Cement mortar composition and method of forming the same

Abstract

Various embodiments may relate to a cement mortar composition. The cement mortar composition may include cement, sand, and water. The cement mortar composition may also include iron phosphate dominated waste (FPW) mixed with the cement, the sand and the water. The iron phosphate dominated waste (FPW) may include iron oxide (Fe2O3) and phosphorus pentoxide (P2O5).

Description

CEMENT MORTAR COMPOSITION AND METHOD OF FORMING THE SAMECROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of priority of Singapore application No. 10202303133P filed November 3, 2023, the contents of it being hereby incorporated by reference in its entirety for all purposes.TECHNICAL FIELD

[0002] Various embodiments of this disclosure may relate to a cement mortar composition. Various embodiments of this disclosure may relate to a method of forming a cement mortar composition.BACKGROUND

[0003] Electric vehicles (EVs) due to the use of clean energy have become an important direction for the development of the automotive industry. The sales of EVs increase in leaps and bounds, which accounted for just 4% of total vehicle sales in 2020 and rose to around 18% in 2023. Moreover, the three major EVs markets, China, Europe and the United States are set to increase the average share of EVs to 60% by 2030. The rapid development of EVs industry is accompanied by the blooming of lithium-ion batteries (LIBs) industry. The demand for LIBs from EVs increased by around 65% in 2022, in which lithium iron phosphate (LFP or LiFePO4 i ) battery as an alternative to traditional LIBs experienced the highest increase of over 25%. LFP is now the second most sold LIBs behind just lithium nickel manganese cobalt oxide (NMC) batteries. They share -30% and - 60% of total LIBs market, respectively. LFP batteries have been attracting special attention because of lower price, longer lifetime and less environmental impact. The main disadvantage of LFP batteries lies in their relatively lower energy density. However, recent technological innovation has substantially improved the performance of LFP. The blade battery, a type of LFP battery released by BYD in 2020, already has comparable volumetric energy density as NMC batteries, allowing a similar level of range and is ultra safe. The LFP battery has been attracting more and more market interest, which is typically manifested by the shift of traditional LIBs to LFP batteries in the two largest EVs seller, i.c., BYD and Tesla.

[0004] The life cycle of powder LIBs is only 6-8 years. Thus, there will be a large amount of retired batteries in the near future. Awareness about the retirement of LIBs should be raised and efficient ways of disposal should be developed accordingly to accommodate the large number of spent car batteries. Special focus should be placed on the LFP batteries as they are becoming one of the mainstream choices for EVs. In recent years, there are already some emerging companies devoted to recycling LFP batteries, where in most cases, lithium (Li) is the element of interest in spent cathodes. The less valuable residue after lithium extraction is generally disposed of by lithium recycling companies. The residue mainly includes iron phosphate FP (FePO ) and a small amount of other impurities. The by-product powder in principle does not contain toxic heavy metals such as lead (Pb), mercury (Hg), nickel (Ni), cobalt (Co) and manganese (Mn) commonly found in traditional batteries or other types of LIBs. Moreover, FP has a similar hazardous statement as Ground Granulated Blast Furnace Slag (GGBS) and silica fume in Material Safety Data Sheet.SUMMARY

[0005] Various embodiments may relate to a cement mortar composition. The cement mortar composition may include cement, sand, and water. The cement mortar composition may also include iron phosphate dominated waste (FPW) mixed with the cement, the sand and the water. The iron phosphate dominated waste (FPW) may include iron oxide ( (Fe2O3) and phosphorus pentoxide (P2O5).

[0006] Various embodiments a method of forming a cement mortar' composition. The method may include mixing iron phosphate dominated waste (FPW) with cement, sand and water to form the cement mortar composition. The iron phosphate dominated waste (FPW) may include iron oxide (Fe2O3 ) and phosphorus pentoxide (P2O5).BRIEF DESCRIPTION OF THE DRAWINGS

[0007] In the drawings, like reference characters generally refer to the same parts throughout the different views. The drawings arc not necessarily drawn to scale, emphasis instead generally being placed upon illustrating the principles of various embodiments. In the following description, various embodiments of the invention arc described with reference to the following drawings.FIG. 1 shows a general illustration of a cement mortar composition according to various embodiments.FIG. 2 shows a general illustration of a method of forming a cement mortar composition according to various embodiments.FIG. 3 shows a general illustration of a cement paste composition according to various embodiments.FIG. 4 shows a general illustration of a method of forming a cement paste composition according to various embodiments.FIG. 5A shows a table illustrating the main chemical composition and phase composition of the Portland cement according to various embodiments.FIG. 5B shows a schematic illustrating the components of a lithium iron phosphate (LFP or LiFePOr) battery according to various embodiments.FIG. 5C shows a schematic illustrating the cathode of the lithium iron phosphate (LFP or LiFcPCL) battery according to various embodiments.FIG. 6A shows a scanning electron microscopy (SEM) image of iron phosphate dominated waste (FPW) powder according to various embodiments.FIG. 6B shows a scanning electron microscopy (SEM) image of the structure Objl indicated in FIG. 6A according to various embodiments.FIG. 6C shows a magnified scanning electron microscopy (SEM) image of the structure Objl according to various embodiments.FIG. 6D shows a scanning electron microscopy (SEM) image of the area Obj2 indicated in FIG. 6A according to various embodiments.FIG. 6E shows a magnified scanning electron microscopy (SEM) image of the area Obj2 according to various embodiments.FIG. 6F shows a plot of weight percentage (%) / iron / phosphorous (Fe / P) as a function of particles illustrating the energy-dispersive X-ray spectroscopy (EDS) results of the various particles according to various embodiments shown in FIG. 6C and FIG. 6E.FIG. 7A shows a table illustrating the chemical composition of iron phosphate dominated waste (FPW) according to various embodiments determined by X-ray fluorescence (XRF).FIG. 7B shows a plot of weight (in weight percentage or wt. %) / differential thermogravimetry (DTG) (in weight percentage per degree Celsius or wt.% / °C) as a function of temperature (indegree Celsius or °C) illustrating the thcrmogravimctric analysis (TGA) of iron phosphate dominated waste (FPW) powder according to various embodiments.FIG. 8A shows the main crystalline phases present in the iron phosphate dominated waste (FPW) powder according to various embodiments.FIG. 8B shows a table illustrating the crystalline phases of iron phosphate dominated waste (FPW) according to various embodiments determined by quantitative X-ray diffraction (Q- XRD) analysis.FIG. 8C shows a table summarizing the phase composition of iron phosphate dominated waste (FPW) powder according to various embodiments.FIG. 9 shows a plot of compressive strength (in Mega-Pascals or MPa) / diameter (in millimeters or mm) as a function of mortar samples illustrating the effects of iron phosphate dominated waste (FPW) powder according to various embodiments on compressive strength and flowability.FIG. 10A shows a plot of heat flow (in milli-Watts per gram or mWg"1) as a function of time (in hours) illustrating the variation of heat flow of various samples according to various embodiments with time.FIG. 10B shows a plot of cumulative heat (in Joules per gram or Jg"1) as a function of time (in hours) illustrating the variation of cumulative heat of various samples according to various embodiments with time.FIG. 11A shows scanning electron microscopy (SEM) images illustrating cement grains in the control sample FPW-C after 6 hours of hydration.FIG. 11B shows scanning electron microscopy (SEM) images illustrating cement grains in the sample FPW-5% according to various embodiments after 6 hours of hydration.FIG. 11C shows scanning electron microscopy (SEM) images illustrating cement grains in the sample FPW- 10% according to various embodiments after 6 hours of hydration.FIG. 12A shows a scanning electron microscopy (SEM) image of graphite in the FPW- 10% sample according to various embodiments after 6 hours of hydration.FIG. 12B shows a magnified scanning electron microscopy (SEM) image of graphite in the FPW- 10% sample according to various embodiments after 6 hours of hydration.FIG. 12C shows a scanning electron microscopy (SEM) image of iron phosphate (FP) lump in the FPW- 10% sample according to various embodiments after 6 hours of hydration.FIG. 12D shows a magnified scanning electron microscopy (SEM) image of iron phosphate (FP) lump at location 1 in the FPW-10% sample according to various embodiments after 6 hours of hydration.FIG. 12E shows a magnified scanning electron microscopy (SEM) image of iron phosphate (FP) lump at location 2 in the FPW-10% sample according to various embodiments after 6 hours of hydration.FIG. 12F shows a table illustrating the main elements (in weight percent or wt. %) of different objects of the iron phosphate (FP) lump at location 2 detected by energy-dispersive X-ray spectroscopy (EDS) at 15 kV according to various embodiments.FIG. 12G shows a table illustrating the main elements (in weight percent or wt. %) of different objects of the iron phosphate (FP) lump at location 2 detected by energy -dispersive X-ray spectroscopy (EDS) at 7 kV according to various embodiments.FIG. 13 A shows a plot of degree of hydration (DoH) of cement (in percent or %) as a function of hydration time (in days) illustrating the degree of hydration of various samples according to various embodiments over time.FIG. 13B shows a plot of weight of iron phosphate FP (in percent or %) as a function of hydration time (in days) illustrating the content changes of crystal iron phosphate FP in the various samples according to various embodiments over time.FIG. 13C shows a plot of degree of hydration (DoH) of tricalcium silicate C 3S and bicalcium silicate C2S (in percent or %) as a function of hydration time (in days) illustrating the degree of hydration of C3S and C2S of various samples according to various embodiments over time.FIG. 13D shows a plot of degree of hydration (DoH) of tricalcium aluminate C3A and tetracalcium aluminoferrite C4AF (in percent or %) as a function of hydration time (in days) illustrating the degree of hydration of C3A and C4AF of various samples according to various embodiments over time.FIG. 14A shows a plot of weight percentage of calcium hydroxide CH (in percent or %) as a function of hydration of time (in days) illustrating the weight percent changes of CH of various samples according to various embodiments over time.FIG. 14B shows a plot of weight percentage of aluminate ferrite trisubstituted (AFt) and aluminate ferrite monosubstituted (AFm) (in percent or %) as a function of hydration of time (in days) illustrating the weight percent changes of AFt and AFm of various samples according to various embodiments over time.FIG. 14C shows a plot of intensity (in arbitrary units or a.u.) as a function of angle 29 (in degrees or °) illustrating of the observation between 8° and 20° 29 angles of aluminate ferrite trisubstituted (AFt) and aluminate ferrite monosubstituted (AFm) phases of various samples according to various embodiments.FIG. 15A shows a plot of pore volume (in percent or %) / first derivative dV / d(logr) (in arbitrary units or a.u.) as a function of pore diameter (in micrometers or pm) illustrating the mercury intrusion porosimetry (MIP) cumulative pore volume curves and first derivative curves of the various samples according to various embodiments.FIG. 15B shows a table illustrating the solubility product constants for various phases at 25°C according to various embodiments.FIG. 16A shows a plot of compressive strength (in Mega-Pascals or MPa) as a function of samples comparing the compressive strength of samples according to various embodiments when mixed with calcium hydroxide and pore solution in a solution to solid ratio of 0.8 (FPW- CH-pore-0.8), when mixed with quartz and pore solution in a solution to solid ratio of 0.6 (FPW-Qua-porc-0.6), and when mixed with calcium hydroxide and water in a solution to solid ratio of 0.6 (FPW-CH-water-0.6).FIG. 16B shows a schematic illustrating reaction mechanism of iron phosphate (FP) in cement paste according to various embodiments.FIG. 16C is a schematic illustrating the role of different components of iron phosphate dominated waste (FPW) in cement paste according to various embodiments.DESCRIPTION

