Urban viaduct drainage noise reduction and alkali bleeding prevention steel slag asphalt concrete bridge deck paving construction method

Abstract

The present application belongs to the technical field of bridge deck pavement, and particularly relates to a construction method of urban elevated bridge drainage noise reduction alkali bleeding prevention steel slag asphalt concrete bridge deck pavement. The construction method comprises bridge deck partitioning scarification treatment, laying of high-viscosity modified asphalt waterproof layer, laying of bridge deck pavement structure, and construction of the waterproof and drainage system of the bridge deck pavement structure. The construction method utilizes low-cost solid waste steel slag in the large-void permeable asphalt pavement with excellent drainage and noise reduction functions through the synergistic mechanism of mechanical scarification anchor locking, high-toughness sealing water blocking and gradient drainage, and overcomes the technical difficulties of water swelling, poor volume stability and easy alkali bleeding of the large-void steel slag mixture.

Description

Technical Field

[0001] This invention belongs to the field of bridge deck paving technology, specifically relating to a construction method for drainage, noise reduction, and efflorescence prevention steel slag asphalt concrete bridge deck paving for urban elevated bridges. Background Technology

[0002] Urban elevated highways, serving as multi-level arteries to alleviate traffic congestion in the city center, are typically characterized by steep gradients, numerous small-radius curves, and close proximity to buildings and residential areas beneath them. To ensure driving safety and comfort, the bridge deck paving must not only possess excellent anti-skid properties but also address the issue of water mist obscuring the road during high-speed driving in rainy weather, as well as the noise pollution complaints faced by nearby residential areas.

[0003] In the current renovation project of elevated bridges, in order to achieve the dual goals of drainage and noise reduction, the existing technology adopts large-void permeable asphalt pavement (drainage asphalt mixture, abbreviated as PA). Although the PA structure has a high porosity of about 20%, it can quickly drain the surface water, eliminate water mist and significantly reduce tire noise. However, in practical applications, especially when steel slag aggregate is involved, there are still the following drawbacks: (1) Insufficient treatment of the base surface and anchoring force of the large longitudinal slope. The longitudinal slope of the elevated bridge is often greater than 3%, or even reaches 5%-6%. Traditional shot blasting or mobile milling equipment is difficult to brake when operating on the large longitudinal slope, and the cutting power is limited. It is difficult to completely remove the thick laitance layer formed by years of wear on the bridge deck surface. This results in a low base surface exposed rate, which cannot provide sufficient shear anchoring force for the large-void asphalt layer. Potholes are very easy to occur at sudden braking or curves. (2) Steel slag is generally not used in large-void mixtures in the existing technology. Although steel slag aggregate has the advantages of high hardness, excellent anti-skid performance, and environmentally friendly solid waste utilization, it contains undigested free calcium oxide (f-CaO). In existing technologies using a PA (pavement layer) structure, surface water can directly seep into the structure through interconnected pores and remain there for a long time. The reaction between water and f-CaO in the steel slag triggers a violent hydration and expansion reaction, causing the asphalt film to rupture, white calcification to effloresce, and ultimately resulting in a loose and fragmented pavement layer. Therefore, current technologies avoid using steel slag in PA layers in actual paving projects, necessitating the use of expensive basalt aggregate, leading to low solid waste utilization and high costs.

[0004] To address the aforementioned issues, existing technologies employ two approaches: First, dense asphalt concrete can reduce the risk of efflorescence, but it also reduces drainage and noise reduction capabilities. Second, increasing the thickness of the asphalt film to fully encapsulate the steel slag can lead to a decrease in the high-temperature stability of the road surface and still fails to resolve the interfacial adhesion problem.

[0005] In summary, there is an urgent need for a paving construction method that can efficiently utilize low-cost solid waste steel slag in noise-reducing and drainage PA structures and effectively prevent efflorescence of the steel slag. Summary of the Invention

[0006] The purpose of this invention is to provide a construction method for drainage, noise reduction, and efflorescence prevention of steel slag asphalt concrete bridge deck paving for urban elevated bridges. This construction method utilizes a synergistic mechanism of mechanical roughening and anchoring, high-toughness sealing and water blocking, and gradient drainage to efficiently utilize low-cost solid waste steel slag in large-void permeable asphalt pavements with excellent drainage and noise reduction functions. It also overcomes the technical problems of large-void steel slag mixtures expanding when exposed to water, poor volume stability, and easy efflorescence.

[0007] The technical solution of this invention is as follows: A method for constructing drainage, noise reduction, and efflorescence prevention steel slag asphalt concrete bridge deck pavement for urban elevated bridges includes the following steps: (1) Roughening treatment of bridge deck sections: First, based on the standard cross-section of the elevated bridge and drainage requirements, the bridge deck of the elevated bridge is divided laterally into the main traffic lane, the transition buffer zone, and the curb guide zone.

[0008] The main driving lane refers to the area including the overtaking lane and the driving lane; this area bears high-frequency wheel loads and braking horizontal forces.

[0009] The transition buffer zone refers to the lane dividing line and the widening section; the stress in this area is between that of the road and the curb, and stress dissipation must be taken into account.

[0010] The curb guide zone refers to the area within 0.5m of the base of the crash barrier; this area requires special attention to address water accumulation at the base of the wall and equipment avoidance.

[0011] Then, differentiated roughening is performed, as follows: Main gantry: A spiral cloth-blade roughening trolley is used to roughen the surface of the bridge deck of the main gantry, forming a rough surface with no directional texture. The roughening depth is controlled at 4~6mm, the exposed aggregate rate is ≥60%, and the structural depth is ≥0.8mm.

[0012] This treatment method results in a randomized texture direction, a large and uniform depth, avoiding the deficiency of oriented textures in shear resistance under specific load directions. It provides an omnidirectional mechanical interlocking effect for subsequent pavement layers, effectively resisting longitudinal, transverse, and multi-directional horizontal shear forces generated by traffic loads and preventing slippage of the pavement layer in all directions.

