DE202023100087U1 - A system for producing ultra high performance concrete - Google Patents

Abstract

A system for producing ultra high performance concrete, the system comprising:
a sonicator to disperse the nano-Al ₂ O ₃ particles in 20% PCE and 20% water using a bath sonication technique for 30 minutes;
a mortar mixer to slowly mix cement, silica fume, quartz flour and sand for 5 minutes to make the dry mix;
a mixing chamber with an agitator to automatically mix 60% PCE with 80% water and add it slowly to the dry mix to convert granules, adding the dispersed nano-Al ₂ O ₃ particles, mix slowly for 5 minutes, adding the remaining 20% of the PCE to the mixture and mixing at high speed for 5 minutes until the mixture turns into a homogeneous mixture, the polypropylene fibers are slowly added to the mixture and mixed for 5 minutes, mixing for a further period of 5 minutes is continued to achieve good dispersion of the UHPC mixture;
a mold to shape the UHPC mixture, covering the surface with the plastic sheets covering the surface and keeping at laboratory temperature for 24 hours; and
a treatment chamber for curing the demolded specimens with ordinary water at room temperature.

Description

FIELD OF THE INVENTION

The present disclosure relates to concrete production systems, and more particularly to a system for producing ultra-high performance concrete using a bath sonication technique.

BACKGROUND OF THE INVENTION

Today's concrete is the result of a continuous process of innovation that perhaps began as early as the Roman Empire. The modern history of concrete may have developed after the invention of Portland cement in 1824. Traditional concrete is generally made by mixing cement with aggregate and water. In 1849, steel reinforcement was introduced into the concrete to give it greater tensile strength and deformability, which came to be known as "reinforced concrete". In the 19th and 20th centuries, concrete technology advanced as many people were interested in optimizing strength and particle packing density. In the 1980s, High Strength Concrete (HSC) and High Performance Concrete (HPC) with compressive strengths up to 100 MPa and improved durability were invented. Shortly thereafter, fiber reinforced concrete (FRC) was developed to counteract the brittle matrix and increase ductility, strength and resistance through the use of fibers. The incorporation of fibers into the concrete controls cracks and improves impact performance. Research into improving compressive strength and durability was also the focus of interest in the 1990s. In 1994, the term ultra high performance concrete (UHPC) was officially introduced and soon after was used in North America for applications with a compressive strength of 100 to 200 MPa. Extensive research work has also been carried out on reactive powder concrete with a compressive strength of over 200 MPa.

The UHPC is a new type of concrete; according to the ASTM code, a minimum compressive strength of 120 MPa is required, the slump is between 200 and 250 mm and the maximum aggregate size is limited to 5 mm. It is characterized by high strength and durability with low life cycle costs. The homogeneous mix was achieved by eliminating coarse aggregate, and efficiency was maximized by optimizing the mix's particle packing density. The use of new generation polymer-based superplasticizers as water reducers and ultra-fine ingredients to optimize the particle packing density of the UHPC blend results in improved rheological properties of the fresh blend with a low w/b ratio. The current scenario increases the demand for the use of UHPC in structures as the developed and developing countries mainly focus on the conservation of natural resources to protect the changing environment. Energy saving has become a priority for the design of sustainable buildings with low life cycle costs.

The use of alternative binders is important to improve sustainability in construction and reduce global CO2 emissions into the environment. In the manufacture of UHPC, a large amount of cement is consumed in the mix. Supplemental cementing materials (SCMs) are important and contribute to improving the properties of UHPC through hydraulic and pozzolanic activities. Typical SCMs such as silica fume, fly ash, blast furnace slag, limestone, metakaolin, palm oil fuel ash, bagasse ash, and rice hull ash are commonly used for the production of UHPC. These can be used individually with Portland or blended cement, or in various combinations. The microscopic SCMs are often added to UHPC to make the mixes more economical, increase strength, reduce permeability, and affect other concrete properties.