[0008] The following detailed description refers to the accompanying drawings that show, by way of illustration, specific details and embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments may be utilized and structural, logical, and electrical changes may be made without departing from the scope of the invention. The various embodiments are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments.

[0009] Features that are described in the context of an embodiment may correspondingly be applicable to the same or similar features in the other embodiments. Features that arc described in the context of an embodiment may correspondingly be applicable to the other embodiments,even if not explicitly described in these other embodiments. Furthermore, additions and / or combinations and / or alternatives as described for a feature in the context of an embodiment may correspondingly be applicable to the same or similar feature in the other embodiments.

[0010] In the context of various embodiments, the articles “a”, “an” and “the” as used with regard to a feature or element include a reference to one or more of the features or elements.

[0011] In the context of various embodiments, the term “about” or “approximately” as applied to a numeric value encompasses the exact value and a reasonable variance, e.g. within 10% of the specified value.

[0012] As used herein, the tenn “and / or” includes any and all combinations of one or more of the associated listed items.

[0013] By “comprising” it is meant including, but not limited to, whatever follows the word “comprising”. Thus, use of the term “comprising” indicates that the listed elements are required or mandatory', but that other elements are optional and may or may not be present.

[0014] By “consisting of’ is meant including, and limited to, whatever follows the phrase “consisting of’. Thus, the phrase “consisting of’ indicates that the listed elements are required or mandatory, and that no other elements may be present.

[0015] Embodiments described in the context of one of the compositions arc analogously valid for the other compositions. Similarly, embodiments described in the context of a method are analogously valid for a composition, and vice versa.

[0016] Iron is itself an element that is present in cement concrete (e.g. ferrite and steel bar) and some phosphates are used as concrete retarders. Thus, it may be of interest to explore the possibility of using the iron phosphate dominated waste (FPW) in the cement concrete industry.

[0017] FIG. 1 shows a general illustration of a cement mortar composition according to various embodiments. The cement mortar composition may include cement 102, sand 104, and water 106. The cement mortar composition may also include iron phosphate dominated waste (FPW) 108 mixed with the cement 102, the sand 104 and the water 106. The iron phosphate dominated waste (FPW) 108 may include iron oxide (Fe2O3) and phosphorus pentoxide (P2O5).

[0018] In other words, various embodiments may relate to a cement mortal- composition including cement 102, sand 104, water 106 as well as iron phosphate dominated waste (FPW) 108 including iron oxide (FC2O3) and phosphorus pentoxide (P2O5).

[0019] For avoidance of doubt, FIG. 1 is intended to illustrate some features of a cement mortar composition, and is not intended to limit the ratio, arrangement, sequence of mixing etc.of the various features. In various embodiments, the cement mortar composition may include any other suitable constituents in addition to those illustrated in FIG. 1.

[0020] In various embodiments, the iron phosphate dominated waste (FPW) 108 may include graphite and / or (amorphous) carbon. The iron phosphate dominated waste (FPW) 108 may include any suitable percentage composition of graphite and / or (amorphous) carbon. For instance, a weight percentage of graphite in the cement mortar composition may be selected from a range from 1 weight percent (wt. %) to 15 wt. %, e.g., 9.2 wt. %.

[0021] In various embodiments, the iron phosphate dominated waste (FPW) 108 may also include fluoride (F), aluminum oxide (AI2O3), copper oxide (CuO), manganese oxide (MnO), nickel oxide (NiO), sodium oxide (Na2O), calcium oxide (CaO), sulfur trioxide (SO3) and / or magnesium oxide (MgO). In various embodiments, the iron phosphate dominated waste (FPW) 108 may include any other suitable elements and / or compounds.

[0022] In various embodiments, the cement 102 may be any suitable cement, e.g., Portland cement, Portland pozzolana cement, rapid-hardening cement or quick-setting cement.

[0023] In various embodiments, the sand 104 may be any suitable sand, e.g., river sand, concrete sand or manufactured sand.

[0024] In various embodiments, a weight ratio of the water 106 to the cement 102 may be selected from a range from 0.4 to 0.6. For instance, the weight ratio of the water 106 to the cement 102 may be 0.48.

[0025] In various embodiments, a weight ratio of the sand 104 to the cement 102 may be selected from a range from 1 to 3. For instance, the weight ratio of the sand 104 to the cement 102 may be 2.25.

[0026] In various embodiments, a weight ratio of the iron phosphate dominated waste (FPW) 108 to the cement 102 may be equal to or less than 10 : 90.

