A pipe culvert type explosion vent for an underground combustion equipment room and a construction method thereof

Abstract

The present invention provides a pipe culvert type explosion vent and construction method for an underground combustion equipment machine room. An explosion vent formed by splicing and butting multiple sections of explosion vent pipe culverts connects the underground machine room, the explosion vent chamber and the turning chamber. The explosion vent chamber is covered with a lightweight roof and connected to the ground. After the explosion vent pipe culverts are butted together, a sealing layer is covered at the joint; the ports at which the explosion vent pipe connects the underground machine room and the explosion vent chamber are first sealed by a sealing ring and then fixed by a reinforcement ring. The advantages are: the explosion vent pipe culvert can be laid flexibly, the explosion vent can be flexibly directed to other suitable locations without changing the site selection of the machine room, which improves the applicability of the scheme, the explosion vent path is flexible, and the construction cost is reduced. The explosion vent hole is transferred to the side wall structure, the structural cost of the roof's shear resistance is reduced, and the reinforcement cost of the project is reduced. The explosion venting method of venting the explosion to the sky will not cause a chain explosion of adjacent personnel and structures, and avoid secondary damage to the surrounding area.

Description

Technical Field

[0001] The invention relates to the field of fire safety of underground combustion equipment room, and in particular to a pipe culvert type explosion vent of an underground combustion equipment room and a construction method thereof. Background Art

[0002] The room of equipment for burning flammable gases such as gas may explode. According to fire safety requirements, in order to protect personnel safety, the maintenance structure of the production room should be equipped with a certain area ratio of explosion relief area, so that when a gas explosion occurs, the explosion will be vented to the outside. According to the latest national standards, the pressure relief area of ​​the boiler room shall not be less than 10% of its floor area.

[0003] At present, many combustion equipment rooms are located on the first underground floor, and it is impossible to achieve the purpose of explosion relief by using doors and windows. Most of the explosion relief ports in underground combustion equipment rooms are located directly above the equipment room, and are extended from the underground room to the outdoors by building an explosion relief shaft. The net cross-sectional area of ​​the shaft meets the pressure relief area requirements. Correspondingly, the location of the explosion relief ports extending to the outdoors has the following restrictions: the pressure relief direction must not be toward gathering places, rooms, pedestrian walkways and other areas where people move. When the explosion relief ports are adjacent to other buildings and structures, the fire safety distance requirements of the regulations must be met. At the same time, the explosion relief ports and buildings must meet the safety fire protection distance according to the regulations. Taking the above factors into consideration, most explosion relief ports in underground combustion equipment rooms of general projects are built in green areas of residential areas or factory areas.

[0004] However, in order to maximize the value of land, real estate and park development now have compact overall planning and complex architectural design and structure. Often, the location of the underground equipment room is selected to meet the process requirements and convenient operation, but the explosion vent does not meet the safety and landscape requirements on the ground, and it is impossible to have the best of both worlds. When selecting and adjusting the location, it is often a matter of one thing affecting the whole body, especially for renovation projects: it is difficult to find a location suitable for building an explosion vent shaft and opening an explosion vent directly above the underground equipment room in the original layout and planning, which causes great difficulties in the implementation of the project plan. Therefore, how to provide a flexible explosion venting device has become an urgent problem to be solved. Summary of the invention

[0005] The invention provides a pipe culvert type explosion relief port in an underground combustion equipment room and a construction method thereof, which are used to solve the problem in the prior art that it is difficult to carry out a renovation project plan of the explosion relief shaft due to the large occupied area of ​​the fixed structure.

[0006] In order to achieve the above-mentioned purpose, the technical solution of the present invention provides a pipe culvert type explosion vent for an underground combustion equipment room, which includes an explosion vent pipe culvert, an explosion vent chamber, a lightweight roof, a reinforcement ring, and a sealing ring. Multiple sections of explosion vent pipe culverts are connected in sequence to form an explosion vent pipe, one end of which is connected to the explosion vent hole on the side wall of the underground room, and the other end is connected to the explosion vent hole on the side wall of the explosion vent chamber, which is covered with a lightweight roof and connected to the ground. After the explosion vent pipe culverts are butt-jointed, a sealing layer is covered at the joint; the ports at which the explosion vent pipe is connected to the underground room and the explosion vent chamber are first sealed by a sealing ring and then fixed by a reinforcement ring; wherein the reinforcement ring is composed of an inner ring, a rib plate, and an outer ring.