Nanotechnology is a multidisciplinary field of science and technology concerned with understanding and controlling matter at dimensions between 1 and 100 nanometers. Nanomaterials are used in various novel applications in fields such as agriculture, medicine, electronics, construction, food, fuel, air and water purifiers, chemical sensors, tissues, etc. Depending on the size of the nanomaterials, they can be divided into four different groups: zero-dimensional (0D), one-dimensional (1D), two-dimensional (2D) and three-dimensional (3D). The incorporation of nanomaterials into the cement matrix is a new and promising area of research. Various nanomaterials such as Al ₂ O ₃ , CaO, CaCO ₃ , CuO, Fe ₂ O ₃ , MgO, SiO ₂ , TiO ₂ , ZrO ₂ , nano-ZnO, CNT, CNF and nano-clay are used in cement and concrete recently to improve their mechanical properties and durability.

The use of nanomaterials has greater potential to reduce the environmental impact of energy intensity and extend the lifespan of structures. Therefore, research into nanomaterials in concrete is crucial to make concrete more environmentally friendly make. It is important to investigate the application of nanomaterials to improve the properties of cement-based composites. In the past two decades, the increasing application of nano Al203 particles as SCM only in cement paste, mortar, shotcrete, normal strength concrete, high strength concrete, high performance concrete, fiber reinforced concrete and self-compacting concrete has been widely studied. However, there are few studies on the use of nanomaterials in UHPC. The admixture of nanomaterials in UHPC would be a breakthrough with regard to future sustainability requirements and would enable extraordinary applications in the construction sector.

In view of the above, it is clear that a system for the production of ultra high performance concrete is required.

SUMMARY OF THE INVENTION

The present disclosure aims to provide a system for producing ultra high performance concrete for reducing the volume of permeable voids in concrete.

In one embodiment, a system for producing ultra high performance concrete is disclosed. The system includes a sonicator to disperse the nano-Al ₂ O ₃ particles in 20% polycarboxylic acid ether (PCE) based superplasticizer and 20% water using a bath sonication technique for 30 minutes. The system also includes a mortar mixer to slowly mix cement, silica fume, quartz powder and sand for 5 minutes to make the dry mix. The system further includes a mixing chamber with an agitator for automatically mixing 60% PCE with 80% water and adding it slowly to the dry mix to convert granules, slowly mixing the dispersed nano-Al ₂ O ₃ particles for 5 minutes, adding the remaining 20% of the PCE to the mixture and mixing at high speed for 5 minutes until the mixture turns into a homogeneous mixture, adding the polypropylene fibers slowly to the mixture and mixing for 5 minutes, mixing for is continued for a further period of 5 minutes to achieve good dispersion of the UHPC blend. The system further includes a mold for shaping the UHPC mixture, thereby covering the surface with the plastic sheets covering the surface and keeping it at laboratory temperature for 24 hours. The system also includes a treatment chamber for curing the demolded specimens with ordinary water at room temperature.

In another embodiment, the water-binder ratio is set to 0.24 for all mixes, dividing the seven types of UHPC mixes into two series, each with different dosage of cement and nanoparticles, with the total cement content always 570.45 kg/m ³ amounts to.

In another embodiment, the seven types of UHPC blends include a control blend (CON blend - without nanoparticles), and the other six blends are made with different dosages of nano-Al2O3 particles replacing 0.5% to 3%, with a Increase of 0.5%.

In another embodiment, the polypropylene fiber (PP) content is added by 0.4% to the volume of the concrete.

In another embodiment, preferably 171.20 kg/m ³ silica fume, 245.28 kg/m ³ quartz flour and 1245.38 kg/m ³ water with a proportion of sand are mixed in all mixtures.

In another embodiment, all seven mixtures are prepared in a mortar mixer with a total mixing time of 30 minutes, mixing always taking place under laboratory conditions with dried, tempered aggregate and powder materials.

In another embodiment, room temperature is maintained at 24°C during mixing, testing and pouring of the ultra high performance concrete.

Alternatively, mixing is continued until the granules are transformed, which preferably takes 10 minutes.

In another embodiment, the sand weight fractions are preferably selected from 70% sand with a grain size of 2.36 mm-600 μm and 30% sand with a grain size of 600 μm-90 μm.

In another embodiment, the nano Al2O3 particles are selected from an average particle size of 20-30 nm and a specific surface area of 180 m ² /g.