[0013] Transition buffer zone: The roughening process is carried out by a spiral cloth knife roughening trolley, and the roughening depth is controlled at 3~4mm, the exposed bone rate is ≥50%, and the structural depth is ≥0.6mm.

[0014] While ensuring sufficient roughness, excessively deep chiseling textures should be avoided to prevent the concentrated propagation of microcracks on the base surface in areas with complex stress, thus adapting to the frequent expansion and contraction deformation of the bridge deck.

[0015] The curb guide strip is roughened using a vertical short-toothed spiral cutter; the roughening depth is controlled at 2~3mm.

[0016] The vertically oriented short-toothed cutter head moves back and forth perpendicular to the wall surface of the crash barrier, forming a micro-channel in the direction of the bridge. This channel can guide the small amount of water seeping down the wall base to the edge drainage facilities in the direction of the bridge, preventing water from accumulating and seeping into the joints along the wall base. At the same time, the shallow roughening can effectively prevent the cutter from hitting the crash barrier, ensuring construction safety.

[0017] (2) Laying of high-viscosity modified asphalt waterproof layer: A high-viscosity and toughness sealing layer and a stress-absorbing layer are laid sequentially from bottom to top.

[0018] First, a high-viscosity and toughness sealing layer is laid on the bridge deck after the roughening treatment in step (1); the sealing layer is made of high-viscosity modified asphalt with a dynamic viscosity ≥50000Pa·s at 60℃, and the application rate is controlled at 1.8~2.2kg / m. 2 (Based on pure asphalt). High-viscosity modified asphalt can be made of SBS modified asphalt or polyurethane modified asphalt.

[0019] Compared to the conventional sealing layer's 0.8~1.2 kg / m 2 The present invention employs a high-viscosity design, increasing the amount of asphalt used by approximately 50% to 80%. Based on the multi-directional, high-depth rough texture formed after the main carriageway is roughened in step (1), using a conventional application rate would result in water seepage channels in the bridge deck. However, the high-viscosity modified asphalt applied at the aforementioned application rate can deeply penetrate the roughened gaps, not only forming nail-like anchor points but also constructing a dense, elastic, waterproof membrane beneath the subsequently laid steel slag layer, physically blocking the contact between moisture and f-CaO in the steel slag.

[0020] Then, a stress-absorbing layer is laid on top of the high-viscosity and toughness sealing layer; the amount of binder in this stress-absorbing layer is controlled at 0.4-0.6 kg / m². 2 .

[0021] The binder for the stress-absorbing layer is either rubber-modified asphalt or high-viscoelastic asphalt.

[0022] The method for synchronous crushed stone application is as follows: the amount of crushed stone applied to the main traffic lane of the bridge deck is controlled at 4-5 kg / m². 2 The amount of gravel spread in the bridge deck transition buffer zone and curb guide zone should be controlled at 2-3 kg / m². 2 .

[0023] Before applying the stress-absorbing layer, a protective membrane should be laid at the initial application section, longitudinal joints, and artificial structures to prevent contamination.

[0024] The difference between this invention and traditional single-layer waterproofing for bridge decks is that this high-viscosity modified asphalt waterproofing layer adopts a double-layer waterproofing structure that combines a high-viscosity and toughness sealing layer with a stress-absorbing layer. The stress-absorbing layer, as a key mechanical buffer and waterproof reinforcement layer, plays the following roles: First, its high viscoelasticity forms a flexible buffer zone, effectively absorbing and dissipating concentrated stress caused by temperature changes and loads on the bridge deck, thereby delaying or preventing the generation and propagation of reflective cracks in the upper steel slag asphalt concrete. Second, this layer, through the simultaneous application of rubber-modified asphalt and single-size crushed stone, forms an embedded anchoring structure after compaction, firmly bonding the upper steel slag asphalt pavement layer and the lower high-viscosity and toughness sealing layer into a whole, enhancing the interlayer synergy. Finally, the stress-absorbing layer itself has excellent waterproof sealing performance, forming a dense double waterproof barrier together with the high-viscosity and toughness sealing layer, further blocking the path of water infiltration and preventing the steel slag aggregate from undergoing f-CaO hydration expansion due to contact with free water, thus fundamentally solving the problems of water damage and efflorescence between steel slag asphalt mixture bridge deck pavement layers.

[0025] (3) Laying bridge deck pavement structure: The layers are laid from bottom to top in sequence: a water-permeable leveling layer, a first adhesive layer, a lower permeable load-bearing layer, a second adhesive layer, and an upper permeable noise-reducing layer.

[0026] The asphalt content of the bleeding leveling layer is 6.5%-7.0%; the coarse aggregate is hot-quenched steel slag, the fine aggregate is limestone manufactured sand, and the binder is SBS modified asphalt.

[0027] The aforementioned water-regulating and leveling layer adopts a fine-grained discontinuous gradation, and the gradation range of the mixture is (volume percentage): 100% passing through a 9.5mm sieve, 90%-100% passing through a 4.75mm sieve, 28%-65% passing through a 2.36mm sieve, 22%-36% passing through a 1.18mm sieve, 18%-28% passing through a 0.6mm sieve, 15%-22% passing through a 0.3mm sieve, 13%-18% passing through a 0.15mm sieve, and 12%-15% passing through a 0.075mm sieve.

[0028] The bleeding leveling layer adopts a fine-grained dense gradation, with the 4.75mm sieve passing rate controlled at 90%~100%. Fine aggregate and asphalt mortar are used to fill the roughened pits and form a continuous and dense bleeding film. The 0.075mm sieve passing rate of 12%~15% ensures the compactness of the mixture, blocks the seepage of water, and achieves the dual functions of leveling and sealing water.

