DESC:FIELD OF THE INVENTION

The present invention relates to composite concrete panels. Specifically, the present invention relates to dual reinforced thin composite concrete panels with nano-engineered admixtures and alkali-resistant glass fiber net along with stiffener.

BACKGROUND OF THE INVENTION

Reinforcement is typically used in concrete to carry the tensile stresses developed under different loading conditions. Due to the corrosion risk associated with adding steel to concrete elements, providing a clear cover is essential. This requirement makes it challenging to develop thin concrete elements. There are several alternatives to steel reinforcement namely glass, carbon, aramid, and basalt. Alkali Resistant Glass Fiber net (ARGF) considering its enhanced durability, high toughness, increased flexural capacity is used in the present invention in the form of a mesh. AR- Glass fibres are chemical fibres made from inorganic nonmetallic raw materials. AR-glass is made primarily of silica sand (SiO2) with the addition of up to 15-16 wt-% zirconium oxide (ZrO2) that provides higher alkali resistance, (Bentur et al., 2006, Brameshuber, 2006) which is proportioned by a batching technique.

ARGF net may be prefabricated and readily placed into precast components, enabling faster and more efficient construction, (Scholzen et al., 2015). Textile reinforcement offers a huge potential for producing precast concrete components including pretensioned panels (Huy et al., 2020), exterior cladding panels, sandwich panels (Zhang et al., 2021, Xie et al., 2022 , Xie et al., 2021 , Thanh et al., 2020), boundary walls, building façade elements, and partition of cubicles in the office that are often used in precast projects.

Horizontal casting is a time-consuming process as concrete placement is done layer-by-layer, or rigid positioning of the AR glass net to prevent undulations during pouring of concrete. Furthermore, in horizontal casting, the impression of the AR glass fiber net may be visible at the bottom of the panel. After considering the limitations of horizontal casting, the decision was made to adopt the vertical casting methodology.
The existing thin panels in the market are manufactured using bird net or reinforcing chicken mesh. These kinds of elements are highly susceptible to corrosion. In contrast, our innovation involves dual reinforcement—a combination of alkali-resistant glass fiber net and a stiffener. This approach enhances the structural integrity of precast thin elements, promoting ductile failure over brittle failure. Usually, structural and non-structural elements eventually fail after owing to several factors like fracture, excessive deformations, delamination, cracking, fiber breakage. A variety of failure modes can be initiated depending on the type of loading, geometric dimensions and material properties of the constituents.

The development of new technological products can help in enhancing their viability and address the shortcomings of existing materials in the market. The thin panels available in the market (ferrocement panels) are manufactured with a chicken mesh/ bird net for cast in-situ applications. Ferrocement application is not available for precast applications.

The present invention addresses current challenges in the precast concrete elements, particularly regarding high self-weight and more thickness, low strength to weight ratio, poor shear and flexural characteristics, and non-availability of tailor-made configurations.

SUMMARY OF THE INVENTION

The following presents a simplified summary of the disclosure in order to provide a basic understanding to the reader. This summary is not an extensive overview of the disclosure and it does not identify key or critical elements of the invention or delineate the scope of the invention. Its sole purpose is to present some concepts disclosed herein in a simplified form as a prelude to the more detailed description that is presented later.

The primary objective of the invention is to develop dual reinforced thin composite concrete panels with nano-engineered admixtures and alkali resistant glass fiber net along with stiffener.

Another objective of the invention is to provide a high-performance nano engineered concrete coat over the dual reinforcement in gang molds using the vertical casting method is a distinctive feature of this invention.

Yet another objective of the invention is to provide high-performance nano-engineered concrete with high strength-to-weight ratio, non-corrosive, water-resistant concrete.

According to one aspect of the invention, coarse aggregate is being eliminated, as the thickness of the panel is very low and to avoid the Interfacial Transition Zone (ITZ) issue. To overcome the voids formed due to sphericity, the nano admixture is used for making dual-reinforced thin concrete panels. Nano admixture is made of carbon-based graphene nanosheets. The sheet-like structure helps the panel to withhold the nano and micro level voids by promoting a hydration reaction. The hydration reaction in the micro and nano voids helps in in gaining the desired density of the concrete to attain the early-stage strength, lowers the water permeability, and provides corrosion resistance to the concrete.