[0027] In various embodiments, the weight ratio of the iron phosphate dominated waste (FPW) 108 to the cement 102 may be equal to or less than 5 : 95. A weight ratio of the iron phosphate dominated waste (FPW) 108 to the cement 102 of about 5 : 95 may lead to higher compressive strength as well as more refined pore structure compared to a cement mortal' composition without FPW.

[0028] In various embodiments, a weight percentage of the iron oxide (Fe2O3) included in the iron phosphate dominated waste (FPW) 108 may be more than a weight percentage of the phosphorus pentoxide (P2O5) included in the iron phosphate dominated waste (FPW) 108.

[0029] In various embodiments, the cement mortar composition may include amorphous hydroxyapatite (Ca5(PO4)3OH). The amorphous hydroxyapatite may be formed by reaction of phosphate ions with calcium hydroxide (Ca(OH)2).

[0030] FIG. 2 shows a general illustration of a method of forming a cement mortar composition according to various embodiments. The method may include, in 202, mixing iron phosphate dominated waste (FPW) with cement, sand and water to form the cement mortar composition. The iron phosphate dominated waste (FPW) may include iron oxide (FeoOs) and phosphorus pentoxide (P2O5).

[0031] In various embodiments, the iron phosphate dominated waste (FPW) may include graphite and / or (amorphous) carbon.

[0032] In various embodiments, the iron phosphate dominated waste (FPW) may include fluoride (F), aluminum oxide (AI2O3), copper oxide (CuO), manganese oxide (MnO), nickel oxide (NiO), sodium oxide (Na2O), calcium oxide (CaO), sulfur trioxide (SO3) and magnesium oxide (MgO).

[0033] In various embodiments, the method may include removing lithium from battery waste to form the iron phosphate dominated waste (FPW).

[0034] In various embodiments, the iron phosphate dominated waste (FPW) obtained from the battery waste is in the form of a powder including a plurality of particles. The method may include ball milling the powder to reduce a particle size of the plurality of particles before the powder is mixed with the cement, the sand and the water to form the cement mortar composition. For instance, the median particle size of the plurality of particles of the FPW obtained from the battery waste may initially be a value selected from 120 pm to 170 pm, c.g., 147.16 pm, and may be reduced to a value selected from 5 pm to 20 pm, e.g., 17.98 pm.

[0035] In various embodiments, a weight ratio of the water to the cement may be selected from a range from 0.4 to 0.6. For instance, the weight ratio of the water to the cement may be 0.48.

[0036] In various embodiments, a weight ratio of the sand to the cement may be selected from a range from 1 to 3. For instance, the weight ratio of the sand to the cement may be 2.25.

[0037] In various embodiments, a weight ratio of the iron phosphate dominated waste (FPW) to the cement may be equal to or less than 10 : 90.

[0038] In various embodiments, a weight ratio of the iron phosphate dominated waste (FPW) to the cement may be equal to or less than 5 : 95.

[0039] In various embodiments, a weight percentage of the iron oxide (FC2O3) included in the iron phosphate dominated waste (FPW) may be more than a weight percentage of the phosphorus pentoxide (P2O5) included in the iron phosphate dominated waste (FPW).

[0040] In various embodiments, the cement mortar composition may include amorphous hydroxyapatite (Ca5(PO4)3OH). The amorphous hydroxyapatite may be formed by reaction of phosphate ions with calcium hydroxide (Ca(OH)2).

[0041] FIG. 3 shows a general illustration of a cement paste composition according to various embodiments. The cement paste composition may include cement 302 and water 306. The cement paste composition may also include iron phosphate dominated waste (FPW) 308 mixed with the cement 302 and the water 306. The iron phosphate dominated waste (FPW) 308 may include iron oxide (Fe2O3) and phosphorus pentoxide (P2O5).

[0042] FIG. 4 shows a general illustration of a method of forming a cement paste composition according to various embodiments. The method may include, in 402, mixing iron phosphate dominated waste (FPW) with cement and water to form the cement paste composition. The iron phosphate dominated waste (FPW) may include iron oxide (FC2O3) and phosphorus pentoxide (P2O5).

[0043] FPW powder was used to replace cement at different ratios until 10 wt. %. Detailed multiple-technique characterization and analyses are provided at first to reveal the characteristics and composition of the FPW powder. Then, its effects on the hydration of Portland cement and the basic performance of mortar were investigated.

[0044] Experiments

[0045] Materials

[0046] The FPW was provided by a lithium recycling company, NEU Battery Materials, in Singapore. In the first stage of recycling, the collected spent lithium iron phosphate (LFP) batteries were treated with procedures including dismantling, crushing / shredding, grinding and separation to get black mass (mainly LFP and graphite). The lithium of the black mass was extracted by a redox targeting-based strategy where the closed-loop regeneration reaction prevents the redox mediator from remaining in the powder. According to the supplier, the FPW obtained from the recycling procedure may include only substances from the LFP battery itself, essentially electrodes and possibly a small amount of other residues like electrolytes. The as- rcccivcd FPW is in black color and has a median particle size of 147. 16 pm. It was milled in a ball mill machine for 30 min and achieved a median particle size of 17.98 pm. The particledensity of the milled powder was measured as 2.91 g / cm3, close to 3.13 g / cm3of the particle density of the Portland cement (PC) used. The composition of the powder may not be readily determined. The detailed characterization and analysis arc provided below. EM I 52.5 N Portland cement and river sand were used for the preparation of cement paste and mortar samples. FIG. 5A shows a table illustrating the main chemical composition and phase composition of the Portland cement according to various embodiments.

[0047] Sample Preparation

[0048] Cement mortar was prepared for compressive strength and flowability tests while cement paste was prepared for the hydration and microstructure related characterization and tests. The water to solid ratio adopted was a constant value of 0.48. For mortar preparation, the sand to cement ratio was 2.25. FPW powder was added by replacing cement at ratios of 0 wt. % (control), 3 wt. %, 5 wt. %, 7 wt. % and 10 wt. % for compressive strength, flowability and heat of hydration analysis. Paste samples with the replacing ratios of 0 wt. %, 5 wt. % and 10 wt. % were prepared for further investigations, including scanning electron microscope (SEM) observation, energy-dispersive X-ray spectroscopy (EDS) analysis, quantitative X-ray diffraction (Q-XRD) analysis, thermogravimetric analysis (TGA) and mercury intrusion porosimetry (MIP) tests. FPW powder was manually mixed with anhydrous cement for 5 minutes to make the solid more even before formal mixing. The paste samples were mixed for 2 minutes by a small stirrer and the mortar samples were mixed in accordance with ASTM C305 Standard Practice for Mechanical Mixing of Hydraulic Cement Pastes and Mortars of Plastic Consistency. The paste samples were cast in cylindrical plastic vessels with a diameter of 30 mm and a height of 100 mm and scaled with plastic film, except for the heat of hydration test where the paste was poured into a flask directly for testing. Both paste and mortar samples were stored in a moist room with a temperature of 23 ± 2.0 °C and relative humidity > 95%. After 24 hours, the mortar samples with 0 wt. %, 3 wt. %, 5 wt. % and 7 wt. % of FPW were demolded. The demolding for mortar samples with 10 wt. % of FPW were postponed until 48 hours as the samples have not yet hardened at 1 day. The 3, 7 and 28 days compressive strength were tested.

[0049] To characterize the samples after 6 hours of hydration by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), ~ 0.5 g of paste was taken and immersed in isopropanol for 24 hours where the isopropanol was replaced after 1 hour and 3 hours and the solution was agitated to ensure efficient hydration stoppage. After 24hours, the top isopropanol was removed. The powder was dried in a 40 °C vacuum oven for 3 hours and stored in a desiccator over silica gel before analysis.

[0050] Characterization And Test Methods

[0051] The particle size of the FPW powder was determined by using Partica LA-950 V2 Laser Scattering Particle Size Distribution Analyzer and the density was measured by using Quantachrome Ultrapyc 1200e Auto-matical Density Analyzer.

[0052] Compressive Strength And Flowability

[0053] The compressive strength was tested in accordance with ASTM C109 and the consistence of fresh mortar was determined by flow table test in accordance with BS EN 1015—3.