[0029] The free calcium oxide (f-CaO) content in the steel slag used is ≤3.0%, the water immersion expansion rate is ≤0.8%, and the crushing value is ≤18%. Within 24 hours before use, the slag is pretreated by spraying with 0.5% silane coupling agent and then dried in an 80℃ oven until the moisture content is <0.5%, forming a hydrophobic layer on the aggregate surface to block the penetration path of water molecules.

[0030] The first bonding layer uses SBS modified emulsified asphalt, with an asphalt application rate of 0.5-0.8 kg / m³. 2 .

[0031] The asphalt content of the lower permeable load-bearing layer is 4.7%-4.9%; the coarse aggregate is hot-quenched steel slag, and the gradation range of the lower permeable load-bearing layer mixture is as follows: 100% passing through a 19mm sieve, 100% passing through a 16mm sieve, 90%-100% passing through a 13.2mm sieve, 50%-80% passing through a 9.5mm sieve, 12%-30% passing through a 4.75mm sieve, 10%-22% passing through a 2.36mm sieve, 6%-18% passing through a 1.18mm sieve, 4%-15% passing through a 0.6mm sieve, 3%-12% passing through a 0.3mm sieve, 3%-8% passing through a 0.15mm sieve, and 2%-6% passing through a 0.075mm sieve.

[0032] The gradation design of the lower permeable load-bearing layer effectively ensures the load-bearing capacity and smooth drainage of the layer. The 4.75mm sieve aperture is controlled within a low range to ensure the interlocking force of the skeleton, ensure that the coarse aggregate forms stone-to-stone contact, prevent the voids from being compacted under heavy load, and maintain smooth drainage.

[0033] The second bonding layer uses SBS modified emulsified asphalt, with an asphalt application rate of 0.5-0.8 kg / m³. 2 .

[0034] The asphalt content of the upper permeable noise reduction layer is 5.0%-5.2%; the coarse aggregate is hot-quenched steel slag, and the gradation range of the upper permeable noise reduction layer mixture is as follows: 100% passing through a 19mm sieve, 100% passing through a 16mm sieve, 90%-100% passing through a 13.2mm sieve, 55%-75% passing through a 9.5mm sieve, 22%-35% passing through a 4.75mm sieve, 18%-28% passing through a 2.36mm sieve, 12%-22% passing through a 1.18mm sieve, 10%-18% passing through a 0.6mm sieve, 8%-15% passing through a 0.3mm sieve, 6%-12% passing through a 0.15mm sieve, and 4%-8% passing through a 0.075mm sieve.

[0035] The graded design of the upper permeable noise reduction layer effectively ensures the noise reduction and anti-skid performance of this layer. The 4.75mm sieve aperture of this layer is controlled at 22%-35%, which is slightly higher than that of the lower layer. Combined with the moderate increase of the 2.36mm sieve aperture aperture of 18%-28%, the surface structure is made more delicate and uniform while maintaining the basic consistency of the skeleton interlocking structure. This effectively absorbs tire noise and takes into account the anti-skid performance.

[0036] The drainage path design for the above-mentioned bridge deck pavement structure is as follows: First, there is surface water: during rainfall, most rainwater seeps into the pavement structure through the interconnected gaps in the upper permeable and noise-reducing layer, while a small portion flows along the cross slope of the bridge deck to the edge drainage facilities.

[0037] Secondly, there is the upper layer seepage: rainwater seeps into the upper layer and flows laterally along the transverse slope of the bridge deck under the action of gravity through the interconnected gaps inside the upper layer. Most of it is discharged laterally into the edge blind ditch inside the upper layer.

[0038] Secondly, there is water seepage in the lower layer: a small amount of water that penetrates the second bonding layer enters the lower permeable load-bearing layer, and continues to drain laterally along the cross slope by utilizing the interconnected gaps inside the lower layer, ensuring that the water is guided away layer by layer before reaching the water-absorbing leveling layer.

[0039] Finally, there is the bottom waterproofing: the water-leveling layer, as the last line of defense against water seepage, physically blocks the contact between seepage water and the bridge deck with its dense gradation characteristics. Combined with the high-viscosity and tough sealing layer and stress-absorbing layer on the surface of the bridge deck, it forms a multi-layer waterproof barrier. Rainwater in the upper and lower permeable structures can be quickly discharged laterally through the interconnected gaps in the layers, significantly shortening the residence time of water on the surface of the steel slag aggregate. Combined with the steel slag hydrophobic pretreatment and the bottom sealing system, the f-CaO hydration reaction is inhibited, reducing the risk of efflorescence and eliminating efflorescence disease from the root.

[0040] The aforementioned pavement structure forms a functionally distinct interlayer collaborative system: the lower permeable load-bearing layer adopts a coarser permeable gradation, with the 4.75mm sieve aperture passing rate controlled at 12%-30%, forming a stable stone-stone contact skeleton interlocking structure, undertaking the main tasks of rutting resistance and structural load-bearing; the upper permeable noise-reducing layer adopts a gradation range basically consistent with the lower layer, with the 4.75mm sieve aperture passing rate controlled at 22%-35%, slightly higher than the lower layer, making the surface texture finer, taking into account both noise reduction and anti-skid functions. The two permeable structures are firmly bonded through a second bonding layer, forming a series drainage path while ensuring interlayer collaborative stress distribution—the upper layer drainage is the main method, and the lower layer drainage is the auxiliary method. The two layers work together to ensure smooth drainage of the bridge deck without damaging the lower structure.

[0041] (4) Construct a drainage system for the bridge deck pavement structure: The interconnected gaps between the lower permeable load-bearing layer and the upper permeable noise reduction layer form an internal drainage channel.

[0042] During the paving and compaction of the lower permeable load-bearing layer and the upper permeable noise-reducing layer, drainage channels are formed by the interconnected voids within each layer. During rainfall, rainwater infiltrates through these voids in the upper permeable noise-reducing layer, flows laterally along the cross slope within the upper layer, and is discharged laterally through the same voids. A small amount of water permeates through the second bonding layer into the lower permeable load-bearing layer, and is similarly discharged laterally along the cross slope using the interconnected voids within the lower layer. The two permeable layers form a series drainage path, ensuring that water is gradually diverted before reaching the leveling layer.