[0007] As a preferred embodiment of the above technical solution, it is better to further include a turning chamber, which is a structure for realizing the turning function of the explosion-proof pipe, specifically a chamber with a bending structure, whose internal net cross-sectional area is not less than the net cross-sectional area of ​​the explosion-proof pipe, and the explosion-proof hole of the turning chamber is arranged on its side wall.

[0008] As a preferred embodiment of the above technical solution, preferably, the socket-joint connection between the explosion-relief culverts includes that a socket groove and a socket protrusion corresponding to the joint surface of the explosion-relief culvert are provided on the joint surface of the explosion-relief culvert.

[0009] As a preferred embodiment of the above technical solution, preferably, the explosion venting chamber is exposed to the ground by at least 600 mm, and a weight of less than 120 kg / m is installed on the top. 2 The net cross-sectional area of ​​the explosion-proof chamber shall not be less than the net cross-sectional area of ​​the explosion-proof pipe.

[0010] As a preferred embodiment of the above technical solution, preferably, the gap between the lightweight roof and the explosion-proof chamber is filled with gypsum or cement mortar.

[0011] As a preferred embodiment of the above technical solution, preferably, the sealing ring is a rubber ring, the inner diameter of which is the same as the outer diameter of the explosion-proof culvert, and the ring width of which is not less than the ring width of the reinforcement ring.

[0012] As a preferred embodiment of the above technical solution, preferably, the reinforcement ring is a steel ring structure, the ribs include annular ribs and sheet ribs, a plurality of sheet ribs are evenly arranged between the inner ring and the annular ribs, and the three are connected by welding; the outer ring is arranged outside the annular ribs, and the two are connected by welding, and the width of the outer ring is consistent with the thickness of the vertical maintenance structure of the explosion-proof culvert, the outer wall of the machine room and the explosion-proof chamber.

[0013] The technical solution of the present invention also provides a method for constructing a pipe culvert type explosion vent in an underground combustion equipment room, which is used to construct the above-mentioned pipe culvert type explosion vent in an underground combustion equipment room, including: a plurality of sections of the explosion vent pipe culvert are connected by sockets to form an explosion vent pipe to connect the underground machine room and the explosion vent chamber and / or the turning chamber. When connected, a sealing ring is first sleeved on the port of the explosion vent pipe, and then a reinforcement ring is arranged outside the sealing ring and fixed to the explosion vent hole on the wall of the underground machine room or the explosion vent chamber or the turning chamber. The reinforcement ring is directly pre-buried and cast in the concrete wall, or fixed to the explosion vent hole through cement mortar.

[0014] As a preferred embodiment of the above technical solution, preferably, the portion of the explosion-proof culvert above the ground is painted with modified asphalt paint to prevent oxidation and rain acidification corrosion; the explosion-proof culverts are first wrapped with wire mesh cement mortar tape, then coated with cement mortar, and finally coated with melted asphalt.

[0015] As a preferred embodiment of the above technical solution, preferably, the explosion-proof chamber and the turning chamber are paved with a waterproof cushion layer, a load-bearing layer, a base plate, a vertical maintenance structure, and a top plate from bottom to top, wherein the vertical maintenance structure and the top plate are leveled with cement mortar and then externally adhered with waterproof membrane.

[0016] The technical solution of the present invention provides a pipe culvert type explosion vent and construction method for an underground combustion equipment room. The explosion vent pipe formed by the socket-jointed connection of multiple sections of explosion vent pipe culverts connects the underground machine room, the explosion vent chamber and the turning chamber. The explosion vent chamber is covered with a lightweight roof and connected to the ground. After the explosion vent pipe culverts are socket-jointed, a sealing layer is covered at the joint; the ports at which the explosion vent pipe connects the underground machine room and the explosion vent chamber are first sealed by a sealing ring and then fixed by a reinforcement ring.