The aim of the present disclosure is to fill the information gap regarding the effects of replacing nano-Al ₂ O ₃ particles on fresh concrete rheology, mechanical properties, durability properties and resistance to aggressive chemical attacks such as attack by organic acids, inorganic acids, Chlorides, sulphates, alkalis and sea water on ultra high performance concrete.

Another object of the present disclosure is to reduce the ratio of crystals to CSH gel, which tends to increase water uptake in concrete.

Another object of the present invention is to provide a fast and inexpensive system for producing ultra high performance concrete.

In order to further clarify the advantages and features of the present disclosure, a more detailed description of the invention is provided by reference to specific embodiments that are illustrated in the accompanying figures. It is understood that these figures represent only typical embodiments of the invention and therefore should not be considered as limiting the scope of the invention. The invention will be described and illustrated with additional specificity and detail with the accompanying figures.

character list

• 1 zeigt ein Blockdiagramm eines Systems zur Herstellung von ultrahochfestem Beton in Übereinstimmung mit einer Ausführungsform der vorliegenden Offenbarung;
• 2 zeigt die Ergebnisse eines Fließversuchs mit verschiedenen Betonmischungen gemäß einer Ausführungsform der vorliegenden Offenbarung;
• 3 veranschaulicht die physikalischen und chemischen Eigenschaften von Silikastaub, einer Ausführungsform der vorliegenden Offenbarung.
• 4 zeigt die physikalischen und chemischen Eigenschaften von nano-Al₂O₃, einer Ausführungsform der vorliegenden Offenbarung.
• 5 veranschaulicht die physikalischen und chemischen Eigenschaften des Quarzpulvers, einer Ausführungsform der vorliegenden Offenbarung.
• 6 veranschaulicht die physikalischen Eigenschaften Polypropylen-Faser, eine Ausführungsform der vorliegenden Offenbarung.
• 7 veranschaulicht die Eigenschaften von Fließmitteln auf Polycarbonsäureetherbasis, einer Ausführungsform der vorliegenden Offenbarung; und
• 8 veranschaulicht die Mischungsverhältnisse von Ausführungsformen der vorliegenden Offenbarung.

These and other features, aspects, and advantages of the present disclosure will be better understood when the following detailed description is read with reference to the accompanying figures, in which like characters represent like parts throughout the figures, wherein:

• 1 Figure 1 shows a block diagram of a system for producing ultra high performance concrete in accordance with an embodiment of the present disclosure;
• 2 Figure 12 shows the results of a flow test on various concrete mixes according to an embodiment of the present disclosure;
• 3 illustrates the physical and chemical properties of silica fume, an embodiment of the present disclosure.
• 4 Figure 1 shows the physical and chemical properties of nano-Al ₂ O ₃ , an embodiment of the present disclosure.
• 5 Figure 1 illustrates the physical and chemical properties of quartz powder, an embodiment of the present disclosure.
• 6 illustrates the physical properties of polypropylene fiber, an embodiment of the present disclosure.
• 7 illustrates the properties of polycarboxylic acid ether based flow aids, an embodiment of the present disclosure; and
• 8th illustrates the mixing ratios of embodiments of the present disclosure.

Those skilled in the art will understand that the elements in the figures are presented for simplicity and are not necessarily drawn to scale. For example, the flow charts illustrate the method of key steps to enhance understanding of aspects of the present disclosure. In addition, one or more components of the device may be represented in the figures by conventional symbols, and the figures only show the specific details relevant to understanding the embodiments of the present disclosure, not to encircle the figures with details to overload, which are easily recognizable to those skilled in the art familiar with the present description.

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the invention, reference will now be made to the embodiment illustrated in the figures and specific language will be used to describe the same. It should be understood, however, that no limitation on the scope of the invention is intended, and such alterations and further modifications to the illustrated system and such further applications of the principles of the invention set forth therein are contemplated as would occur to those skilled in the art invention would normally come to mind.

Those skilled in the art will understand that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not intended to be limiting.