[0043] After the lower permeable load-bearing layer is laid and compacted 1-2 times, and before laying the second bonding layer and the upper permeable noise reduction layer, emulsified asphalt is applied to the side of the high side guardrail on the transverse slope and hot melt tape is pasted to form a physical barrier wall to prevent surface water and upper layer seepage water from seeping down into the lower structure through the gaps at the base of the guardrail.

[0044] Longitudinal blind drains or drainage channels are installed in the low-side edge area of ​​the transverse slope. The blind drains are 10-20cm wide and filled with single-size crushed stone or open-graded asphalt mixture to form a highly permeable zone; the drainage channels are 5-10cm wide. The blind drains or drainage channels are closely connected to the bridge's drainage holes, and the top surface of the drainage outlet is 5-10mm lower than the pavement surface to ensure that interlayer seepage water from the upper and lower layers can be quickly discharged into the drainage holes by gravity, avoiding water accumulation that could lead to the hydration and expansion of steel slag f-CaO.

[0045] The bridge deck pavement structure described in this invention adopts a combined upper and lower layer drainage system with multi-layer waterproofing at the bottom. The upper permeable noise reduction layer and the lower permeable load-bearing layer serve as the main drainage channels, allowing water that has seeped into the pavement structure to be discharged laterally along the cross slope of the bridge deck through interconnected gaps before reaching the water-absorbing and leveling layer. The water-absorbing and leveling layer, along with the high-viscosity and tough sealing layer and stress-absorbing layer below it, act as multiple waterproof barriers at the bottom, physically blocking the contact between residual seepage water and the bridge deck. Rainwater in the upper and lower permeable structures is quickly discharged laterally through interconnected gaps, significantly shortening the residence time of water on the surface of the steel slag aggregate. Combined with the steel slag hydrophobic pretreatment and the bottom water-sealing system, the f-CaO hydration reaction is inhibited.

[0046] In view of the general working conditions of complex urban viaducts with varying longitudinal and transverse slopes, the roughening treatment in step (1) of the bridge deck paving construction method of the present invention uses a roughening trolley equipped with a spiral alloy cutter array and a vacuum negative pressure adsorption track to ensure stable movement and constant force cutting under any slope, solving the problems of easy slippage and cutting depth drift of traditional equipment, and ensuring that the roughening trolley can meet the roughening treatment requirements in step (1).

[0047] The roughening trolley used in step (1) employs a combination of high-frequency micro-vibration and rotary cutting. The spiral cutter generates high-frequency vibration while rotating at high speed, physically breaking down the dense cement paste shell formed by frictional heat melting, thoroughly exposing the solid aggregate, ensuring that the exposed aggregate rate meets the standard, and providing a clean interface for the subsequent waterproofing layer.

[0048] The beneficial effects of this invention are as follows: The construction method for drainage, noise reduction, and efflorescence prevention steel slag asphalt concrete bridge deck pavement of urban elevated bridges described in this invention firstly involves differentiated roughening treatment of different zones using a spiral-bladed roughening trolley. This physically removes the surface laitance of the bridge deck, solving the technical problems of thick laitance and poor flatness commonly found in urban elevated bridge decks. The random, multi-directional micro-texture formed by the roughening treatment enables omnidirectional mechanical anchoring of the pavement layers, significantly improving the interlayer shear and anti-slip capabilities and solving the problem of insufficient anchorage force of the bridge deck pavement base surface.

[0049] By laying a high-viscosity and tough sealing layer to block the contact between seepage water and the bridge deck and the bottom of the steel slag layer, and combining the series of transverse drainage functions of the upper permeable noise reduction layer and the lower permeable load-bearing layer, the water entering the pavement structure is laterally discharged layer by layer before reaching the bleeding leveling layer, thus solving the problem of traditional steel slag pavement being prone to efflorescence due to long-term contact of water with f-CaO.

[0050] The composite structure, combining a drainage leveling layer, a lower permeable load-bearing layer, and an upper permeable noise reduction layer, ensures that drainage and noise reduction requirements are met while also considering high and low temperature performance and water stability. The lower permeable load-bearing layer uses a coarser permeable gradation to form a stable skeletal interlocking structure to resist rutting; the upper permeable noise reduction layer uses a permeable gradation range basically the same as the lower layer, with a slightly higher 4.75mm sieve aperture than the lower layer, resulting in a finer surface texture and noise reduction function.

[0051] The drainage system constructed in this invention blocks water seepage at the base of the guardrail by sealing the edges with hot-melt tape. Combined with the series drainage path of the upper and lower permeable load-bearing and noise-reducing layers and the bottom water-sealing line of the water-leveling layer, a complete drainage closed loop is formed. This not only eliminates water mist and glare during rainy weather, but also ensures the dry state of the bridge deck structure throughout its entire life cycle. It further strengthens the bond strength between the pavement layer and the concrete substrate, achieving the long-term use goals of drainage, noise reduction, and efflorescence prevention for viaducts. Attached Figure Description

[0052] Figure 1 This is a construction diagram of the application of a tack coat after roughening the surface in the paving method described in this invention. Detailed Implementation

[0053] The technical solution of the present invention will be described in detail below.

[0054] Example 1 The specific steps of the construction method for drainage, noise reduction, and efflorescence prevention steel slag asphalt concrete bridge deck paving of urban elevated bridges are as follows: (1) Roughening treatment of bridge deck sections: First, based on the original bridge deck laitance thickness > 3mm and longitudinal slope conditions, the viaduct's bridge deck is divided laterally into the main traffic lane, transition buffer zone, and curb guide zone.