[0017] The advantages of the present invention are: (1) because the explosion relief pipe culvert of the invention can be laid flexibly, the explosion relief port can be flexibly directed to other suitable locations without changing the site selection of the machine room, so that the site selection of the underground machine room is not restricted by the ground landscape planning and fire protection distance, which greatly improves the applicability of the scheme, the explosion relief path is flexible, and the construction cost is reduced. (2) There is no need to open a hole in the roof of the underground machine room, and the hole is transferred to the side wall structure, which reduces the structural cost of the roof's shear resistance and reduces the reinforcement cost of the project. (3) The movable feature of the explosion relief port can reduce noise interference to people in the building. (4) The explosion relief method of venting the explosion to the sky will not cause a chain explosion of adjacent people and structures, avoiding secondary damage to the surrounding area. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 A schematic structural diagram of a pipe culvert type explosion vent in an underground combustion equipment room provided by an embodiment of the present invention.

[0020] Figure 2 for Figure 1 A partial enlarged view of the dotted line.

[0021] Figure 3 It is a schematic diagram of the structure of the reinforcement ring in the technical solution of the present invention.

[0022] Figure 4 A flow chart of a method for constructing a pipe culvert type explosion vent in an underground combustion equipment room provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] The technical solution of the present invention is now described in conjunction with specific embodiments. Figure 1 A schematic diagram of the structure of a pipe culvert type explosion vent in an underground combustion equipment room provided by an embodiment of the present invention, Figure 2 for Figure 1 The enlarged view of the dotted line is as follows: Figure 1 and Figure 2 As shown, it includes: an explosion-relief culvert 11, an explosion-relief chamber 13, a lightweight roof 14, a turning chamber 12, a reinforcement ring 23, and a sealing ring 22.

[0025] First, Figure 1 As shown: multiple sections of explosion relief pipe culverts 11 are connected in sequence to form a plurality of explosion relief pipes. One end of an explosion relief pipe is connected to the explosion relief hole on the side wall of the underground machine room, and the other end is connected to the explosion relief hole on the side wall of the turning chamber 12. The explosion relief hole on the other side wall of the turning chamber 12 is connected to another section of explosion relief pipe, and the other end of this explosion relief pipe is connected to the explosion relief hole on the side wall of the explosion relief chamber 13. The explosion relief chamber 13 is connected to the ground, and the connection point is covered with a lightweight roof.

[0026] The turning chamber 12 is a structure used to realize the turning function of the explosion-proof pipe. If the explosion-proof pipe does not need to be bent, it can be omitted. The turning chamber 12 is specifically a chamber with a bending structure, and its internal net cross-sectional area is not less than the net cross-sectional area of ​​the explosion-proof pipe. The explosion-proof hole of the turning chamber 12 is set on its side wall. Its wall is cast-in-place reinforced concrete or masonry structure. The internal structure of the turning chamber 12 is waterproof cushion layer, load-bearing layer, bottom plate, vertical maintenance structure, and top plate from bottom to top. After the vertical maintenance structure and the top plate are leveled with cement mortar, waterproof membrane is attached to the outside.

[0027] The explosion-proof chamber 13 is at least 600 mm above the ground and has a top portion with a mass of less than 120 kg / m 2 The lightweight roof 14 has a net internal cross-sectional area of ​​the explosion-proof chamber 13 that is not less than the net cross-sectional area of ​​the explosion-proof pipe. The explosion-proof chamber 13 is composed of a waterproof cushion layer, a load-bearing layer, a base plate, a vertical maintenance structure, and a top plate from bottom to top. The vertical maintenance structure and the top plate are leveled with cement mortar and waterproof membrane is pasted on the outside. The outer edge of the lightweight roof 14 is larger than the outer edge of the explosion-proof chamber 13, so that it can completely cover the explosion hole of the explosion-proof chamber 13, and the gap between the lightweight roof 14 and the explosion-proof chamber 13 is filled with gypsum or cement mortar for dense waterproof and insect-proof treatment.

