type of base course, carry out initial inspection on the bonding strength of facing bricks, and pass the acceptance The formal construction can only be carried out after the construction scheme is qualified and determined Only by strengthening the sense of responsibility of the construction unit and improving the process control of construction quality can the overall quality of the project be guaranteed ③ When the tensile strength of the substrate is less than the bonding strength of the external wall facing brick, reinforcement must be carried out After reinforcement, the strength of the pasted sample plate shall be inspected ④ The facing brick shall be inlaid on the flat and rough base course, and the smooth base course surface shall be treated before inlaying Residual mortar, dust and oil stains shall be removed ⑤ The bottom of brick wall shall be watered one day in advance, and then plastered with ash cake and then reinforced, and then bottomed with 1:3 cement mortar, rubbed with wood trowel, and watered and maintained for at least 7 days after forming for 48 hours 2 Testing of facing brick 2.1 testing of raw materials generally, the purchased external wall brick must contain the delivery inspection report of this batch of products The physical properties of all products (moisture content, flatness, compressive strength, wear resistance, glaze smoothness) must conform to the standard technical indicators, and can be used only with the certificate of conformity issued by the relevant authority If there are special requirements, the radioactivity index of tile shall be additionally tested 2.2 pull out strength test of finished products 2.2.1 sampling requirements for prefabricated wallboard with facing brick shall provide type test report containing the test results of bonding strength of facing brick, and the test results shall conform to the provisions of line standard jgj110-2008 In addition, the bond strength of the facing shall be retested For the retest, the precast wallboard with the same type of facing brick of the 1000m2 shall be taken as an inspection batch If it is less than 1000m2, it shall be counted as 1000m2 Each batch shall be taken as a group, each group of which shall be 3 boards, and each board shall be taken as a sample for inspection The adhesive strength test of the on-site pasted facing brick shall take every 1000m2 of the same kind of wall facing brick as an inspection batch If it is less than 1000m2, it shall be calculated as 1000m2 Three samples shall be taken for each batch, and at least one group of samples shall be taken for each adjacent three floors The samples shall be randomly selected, and the sampling interval shall not be less than 500mm 2.2.2 detection method cutting seam shall be cut from the surface of facing brick to concrete The depth of the wall or masonry surface shall be the same For the aerated concrete, light block, light wallboard with strengthening treatment measures and the external wall facing brick pasted on the external wall external insulation system, on the premise that the strengthening treatment measures or insulation system meet the requirements of relevant national standards and the acceptance certificate of concealed work is provided, it can be cut to the surface of the strengthened plastering layer The cross-section area of the sample is the actual breaking area of the area surrounded by the fracture under the normal tension The length of the cross-section side of the sample is the middle length of each pair of cutting edges of the fracture surface The measurement accuracy is 1mm The middle length of the cutting edge is generally close to the average value of the three measured values at both ends and the middle The standard block shall be evenly coated and pasted on the surface of the cut facing brick as soon as possible The surface shall be clean and dry When the site temperature is lower than 5 ℃, it is better to preheat and then paste The bond strength of standard block adhesive should be 0.3MPa For aerated concrete, lightweight block and lightweight wall panel with low strength, if the external wall facing brick is to be pasted, reliable reinforcement treatment must be carried out, and the broken joint shall be cut to the surface of qualified reinforcement layer At present, the external wall external insulation system of ordinary paste method should not paste the external wall facing bricks Only when the density of the insulation layer, the bonding area with the wall, the strengthening treatment measures, the bonding and pointing of the facing bricks meet the national industry standards, can they be cut to the surface of the plastering layer of the insulation system Otherwise, it shall be cut to the surface of concrete or masonry The facing brick with uneven surface shall be first filled with adhesive and then pasted with standard block The surface of facing brick shall not be polished to prevent the strength of facing brick from decreasing After the standard block is stuck, it shall be kept still for three to five minutes, and a pull rod with universal joint shall be installed so that the pull rod passes through the center of the jack and is perpendicular to the standard block Adjust the jack piston, adjust the reading to zero, tighten the tension rod nut, and then turn the handle at a constant speed to increase the pressure until the facing brick is disconnected 2.2.3 the bond strength of the test sample for bond strength inspection and evaluation shall be calculated according to the following formula: RI -- the bond strength of the ith test sample (MPA), accurate to 0.1MPa; Xi -- the bond strength of the ith test sample (KN), accurate to 0.01kN; Si -- the cross section area of the ith test sample (mm) 2, accurate to mm2 The average bond strength of each group of samples shall be calculated according to the following formula: RM = 1 / 3 Σ RI formula: RM - average bond strength of each group of samples (MPA), accurate to 0.1MPa For the same kind of facing brick pasted on site, when a group of samples meet the requirements of the following two indicators, the basic bond strength is determined as qualified; when a group of samples do not meet the following two indicators, the basic bond strength is determined as unqualified; when a group of samples only meet the requirements of one of the following two indicators, two groups of samples shall be taken again in the original sampling area of the group of samples for inspection, if there is still one result If the items do not meet the following requirements, the bond strength of this group of facing bricks shall be determined as unqualified: ① the average bond strength of each group of samples shall not be less than 0.4MPa; ② the bond strength of one sample in each group may be less than 0.4MPa, but not less than 0.3MPa For the prefabricated wall panel with facing brick, when a group of samples meet the requirements of the following two indicators, the base bond strength is determined to be qualified; when a group of samples do not meet the following two indicators, the base bond strength is determined to be unqualified; when a group of samples only meet the requirements of one of the following two indicators, two groups of samples shall be taken again in the original sampling area of the group of samples for inspection, if the results still have If one item does not meet the following index requirements, the bond strength of this group of facing bricks is determined as unqualified ① The average bond strength of each group of samples shall not be less than 0.6MPa; ② the bond strength of one sample in each group shall be less than 0.6MPa, but not less than 0.4MPa When the test results are in the first and second disconnected state, and the bond strength is not less than the standard average value, and the fracture meets the requirements, the test results are taken as the test values at the time of disconnection Matrix fracture is a normal phenomenon In addition to cutting the surface layer of the matrix when the fracture occurs and the bond strength is less than the standard average value, it is necessary to select a new point for testing The test value of matrix fracture is also the result of whether the bond strength is qualified The disconnected state of the test piece is shown in Table 1 Table 1 for projects with urgent use and short construction period, it can be considered that under the verification of relevant departments, 14 day old veneer brick bonding surface test can be selected, or according to the use of rapid hardening cement-based adhesive