[0054] Heat Of Hydration

[0055] The heat of hydration was conducted on isothermal conduction calorimetry (Thermometric TAM Air) for 72 h with 5 g of fresh paste. The very early data between 0 and 30 min after the contact of solid with water was ignored in the analysis. The results were normalized to the binder content.

[0056] SEM And EDS

[0057] The samples for SEM observation were coated with 15 nm gold (Au). For FPW battery powder characterization, the accelerating voltage was set as 15 kV to ensure the overvoltage of at least 2 to effectively detect the possible elements present in the battery powder (until nickel (Ni) / copper (Cu)). For the SEM observation of hydrated binders, a lower accelerating voltage of 5 kV and a short working distance was applied to more clearly reveal the detailed features. Different voltages of 15 kV and 7 kV were applied in the EDS analysis of hydrated phases on FP lump to allow different involved ranges.

[0058] XRD And TGA

[0059] Tn XRD tests, the 20 range and step size were taken as 5° ~ 65° and 0.02° 20, respectively. X’Pert HighScore Plus software was used for phase identification and Rietveld refinement. In quantitative analysis, calcium fluoride was used as internal standard and evenly mixed with FPW powder at the ratio of 1:4 by mixer. Three replicate tests were performed where the powder was randomly sampled from different locations of raw materials.

[0060] In the Q-XRD analysis of FPW powder, both LFP and FP are incorporated for Rietveld quantitative analysis. In the analysis, global parameters, scale factor, unit cell parameters and phase profile parameters were refined in sequence. Preferred orientation wasrefined where necessary such as for the (002) peak of graphite. Damping factors were applied to prevent large shifts of the parameters. Similar refinement was conducted for anhydrous cement. For the subsequent analysis of hydrated cement paste, the lattice parameters and peak shape parameters of raw material phases were held constant. Generally, only scale factor was refined for the raw material phases, but sometimes preferred orientation was considered as well. For instance, the plate shaped graphite would be adhered with cement paste in the XRD analysis of hydrated samples which should decrease the preferred orientation due to the changed shape of the particles. The Q-XRD quantitative phase results were rescaled to per 100 g of anhydrous cement. The degree of hydration (DoH) of cement (clinker phases) and the content of main hydration products calcium hydroxide (CH), aluminate ferrite trisubstituted (AFt) and aluminate ferrite monosubstituted ( AFm) were determined. Preferred orientation was refined for CH (00 1), AFt (1 00) and AFm (00 1).

[0061] In TGA of FPW powder, isopropanol was avoided in case of dissolving some components of the powder. The FPW powder was oven dried under 40 °C for 2 weeks to get stable weight. TGA was conducted for the FPW powder under air atmosphere. The powder was heated to 1000 °C at a heating rate of 20 °C / min. TGA for cement paste samples was performed under a nitrogen atmosphere at a rate of 20 °C / min until 985 °C. The TGA results are used to get the bound water for the back calculation of the Q-XRD results. The bound water was determined as the weight loss at 600 °C.

[0062] Mercury Intrusion Porosimetry (MIP)

[0063] After hydration stoppage, around 2 g of paste sample was used for measuring the pore structure by using Micro Active Autoporc V 9600. The maximum pressure in the tests is 380 MPa which can detect pores with a size down to 3.3 nm. The contact angle of 130° is adopted in the calculation.

[0064] Results And Discussion

[0065] Determining The Composition Of FPW Powder

[0066] LFP batteries are mainly composed of electrodes (LFP, graphite), current collectors (aluminum (Al), copper (Cu)), electrolyte (a mixture of lithium salts and organic carbonates), shell and organic separator. FIG. 5B shows a schematic illustrating the components of a lithium iron phosphate (LFP or LiFePO4) battery according to various embodiments. FIG. 5C shows a schematic illustrating the cathode of the lithium iron phosphate (LFP or LiFcPOQ battery according to various embodiments. The cathode structure may be a mixture of multiple phases.Characterization results were analyzed based on the known constituents of commercial LFP batteries.

[0067] SEM AND EDS Analysis

[0068] The representative SEM and EDS results for the FPW powder are provided in FIGS. 6A - 6F. FIG. 6A shows a scanning electron microscopy (SEM) image of iron phosphate dominated waste (FPW) powder according to various embodiments. It can be seen that the powder is heterogenous and generally includes constituents with two types of appearance. One is particles with dense structure (c.g. Objl) and the other is lumps with a loose structure (c.g. Obj2).

[0069] FIG. 6B shows a scanning electron microscopy (SEM) image of the structure Objl indicated in FIG. 6A according to various embodiments. FIG. 6C shows a magnified scanning electron microscopy (SEM) image of the structure Objl according to various embodiments. FIG. 6D shows a scanning electron microscopy (SEM) image of the area Obj2 indicated in FIG. 6A according to various embodiments. FIG. 6E shows a magnified scanning electron microscopy (SEM) image of the area Obj2 according to various embodiments.

[0070] FIG. 6F shows a plot of weight percentage (%) I iron / phosphorous (Fe / P) as a function of particles illustrating the energy-dispersive X-ray spectroscopy (EDS) results of the various particles according to various embodiments shown in FIG. 6C and FIG. 6E. According to the EDS results in FIG. 6F, the dense structure (Objl) with 97.4% of carbon (C) should be the anode material graphite while the lump (Obj2) should be the cathode material since the Fe / P ratio of small particles P2 - P6 conform well with FcPO i. A duplicated test on one more dense particle and one more lump obtained almost the same EDS results. The cathode of LFP batteries includes LFP active material (generally > 80 wt. %), conductive additive and binder as shown in FIG. 5C. In most commercial batteries, the conductive additive may be conductive carbon (e.g. carbon black), while the binder used may be polyvinylidene fluoride (PVDF). The binder may hold the cathode materials together in the form of a composite. Except for hydrogen (H) and lithium (Li), EDS may be able to detect all the possible elements present in the powder. For all the particles examined in the lump, oxygen (O). carbon (C), iron (Fe) and phosphorous (P) arc the primary elements, accounting for > 99.5% of the elements detected. Surface coatings (e.g. carbon and conducting polymer) may commonly be applied to the surface of LFP particles to improve electronic conductivity. Additionally, the cathode may come in contact with electrolytes. Electrolytes in LFP may be a mixture of lithium salts (e.g. 1 mol / L LiPFe) andorganic carbonates such as ethylene carbonate (EC) and diethyl carbonate (DEC). The organic electrolytes and surface coating may contribute to the high C and O content in the EDS analysis where the penetration depth of incident electrons at 15 kV may be only several microns. The presence of residual organic materials on the cathode material was also reported by previous studies.[0071 J X-ray Fluorescence (XRF), Thermogravimetric Analysis (TGA) and QuantitativeX-ray Diffraction (Q-XRD) Analysis

[0072] Based on the local sample information revealed by SEM and EDS, XRF, TGA and Q-XRD were further conducted to understand the composition of the powder.

[0073] The XRF results are listed in FIG. 7A. FIG. 7A shows a table illustrating the chemical composition of iron phosphate dominated waste (FPW) according to various embodiments determined by X-ray fluorescence (XRF). It shows that the FPW powder contains primarily FePO4 related compositions Fe2O3 and P2O5. The fluorine (F) detected indicates the presence of remaining PVDF or electrolytes related constituents in the powder. It should be noted that the XRF equipment is unable to detect light elements (i.c., elements before oxygen), and hence does not take into account compositions such as electrolytes, amorphous carbon, PVDF and graphite.