When this specification refers to "an aspect," "another aspect," or the like, it means that a particular feature, structure, or characteristic described in connection with the embodiment is present in at least one embodiment included in the present disclosure. Therefore, the phrases "in one embodiment," "in another embodiment," and similar phrases throughout this specification may or may not all refer to the same embodiment.

The terms "comprising,""including," or other variations thereof are intended to cover non-exclusive inclusion such that a method or method that includes a list of steps does not include only those steps includes, but may also contain other steps not expressly listed or pertaining to such a process or method. Likewise, any device or subsystem or element or structure or component preceded by "comprises...a" does not, without further limitation, exclude the existence of other devices or other subsystem or other element or other structure or other component or additional device or additional subsystems or additional elements or additional structures or additional components.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one skilled in the art to which this invention pertains. The system, methods, and examples provided herein are for purposes of illustration only and are not intended to be limiting.

Embodiments of the present disclosure are described in detail below with reference to the attached figures.

1 12 shows a block diagram of a system for producing ultra high performance concrete in accordance with an embodiment of the present disclosure. The system 100 includes a sonicator 102 for dispersing the nano Al2O3 particles in 20% PCE and 20% water using a bath sonication technique for 30 minutes.

In one embodiment, a mortar mixer 104 is used to slowly mix cement, silica fume, quartz flour, and sand for 5 minutes to produce the dry mix.

In one embodiment, a mixing chamber 106 with an agitator is used to automatically mix 60% PCE with 80% water and add it slowly to the dry mix for the conversion of granules, slowly mixing the dispersed nano-Al2O3 particles for 5 minutes , adding the remaining 20% of the PCE to the mixture and mixing at high speed for 5 minutes until the mixture turns into a homogeneous mixture, slowly adding the polypropylene fibers to the mixture and mixing for 5 minutes, mixing for one an additional period of 5 minutes to achieve good dispersion of the UHPC blend.

In one embodiment, a mold 108 is used to mold the UHPC blend, covering the surface with the plastic sheets covering the surface and storing at laboratory temperature for 24 hours.

In one embodiment, a treatment chamber 110 is provided for curing the demolded samples with ordinary water at room temperature.

In another embodiment, the water-to-binder ratio is fixed at 0.24 for all mixes throughout, dividing the seven types of UHPC mixes into two series, each with a different dosage of cement and nanoparticles, with the total cement content always is low and 570.45 kg/m ³ .

In another embodiment, the seven types of UHPC blends include a control blend (CON blend - without nanoparticles), and the other six blends are made with different dosages of nano-Al ₂ O ₃ particles replacing 0.5% to 3% , with an increase of 0.5%.

In another embodiment, the polypropylene fiber (PP) content is added by 0.4% to the volume of the concrete.

In another embodiment, preferably 171.20 kg/m ³ silica fume, 245.28 kg/m ³ quartz flour and 1245.38 kg/m ³ water with a proportion of sand are mixed in all mixtures.

In another embodiment, all seven mixes are prepared in a mortar mixer 104 for a total mix time of 30 minutes, all mixing being done under laboratory conditions with dried, tempered aggregate and powder materials.

In another embodiment, room temperature is maintained at 24°C during mixing, testing and pouring of the ultra high performance concrete.

Alternatively, mixing is continued until the granules are transformed, which preferably takes 10 minutes.

In another embodiment, the sand weight fractions are preferably selected from 70% sand with a grain size of 2.36 mm-600 μm and 30% sand with a grain size of 600 μm-90 μm.

In another embodiment, the nano-Al ₂ O ₃ particles are selected from a average particle size of 20-30 nm and a specific surface area of 180 m ² / g.

materials

Cement, nano-Al ₂ O ₃ , silica fume, quartz flour, sand, polycarboxylate ether-based superplasticizer, polypropylene fibers and drinking water are used to produce the ultra-high performance concrete.

cement

Class 53 ordinary Portland cement is used to confirm IS 12269-2013. Consistency, specific gravity, initial and final setting time, strength, fineness and compressive strength of the cement are 31%, 3.12, 45 min, 265 min, 0.6 mm, 311.7 m ² / kg and 57.02 MPa, respectively.