[0055] Then, a chiseling trolley equipped with a spiral alloy cutter array and a vacuum negative pressure adsorption track is used for differentiated chiseling. The details are as follows: Main conveyor belt: The surface is roughened using a spiral cloth-blade roughening trolley, with the roughening depth controlled at 5mm, forming a rough surface with no directional texture, an exposed surface rate of ≥60%, and a structural depth of ≥0.8mm.

[0056] Transition buffer zone: The roughening process is carried out using a spiral cloth-blade roughening trolley, with the roughening depth controlled at 3.5mm, the exposed bone rate ≥50%, and the structural depth ≥0.6mm.

[0057] The curb guide strip is roughened using a vertical short-toothed spiral cutter, with the roughening depth controlled at 2.5mm, forming a micro guide groove along the bridge direction.

[0058] The scabbing trolley adopts a high-frequency micro-vibration + rotary cutting composite process. The spiral cutter generates high-frequency vibration while rotating at high speed, which physically breaks up the dense thick slurry layer and completely exposes the solid aggregate.

[0059] (2) Laying of high-viscosity modified asphalt waterproof layer: A high-viscosity and toughness sealing layer and a stress-absorbing layer are laid sequentially from bottom to top.

[0060] First, a high-viscosity and toughness sealing layer is laid on the bridge deck after the roughening treatment in step (1); the sealing layer is made of SBS modified asphalt with a dynamic viscosity of ≥50000 Pa·s at 60℃, and the application rate is controlled at 2.0 kg / m. 2 (Based on pure bitumen).

[0061] The high-viscosity modified asphalt used penetrates deeply into the multi-directional, high-texture-depth rough texture formed by chiseling, creating nail-in anchor points and an elastic waterproof membrane.

[0062] Then, a stress-absorbing layer is laid on top of the high-viscosity and toughness sealing layer, with a binder dosage of 0.5 kg / m². 2 The stress-absorbing layer asphalt is made of rubber-modified asphalt (mixed with 20wt% waste tire rubber powder).

[0063] The method for spreading the stress-absorbing layer with synchronous crushed stone is as follows: the amount of crushed stone spread on the main traffic lane of the bridge deck is 4.5 kg / m². 2The amount of crushed stone spread in both the transition buffer zone and the curb guide zone is 2.5 kg / m². 2 .

[0064] A protective membrane is laid at the joints before construction. This stress-absorbing layer has a fracture elongation rate of >800%, which can effectively absorb and dissipate concentrated stress caused by temperature changes and loads on the bridge deck, and reduce microcracks in the bridge joints.

[0065] (3) Laying bridge deck pavement structure: From bottom to top, the layers are: a water-permeable leveling layer, a first adhesive layer, a lower permeable load-bearing layer, a second adhesive layer, and an upper permeable noise-reducing layer.

[0066] The asphalt content of the bleeding leveling layer is 6.8%, which uses high fluidity to automatically fill roughened pits, restore flatness and block water seepage.

[0067] The coarse aggregate is hot-quenched steel slag, and the hot-quenched steel slag used is subject to strict control of the following indicators: f-CaO content ≤3.0%, water immersion expansion rate ≤0.8%, and crushing value ≤18%. It is also pretreated by spraying with 0.5% silane coupling agent 24 hours before use and dried until the moisture content is <0.5%.

[0068] The fine aggregate is limestone manufactured sand, and the binder is SBS modified asphalt.

[0069] The water-regulating and leveling layer adopts a fine-grained discontinuous gradation, and the gradation range of the mixture is as follows: 100% passing rate through a 9.5mm sieve, 94.1% passing rate through a 4.75mm sieve, 37.9% passing rate through a 2.36mm sieve, 29.6% passing rate through a 1.18mm sieve, 23.8% passing rate through a 0.6mm sieve, 19.4% passing rate through a 0.3mm sieve, 17.9% passing rate through a 0.15mm sieve, and 13.7% passing rate through a 0.075mm sieve.

[0070] The first bonding layer uses SBS modified emulsified asphalt, with an asphalt application rate of 0.6 kg / m³. 2 .

[0071] The lower permeable load-bearing layer has an asphalt content of 4.8%; the coarse aggregate is hot-quenched steel slag.

[0072] The gradation range of the lower permeable load-bearing layer mixture is as follows: 100% passing rate through a 19mm sieve, 100% passing rate through a 16mm sieve, 95.2% passing rate through a 13.2mm sieve, 65.7% passing rate through a 9.5mm sieve, 20.6% passing rate through a 4.75mm sieve, 16.7% passing rate through a 2.36mm sieve, 12.5% ​​passing rate through a 1.18mm sieve, 10.4% passing rate through a 0.6mm sieve, 8.6% passing rate through a 0.3mm sieve, 6.9% passing rate through a 0.15mm sieve, and 4.2% passing rate through a 0.075mm sieve.

[0073] The second bonding layer uses SBS modified emulsified asphalt, with an asphalt application rate of 0.5 kg / m³. 2 .

[0074] The asphalt content of the upper permeable noise reduction layer is 5.1%; the coarse aggregate is hot-quenched steel slag.

[0075] The gradation range of the upper permeable noise reduction layer mixture is as follows: 100% passing rate through a 19mm sieve, 100% passing rate through a 16mm sieve, 95.4% passing rate through a 13.2mm sieve, 68.3% passing rate through a 9.5mm sieve, 29.2% passing rate through a 4.75mm sieve, 24.2% passing rate through a 2.36mm sieve, 18.6% passing rate through a 1.18mm sieve, 14.3% passing rate through a 0.6mm sieve, 12.2% passing rate through a 0.3mm sieve, 9.8% passing rate through a 0.15mm sieve, and 6.7% passing rate through a 0.075mm sieve.

[0076] (4) Construct a drainage system for the bridge deck pavement structure: The interconnected gaps between the lower permeable load-bearing layer and the upper permeable noise reduction layer form an internal drainage channel.

[0077] After the lower permeable load-bearing layer has been laid and compacted 1-2 times, and before laying the second bonding layer and the upper permeable noise reduction layer, apply emulsified asphalt and attach hot melt tape to the side of the high side guardrail on the transverse slope.