[0074] TGA is then employed to determine the quantity of electrolytes and amorphous carbon / PVDF according to their weight loss ranges. The TGA and differential thermogravimetry (DTG) results are shown in FIG. 7B. FIG. 7B shows a plot of weight (in weight percentage or wt. %) / differential thermogravimetry (DTG) (in weight percentage per degree Celsius or wt.% / °C) as a function of temperature (in degree Celsius or °C) illustrating the thermogravimetric analysis (TGA) of iron phosphate dominated waste (FPW) powder according to various embodiments. The powder loses weight continuously, and the peaks may sometimes overlap with one another in the DTG curve. The most distinct peak is observed at around 860 °C for graphite. Before this is a segment with many minor peaks, indicating the presence of multiple constituents in the recycled powder. Under air atmosphere, FePO4 compounds may generally be stable under high temperatures, even up to 1000 °C, while small size graphite may start to lose weight when the temperature is higher than approximately 650 °C. Studies indicate that the commercial electrolyte may all evaporate below 200 °C. The carbon used as the surface coatings of LFP and conductive additives may bum under air or oxygen atmosphere at around 350 - 600 °C. PVDF may have higher temperature resistance but maystill lose > 70% of its weight at 650 °C. For the current ease, the weight loss before 180 °C (i.c., 2.64 %) can be used to estimate the quantity of electrolyte, while the weight loss between 180 °C and 680 °C (i.c. 9.22%) can be used to determine the amount of binder, amorphous carbon and possibly other minor additives. The weight loss at 680 °C is 11.86%. The remaining weight of 88.14% would be the weight for graphite, FePCh related phases and minor phases excluding F, as given in FIG. 7A from XRF analysis.

[0075] The crystalline phases identified in the powder are shown in FIG. 8 A and the quantitative results arc listed in FIG. 8B. FIG. 8 A shows the main crystalline phases present in the iron phosphate dominated waste (FPW) powder according to various embodiments. FIG. 8B shows a table illustrating the crystalline phases of iron phosphate dominated waste (FPW) according to various embodiments determined by quantitative X-ray diffraction (Q-XRD) analysis. The main crystalline phases detected are FePO i and graphite, the cathode and anode materials, respectively, which is in line with the SEM results above. The small-proportion phases may have peak overlap and may incur errors. However, the XRD results may be considered to be able to accurately evaluate the main crystalline phases FcPCU (i.c. 47.2 wt. %) and graphite (i.e. 9.2 wt. %). The graphite determined by Q-XRD and TGA have values of 9.2 wt. % and 8.4 wt. %, respectively. Ignoring the initial peaks overlap stage in TGA calculation and possible unbumed large particles, the XRD results may be adopted to determine the amount of graphite. Then, it can be known from XRF results that the powder contains around 72.13 wt. % of FePO4 related phases. A Q-XRD examination of waste LFP battery powder before lithium extraction indicated ~77 wt. % of LFP (~4.6 wt. % of amorphous phases). The result may provide some credit for the quantity of FcPCL determined. It shall be noted that the content of FePO i determined by XRD is much less than that determined by XRF. Q-XRD indicated ~40 wt.% of amorphous phases in the FPW powder. The low amount of FePCh detected by XRD may be caused by amorphous FePO4 related phases. The recycling process may destroy the structure of FePCU. It has also been previously reporting that amorphous FePO i may be obtained from spent LFP battery using other recycling strategies. The final composition determined is summarized in FIG. 8C. FIG. 8C shows a table summarizing the phase composition of iron phosphate dominated waste (FPW) powder according to various embodiments. FePO4-related phases mean FePO4 and destroyed FePCL (non-crystalline), while “Others” in FIG. 8C refers to components other than Fe2O3, P2O5 and F in FIG. 8B.

[0076] Effects of FPW Powder On The Mechanical Properties And Flowability Of Mortar

[0077] The compressive strength of mortars containing different percentages of FPW is shown in FIG. 9. FIG. 9 shows a plot of compressive strength (in Mega-Pascals or MPa) I diameter (in millimeters or mm) as a function of mortar samples illustrating the effects of iron phosphate dominated waste (FPW) powder according to various embodiments on compressive strength and flowability. FPW-C refers to the control sample which does not include FPW powder, while FPW-3%, FPW-5%, FPW-7% and FPW-10% refer to samples in which 3 wt.%, 5 wt.%, 7 wt. % and 10 wt.% of the cement in the respective mortal' sample is replaced by FPW powder. The numbers above the respective bars indicate the age (in days) of the respective mortar sample.

[0078] At 3 days, samples with cement replaced by FPW all exhibit slightly lower strength than that of the control sample. However, the strength of the samples containing FPW may increase significantly from 3 days to 7 days, which make the strength of the samples containing FPW achieve to be higher or comparable in comparison to that of the control sample. Thereafter, the growth of strength from 7 to 28 days may be less remarkable for samples containing FPW. The FPW-5% sample is shown to achieve the highest compressive strength, which may be 5.1% higher than that of the control sample, while the FPW-10% sample shows the lowest strength, which may be 8.4% lower than that of the control sample. The results indicate that replacing cement with a proper amount of FPW powder (e.g. 5 wt. %) may increase the compressive strength. The FPW powder is found to decrease the flowability of mortar, but the impact may not be significant if low dosage is used. The flow value was decreased by 3.4% and 10.0%, respectively, when 5 wt. % and 10 wt. % of cement were substituted by FPW. The decreased flowability may primarily be attributed to the porous structure of the lumps, as depicted in FIGS. 6A-E. The porous surface may increase the adhesion with the cement paste. Besides, these pores may be likely to retain some water within the lumps, especially considering that the conductive carbon black in the electrode typically possesses a large Brunauer, Emmett and Teller (BET) surface area and high liquid absorption rate.

[0079] Effects of FPW Powder On The Hydration And Microstructure Of Cement BinderHeat Of Hydration

[0080] The evolution of heat of hydration of binders containing different percentages of FPW powder over time is shown in FIGS. 10A - B. FIG. 10A shows a plot of heat flow (in milli-Watts per gram or mWg1) as a function of time (in hours) illustrating the variation ofheat flow of various samples according to various embodiments with time. Compared with the control sample, the binders with FPW powder may exhibit a delayed accelerating period and main hydration peak (mainly the hydration of tricalcium silicate C3S and tricalcium aluminate C3A). Besides, the main hydration peaks of binders with FPW powder show decreased peak height and peak width. These phenomena may indicate the retarding effect of FPW powder on hydration. The retarding effect may be more significant for samples with higher percentages of FPW.

[0081] FIG. 10B shows a plot of cumulative heat (in Joules per gram or Jg1) as a function of time (in hours) illustrating the variation of cumulative heat of various samples according to various embodiments with time. All samples containing FPW powder may show lower cumulative heat than the control sample, and the increase of proportion of FPW may lead to a decrease in the cumulative heat, which again may indicate lower early hydration of samples containing FPW powder. The retarding effect may lead to delayed setting and early strength development, which could be a reason for the lower 3 days strength of samples containing FPW powder. Considering the regular phenomena observed herein, in the following parts, only the sample FPW-C, the sample FPW- 5% exhibiting the best strength, and the sample FPW- 10% with the highest FPW content were further investigated to understand the effects of FPW on the hydration and micro structure of cement paste.

[0082] Early-Age Morphology

[0083] The typical morphology of cement grains in different samples after 6 hours of hydration is shown in FIGS. 11A - C. FIG. 11A shows scanning electron microscopy (SEM) images illustrating cement grains in the control sample FPW-C after 6 hours of hydration. FIG. 11B shows scanning electron microscopy (SEM) images illustrating cement grains in the sample FPW-5% according to various embodiments after 6 hours of hydration. FIG. 11C shows scanning electron microscopy (SEM) images illustrating cement grains in the sample FPW- 10% according to various embodiments after 6 hours of hydration. It is clear that cement grains in the control sample already underwent some degree of hydration where bushes-like calcium silicate hydrates (C-S-H) and a few needle-shaped ettringites (aluminate ferrite trisubstituted or AFt) can be identified. However, for the FPW-5% and FPW- 10% samples, the cement grains are not covered with dense hydration products, indicating that they may remain almost un- hydrated. Only sparsely distributed particles can be observed on the surface of cement grains in these samples. The hydration products are generally ettringite, blobs of C-S-H nuclei, andplate-form aluminate ferrite monosubstituted or AFm phases. In line with the heat of hydration results, the SEM observation clearly indicates the delay of hydration by the FPW powder.

