AU2019202413A1

AU2019202413A1 - Improved concrete road pavement with more sustainability benefits

Info

Publication number: AU2019202413A1
Application number: AU2019202413A
Authority: AU
Inventors: Duy Huu Nguyen
Original assignee: Nguyen Duy Huu Dr
Current assignee: Nguyen Duy Huu Dr
Priority date: 2018-06-17
Filing date: 2019-04-07
Publication date: 2020-01-16
Anticipated expiration: 2039-04-07
Also published as: AU2019202413B2

Abstract

This invention describes an improved concrete road pavement, specially designed for a safer, cheaper and ultimately more sustainable road network. Its unique characteristics, accompanied by practical advantages over traditional pavements, are presented in the following dot points: • Conventionally, a solid section is employed in concrete road pavement. In this invention, concrete road pavement is redesigned to create a hollow channel inside the cross section. The hollow channel can either replace or cooperate with existing drainage system to multiply drainage capacity of the road. This is beneficial to most road networks, especially those suffering the high risk of regular and/or periodical flooding. • As concrete material is more reasonably distributed, the pavement consumes less concrete while ensuring its strength and serviceability under standard traffic. Inside the hollow channel, a permanent formwork structure made of waste plastic is installed, serving as formwork to support concrete placement and water insulation to protect concrete from direct contact with water. The utilisation of waste plastic helps significantly reduce its direct disposal into environment, increasing recycling rate and fostering a sustainable development in modem infrastructure. • The improved pavement utilizes the advanced technology of self-compacting concrete reinforced with steel fibres, resulting in a convenient and easy construction method. This is a dual benefit, as it not only facilitates the construction of the pavement itself, but the integrated hollow drainage channel also evidences a relief of the crucial need of large clearance and/or deep excavation/tunnelling to build new drainage systems. • The pavement is constructed in modules/segments which are assembled on site by flexible joints. The flexible joints increase the flexibility of the pavement compared to conventional design. Combined with more even and smoother top surfaces (benefitted from the technology of self-compacting concrete), the structure promises a noise reduction in service. • The improved concrete road pavement is suitable for both new construction and replacement, with little influence on existing structural facilities. Along with its affordability and constructability, the pavement helps harmonize or overcome most sustainability issues in modem infrastructure, particularly in transport systems. Pa 9 cia CONVENTIONAL CONCRETE PAVEMENT IMPROVED CONCRETE PAVEMENT Example design of an urb n road with 4 traffic lanes Side walk I traffic lane traffic lane 1 traffic lane 1 traffic lane Side walk Hollow concrete pavement (precast in segments/modules) Solid concrete pavement Plastic formwork ( aa ScutPaade Subgrade Lane mark Trench drain Also, lane division DETAIL 1 -W ater drain Additional water storage channel Water drain Longitudinal trench drain Secondary filter Also, lane division Upper plate Base layer Lower plate LVertical wall Flexible connection joint - Internal formiwork (between 2 adjacent Plastic pavement segments)

Description

IMPROVED CONCRETE ROAD PAVEMENT

WITH MORE SUSTAINABILITY BENEFITS

1. TECHNICAL FIELD

The present specification relates directly to the field of civil engineering.

2. AIMS AND BACKGROUND

This specification describes an improved concrete pavement structure with its numerous benefits toward a safer, cheaper and more sustainable road network. The new structure aims to address four persisting issues that happen in most places globally, listed as follows:

First, severe and/or periodical flooding, especially in urban road networks, where the arrangement and construction of sufficient drainage facilities are normally difficult;

Second, rapidly increasing consumption of such construction materials as cement and asphalt, meaning higher environmental impacts from their manufacturing processes;

Third, low recycling rate of waste materials and the critical necessity to promote more applications, particularly of waste plastic, in modem infrastructure;

Fourth, intense noise emission due to traffic-pavement interaction, especially on rigid concrete pavements, and its direct link to a variety of health problems.

3. DESCRIPTIONS OF THE INVENTION AND ITS BENEFITS

Figures 1 and 2 illustrate the improved concrete pavement structure (right) compared to conventional design (left). It should be noted that all the design values provided in this section are for illustration purposes only and are subject to change, according to specific circumstances. Major characteristics and dominant benefits of the improved design are given as follows:

First, from conventional design, a solid section is employed in concrete road pavement. In this invention, concrete material is redistributed to create a hollow channel inside the cross section. The purpose is to create an additional water storage channel under and close to the traffic surface. The channel may work either independently or cooperatively with existing drainage system (e.g. longitudinal water drain pipes). Once successfully constructed, the channel multiplies drainage capacity of the road. For example, for an urban road with 4 traffic lanes in figures 1 and 2, assuming that the width of each lane is 3.5m and inner diameter of each longitudinal water drain pipe is 0.8m (i.e. cross-sectional area of 0.5m² each), the hollow channel with its average depth ranging from 15cm to 20cm can provide an additional cross-sectional storage area of 1.0-1.4m² each side, which is at least 2 times larger than the capacity of the main water drain pipe alone.