Fine aggregate

The locally available river sand is used as a fine aggregate and has a bulk density, specific gravity and water absorption of 1620 kg/m ³ , 2.65 and 0.55% respectively, tested according to IS 2386 - Part 1. The sand weight fractions of 70% of the sand with a Grain size of 2.36 mm - 600 µm and 30% of the sand with a grain size of 600 µm - 90 µm are used for this study in order to achieve a higher packing density of the mixture.

silicate dust

The commercially available compressed silica fume of the type Elkem Microsilica® 940, which conforms to IS 15388: 2003, is used.

Nano _{- Al2O3}

Nano-Al ₂ O ₃ particles have an average particle size of 20-30 nm and a specific surface area of 180 m ² /g. shows the physical and chemical properties of the nano-Al ₂ O ₃ particles.

quartz powder

The quartz powder has an average particle size of 19 µm. The physical and chemical properties of quartz powder declared by the manufacturer are in shown.

Polypropylene fibre

Polypropylene fibers are used which comply with the BS EN 14889-2:2006 standard. The physical properties of polypropylene fibers are in shown.

flow agent

Aramex 400, a new generation modified superplasticizer based on polycarboxylic acid ether, is used and its properties are in shown.

Water

The potable water available in the laboratory is used for pouring and curing of the concrete samples according to IS 456-2000.

mixing ratio

Since there is no design code for UHPC compound design, UHPC compound is optimized according to literature and manufactured according to ASTM C1856/C1856M-17 requirements. Based on the laboratory tests, a total of seven UHPC mixtures were optimized, which are listed. The water/binder ratio was consistently set at 0.24 for all mixtures. The seven UHPC mix types are divided into two series, each with a different dosage of cement and nanoparticles, with the cement content always being 570.45 kg/m ³ . These include a control mix (CON mix - without nanoparticles) and the other six mixes prepared with different dosages from 0.5% to 3% nano-Al ₂ O ₃ particles with an increment of 0.5% each. Polypropylene fiber (PP) content is added at 0.4% to the volume of the concrete. Silica fume, quartz flour and sand content water are specified in all mixtures at 171.20 kg/m ³ , 245.28 kg/m ³ and 1245.38 kg/m ³ respectively.

• Die Nano-Al₂O₃-Partikel werden in 20 % PCE und 20 % Wasser mit Hilfe einer Badbeschallungstechnik für 30 Minuten dispergiert.

All seven mixes are made in a mortar mixer with a total mixing time of 30 minutes. In addition, mixing is always carried out in laboratory conditions, using dried, tempered aggregates and powdered materials. The room temperature during mixing, testing and concreting is 24°C. The mixing, pouring and curing process is carried out as follows:

• The nano-Al ₂ O ₃ particles are dispersed in 20% PCE and 20% water using a bath sonication technique for 30 minutes.

Cement, silica fume, quartz flour and sand are placed in a mortar mixer and mixed slowly for 5 minutes.

60% PCE is mixed with 80% water and slowly added to the dry mixture. Mixing is continued until the granules are transformed (about 10 minutes).

After the formation of the granules, the mixture of dispersed nano-Al ₂ O ₃ particles is slowly added and mixed for another 5 minutes. Then the remaining 20% of the PCE is added to the mixture and mixed at high speed for 5 minutes until the mixture turns into a homogeneous mixture.

Polypropylene fibers are then slowly added to the mixture and mixed for 5 minutes. Thereafter, mixing is continued for another 5 minutes to achieve good dispersion of the UHPC mixture.

The manufactured UHPC mixture is partly used for fresh concrete tests. The remaining concrete is poured into molds with the surface covered with plastic sheeting and left at laboratory temperature for 24 hours.