The invention may also relate to any alternative methods or processes comprising any combination of the above or below features within the scope of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages of the present invention will become apparent to those skilled in the art upon reading the following detailed description of the preferred embodiments, in conjunction with the accompanying drawings, wherein like reference numerals have been used to designate like elements, and wherein:

FIG. 1 illustrates a schematic diagram of dual-reinforced thin composite concrete panels according to one embodiment of the invention.

FIG. 2 illustrates the stiffener and its aperture size according to one embodiment of the invention.

FIG. 3 illustrates the Alkali-Resistant Glass Fiber net with aperture size of 10 mm according to one embodiment of the invention.

FIG. 4 illustrates the longitudinal section of dual reinforced thin composite concrete panels with nano-engineered admixtures and alkali resistant glass fiber net along with stiffener and the spacer’s arrangement according to one embodiment of the invention.

FIG. 5 illustrates 3D-view of the panel according to one embodiment of the invention.

FIG. 6 illustrates dual reinforced thin composite concrete panels with nano-engineered admixtures and alkali resistant glass fiber net along with stiffener structure in 3D view.

FIG. 7 illustrates complete 3D view of the mould according to one embodiment of the invention.

FIG. 8 illustrates the flow chart of the manufacturing process of thin panel according to one embodiment of the invention.

The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present invention in any way.

DETAILED DESCRIPTION OF THE INVENTION

It is to be understood that the present disclosure is not limited in its application to the details of composition set forth in the following description. The present disclosure is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

According to one embodiment of the present invention, the present invention relates to developing a thin structural element with dual reinforcement with alkali-resistant glass fiber net and stiffener with high-performance concrete with nano-engineered admixtures.

According to one embodiment of the present invention, the product is made with a non-corrosive alkali resistant glass fiber net and stiffener along with high-performance concrete with nano engineered admixture which is chosen to carry additional load even after the panels have reached their ultimate stress. This will provide an early warning prior to the fracture.

Table 1: load test analysis results for different types of dual-reinforced composite panels
S.No Number of samples Size of panel Type of superplasticizer used No of fiber net layers Type of Stiffener used Average live load for ultimate failure (Kg)
1 3 1.8 x 0.6 x 0.02 m Nano based 2 Type-1: 1.2 mm diameter 140
2 3 1.8 x 0.6 x 0.02 m Nano based 2 Type-2: 2.3 mm diameter 170
3 3 1.8 x 0.6 x 0.02 m Nano based 4 Type-2: 2.3 mm diameter 230
4 3 1.8 x 0.6 x 0.015 m Nano based 2 No Stiffener 70

The proposed dual reinforced thin composite concrete panels with nano-engineered admixtures and alkali-resistant glass fiber net is 1800-2400 mm (about 8 ft) in length and 600-1500 mm (about 5 ft) in height with 8-25 mm (about 1 inch) thickness. To prepare thin panels, industrial waste such as GGBS is utilized as an alternative to cement. The panel will be customized to suit the dimensions of varying thicknesses starting from 8-25 mm (about 0.98 in) with various layers of alkali -resistant glass fiber nets. Test results with different number of layers of ARGF nets and with different stiffeners are shown in Table 1. From the test results, it is evident that the higher the number of layers of ARGF net with the higher diameter of stiffener will bear a more load than the others as mentioned in Table 1. In addition to this, the advantages of the thin composite panels are briefly explained in Table 3.

As shown in Figure 6, two layers of alkali-resistant glass fiber nets are connected with ties and separated by a stiffener of 5 cm (about 1.97 in) aperture size (cf. figure 2) and 1.6 mm (about 0.06 in) diameter also 2.3 mm diameter stiffener has also been used and its flow has been clearly depicted in the below flowchart (cf. figure 8). Furthermore, spacers were knotted in a scattered pattern on either side of the ARGF nets as depicted in Figure 6 to maintain equal spacing on either side of the panel for concrete pouring. With this mechanism, the stiffener along with the AR sheets will be precisely positioned in the centre of the mold without any undulations and high-performance nano-engineered concrete was poured. High-performance concrete mortar with nano-engineered admixture can lead to attaining a glassy finish along with water-resistant skin with high strength.

A detailed stepwise installation of composite reinforcement and mold commissioning procedure is clearly shown in Figures 2, 3, and 4. L angles were connected at the top of the mold as shown in Figure 7 to ensure the exact dimension without any bulging of the panel throughout its running length. The final product can be de-molded after 20 hours of casting. A 3D view of the complete panel has been depicted in Figure 5.