Importantly, the water channel utilizes free- as well as large area right under road surface; as a result it eases up the critical need for a large area clearance to build new drainage systems. Moreover, the channel is close to the surface, making it easier to construct compared to deep excavation/tunnelling.

Second, cross section of the improved pavement is redesigned with more reasonable material distribution, resulting in less concrete consumption while ensuring its sufficient strength under heavy moving traffic. For the example design in figures 1 to 3, with chosen thicknesses of the top and bottom plates of 8cm and connection walls of 20cm, depending on the average depth of the water channel, the new pavement consumes 20-30% less concrete compared to conventional design. Less material consumption in the

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2019202413 07 Apr 2019 improved pavement also means lighter pavement self-weight, which is another plus point for foundation treatment.

From structural analysis, beside its self-weight and water, the improved pavement in the example above performs well under a moving traffic load of 30 tonnes. For all critical situations considered in the analysis, maximum tensile stresses in the pavement are lower than 50% tensile strength of concrete (assuming that a concrete type with a compressive strength of 40MPa at 28 days of age is in use).

Third, self-compacting concrete (SCC) with steel fibres addition are preferably primary materials of the improved pavement, although other types of concrete and fibres may also be used. Employment of SCC and steel fibres results in a high-quality structural member, accompanied by a convenient construction method (i.e. less labour and machine demand).

Importantly, a permanent internal formwork made of either new, waste plastic or other suitable materials is introduced as a direct water storage. The formwork is designed to be sufficiently strong and impervious, which not only supports concrete placement but also covers all surfaces of the internal water channel. From that, it prevents water seepage through concrete that may downgrade the pavement itself and other structural layers (e.g. base, subgrade, foundation etc.). In this invention, waste plastic is strongly promoted. Once applied, the amount of waste plastic consumed for the improved pavement significantly contributes to sustainability goals in the area. As an illustration, with a 4-lane road shown in figures 1 and 2, assuming a uniform formwork thickness of 8mm, an average depth of the internal water channel of 20cm and a plastic density of lg/cm³, the amount of waste plastic required for 100m length of the road is approximately 22 tonnes.

Fourth, the improved pavement is preferably constructed in modules/segments. Such segments are then connected on site with flexible joints to form a semi-rigid structure (i.e. with higher flexibility compared to conventional design). Combined with more even and smoother top surface (i.e. because of finer aggregates employed for SCC), the structure promises noise reduction in service.

Finally, the improved pavement may be flexibly cast in situ or precast and is appropriate for both small and large-scale applications. Its new construction or replacement can be carried out with little influence on existing structural facilities, as shown in figures 1 and 2.

These five characteristics, along with its affordability and constructability, help the new structure significantly reduce severe impacts caused by all the persisting issues mentioned in Section 2.

4, ADDITIONAL CHARACTERISTICS PROVIDED IN FIGURES 1 TO 3

FIGURE 1:

Figure 1 describes a typical arrangement of the improved pavement and its relationship to other structural facilities on road. In this example (i.e. from both figure 1 and other figures), internal formwork is specified as plastic, however other suitable materials may also be used.

Structural road layers beneath the pavement may remain similar to those in conventional design. Affected structures include concrete kerbs and median strip, where slight adjustments in their designs (as shown in the figure) may be necessary to facilitate the integrations with the pavement segments.

Bottom plate of the cross section is preferably constructed with a transverse downward grade to facilitate water drainage. In case a downward grade is applied, the improved pavement, as a result, has increasing depth from inner lane(s) outward.

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2019202413 07 Apr 2019

Top plate of the cross section may be either flat (i.e. with no transverse grade) or with a downward grade. The downward grade of the top plate should not be greater than that of the bottom plate.

Internal water channel in the improved pavement is preferably connected to existing water drain pipes, or it may work independently. If the channel is designed as an independent drainage system, longitudinal grade of the road may be included to facilitate water flow.

FIGURE 2:

Figure 2 shows a 3D perspective view of the improved pavement, with more details over the longitudinal and transverse flexible joints.

Longitudinal joints, also acting as trench drains, are preferably made of high-strength steel covers and plastic seals; however, other suitable types of connection joint and material may also be applied.

Longitudinal trench drains are preferably arranged at lane separation locations. In that case, top covers are designed to have sufficient width to facilitate the installations of lane marks and other facilities, as required in current standards.

To prevent coarse materials from entering and being trapped inside the water channel, a secondary filter layer may be employed along each longitudinal trench drains. Steel grate with fine round holes is preferable in this design; however, other suitable materials and grate designs may also be used.

Transverse joints are employed to connect two neighbouring pavement segments along the road, to provide a continuous top surface and ensure comfortable traffic. Transverse joints are constructed on site, which may contain reinforcement grids with internal anchors and filling concrete. However, other suitable connection methods and materials may also be used.

Thickness of transverse joints is less than the average depth of the pavement segments. The purpose is to create higher longitudinal flexibility of the whole pavement system. The presence of such flexible joints helps reduce possible damage in pavement segments due to non-uniform settlement of foundation. In addition, it allows convenient repair/maintenance in service.

FIGURE 3:

Figure 3 provides the basic design of one pavement segment with its three typical cross-sections.