[0028] Furthermore, the connection between the explosion relief pipe culverts 11 is a socket-and-spigot joint, and after the joint is joined, a sealing layer is covered at the joint, and the sealing layer is composed of a steel mesh cement mortar tape, a cement mortar coating and asphalt in sequence, which can prevent corrosion and insect holes. The joint surface of the explosion relief pipe culvert 11 is provided with a socket groove and a socket protrusion corresponding to the joint surface of the next section of the explosion relief pipe culvert 11.

[0029] refer to Figure 2 : The explosion-proof pipe and the explosion-proof hole of the underground machine room, the explosion-proof pipe and the explosion-proof hole of the explosion-proof chamber 13, and the explosion-proof pipe and the explosion-proof hole of the turning chamber 12 are first sealed by the sealing ring 22 and then fixed by the reinforcement ring 23. The sealing ring 22 plays a role of sealing and waterproofing. Further, Figure 2 The wall 24 shown is the wall of the turning chamber 12, and only uses it to specifically illustrate the connection relationship between the explosion relief pipe and the wall. The connection between the explosion relief pipe and the explosion relief hole of the underground machine room and the explosion relief chamber 13 can be referred to. Figure 2 .

[0030] The sealing ring 22 is a rubber ring, whose inner diameter is the same as the outer diameter of the explosion relief pipe 11, and whose ring width is not less than the ring width of the reinforcement ring 23. The thickness of the sealing ring 22 is the difference between the outer diameter of the explosion relief pipe 11 and the inner diameter of the reinforcement ring 23 plus 3-5mm, where 3-5mm is the expansion amount of the rubber.

[0031] like Figure 3As shown: the reinforcement ring 23 is composed of an inner ring 31, ribs 32, and an outer ring 33. The reinforcement ring 23 is a steel ring structure. The ribs 32 include annular ribs 32 and sheet ribs 32. A plurality of sheet ribs 32 are evenly arranged between the inner ring 31 and the annular ribs 32, and the three are connected by welding; the outer ring 33 is arranged outside the annular ribs 32, and the two are connected by welding. The width of the outer ring 33 is consistent with the thickness of the vertical maintenance structure of the explosion-proof pipe culvert 11, the outer wall of the machine room, and the explosion-proof chamber 13. The inner and outer rings 33 below DN800 are made of steel pipes and steel plates, and those greater than DN800 are made of steel plates spliced ​​together. The width of the outer ring 33 of the reinforcement ring 23 is consistent with the thickness of the vertical maintenance structure of the explosion-proof pipe culvert 11, the outer wall of the machine room, and the explosion-proof chamber 13.

[0032] In the present invention, the internal net cross-sectional areas of the explosion-relief chamber 13 and the turning chamber 12 may be different, but both are larger than the sum of the cross-sectional areas of the explosion-proof pipe culverts.

[0033] The construction method for constructing the above-mentioned underground combustion equipment room pipe culvert type explosion vent provided by the present invention is now described in conjunction with the flow chart. Figure 4 As shown:

[0034] Step 101, according to project requirements, multiple sections of explosion-proof culverts are connected by sockets and spigots to form an explosion-proof pipe.

[0035] The explosion relief pipe culvert 11 needs to be sealed externally: first wrap it with steel mesh cement mortar tape, then apply cement mortar, and finally apply melted asphalt. The explosion relief pipe culvert 11 is composed of multiple sections of cylindrical cement pipes. The material of each section of the explosion relief pipe culvert 11 must be fire-resistant and corrosion-resistant, and meet the same fire resistance requirements as the underground machine room. The ground accumulation load is not more than 10kN / m 2 When using the prefabricated concrete pipes used in municipal drainage projects, high-strength HDPE municipal drainage pipes can also be used. The ground accumulation load is greater than 10kN / m 2 Concrete jacking pipes are used, and generally type II or above jacking pipes are selected. Direct burial construction is sufficient. The total cross-sectional area of ​​the explosion relief culvert 11 should not be less than the explosion relief area required by the underground machine room. The explosion relief culvert 11 is laid on the original soil foundation with high bearing capacity and strong support strength, or on the soil foundation after backfilling and compaction after excavation. The backfill compaction materials are generally graded crushed stone, natural graded sand and gravel, medium sand, coarse sand and other sands from bottom to top. The compaction coefficient and cross-section method can be found in the national standard drawing 04S516 "Concrete Drainage Pipe Foundation and Interface".