[0078] A 15cm wide longitudinal blind ditch is set up in the low side edge area of ​​the transverse slope, filled with single-size crushed stone. The blind ditch is closely connected to the bridge drainage hole, and the top surface of the drainage outlet is 6mm lower than the pavement surface. This ensures that the interlayer seepage water from the upper and lower layers can be quickly discharged into the drainage hole by gravity, avoiding water accumulation and stagnation that could lead to the hydration and expansion of steel slag f-CaO.

[0079] Example 2 The difference between this embodiment and Embodiment 1 is that: The high-viscosity modified asphalt waterproof layer in step (2) is designed to have an asphalt spraying amount of 2.2 kg / m² (based on pure asphalt) to further enhance the density of the bottom waterproof membrane, making it suitable for urban viaducts in high-humidity and rainy areas.

[0080] The gradation of the lower permeable load-bearing layer mixture in step (3) is generally coarse, specifically: 100% passing through a 19mm sieve, 100% passing through a 16mm sieve, 90.5% passing through a 13.2mm sieve, 52.7% passing through a 9.5mm sieve, 14.2% passing through a 4.75mm sieve, 11.6% passing through a 2.36mm sieve, 7.8% passing through a 1.18mm sieve, 5.2% passing through a 0.6mm sieve, 4.6% passing through a 0.3mm sieve, 3.5% passing through a 0.15mm sieve, and 2.3% passing through a 0.075mm sieve. The asphalt content is 4.7%.

[0081] The gradation of the upper permeable noise reduction layer mixture in step (3) is relatively coarse, specifically: 100% passing through a 19mm sieve, 100% passing through a 16mm sieve, 90.2% passing through a 13.2mm sieve, 56.7% passing through a 9.5mm sieve, 24.2% passing through a 4.75mm sieve, 19.6% passing through a 2.36mm sieve, 13.4% passing through a 1.18mm sieve, 11.8% passing through a 0.6mm sieve, 9.2% passing through a 0.3mm sieve, 7.3% passing through a 0.15mm sieve, and 4.5% passing through a 0.075mm sieve. The asphalt content is 5.0%.

[0082] By adjusting the gradation towards the coarse end, the measured dynamic stability is 8100 cycles / mm, and the degree of coarse aggregate skeleton interlocking is improved, making it suitable for heavy-load or steep longitudinal slope road sections.

[0083] Example 3 The difference between this embodiment and Embodiment 1 is that: In step (2), the high-viscosity and toughness sealing layer uses polyurethane modified asphalt instead of SBS modified asphalt, and the application rate is controlled at 1.8 kg / m³. 2 (Based on pure bitumen).

[0084] Polyurethane-modified bitumen has higher viscosity and toughness and better low-temperature crack resistance. Its wetting and anchoring effect with the multi-directional rough texture formed after chiseling is better. The measured interlayer pull-out strength is 1.7 MPa, which is about 6% higher than that of Example 1.

[0085] The specific gradation of the permeable load-bearing layer mixture in step (3) is as follows: 100% passing through a 19mm sieve, 100% passing through a 16mm sieve, 98.5% passing through a 13.2mm sieve, 76.2% passing through a 9.5mm sieve, 28.6% passing through a 4.75mm sieve, 20.1% passing through a 2.36mm sieve, 16.5% passing through a 1.18mm sieve, 14.6% passing through a 0.6mm sieve, 10.7% passing through a 0.3mm sieve, 7.8% passing through a 0.15mm sieve, and 5.2% passing through a 0.075mm sieve. The asphalt content is 4.9%.

[0086] The specific gradation of the upper permeable noise reduction layer mixture in step (3) is as follows: 100% passing rate through a 19mm sieve, 100% passing rate through a 16mm sieve, 98.2% passing rate through a 13.2mm sieve, 74.5% passing rate through a 9.5mm sieve, 34.7% passing rate through a 4.75mm sieve, 26.4% passing rate through a 2.36mm sieve, 20.2% passing rate through a 1.18mm sieve, 17.6% passing rate through a 0.6mm sieve, 13.5% passing rate through a 0.3mm sieve, 11.8% passing rate through a 0.15mm sieve, and 8.0% passing rate through a 0.075mm sieve. The asphalt content is 5.2%.

[0087] This embodiment replaces SBS modified asphalt with polyurethane modified asphalt and uses a finer gradation scheme. While ensuring drainage function, it focuses on enhancing the interlayer adhesion durability and low-temperature crack resistance of the waterproof layer, making it suitable for urban viaducts in cold regions or with large temperature differences.

[0088] Example 4 The difference between this embodiment and Embodiment 1 lies in step (3) the paving structure: In step (3), the lower permeable load-bearing layer and the upper permeable noise reduction layer adopt an economical gradation scheme, specifically: The aggregate gradation of the lower permeable load-bearing layer is as follows: 100% passing through a 19mm sieve, 100% passing through a 16mm sieve, 98.2% passing through a 13.2mm sieve, 72.7% passing through a 9.5mm sieve, 29.6% passing through a 4.75mm sieve, 21.3% passing through a 2.36mm sieve, 17.5% passing through a 1.18mm sieve, 14.6% passing through a 0.6mm sieve, 10.8% passing through a 0.3mm sieve, 8.0% passing through a 0.15mm sieve, and 5.2% passing through a 0.075mm sieve. The asphalt content is 4.8%.

[0089] The aggregate gradation of the upper permeable noise reduction layer is as follows: 100% passing through a 19mm sieve, 100% passing through a 16mm sieve, 98.7% passing through a 13.2mm sieve, 72.6% passing through a 9.5mm sieve, 34.7% passing through a 4.75mm sieve, 26.9% passing through a 2.36mm sieve, 21.4% passing through a 1.18mm sieve, 17.8% passing through a 0.6mm sieve, 13.4% passing through a 0.3mm sieve, 11.4% passing through a 0.15mm sieve, and 7.6% passing through a 0.075mm sieve. The asphalt content is 5.1%.

