Preparation, characterization and properties of high anti-erosion grouting materials from industrial solid waste

doi:10.21203/rs.3.rs-1609120/v1

To address the environmental problems caused by the storage of solid waste and the poor corrosion resistance of Portland cement (PC), high anti-erosion grouting materials (HAGM) were synthesised from red mud (RM), silica fume (SF), carbide slag (CS), and flue gas desulfurization gypsum (FGD). The synthesis, structural characterisation, and properties of HAGM were reported, and compared with those of a typical PC. The results showed that the main mineral composition of the HAGM matrix is hydration phases: 68.3 wt.% β-C₂S, 21 wt.% C₄AF, and 8.4 wt.% C₃A. The compressive strength and rheological characteristics of HAGM prepared with 8 wt.% FDG is the best. The hydration of the HAGM led to the formation of ettringite, C₃(A, F)H₆, aluminum gel, resulted in compressive strength of 16.70 MPa after curing for 28 d. The anti-erosion coefficient K of HAGM after exposure to different erosion solutions for 28 d was greater than 0.99, which indicated better corrosion resistance than PC. This high anti-erosion resulted from the mineral composition of low C₃S content and high C₄AF content. This study provides a feasible and promising way for the preparation of disaster prevention materials in coastal engineering.

solid waste

calcination

anti-erosion

phase composition

microstructure

This work was the frst report on useing all solid waste instead of cement raw materials to prepare high anti-erosion grouting materials (HAGM), breaking the mineral phase composition of Portland cement, solving the poor corrosion resistance of existing cement, and alleviating the increasing shortage of natural resources of cement raw materials and the massive stockpiling of industrial solid waste. Previous studies have focused on the preparation of sulphoaluminate cement or belite cement from solid waste. This study investigates the synthesis, characterisation, and properties of HAGM to prove the feasibility of using solid waste. The results indicated that solid waste gypsum can improve the compressive strength and rheology properties of HAGM, and the HAGM had better corrosion resistance than Portland cement.

The 21st century has been a period of vigorous development for marine engineering in China. During the process of coastal urban construction, diverse geological bodies such as karst caves, broken zones, and fault beds are often encountered. These not only delay construction, but also cause great harm to life and property, the ecological environment, and social stability [1–4]. At the same time, the infrastructure often bears strong effects of erosion, the freeze-thaw cycle, and other factors that characterize a complex and changeable marine environment, resulting in extensive damage [5–6].

Grouting technology is often used to remedy all kinds of geological disasters in underground engineering in coastal karst areas [7–9]. As one of the most widely used grouting materials, cement-based material still has shortcomings [10–11]. Its anti-erosion ability is poor, and the long-term stability of its treatment effect is difficult to guarantee, especially in a complex marine environment [12–13]. In addition, the production and preparation of cement-based materials consume a large number of natural mineral resources [14–15], and at the same time, produce a large amount of CO₂ [16], which is not in line with the requirements of green development. With the increasing scale and difficulty of underground engineering, as well as the increasing threat to the safety of operation and maintenance, finding high anti-erosion grouting materials (HAGM) that can replace cement-based materials has become a major demand in present-day construction, operation, and maintenance. Thus, the safe construction and healthy operation of coastal urban areas is faced with severe challenges, and there is great demand for HAGM.

At the same time, with the rapid development of China's economy, the output of industrial solid waste has a large output and covers a large area [17–18]. According to statistics, the accumulation of industrial solid waste has exceeded 16.4 billion tons and covers an area of approximately 366,000 km² in China [19]. At present, this large amount of industrial solid waste is mainly disposed of in landfills and open-air stacking using a simple disposal method [20]. In addition to blast furnace slag and fly ash, which have been widely and efficiently utilised, other solid wastes, such as red mud (RM) [21], steel slag [22], carbide slag (CS) [23], and silica fume (SF) [24], have very low comprehensive utilization and disposal rates. Some solid wastes may be toxic, radioactive, corrosive, and difficult to degrade or treat, and can easily cause a series of environmental problems, occupy a large amount of land, and become a serious source of pollution [25–26]. Given the potential for the resource utilization of solid waste [27], realizing environmental protection and the value-added utilization of solid waste has become an urgent problem.

Given the above situation, relevant scholars have integrated the research for marine engineering construction materials and the technology for the utilization of solid waste. Industrial solid waste has achieved relevant results in cement-based materials as an admixture [28–29]. There is a consensus among material engineers to improve the durability and later strength of marine concrete by adding a mineral admixture. Bernal Camacho et al. [30] used SF and fly ash as admixtures in marine engineering concrete to study their enhancing effects on its mechanical properties and chloride ion erosion resistance. Kim et al. [31] added slag to steel fibre reinforced concrete to study its influence on durability in a marine environment. However, these studies were all based on solid waste as the admixture for cement-based materials to improve corrosion resistance of the materials, but they failed to improve the corrosion resistance of the materials by increasing the content of tetra calcium aluminate [32]. From the perspective of the mineral phase in cementitious materials, poor corrosion resistance has not been fundamentally solved.