Thereafter, the demolded specimens are cured in normal water at room temperature.

testing of the concrete

According to ACI, ASTM, BS and IS standard methods, UHPC is tested for rheological properties, mechanical properties, microstructural properties, durability properties and aggressive chemical attack.

fresh concrete properties

The flow behavior of the fresh concrete mix is measured using a Minislip cone in accordance with ASTM C1437-07. The freshly prepared concrete mix is poured into the mini sink cone with a lower diameter of 100mm, an upper diameter of 70mm and a height of 50mm. The concrete mix is poured in a single layer without compaction as required by ASTM 1856/C1856-17. Then the cone is slowly raised, allowing the concrete to flow. The greatest width of concrete spread is noted as _d1 , then _d2 is measured at right angles to d1. The yield value (f) of the fresh concrete is calculated using Equation 1. $$\text{Mini}-\text{swamp stream}=\frac{{\mathrm{i.e}}_1+{\mathrm{i.e}}_2}{2}$$

2 12 shows the results of a slump flow test for various concrete mixes according to an embodiment of the present disclosure. The minislump flow was tested according to ASTM C1437-07. It can be seen that the lowest slump yield range of 240 mm is observed for the control mixture without nano-Al ₂ O ₃ particles, and for the nano-Al ₂ O ₃ -spiked mixtures the slump value is between 242 mm and 251 mm. The results show that the addition of nano-Al ₂ O ₃ particles improved the flow behavior of the mixture without adjusting the flow agent dosage. However, when 3% nano-Al ₂ O ₃ particles were added to the mix, the greatest spread of 251 mm was achieved, increasing flowability by 3.33% compared to the control mix. The researchers reported that the higher dosage of nano-alumina reduced the flowability of the mortar as it increased the cohesion of the mixes. When the nano-alumina particles are added directly into the mix without dispersing them, the yield stress and viscosity of the mortar increases due to their high reactivity and surface area.

Researchers have reported that the concrete mixes mixed with nano-alumina particles have low slump values and poor workability. Replacing cement with nano-alumina particles increases water requirements due to the increase in surface area. However, the addition of nano-Al ₂ O ₃ particles has increased the fluidity of the mixture, making it more workable and easier to incorporate in all mixtures with nano-Al ₂ O ₃ particles. This may be due to the fact that the good dispersion of the nano-Al ₂ O ₃ particles reduced the yield stress and viscosity of the mix, leading to an improvement in the workability of the fresh concrete.

Effects of nano-Al ₂ O ₃ particles on the mechanical properties of UHPC

The results and discussion of the effects of nano-Al ₂ O ₃ particles on the mechanical properties of UHPC studied by compressive strength, flexural strength, splitting tensile strength, Young's modulus, ultrasonic pulse velocity and density of the cured concrete are presented in this section explained.

The compressive strength of the specimens was tested according to ASTM C109/C10M - 07 at 1, 3, 7, 14, 28 and 56 days. The effect of replacing nano-Al ₂ O ₃ particles on compressive strength and strength increase percentage. The minimum compressive strength of the control mixture was found to be 55.05 MPa, 71.28 MPa, 91.41 MPa, 103.32 MPa, 122.65 MPa and 129.57 MPa at 1, 3, 7, 14, 28 and 56 days of age. However, in any case, the compressive strength of UHPC increases with the percentage of nano-Al ₂ O ₃ particles and is higher than the strength of the control mixture. The highest compressive strength of the 2.0 AL compound is 67.65 MPa, 83.57 MPa, 113.28 MPa, 126.13 MPa, 155.59 MPa and 161.92 MPa at 1, 3, 7, 14, 28 and 56 days aged. The 2% replacement of Al2O3 particles proved to be optimal for the efficiency and the economic aspect and the compressive strength increased by 22.89%, 17.24%, 23.93%, 22.09%, 26.86% and 24.97% after 1, 3, 7, 14 , 28 and 56 days compared to the control mixture.

This improvement in strength is mainly due to the filling effect and the pozzolanic reactivity of the nano-Al ₂ O ₃ particles. The nano-Al ₂ O ₃ particles act as a dynamic reactive substance in nucleation assembly during CSH gelation and promote the hydration process, resulting in pore refinement and microstructure densification. In addition, the nano-Al ₂ O ₃ particle has reduced the distance between cement grains and SCM particles, giving the cement matrix a more homogeneous and compact structure. As a result, the compressive strength increased rapidly in the early years and later gradually increased with increasing curing time.

flexural strength

The flexural strength of the prism samples is tested according to ASTM C 348 - 02. The flexural strength increases with the percentage of nano-Al ₂ O ₃ particles in the mixture. It was found that replacing cement with nano-Al ₂ O ₃ particles behaves similarly to compressive strength. The test results show that the lowest flexural strength in the control mix is 8.55 MPa, 12.36 MPa and 19.02 MPa after 7, 14 and 28 days, respectively. However, the highest flexural strength was observed for the 2.0 AL compound at 11.57 MPa, 18.29 MPa, and 22.52 MPa at 7, 14, and 28 days of age, respectively. The proportion of 2% nano-Al ₂ O ₃ particles increased the flexural strength by 35.32%, 47.98% and 18.40% after 7, 14 and 28 days compared to the control mixture.