[0090] The economic benefits of this embodiment are reflected in the following aspects: (1) The overall gradation is relatively fine, and the amount of coarse aggregate (>4.75mm) is reduced compared with that of Example 1. Since the crushing and processing cost of coarse aggregate is significantly higher than that of fine aggregate (coarse aggregate needs to go through multiple stages of crushing, screening and shaping, while fine aggregate can directly utilize the undersize material in the crushing process), the reduction in the amount of coarse aggregate directly reduces the material processing cost; (2) The proportion of fine aggregate of 2.36mm and below in the relatively fine gradation increases, which improves the workability of the mixture, reduces the difficulty of paving and compaction, reduces construction energy consumption and the number of compaction passes, and reduces construction cost; (3) The amount of asphalt is in the middle value of the main scheme range, and the amount of asphalt does not increase significantly due to the relatively fine gradation, thus avoiding the increase in asphalt cost caused by the increase in the specific surface area of ​​fine aggregate.

[0091] Comparative Example 1 The difference between this comparative example and Example 1 is that: step (1) did not involve differentiated roughening of the bridge surface, but instead used uniform milling for the entire bridge surface, with a milling depth of 3 mm and an exposed bone rate of about 30%. The remaining steps are the same as in Example 1.

[0092] Because the main traffic lane lacks multi-directional rough texture, the interlayer mechanical anchoring effect is weak; the transition buffer zone is not shallowly roughened, making it prone to microcracks in areas with complex stress; the curb guide strip does not form a guide channel along the bridge, causing water retention at the wall base. Measured interlayer shear strength and pull-out strength decreased, interlayer seepage height increased, and efflorescence area increased.

[0093] Comparative Example 2 The difference between this comparative example and Example 1 is that: in step (2), the high viscosity and toughness sealing layer still uses high viscosity modified asphalt with a dynamic viscosity of ≥50000Pa·s at 60℃, but the spraying amount is reduced to the conventional amount of 1.0kg / m², and the other steps are the same as in Example 1.

[0094] Due to insufficient application, the high-viscosity asphalt could not fully penetrate the roughened texture to form a nail-like anchor, resulting in a discontinuous sealing layer. Actual measurements showed a decrease in interlayer shear strength, an increase in interlayer water seepage height, and an increase in efflorescence area.

[0095] Comparative Example 3 The difference between this comparative example and Example 1 is that: in step (2), the stress-absorbing layer of synchronous crushed stone was not spread in sections according to the traffic lane, but the entire bridge surface was fully covered with the same amount. The remaining steps are the same as in Example 1.

[0096] Due to the excessive amount of gravel in the transition buffer zone and curb guide zone, the stress-absorbing layer thickness is uneven. Measured interlayer shear strength decreased, and interlayer permeability increased.

[0097] Comparative Example 4 The difference between this comparative example and Example 1 is that: in step (3), no water-sealing and leveling layer is set, and the first adhesive layer and the lower permeable load-bearing layer are directly laid on the waterproof layer. The remaining steps are the same as in Example 1.

[0098] Due to the lack of a sealing and leveling layer to fill the roughened pits, the interface voids and seepage channels increased. Actual measurements showed a decrease in interlayer pull-out strength, an increase in interlayer seepage height, and an increase in efflorescence area.

[0099] Comparative Example 5 The difference between this comparative example and Example 1 is that: in step (4), no longitudinal blind ditch or drainage channel is set up, and no hot melt sticker is pasted on the high side of the transverse slope anti-collision guardrail. Only the original drainage hole of the bridge deck is retained. The rest of the steps are the same as in Example 1.

[0100] Because water seepage at the base of the high-side guardrail was not blocked, and seepage at the low-side edge could not be promptly drained into the drainage holes, moisture remained at the edges. Actual measurements showed increased interlayer seepage height and increased efflorescence area.

[0101] The performance test results of the pavement structures obtained in each embodiment and comparative example are shown in Table 1.

[0102] Table 1

[0103] Note: The efflorescence area in the table is calculated based on the area percentage after a 28-day immersion-drying cycle.

[0104] Tire / road noise was measured using the CPX method.

[0105] The sound absorption coefficient was determined using the standing wave tube method at 500 Hz.