In order to achieve better strength and durability, dual reinforcement along with high-performance nano-engineered mortar without coarse aggregate were adopted as a coating material in this innovation. The thickness of the entire panel will substantially decrease with the usage of the composite reinforcement (the thickness may vary from 8-25 mm). The panel can also be used as eco-friendly and multi-functional non-structural and structural elements. The mechanical and durability properties of the composite panel offer significant advantages over conventional thin panels, as demonstrated in the technical specification sheet Table 2:

Table 2: Technical Specification Sheet
1 Title of invention: Dual Reinforced Thin Composite Concrete Panels
2 Application of invention: Industrial buildings, masonry walls, retaining walls, curved slabs, retrofitting, U drains, roofing panels, soak pits, rainwater harvesting pits, permanent forms, Walling application for building envelope walls, compound walls, partition walls, facades, and cubical partitions in offices.
3 Type of product: Precast/prefab modular dual reinforced thin composite concrete panels with nano-engineered admixtures and alkali-resistant fiber net

4 Dimensions of product: Length: 1500-2400 mm (about 8 ft)
Width: 600-1500 mm (about 5 ft)
Thickness: 8-25 mm (about 1 in)
Properties
5 High-performance nano-engineered concrete.
Compressive strength (As per IS 516: Part 1: Sec 1: 2021): 40-80 MPa
6 Skin (high-performance nano-engineered concrete) Split tensile strength (As per IS 516: Part 1: Sec 1: 2021): 5.5-6.5 MPa
7 Flexural strength of high-performance nano-engineered concrete
(As per IS 516: Part 1: Sec 1: 2021): 11.5-12.5 MPa
8 Water permeability
(As per IS 3085:1965) 21 mm
9 Water absorption:
(As per ASTM C 1012-1585) 2-4 %
10 Deflection test on panel size 1.8m x 0.6mx 0.020m: (Hou, Hetao, et al. "Flexural behavior of precast insulated sandwich wall panels: Full-scale tests and design implications." Engineering Structures 180 (2019): 750-761.) 5-30 mm
11 The live load capacity of the panel of size 1.8m x 0.6mx 0.020m: 70-230 kg
12 Durability Studies (As per ASTM C 1012:04 & ASTM C 1898:20): Better performance to Sulphate attack and Moderate performance to Acid attack
13 Glass fiber coated with special proprietary Alkali Resistance coating mesh Specifications
Parameter Result
Tensile Strength (MD x CMD) 80 kN/m - x 120 kN/m,
Mesh Size 12.5 mm to 13.5 mm,
Tensile Elongation 3 ± 1 %
Melting Point Coating > 250 ° C
Mass per Unit Area 350-450 g/m2

13 Proportions for high-performance nano-engineered concrete
Material Quantity (kg/m3)
Cement (OPC 53 Grade): 350 to 450
Ground Granulated Blast Slag: 150 to 200
Manufacture Sand 850 to 950
Water to binder ratio 0.28 to 0.32
Nano based superplasticizer in percentage of binder 0.5 % to 0.7%

Table 3: Advantages of Dual Reinforced Thin Composite Concrete Panels
Description Current Invention
Corrosion Resistance Highly corrosion-resistant due to ARGF (Alkali-Resistant Glass Fiber) net with stiffener.
Concrete Composition Utilizes high-performance concrete with nano-engineered admixtures.
Surface Finish Achieves a glassy finish.
Reinforcement Approach Uses a non-corrosive, alkali-resistant glass fiber net and stiffener for dual reinforcement, giving concrete a high degree of ductility.
Casting Methodology Time and space can be saved by using precast for both horizontal and vertical casting. It is also possible to be used as cast in situ.
Customization Huge scope for customization.
Curved Panels Huge scope for the production of curved panels.

Table 4: Advantages of vertical casting over horizontal casting
Observations Horizontal casting Vertical casting

Space Efficiency Required more floor space for casting. Very efficient production within the specified space


Quality
There are chances of getting voids that reduces the overall quality of the element. Better compaction of concrete which reduces the likelihood of voids and improves the precast elements’ overall strength and durability.

Surface finish A smooth surface cannot be obtained in the pouring surface of the casting. An additional finishing work must be done manually. Good finishing will be achieved on all sides of the panel.

Stripping time
Takes more time to stripping. Takes less time for stripping which leads to more production capacity.

Handling Reduce the risk of damage during production and handling. Less risk of damage during production and
handling.