It was found that the replacement of nano-Al ₂ O ₃ particles improved the flexural strength of UHPC samples, which could be due to the pozzolanic reaction and the filler effects of the nano-Al ₂ O ₃ particles. The nano-Al ₂ O ₃ particles have filled the pores, particularly the porous portlandite crystals, located in the transition zone between the cement grains and the SCM in the cement mix. This increase in performance is due to the presence of nano-Al ₂ O ₃ particles that prevent cracking and locking between slip planes, resulting in an improvement in the flexural strength of UHPC.

cleavage strength

Splitting strength is tested according to IS 5816 - 1999. The cleavage strength of the UHPC samples aged 7, 14 and 28 days. The results show that the control mix achieved the lowest splitting strengths of 4.06 MPa, 5.12 MPa and 8.52 MPa after 7, 14 and 28 days, respectively. The cleavage strength of UHPC increases with the proportion of nano-Al ₂ O ₃ particles. These results are also consistent with the compressive strength results, with the higher cleavage tensile strengths being noted for the UHPC blends mixed with nano-Al ₂ O ₃ particles. However, the highest splitting strength was observed in the 2.0 AL compound at 6.05 MPa, 8.90 MPa and 10.23 MPa at 7, 14 and 28 days of age, respectively. Replacement of 2% nano-Al ₂ O ₃ particles improved splitting strength by 49.01%, 73.83% and 20.07% at 7, 14 and 28 days of age.

The improvement in cleavage strength is mainly due to the rapid consumption of Ca(OH) ₂ , which formed a CSH gel with nano-Al ₂ O ₃ particles during the hydration process, especially in the early years. This reduces the interconnectivity of the pores due to the higher reactivity and smaller size of the nano-Al ₂ O ₃ particles. Consequently, the hydration was accelerated 0 20 40 60 80 7d 14d 28d Percent Strength Gain (%) Age (days) 0.5 AL 1.0 AL 1.5 AL 2.0 AL 2.5 AL 3.0 AL process forming a larger volume of reaction products and a denser microstructure.

water absorption

The water absorption of UHPC blends is tested according to ASTM C 642 - 06. The water absorption of UHPC samples containing nano-Al ₂ O ₃ particles in different ratios. The maximum water uptake in the control mixture is 0.66% and 0.54% after 28 and 56 days, respectively. In contrast, the minimum water absorption of the 2.0 AL mixture is 0.53% and 0.42% at the age of 28 and 56 days, respectively. The minimal water absorption of the concrete is an indication of the small pore size of the mix. The results confirm that the replacement of nano-Al ₂ O ₃ particles significantly reduced the water absorption of UHPC. The addition of 2% nano-Al ₂ O ₃ particles reduced water uptake by 22.22% compared to the control mixture. This could be due to the nano-Al ₂ O ₃ particles filling the voids in the mixture as the nano-Al ₂ O ₃ particles densify the microstructure of the UHPC matrix; this leads to a decrease in water absorption in the mixture. If the content of nano-Al ₂ O ₃ particles is increased to more than 2%, the absorption value increases, but these are water-ab sorption values still lower than those of the control sample. This could be due to the fact that the distance between the nanoparticles decreases at higher concentrations, which limits the formation of Ca(OH) ₂ crystals. As a result, the ratio of crystals to CSH gel decreases and water absorption in the concrete tends to increase. The pozzolanic reaction and the filling effect of the nano-Al ₂ O ₃ particles and the hardening age of the concrete play an important role in reducing the volume of the permeable voids in the concrete.