[0036] Step 102: construct an explosion-proof chamber and a turning chamber and open an explosion-proof hole.

[0037] The explosion relief chamber 13 and the turning chamber 12 are paved with a waterproof cushion layer, a load-bearing layer, a bottom plate, a vertical maintenance structure, and a top plate in sequence from bottom to top, wherein the vertical maintenance structure and the top plate are leveled with cement mortar and then externally affixed with waterproof membrane.

[0038] In step 102, for new projects, the reinforcement ring is directly embedded and cast in the concrete wall, and the steel mesh inside the reinforcement ring is welded and connected; for renovation projects, an explosion relief hole is directly opened.

[0039] Step 103: Connect a sealing ring to the port of the explosion relief pipe.

[0040] Step 104, fix one end of the explosion-proof pipe to the explosion-proof hole of the underground machine room.

[0041] Step 105, the other end is fixed to the explosion relief hole on the wall of one side of the turning chamber.

[0042] Step 106, one end of another explosion-proof pipe is fixed to the explosion-proof hole of the wall on the other side of the turning chamber.

[0043] Step 107, the other end is fixed to the explosion-proof hole of the wall on one side of the explosion-proof chamber.

[0044] For the renovation project, in the fixing process of steps 104-107: the sealing ring 22 is sleeved on the port of the explosion-relief pipe (the reinforcement ring is arranged outside the sealing ring 22), and then fixed to the explosion-relief hole on the wall of the underground machine room or the explosion-relief chamber 13 or the turning chamber 12 by cement mortar.

[0045] Step 108: The above-ground portion of each explosion relief culvert is painted with modified asphalt paint to prevent oxidation and rainwater acidification corrosion.

[0046] Step 109: Install a lightweight roof on the explosion-proof chamber.

[0047] The technical solution of the present invention is now further described in conjunction with specific scenarios:

[0048] When a gas leak explosion occurs in the underground machine room, the generated air wave and instantaneous high pressure will be discharged along the explosion relief pipe and the turning chamber 12 (optional) to the explosion relief chamber 13, and then transmitted upward through the explosion relief chamber 13. The light roof can be broken or separated from its original position during the explosion, so as to achieve the purpose of discharging the explosion air wave, thereby realizing the technical solution of the present invention. The explosion relief method of venting the explosion to the sky will not cause a chain explosion of adjacent personnel and structures, and avoid secondary damage to the surrounding environment.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features may be replaced by equivalents. For example, changes in the pipe, box, or arch shape of the explosion-proof culvert, as well as changes in the materials of the culvert and the explosion-proof chamber are all within the scope of the patent. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A pipe culvert type explosion vent for an underground combustion equipment room, characterized in that: It includes explosion relief pipe culvert, explosion relief chamber partially placed underground, turning chamber, lightweight roof, reinforcement ring, and sealing ring: Multiple sections of the explosion relief pipe culvert are connected in sequence to form an explosion relief pipe, one end of the explosion relief pipe is connected to the explosion relief hole on the side wall of the underground machine room, and the other end is connected to the explosion relief hole on the side wall of the explosion relief chamber through the turning chamber, and the explosion relief chamber is covered with the lightweight roof and connected to the ground; Construct explosion relief chambers and turning chambers and open explosion relief holes; the explosion relief pipes are butt-jointed with each other and a sealing layer is provided at the joints; the ports of the explosion relief pipes connecting the underground machine room and the explosion relief chambers are first sealed by the sealing rings and then fixed by the reinforcement rings; wherein the reinforcement rings are composed of inner rings, ribs and outer rings; wherein, for new projects, the reinforcement rings are directly embedded and cast in the concrete wall; and for renovation projects, the sealing rings are sleeved on the ports of the explosion relief pipes and fixed to the explosion relief holes with cement mortar; wherein the reinforcement rings are a steel ring structure, the ribs include annular ribs and sheet ribs, a plurality of sheet ribs are evenly arranged between the inner ring and the annular ribs, the three are connected by welding, the outer ring is arranged outside the annular ribs, the two are connected by welding, and the width of the outer ring is consistent with the thickness of the vertical maintenance structure of the explosion relief pipe culvert, the machine room outer wall and the explosion relief chamber; The turning chamber is a structure for realizing the turning function of the explosion relief pipe, specifically a chamber with a bent structure, the net cross-sectional area of ​​which is not less than the net cross-sectional area of ​​the explosion relief pipe, and the explosion relief hole of the turning chamber is arranged on its side wall; Among them, the explosion-proof chamber and the turning chamber are paved with a waterproof cushion layer, a load-bearing layer, a base plate, a vertical maintenance structure, and a top plate in sequence from bottom to top, wherein the vertical maintenance structure and the top plate are leveled with cement mortar and then externally affixed with waterproof membrane.