Claims

1. A construction method for drainage, noise reduction, and efflorescence prevention steel slag asphalt concrete bridge deck paving of urban elevated bridges, characterized in that, Includes the following steps: (1) Roughening treatment of bridge deck sections: First, the bridge deck of the viaduct is divided laterally into the main traffic lane, the transition buffer zone, and the curb guide zone; Then, differentiated roughening is performed, as follows: Main gantry: A spiral cloth-blade roughening trolley is used to roughen the surface of the main gantry bridge deck, forming a rough surface with no directional texture. The roughening depth is controlled at 4~6mm; the exposed aggregate rate is ≥60% and the structural depth is ≥0.8mm. Transition buffer zone: The roughening process is carried out using a spiral cloth-blade roughening trolley, with the roughening depth controlled at 3~4mm, the exposed bone rate ≥50%, and the structural depth ≥0.6mm. Roadside guide strip: roughened using a vertical short-toothed spiral cutter; the roughening depth is controlled at 2~3mm; (2) Laying of high-viscosity modified asphalt waterproof layer: A high-viscosity and tough sealing layer and a stress-absorbing layer are laid sequentially from bottom to top; First, a high-viscosity and toughness sealing layer is laid on the bridge deck after the roughening treatment in step (1); the sealing layer is made of high-viscosity modified asphalt with a dynamic viscosity ≥50000Pa·s at 60℃, and the application rate is controlled at 1.8~2.2kg / m. 2 ; Then, a stress-absorbing layer is laid on top of the high-viscosity and toughness sealing layer; the amount of binder in this stress-absorbing layer is controlled at 0.4-0.6 kg / m². 2 ; The method for spreading the stress-absorbing layer with synchronous crushed stone is as follows: the amount of crushed stone spread on the main traffic strip of the bridge deck is controlled at 4-5 kg / m². 2 The amount of gravel spread in the bridge deck transition buffer zone and curb guide zone should be controlled at 2-3 kg / m². 2 ; (3) Laying bridge deck pavement structure: The layers are laid from bottom to top in sequence: a water-permeable leveling layer, a first adhesive layer, a lower permeable load-bearing layer, a second adhesive layer, and an upper permeable noise reduction layer. The asphalt content of the bleeding leveling layer is 6.5%-7.0%; the coarse aggregate is hot-quenched steel slag, the fine aggregate is limestone manufactured sand, and the binder is SBS modified asphalt. The aforementioned water-regulating and leveling layer adopts a fine-grained discontinuous gradation, with the following gradation ranges: 100% passing through a 9.5mm sieve, 90%-100% passing through a 4.75mm sieve, 28%-65% passing through a 2.36mm sieve, 22%-36% passing through a 1.18mm sieve, 18%-28% passing through a 0.6mm sieve, 15%-22% passing through a 0.3mm sieve, 13%-18% passing through a 0.15mm sieve, and 12%-15% passing through a 0.075mm sieve. The first bonding layer uses SBS modified emulsified asphalt, with an asphalt application rate of 0.5-0.8 kg / m³. 2 ; The asphalt content of the lower permeable load-bearing layer is 4.7%-4.9%; the coarse aggregate is hot-quenched steel slag, and the gradation range of the lower permeable load-bearing layer mixture is as follows: 100% passing through a 19mm sieve, 100% passing through a 16mm sieve, 90%-100% passing through a 13.2mm sieve, 50%-80% passing through a 9.5mm sieve, 12%-30% passing through a 4.75mm sieve, 10%-22% passing through a 2.36mm sieve, 6%-18% passing through a 1.18mm sieve, 4%-15% passing through a 0.6mm sieve, 3%-12% passing through a 0.3mm sieve, 3%-8% passing through a 0.15mm sieve, and 2%-6% passing through a 0.075mm sieve. The second bonding layer uses SBS modified emulsified asphalt, with an asphalt application rate of 0.5-0.8 kg / m³. 2 ; The asphalt content of the upper permeable noise reduction layer is 5.0%-5.2%; the coarse aggregate is hot-quenched steel slag, and the gradation range of the upper permeable noise reduction layer mixture is as follows: 100% passing through a 19mm sieve, 100% passing through a 16mm sieve, 90%-100% passing through a 13.2mm sieve, 55%-75% passing through a 9.5mm sieve, 22%-35% passing through a 4.75mm sieve, 18%-28% passing through a 2.36mm sieve, 12%-22% passing through a 1.18mm sieve, 10%-18% passing through a 0.6mm sieve, 8%-15% passing through a 0.3mm sieve, 6%-12% passing through a 0.15mm sieve, and 4%-8% passing through a 0.075mm sieve. (4) Construct a drainage system for the bridge deck pavement structure: The interconnected gaps between the lower permeable load-bearing layer and the upper permeable noise reduction layer form an internal drainage channel. After the lower permeable load-bearing layer is laid and compacted 1-2 times, and before laying the second bonding layer and the upper permeable noise reduction layer, apply emulsified asphalt and attach hot melt tape to the side of the cross slope high side guardrail. Longitudinal blind drains or drainage channels should be installed in the low-side edge area of ​​the transverse slope.

2. The construction method for drainage, noise reduction, and efflorescence prevention steel slag asphalt concrete bridge deck paving of urban elevated bridges according to claim 1, characterized in that, The chiseling process in step (1) uses a chiseling trolley equipped with a spiral alloy cutter array and a vacuum negative pressure adsorption track.

3. The construction method for drainage, noise reduction, and efflorescence prevention steel slag asphalt concrete bridge deck paving of urban elevated bridges according to claim 1, characterized in that, In step (2), the high-viscosity and toughness sealing layer uses SBS modified asphalt or polyurethane modified asphalt.

4. The construction method for drainage, noise reduction, and efflorescence prevention steel slag asphalt concrete bridge deck paving of urban elevated bridges according to claim 1, characterized in that, The binder for the stress-absorbing layer in step (2) is either rubber-modified asphalt or high-viscoelastic asphalt.

5. The construction method for drainage, noise reduction, and efflorescence prevention steel slag asphalt concrete bridge deck paving of urban elevated bridges according to claim 1, characterized in that, In step (3), the hot-quenched steel slag is pretreated by spraying with silane coupling agent within 24 hours before use, wherein the amount of silane coupling agent is 0.5% of the mass of the steel slag; and it is dried in an oven at 80°C until the moisture content is <0.5%, forming a hydrophobic layer on the surface of the aggregate.

6. The construction method for drainage, noise reduction, and efflorescence prevention steel slag asphalt concrete bridge deck paving of urban elevated bridges according to claim 1, characterized in that, The width of the longitudinal blind drain in step (4) is 10-20cm.

7. The construction method for drainage, noise reduction, and efflorescence prevention steel slag asphalt concrete bridge deck paving of urban elevated bridges according to claim 1, characterized in that, In step (4), the longitudinal blind drain is filled with single-size crushed stone or open-graded asphalt mixture.

8. The construction method for drainage, noise reduction, and efflorescence prevention steel slag asphalt concrete bridge deck paving of urban elevated bridges according to claim 1, characterized in that, The width of the drainage trough in step (4) is 5-10cm.

9. The construction method for drainage, noise reduction, and efflorescence prevention steel slag asphalt concrete bridge deck paving of urban elevated bridges according to claim 1, characterized in that, The longitudinal blind ditch or drainage channel is closely connected to the bridge drainage hole, and the top surface of the drainage outlet is 5-10mm lower than the pavement surface.

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