3 illustrates the physical and chemical properties of silica fume, an embodiment of the present disclosure.

4 Figure 1 shows the physical and chemical properties of nano-Al ₂ O ₃ , an embodiment of the present disclosure.

5 Figure 1 illustrates the physical and chemical properties of quartz powder, an embodiment of the present disclosure.

6 illustrates the physical properties of polypropylene fiber, an embodiment of the present disclosure.

7 illustrates the properties of polycarboxylic acid ether based flow aids, one embodiment of the present disclosure.

8th illustrates the mixing ratios in an embodiment of the present disclosure.

The figures and the preceding description give examples of embodiments. Those skilled in the art will understand that one or more of the elements described may well be combined into a single functional element. Alternatively, certain elements can be broken down into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, the order of the processes described herein may be changed and is not limited to the manner described herein. Additionally, the actions of a flowchart need not be performed in the order shown; Also, not all actions have to be carried out. Also, the actions that are not dependent on other actions can be performed in parallel with the other actions. The scope of the embodiments is in no way limited by these specific examples. Numerous variations are possible, regardless of whether they are explicitly mentioned in the description or not, e.g. B. Differences in structure, dimensions and use of materials. The scope of the embodiments is at least as broad as indicated in the following claims.

Advantages, other benefits, and solutions to problems have been described above with respect to particular embodiments. However, the benefits, advantages, problem solutions, and components that can cause an advantage, benefit, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or component of any or all claims.

reference list

100

A system for preparing ultra-high performance.

102

sonicator

104

mortar mixer

106

mixing chamber

108

mold

110

treatment chamber

Claims (10)

A system for producing ultra high performance concrete, the system comprising: a sonicator for dispersing the nano-Al ₂ O ₃ particles in 20% PCE and 20% water using a bath sonication technique for 30 minutes; a mortar mixer to slowly mix cement, silica fume, quartz flour and sand for 5 minutes to make the dry mix; a mixing chamber with an agitator to automatically mix 60% PCE with 80% water and add it slowly to the dry mix to convert granules, adding the dispersed nano-Al ₂ O ₃ particles, mix slowly for 5 minutes, adding the remaining 20% of the PCE to the mixture and mixing at high speed for 5 minutes until the mixture turns into a homogeneous mixture, the polypropylene fibers are slowly added to the mixture and mixed for 5 minutes, mixing for a further period of 5 minutes is continued to achieve good dispersion of the UHPC mixture; a mold to shape the UHPC mixture, covering the surface with the plastic sheets covering the surface and keeping at laboratory temperature for 24 hours; and a treatment chamber for curing the ent formed specimens with normal water at room temperature. system after claim 1 , with the ratio of water to binder fixed at 0.24 for all mixes, with the seven types of UHPC mixes divided into two series, each with a different dosage of cement and nanoparticles, with the total content of cement always being 570.45% kg/ ^m3 . system after claim 2 , where the seven types of UHPC blends include a control blend (CON blend - without nanoparticles) and the other six blends with different dosage levels from 0.5% to 3% replacement of nano-Al ₂ O ₃ particles with an increase of 0.5% getting produced. system after claim 1 , where the content of polypropylene fibers (PP) is 0.4% of the volume of the concrete. system after claim 1 , whereby 171.20 kg/m ³ silica dust, 245.28 kg/m ³ quartz flour and 1245.38 kg/m ³ water containing sand are preferably mixed in all mixtures. system after claim 1 , with all seven mixtures being prepared in a mortar mixer with a total mixing time of 30 minutes, with mixing always taking place under laboratory conditions with dried, tempered aggregate and powder materials. system after claim 1 , keeping the room temperature at 24 °C during the mixing, testing and pouring of the ultra high performance concrete. system after claim 1 , with mixing continuing until granular transformation, which preferably lasts 10 minutes. system after claim 1 , wherein the sand weight fractions are preferably selected to be 70% 2.36 mm - 600 µm sand and 30% 600 µm - 90 µm sand. system after claim 1 , wherein the nano-Al ₂ O ₃ particles are selected from an average particle size of 20-30 nm and a specific surface area of 180 m ² /g.

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