2. The pipe culvert type explosion vent for underground combustion equipment room according to claim 1, characterized in that: The socket-joint connection between the explosion-relief culverts includes that a socket groove and a socket protrusion corresponding to the joint surface of the next section of the explosion-relief culvert are provided on the joint surface of the explosion-relief culvert.

3. The pipe culvert type explosion vent for underground combustion equipment room according to claim 1, characterized in that: The explosion relief chamber is at least 600 mm above the ground and has a mass of less than 120 kg / m 2 The lightweight roof of the explosion-proof chamber has an internal net cross-sectional area not less than the net cross-sectional area of ​​the explosion-proof pipe.

4. The pipe culvert type explosion vent for underground combustion equipment room according to claim 3, characterized in that: The gap between the lightweight roof and the explosion-proof chamber is filled with gypsum or cement mortar.

5. The pipe culvert type explosion vent for underground combustion equipment room according to claim 1, characterized in that: The sealing ring is a rubber ring, the inner diameter of which is the same as the outer diameter of the explosion relief culvert, and the ring width of which is not less than the ring width of the reinforcement ring.

6. A method for constructing a pipe culvert type explosion vent in an underground combustion equipment room, used to construct the pipe culvert type explosion vent in an underground combustion equipment room as claimed in any one of claims 1 to 5, characterized in that: Construct explosion-proof chambers and turning chambers and open explosion-proof holes; for new projects, the reinforcement ring is directly embedded and cast in the concrete wall, and the steel mesh inside the reinforcement ring is welded and connected; for renovation projects, an explosion-proof hole is directly opened; The explosion relief pipe formed by the socket-jointed connection of multiple sections of the explosion relief pipe culvert connects the underground machine room, the explosion relief chamber and the turning chamber. When connected, the sealing ring is first sleeved on the port of the explosion relief pipe, and then the reinforcement ring is arranged outside the sealing ring and fixed to the explosion relief hole on the side wall of the underground machine room, the explosion relief chamber or the turning chamber; The reinforcement ring is directly embedded and cast in the concrete wall, or, for a renovation project, the sealing ring is sleeved on the port of the explosion-relief pipe, and the reinforcement ring is arranged outside the sealing ring and fixed to the explosion-relief hole through cement mortar.

7. A method for constructing a pipe culvert type explosion vent in an underground combustion equipment room according to claim 6, characterized in that: The portion of the explosion relief pipe culvert above the ground is painted with modified asphalt paint to prevent oxidation and rainwater acidification corrosion; the explosion relief pipe culverts are first wrapped with wire mesh cement mortar tape, then coated with cement mortar, and finally coated with melted asphalt.

8. A method for constructing a pipe culvert type explosion vent in an underground combustion equipment room according to claim 6, characterized in that: The explosion relief chamber and the turning chamber are paved with a waterproof cushion layer, a load-bearing layer, a base plate, a vertical maintenance structure, and a top plate in sequence from bottom to top, wherein the vertical maintenance structure and the top plate are leveled with cement mortar and then externally adhered with waterproof membrane.

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