The pavement segment consists of a top plate, connection walls and a bottom plate. All those major components are preferably cast simultaneously, based on the internal formwork and other external facilities, to form a monolithic segment. The top and bottom plates may have either similar or different thicknesses.

The connection walls include longitudinal and transverse walls. Number, location and dimension of these walls may vary depending on specific design circumstances. However, one transverse wall is preferably located at each end of the pavement segment, along the road, to carry the impact of moving traffic and reduce possible damage due to the edge-curling effects. Longitudinal walls may have either similar or different thicknesses.

Preferably, the length and width of each pavement segment are equal to the total width of one or more traffic lane(s). With this arrangement, longitudinal connection joints (and trench drains) are located at lane division areas rather than within a traffic lane. From that, it ensures comfortable traffic. The width of each pavement segment may be either equal to its length or different.

The internal water storage channel includes a number of chambers, separated by longitudinal walls. Along the road, these chambers are separated at the positions of transverse walls. The chambers are preferably

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2019202413 07 Apr 2019 connected to each other, and to the neighbouring longitudinal trench drains, at positions adjacent to the transverse walls. For each segment of the water storage channel, at least two connection points should be provided. From that, they may receive, store and transfer water to lower locations with minimum obstruction.

The pavement areas, at the locations of chambers’ connection points, due to less concrete distribution, may be further reinforced by steel grids, both at top and bottom plates.

Reinforcement grid at the top plate may be extended to the closest transverse flexible joints. Internal anchors may be installed on the extended portion of the top reinforcement grid to facilitate the construction of transverse flexible joints on site.

5. LIST OF EXTERNAL REFERENCES ADOPTED IN THIS SPECIFICATION

Figure 2 adopts several external references for demonstration purposes. Although these references have no contribution to the nature of this invention, they are also acknowledged and are listed as follows:

Trees: XfrogPlants Blue-Gum Eucalyptus by xfrog, licensed under Royalty Free License - All Extended Uses https://www.turbosquid.com/3d-models/blue-gum-eucalyptus-tree-blue-3d-model/548015

Buildings: Lowpoly Buildl 1 by ERLHN, licensed under Royalty Free License - All Extended Uses https://www.turbosquid.com/FullPreview/Index.cfm/ID/689820

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Claims

LIST OF CLAIMS

The claims defining this invention are as follows:

1. Conventionally, a solid section is employed in concrete road pavement. In this invention, the concrete θ road pavement is redesigned to create a hollow channel inside the cross section. The hollow channel works either independently or cooperatively with existing drainage system and functions as an additional drainage facility.
2. The improved concrete road pavement (claimed in Claim 1) is made of self-compacting concrete reinforced with steel fibres.

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3. The improved concrete road pavement (claimed in Claim 1) has increasing depth from inner lane(s) outward. The pavement consists of a top plate and a bottom plate, connected by a system of longitudinal CN and transverse walls. All the components are cast simultaneously.
4. The bottom plate of the concrete road pavement (claimed in Claim 3) is constructed with a transverse downward grade to facilitate water drainage. The top plate of the concrete road pavement (claimed in Claim 3) is either flat or with a smaller downward grade, compared to that of the bottom plate. One transverse wall (claimed in Claim 3) is located at each end of a pavement segment.
5. Inside the hollow channel of the improved concrete road pavement (claimed in Claim 1), there is a permanent formwork structure. The formwork covers all surfaces of the hollow channel and serves as (i) Formwork - supporting concrete placement; and (ii) Insulation layer - preventing direct contact between water and concrete.
6. The permanent formwork (claimed in Claim 5) is made of waste plastic.
7. The concrete road pavement (claimed in Claim 1) is constructed in modules/segments. Length and width of each pavement segment are equal to the total width of one or more than one traffic lane(s). Such segments are connected on site by flexible longitudinal and transverse joints.
8. A longitudinal joint (claimed in Claim 7) includes a high-strength steel cover fixed on top of two adjacent pavement segments to carry external loading, a plastic or silicone layer placed at the bottom gap as water sealing, and a secondary filter layer installed underneath the top steel cover. In this design, longitudinal joints also serve as trench drains and lane separators.
9. A transverse joint (claimed in Claim 7) is constructed with filling concrete reinforced by steel grids and embedded anchors. Thickness of the transverse joint is less than the average depth of its adjacent pavement segments, meaning that only an upper portion of the pavement segments are connected at the transverse joint.
10. The internal water storage channel (claimed in Claim 1) includes a number of chambers, separated by longitudinal walls (claimed in Claim 3). Along the road, these chambers are separated at the positions of transverse walls. To ensure effective and continuous water drainage, the chambers are connected to each other, and to the neighbouring longitudinal trench drains, at positions adjacent to the transverse walls. For each pavement segment, at least two connection points are provided.
11. The pavement areas, at the locations of chambers’ connection points (claimed in Claim 10), due to less concrete distribution, are further reinforced by steel grids, both at top and bottom plates.
12. Reinforcement grid at the top plate (claimed in Claim 11) is extended to the closest transverse flexible joint (claimed in Claim 9) to facilitate the construction of the transverse joints on site.