[0084] In addition to cement grains, the graphite and iron phosphate (FP) were also observed to understand their roles. FIG. 12A shows a scanning electron microscopy (SEM) image of graphite in the FPW- 10% sample according to various embodiments after 6 hours of hydration. FIG. 12B shows a magnified scanning electron microscopy (SEM) image of graphite in the FPW- 10% sample according to various embodiments after 6 hours of hydration. As shown in FIGS. 12A - B, the surface of the graphite particle docs not present obvious hydration products, which may be attributed to its hydrophobicity.

[0085] In terms of the FP lump, although the overall appearance does not change much, the magnified observation shows that the surface of some FP particles is covered with a thin layer of gel-like products and some ettringite-like phases. FIG. 12C shows a scanning electron microscopy (SEM) image of iron phosphate (FP) lump in the FPW-10% sample according to various embodiments after 6 hours of hydration. FIG. 12D shows a magnified scanning electron microscopy (SEM) image of iron phosphate (FP) lump at location 1 in the FPW-10% sample according to various embodiments after 6 hours of hydration. FIG. 12E shows a magnified scanning electron microscopy (SEM) image of iron phosphate (FP) lump at location 2 in the FPW-10% sample according to various embodiments after 6 hours of hydration. EDS has been conducted on several objects as shown in FIG. 12E. It should be noted that the smallest dimension of the products is < 200 nm. The EDS results may be affected by the unsmooth surfaces, and the incident electrons would penetrate beyond the objects to the substrate FP as well. The FP may cause the main elements detected to remain as O, C, Fc and P, as listed in FIG. 12F. FIG. 12F shows a table illustrating the main elements (in weight percent or wt. %) of different objects of the iron phosphate (FP) lump at location 2 detected by energy-dispersive X-ray spectroscopy (EDS) at 15 kV according to various embodiments. Nevertheless, the EDS results clearly identified the presence of calcium (Ca). Other important elements such as sulfur (S), aluminum (Al) and silicon (Si) can also be detected but in smaller amounts. The results may indicate the precipitation of species from cement on the surface of FP particles. It is possible that some substances like the carbon black coated on FP may provide nucleation sites. In addition, the FP may be involved in reactions. After all, at least PO43~ should be provided by FP to retard the hydration of cement grains.

[0086] To decrease the effects of substrate FP particles, EDS with a lower accelerating voltage of 7 kV was applied to those test points again with the results shown in FIG. 12G. FIG. 12G shows a table illustrating the main elements (in weight percent or wt. %) of different objects of the iron phosphate (FP) lump at location 2 detected by energy-dispersive X-ray spectroscopy (EDS) at 7 kV according to various embodiments. 7 kV is higher than two times of the Kot X-ray emission lines for all elements in FIG. 12F except for Fe. The results for Fe in FIG. 12G were calculated based on La lines. Compared with FIG. 12F, the cement related elements Ca, S, Si and Al have all increased, and the dominant elements in FPW, i.c., O, C and P, have decreased. An exception is Fe. The percentage of Fe has increased with a lower voltage of 7 kV. It is considered that the gel-like layer could possibly contain Fe(OH)3. Besides, Fe sourced from FP should also enter into the ettringite phase. Amorphous Fe(OH)3, solid solutions between Al- and Fe ettringite and even Fe-ettringite are reported to be able to present in cement binder in the initial hours of hydration.

[0087] Degree Of Hydration And Quantity Of Hydration Products

[0088] The degree of hydration (DoH) of cement is presented in FIG. 13 A. FIG. 13A shows a plot of degree of hydration (DoH) of cement (in percent or %) as a function of hydration time (in days) illustrating the degree of hydration of various samples according to various embodiments over time. In contrast to increasing DoH when replacing cement with fillers, the results indicate the general trend of decreasing DoH of replacing cement with the FPW powder. The decreasing DOH effect may particularly be significant at the very early age of 1 day, and the effect may diminish over time. FIG. 13B shows a plot of weight of iron phosphate FP (in percent or %) as a function of hydration time (in days) illustrating the content changes of crystal iron phosphate FP in the various samples according to various embodiments over time. The crystal FP content in FIG. 13B also exhibits a clear decline trend with increasing age, which may indicate chemical reaction of FP during cement hydration. The reaction may have made FP (which may also include amorphous FP) provide continuous retarding over time, thus resulting in the decreased DoH of cement at even an older age.

[0089] As shown in FIG. 13A, the 1 day DoH is 56.5% for FPW-C, decreasing to 47.6% for FPW-5%. A distinctly lower DoH is observed for FPW-10%, which may have a negligible value of around 1.7%. The serious retardation of hydration may delay the hardening of the sample as well as the dcmolding time to 2 days. FIG. 13C shows a plot of degree of hydration (DoH) of tricalcium silicate C3S and bicalcium silicate C2S (in percent or %) as a function ofhydration time (in days) illustrating the degree of hydration of C3S and C2S of various samples according to various embodiments over time. FIG. 13D shows a plot of degree of hydration (DoH) of tricalcium aluminate C3A and tctracalcium aluminoferrite C4AF (in percent or %) as a function of hydration time (in days) illustrating the degree of hydration of C3A and C4AF of various samples according to various embodiments over time. According to FIGS. 13C - D, after 1 day, the continuous retarding provided by FP may work more on the two clinker phases C2S and the Fe-bearing phase C4AF, which may have relatively lower rates of hydration than C3A and C3S. The proportion of these two phases is relatively small in clinker, and thus may not cause distinct DoH of cement and performance of cement concrete.

[0090] FIG. 14A shows a plot of weight percentage of calcium hydroxide CH (in percent or %) as a function of hydration of time (in days) illustrating the weight percent changes of CH of various samples according to various embodiments over time. FIG. 14B shows a plot of weight percentage of aluminate ferrite trisubstituted (AFt) and aluminate ferrite monosubstituted (AFm) (in percent or %) as a function of hydration of time (in days) illustrating the weight percent changes of AFt and AFm of various samples according to various embodiments over time.

[0091] In terms of the hydration products as illustrated in FIG. 14A, FPW-5% and FPW- 10% samples may show lower CH content than the FPW-C sample. When assuming Ca / Si ratio of 1.7 in C-S-H, per 1 g of C3S and 1 g of C2S can be expected to generate 0.42 g CH and 0.13 g CH, respectively. Typically, for the case of 28 days, the high DoH of C3S in FPW-5% and FPW-10% should not cause such a reduced amount of CH. This may imply the consumption of the CH by FPW as discussed later. As for the AFt phase as illustrated in FIG. 14B, due to the delay of hydration of C3A, the increase of AFt content lasted until 3 days for the FPW-5% and FPW-10% samples, in comparison to reaching the maximum content at 1 day for the FPW- C sample. Besides, the drop in AFt content was found to be more gradual for samples with FPW. AFm phase is generally poorly crystalline and the XRD results should not have high accuracy. In the current study, among various possible AFm phases such as Fe or Al related monocarbonate (Me), monosulfate (Ms) and hemicarbonate (He), only Al-Mc was detected as displayed in FIG. 14C. FIG. 14C shows a plot of intensity (in arbitrary units or a.u.) as a function of angle 20 (in degrees or °) illustrating of the observation between 8° and 20° 20 angles of aluminate ferrite trisubstituted (AFt) and aluminate ferrite mono substituted (AFm) phases of various samples according to various embodiments. Due to the limestone in thecement, monocarbonatc may be a more stable type of AFm than others. However, FIG. 14B indicates that the AFm detected does not exhibit a substantial variance in content across the various samples. There is no solid solution between Al-Mc and Fc-Mc. Thus, the results imply that the Fe from FP may not be significantly present in AFm phase. It should be noted that the sum of the content of AFt and AFm at 7 and 28 days seems to be higher in the FPW-5% sample than in other samples, which may be mainly caused by AFt. At early hydration stages, the remarkable retarding effect for C3A and C3S means a substantial amount of PO43~ in AFm phase. It should be noted that the sum of the content of AFt and AFm at 7 and 28 days seems to be higher in the FPW-5% sample than in other samples, which is mainly caused by AFt. At early hydration stages, the remarkable retarding effect for C3A and C3S means a substantial amount of PCU3-released, which is accompanied by the release of Fe3+. High sulfate content provided by soluble gypsum, bassanite and anhydrate could enable the formation of Fe- ettringite and solid solution between Al- and Fe-ettringite, which show very similar main peaks to Al ettringite in XRD analysis. In fact, the second and third AFt peaks in FIG. 14C show a slight shift between control sample and samples with FPW, which is a signal of forming solid solution. The solubility product of Fe-ettringite is slightly higher than that of Al-ettringite, making it considered to be an unstable phase. However, the stability may be affected by many factors. For instance, when pH is higher than around 13, lower pH may be more favorable for the stability of both Fe-ettringite and Al-ettringite. The formation of Al- and Fe- solid solution may also affect the kinetics and stability of Fe-ettringite. The solubility products of solid solution may either remain the same as Al-ettringite as long as the Al content is not <0.85, or may increase almost linearly with Al content. In the current case, replacing cement with FPW may decrease pH due to decreased Portland cement content and alkalis within it. Besides, replacing cement with FPW powder may result in the binder having increased AI2O3 and FeiCh content as raw materials for the formation of AFt, AFm, etc. The replacing ratio of 5 wt. % FPW in cement may make a relatively low amount of Fe enter ettringite which does not significantly decrease the solubility products. The combined factors may have contributed to the phenomenon observed for the FPW-5% sample.