Reinforcement position Placement of reinforcement in the correct position during the concrete pour is difficult in horizontal casting. Vertical casting can facilitate the alignment of reinforcement in the correct position during
the concrete pour

Customization Versatility in casting complex shapes is a bit challenging in this method. Versatility in casting complex shapes is easy in this method.
Mass Production Difficult for mass production Easy for mass production

According to one embodiment of invention, a method of preparing dual-reinforced thin composite concrete panels is disclosed. The method comprises mixing of nano-engineered admixtures to concrete and an alkali-resistant glass fiber net along with a stiffener as reinforcement. The combination of alkali-resistant glass fiber net and the stiffener forms a dual reinforcement such that the dual reinforcement enhances the maximum utilization of fiber reinforcement with uniform distribution across cross section of the structural member further enhancing the structural integrity of precast thin elements using vertical casting methodology.

Further, the stiffener is made from non-metallic mesh, or any other stiff mesh can be used. The dual reinforcement is placed in gang molds in the vertical position and it is coated with a high-performance nano engineered concrete in vertical casting method to get a form finish on both surfaces of the panel.

A dual reinforcement is placed vertically in a position without any undulations and the casting is done rapidly suitable for mass production of the thin panels.

According to one embodiment of invention, the method has the scope for customization as per the design requirements wherein the thickness of dual-reinforced thin composite concrete panels can be customized by adjusting number of layers of alkali-resistant glass fiber net and diameter of stiffener along with the dimensions (length and breadth) of the panel.

Advantages of the present invention:
The concept of “thin panels with alkali-resistant glass fiber net along with stiffener" plays a crucial role in the realm of civil engineering applications. The size and weight of the thin panels plays a crucial role in transportation cost, cost reduction during production, installation, and the productivity of manpower. Emphasis was also given to sustainability by choosing waste materials in addition to the reduction in size. This will enhance the durability, speed of installation and over conventional panels while maintaining adequate mechanical properties. The following are the main advantages of the present invention.
• Thin panels
• Modular panels
• High strength-to-weight ratio
• Water resistant
• Strong fire rating
• Termite resistant
• Durable
• Good finishing
• Space saving
• Consistency in quality due to factory made
• Ease in handling, erection and assembly
• Reusable and relocatable
• Ductile failure
• Light in weight
• Sustainable and economical product

According to one embodiment of the invention, the panel was mechanically tested with different sizes, and it eventually became apparent that thin panels can be used as building external and internal walls, boundary walls, cubical partitions in offices. and as some structural components such as Industrial buildings, retaining walls, curved slabs, retrofitting, U drains, roofing panels, soak pits, rainwater harvesting pits, permanent forms, and defense applications etc.

It will be recognized that the above-described subject matter may be embodied in other specific forms without departing from the scope or essential characteristics of the disclosure. Thus, it is understood that, the subject matter is not to be limited by the foregoing illustrative details, but it is rather to be defined by the appended claims.

While specific embodiments of the invention have been shown and described in detail to illustrate the novel and inventive features of the invention, it is understood that the invention may be embodied otherwise without departing from such principles. ,CLAIMS:1. A method of preparing dual-reinforced thin composite concrete panels, the method comprising:
mixing of nano-engineered admixtures to concrete and an alkali-resistant glass fiber net along with a stiffener as reinforcement;
characterized in that
the combination of alkali-resistant glass fiber net and the stiffener forms a dual reinforcement such that the dual reinforcement enhances the maximum utilization of fiber reinforcement with uniform distribution across cross section of the structural member further enhancing the structural integrity of precast thin elements using vertical casting methodology.

2. The method as claimed in claim 1, wherein the stiffener is made from non-metallic mesh, or any other stiff mesh can be used.

3. The method as claimed in claim 1, wherein the dual reinforcement is placed in gang molds in the vertical position and it is coated with a high-performance nano engineered concrete in vertical casting method to get a form finish on both surfaces of the panel.

4. The method as claimed in claim 1, wherein a dual reinforcement is placed vertically in a position without any undulations and the casting is done rapidly suitable for mass production of the thin panels.

5. The method as claimed in claim 1, wherein the method has the scope for customization as per the design requirements wherein the thickness of dual-reinforced thin composite concrete panels can be customized by adjusting number of layers of alkali-resistant glass fiber net and diameter of stiffener along with the dimensions including length and breadth of the panel.