[0092] Pore Size Distribution

[0093] The volume distribution of pore of samples at 28 days is provided in FIG. 15 A. FIG. 15A shows a plot of pore volume (in percent or %) / first derivative dV / d(logr) (in arbitrary units or a.u.) as a function of pore diameter (in micrometers or pm) illustrating the mercuryintrusion porosimctry (MIP) cumulative pore volume curves and first derivative curves of the various samples according to various embodiments. As shown in FIG. 15 A, the total connected pore volumes detected for FPW-C, FPW-5% and FPW-10% samples arc 27.46%, 24.70% and 32.26% respectively. Also, the cumulative pore volume curve of the FPW-5% sample may always be below the FPW-C sample, which may be an important reason for the enhanced compressive strength. The cumulative pore volume curves of FPW-10% and FPW-C intersect at a pore diameter of 1.74 pm and pore volume of 1.84%. In the nearby region, with the decrease of pore size, there is a sharp increase of pore volume in FPW-10%, which is manifested in the additional peak of the corresponding first derivative curve. Capillary pores with a diameter larger than 50 nm may be considered to have a more significant impact on the strength and impermeability of cement concrete. The substantial increase in the capillary pores may be a factor responsible for the decreased strength of the FPW-10% sample. The rise in porosity may also be expected to negatively affect the durability of concrete. Both FPW-5% and FPW- 10% samples were found to have decreased very large capillary pores and void pores, although this accounts for a relatively low volume. Overall, the MIP results again indicate that 5 wt. % may be a suitable dosage for FPW to replace cement. The refined pore structure may be caused by the combined factors such as comparable DoH, higher ettringite and micro-filling effects by graphite and amorphous Ca5OH(PO4)3 after the reaction of FP with crystal CH as discussed later. Using FPW may refine the microstructure, but it may also lead to a dilution effect and potentially decrease the DoH. A 5 wt. % may be identified as a turning point where the positive effects can effectively overcome the negative effects.

[0094] Discussion On The Role Of FPW Powder In Cement Hydration

[0095] The Q-XRD results indicate that FP, the main component of FPW powder, may not act as a filler. The solubility product constants of some substances involved in the hydration process are listed in FIG. 15B. FIG. 15B shows a table illustrating the solubility product constants for various phases at 25°C according to various embodiments. Different from commercial soluble sodium salts of phosphorous, FePO4 may be slightly soluble. When not considering effects such as common-ion effect, the solubility product of 1.3 x 10-22for FePC>4 means that in saturated solution the equilibrium concentration of Fc3+and PCU3-may be 1.14 x 10“11mol / L. At the onset of contacting water, the concentration of Fe3+and PO43may be very low and hence would not significantly hinder cement dissolution / hydration. The dissolution of cement ingredients such as alkali sulfate, free lime, and C3S would release ionsNa+, K+, Ca2+, 0H“, SO42“ , etc., which may be accompanied by a rapid rise of pH. The solubility product of Fc(OHh may be as low as 4 x 10“38. The increase of the concentration of OH would make concentration product (Q) exceed the solubility product leading to the precipitation of Fe (OH)., which is followed by the increased dissolution of FcPO_ and release of PO43", as shown in Equation (1).FePO4+ 3OH - — Fe(OH)3+ PO43’ (1)

[0096] It was reported that for normal Portland cement paste with a water / cement (w / c) of 0.5, the concentration of OH after 1.2 min of hydration reaches as high as 85 mM (pH = 12.93). At high pH, the Fe(OH)3 would involve complexation reaction as given in Equation (2).Fe(OH)3+ OH" Fe(OH)4- (2)

[0097] Then, some Fe(OH)4" would have combined with Ca2+, SO42’, OH“ , Al(0H)4" and H2O to form ettringite as shown in Equation (3), while the main stable Fe-bearing phase in hydrated cement should be poorly crystalline Fe-siliceous hydrogarnet C3(A,F)So.84H4.32 as validated by many studies.6Ca2++ 2(Fe(OH)4+ A1(OH)4) + 3SO42+ 4OH + 26H2O Ca6[Fe(OH)6+ A1(OH)6]2(SO4)3.26H2O (3)

[0098] In terms of the PO43-released, it would be instantly adsorbed on cement grains and form a Ca-phosphate layer (calcium phosphate and hydroxyapatite). This layer inhibits the transportation of water and the dissolving of cement and hence retards the hydration process. In addition to being adsorbed on cement grains, PCU3-may precipitate as amorphous hydroxyapatite CasOH(PO4)3. At very early ages, the chemical reaction for PO43is mainly ascribed in Equation (4).5Ca2++ 3PO43" + OH" -> Ca5(PO4)3OH (4)

[0099] As given in the XRD part, the FePCE may be consumed gradually. After the Ca(OH)2 has precipitated, generally known as at the acceleration period of hydration, the concentration of Ca2+in the liquid phase would decrease. The solubility product of Ca.sOl 1( PO_)3 is much lower than that of CH. The dissolved PO43-may thus consume crystal CH which generates CasOH(PO4)3 and compensates for some OH’ as shown in Equation (5).5Ca(OH)2+ 3PO43Ca5(PO4)3OH + 9OH (5)Note: Only main reactions arc provided herein (c.g., phosphate may contain substantial HPO42' when pH is lower than 13).

[0100] As a consequence, the high alkalinity provided by KOH and NaOH may work as a catalyst and the real reactant may be CH. To verify this, FPW (with 92% FP) was mixed with CH and simulated pore solution with a pH measured as 13.21. The paste was prepared and tested following ASTM C593. Due to the very fast setting and hardening, a high solution to solid ratio of 0.8 was used to cast the FPW-CH-pore solution sample. Even in this case, strength was still gained as shown in FIG. 16A. FIG. 16A shows a plot of compressive strength (in Mega-Pascals or MPa) as a function of samples comparing the compressive strength of samples according to various embodiments when mixed with calcium hydroxide and pore solution in a solution to solid ratio of 0.8 (FPW-CH-pore -0.8), when mixed with quartz and pore solution in a solution to solid ratio of 0.6 (FPW-Qua-pore-0.6), and when mixed with calcium hydroxide and water in a solution to solid ratio of 0.6 (FPW-CH-water-0.6). FIG. 16A validates the reaction between iron phosphate dominated waste (FPW) and calcium hydroxide (CH) in a pore solution. When replacing the CH with inert quartz or replacing the alkaline pore solution with water, even the solution to solid ratio was decreased to 0.6, no significant strength was observed. Therefore, the experimental results in FIG. 16A well validate the above analyses and conclusions. The reaction mechanisms of FP are summarized in FIG. 16B. FIG. 16B shows a schematic illustrating reaction mechanism of iron phosphate (FP) in cement paste according to various embodiments. The continuous release of PO43’ from the reaction of FP may make slight retarding effect last until later ages. Reacting with CH to generate an amorphous phase may be kind of similar to the pozzolanic effect, but it is unclear if the produced amorphous hydroxyapatite has good properties as that of C-S-H.

[0101] Behind FcPCE. graphite and binder & amorphous carbon may also account for a substantial proportion as given in FIG. 8C. Since the FPW incorporated must be significantly below 10% to ensure proper setting, the proportion of the graphite and binder & amorphous carbon in cement may be lower than 1 %. Studies generally indicate that graphite may act as an inert filler. Moreover, <10% of graphite was reported to have no significant impact on compressive strength and cement hydration. In terms of PVDF binder & amorphous carbon, amorphous carbon is inert and PVDF undergoes dehydrofluorination reaction in alkaline conditions with pH above 11, but very remarkable reaction may require high alkaline like 4 M NaOH. PVDF can last in concrete and has been studied for mechanical energy harvesting in meta concrete. In the current study, the PVDF binder and amorphous carbon arc at very low amounts in cement. Additionally, they may not be independent particles but act as a binder orcoat in agglomerates as revealed in FIG. 12D. Thus, they may be unable to be efficiently distributed in the cement system and have further diminished impacts on cement. Overall, FCPO4 may be the dominant phase that would affect the hydration of cement while other phases may have limited influence due to the low proportion and almost inert chemical nature. FIG. 16C is a schematic illustrating the role of different components of iron phosphate dominated waste (FPW) in cement paste according to various embodiments.

[0102] Various embodiments may relate to the introduction of FPW, obtain after recycling Li from LFP batteries, to cement and concrete.

[0103] FPW may contain -72% of FcPOi -related phases, -9% of graphite, and - 9% of binder and amorphous carbon. The absence of significant amounts of highly toxic heavy metals may allow FPW to be used in concrete without bringing special safety and environmental concerns.

[0104] Replacing cement with FPW may decrease the 3-day compressive strength of samples, but slightly increased the 7-day and 28-day strength when the replacing ratio was no more than 5%. FPW may slightly decrease the flowability of mortar.

[0105] The heat of hydration results and the morphology observation of cement at 6 hours both indicated the retarding of cement hydration by FPW. High-iron products were found to precipitate on the surface of FP lumps at 6 hours, which are considered to be mainly Fe(OH)3 and ettringite.

[0106] Various embodiments may employ energy-efficient and straightforward treatment methods to transform battery waste into viable cement substitutes. Experimental results demonstrate that battery waste can enhance the performance of cement mortar. Various embodiments may not only offer a value-added approach for managing battery waste, but may also address the pressing issue of reducing the carbon footprint associated with concrete production. The cement manufacturing process may be a major contributor to global carbon dioxide (CO2) emissions, accounting for as much as 8% of total CO2 emissions. By curbing cement usage through the incorporation of battery waste, various embodiments may align with sustainability goals and may contribute to a greener future.

[0107] By recycling battery waste into concrete, various embodiments may efficiently utilize the battery waste after Li extraction, which may traditionally be disposed of in landfills. Various embodiments may lead to decrease in disposal costs, landfilling and associated pollution from Fe and P.

[0108] Further, by replacing 5 wt. % of cement with FPW may lead to a cement mortar with improved mechanical performance and refined pore structure. Replacing cement with 5 wt. % or less battery waste can improve the compressive strength of mortar samples at 7 and 28 days. Even under the replacement percentage of 10 wt. %, the strength reduction of the sample may still be less than 10% at 28 days. The battery waste may chemically react in the cement binder and may help refine the micro structure of hydrated cement paste.

[0109] Only 20-30 minutes of milling may be required to convert the battery waste into cement substitutes. The battery waste may not contain significant toxic heavy metals, and may be compatible with cement-based materials. The available FPW may be projected to high amount of 165,000 tonnes. These may make scaling up viable.

Claims

Claims1. A cement mortar composition comprising: cement; sand; water; and iron phosphate dominated waste (FPW) mixed with the cement, the sand and the water; wherein the iron phosphate dominated waste (FPW) comprises iron oxide (FC2O3) and phosphorus pentoxide (P2O5).

2. The cement mortar composition according to claim 1, wherein the iron phosphate dominated waste (FPW) comprises graphite or carbon.

3. The cement mortar composition according to claim 1 or claim 2, wherein the iron phosphate dominated waste (FPW) comprises fluoride (F), aluminum oxide (AI2O3), copper oxide (CuO), manganese oxide (MnO), nickel oxide (NiO), sodium oxide (NaiO), calcium oxide (CaO), sulfur trioxide (SO3) and magnesium oxide (MgO).

4. The cement mortar composition according to any one of claims 1 to 3, wherein a weight ratio of the water to the cement is selected from a range from 0.4 to 0.6.

5. The cement mortar composition according to claim 4, wherein the weight ratio of the water to the cement is 0.48.

6. The cement mortar composition according to any one of claims 1 to 5, wherein a weight ratio of the sand to the cement is selected from a range from I to 3.

7. The cement mortar composition according to claim 6, wherein the weight ratio of the sand to the cement is 2.25.

8. The cement mortar composition according to any one of claims 1 to 7, wherein a weight ratio of the iron phosphate dominated waste (FPW) to the cement is equal to or less than 10 : 90.

9. The cement mortar composition according to claim 8, wherein the weight ratio of the iron phosphate dominated waste (FPW) to the cement is equal to or less than 5 : 95.

10. The cement mortar composition according to any one of claims 1 to 9, wherein a weight percentage of the iron oxide ( Fe2O3 comprised in the iron phosphate dominated waste (FPW) is more than a weight percentage of the phosphorus pentoxide (P2O5) comprised in the iron phosphate dominated waste (FPW).

11. The cement mortar composition according to any one of claims 1 to 10, further comprising: amorphous hydroxyapatite (Ca5(PO4)3OH).

12. A method of forming a cement mortal' composition, the method comprising: mixing iron phosphate dominated waste (FPW) with cement, sand and water to form the cement mortar composition; wherein the iron phosphate dominated waste (FPW) comprises iron oxide ( Fe2O3) and phosphorus pentoxide (P2O5).

13. The method according to claim 12, wherein the iron phosphate dominated waste (FPW) comprises graphite or carbon.

14. The method according to claim 12 or claim 13, wherein the iron phosphate dominated waste (FPW) comprises fluoride (F), aluminum oxide (AI2O3), copper oxide (CuO), manganese oxide (MnO), nickel oxide (NiO), sodium oxide (Na2O), calcium oxide (CaO), sulfur trioxide (SO3) and magnesium oxide (MgO).

15. The method according to any one of claims 12 to 14, further comprising:removing lithium from battery waste to form the iron phosphate dominated waste (FPW).

16. The method according to claim 15, wherein the iron phosphate dominated waste (FPW) obtained from the battery waste is in the form of a powder comprising a plurality of particles; and wherein the method further comprises ball milling the powder to reduce a particle size of the plurality of particles before the powder is mixed with the cement, the sand and the water to form the cement mortal' composition.

17. The method according to any one of claims 12 to 16, wherein a weight ratio of the water to the cement is selected from a range from 0.4 to 0.6.

18. The method according to claim 17, wherein the weight ratio of the water to the cement is 0.48.

19. The method according to any one of claims 12 to 18, wherein a weight ratio of the sand to the cement is selected from a range from I to 3.

20. The method according to claim 19, wherein the weight ratio of the sand to the cement is 2.25.

21. The method according to any one of claims 12 to 20, wherein a weight ratio of the iron phosphate dominated waste (FPW) to the cement is equal to or less than 10 : 90.

22. The method according to claim 21, wherein a weight ratio of the iron phosphate dominated waste (FPW) to the cement is equal to or less than 5 : 95.

23. The method according to any one of claims 12 to 22, wherein a weight percentage of the iron oxide ( (Fe2O3) comprised in the iron phosphate dominated waste (FPW) is more than a weight percentage of thephosphorus pentoxide (P2O5) comprised in the iron phosphate dominated waste (FPW).

24. The method according to any one of claims 12 to 23, wherein the cement mortar composition comprises amorphous hydroxyapatite (Ca5(PO4)3OH).

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