This work aims to explore the feasibility of using RM, calcium CS, SF, and flue gas desulfurization gypsum as raw materials in the preparation of HAGM. The laser particle size analyser, Brunner-Emmet-Teller (BET) method, X-ray fluorescence (XRF), and X-ray diffraction (XRD) were used to evaluate the quality of the HAGM matrix, including particle size distribution, specific surface area, and chemical and mineral composition. The effects of different levels of flue gas desulfurization gypsum (FGD) content on the mechanical and rheological characteristics of HAGM were also studied, and analysed the mineralogical characteristics and microscopic characteristics of the hydration products of HAGM under the optimal FGD content. Finally, the corrosion resistance of HAGM in different erosion solutions was studied by examining the anti-erosion coefficient, compressive strength, hydrate phase, microstructure, and pore structure characteristics.

2.1. Raw materials

Bayer RM, CS, SF and FGD were used as the raw materials for the preparation of HAGM. Of these materials, RM comes from the Shandong Xinfa aluminium industry. FGD is from Shandong Xiwang Iron and Steel Co., Ltd. CS and SF were purchased from Gongyi Yuanheng water purification material factory and Henan Dingnuo Purification Material Co., Ltd. The particle size of RM, CS, and SF used were 150 mesh. XRF was used to analyse the chemical composition of the raw materials, and their respective chemical compositions are shown in Table 1.

Table 1

Chemical composition of raw materials (wt.%)
Chemical composition	CaO	Fe₂O₃	SiO₂	Al₂O₃	Na₂O	MgO	SO₃	K₂O	LOI
RM	2.19	36.42	13.98	27.38	12.9	0.25	0.17	0.08	6.63
CS	92.11	0.3	4.12	1.1	0.88	0.22	0.31	-	0.96
SF	1.57	0.4	95.25	1.26	0.25	0.24	0.1	0.37	0.56
FGD	41.9	1.02	4.5	1.67	0.18	1.29	47.1	0.37	1.97

The mineral composition of raw materials was analysed by XRD, and the results are shown in Fig. 1. The main mineral components of RM are hematite, perovskite, calcium carbonate, gibbsite, and muscovite. Calcium hydroxide is the main mineral component of CS. The main component of SF is amorphous silica. The main mineral in the composition of FGD is CaSO₄·2H₂O.

2.2. Materials proportion and test procedure

According to the literature [33], research scholars mainly use the lime saturation factor (KH), silica modulus (SM), and iron modulus (IM) as the main indicators to control the production of cement. The raw material proportions for HAGM were designed as shown in Eqs. (1)–(3). The Portland cement (PC) clinker modulus was limited to KH (0.87–0.96), SM (1.7–2.7), and IM (0.9–1.9). The mineral composition of PC was C₃S (61.75 wt.%), C₂S (16.15 wt.%), C₃A (10.72 wt.%), and C₄AF (8.45 wt.%) [34] The mineral composition of HAGM was obtained using four equations (Eqs. (4)-(7)). The SM and IM reflect the relative mass fractions of (C₃S + C₂S)/(C₃A + C₄AF) and C₃A/C₄AF in the clinker, respectively. The purpose of this study is to improve the content of C₄AF, which has excellent corrosion resistance, in the mineral composition of HAGM. Therefore, the design values of SM and IM can be appropriately reduced. A series of experiments were carried out with different mixing ratios. The best mix proportion of raw materials for the desired composition are shown in Table 2.

$$KH=\frac{{{w_{CaO}} - 1.65{w_{A{l_2}O}}_{{_{3}}} - 0.35{w_{F{e_2}O}}_{{_{3}}}}}{{2.8{w_{Si{O_2}}}}}$$

1

$$SM{\text{=}}\frac{{{w_{Si{O_2}}}}}{{{w_{A{l_2}O}}_{{_{3}}}+{w_{F{e_2}O}}_{{_{3}}}}}$$

2

$$IM{\text{=}}\frac{{{w_{A{l_2}O}}_{{_{3}}}}}{{{w_{F{e_2}O}}_{{_{3}}}}}$$

3

$${w_{{C_3}S}}=3.80(3KH - 2){w_{Si{O_2}}}$$

4

$${w_{{C_2}S}}=8.60(1 - KH){w_{Si{O_2}}}$$

5

$${w_{{C_3}A}}=2.65({w_{A{l_2}O}}_{{_{3}}} - 0.64{w_{F{e_2}O}}_{{_{3}}})$$

6

$${w_{{C_4}AF}}=3.04{w_{F{e_2}O}}_{{_{3}}}$$

7

Table 2

Best mix proportion of raw materials and desired composition (wt.%)
Proportion of raw materials			Indicators			Desired chemical composition				Desired phase composition
RM	CS	SF	KH	SM	IM	CaO	Fe₂O₃	SiO₂	Al₂O₃	C₃S	C₂S	C₄AF	C₃A
18.16	64.56	17.28	0.79	1.70	0.86	60.14	6.87	21.66	5.90	30.80	38.85	20.90	3.98

The RM, CS, and SF in amounts according to the design proportion of the raw materials were placed in a planetary ball mill for uniform mixing and grinding for 2 h to obtain a uniform mixture. Next, approximately 10 wt.% of water was added to the mixture to produce a test cake having a diameter of 5 cm and a thickness of 1 cm, which was dried at 100 ^oC. The test cake was fired in a high-temperature sintering furnace at calcination temperatures between 20 ^oC and 1400 ^oC for 2.3 h, and then it was kept at 1400 ^oC for 1 h. At the end of the sintering process, the samples were rapidly cooled in water and then dried. Finally, the synthesised sample was ground and passed through a 150-mesh sieve to obtain the HAGM matrix, and an appropriate amount of gypsum was added to obtain HAGM.

The matrix was mixed with 2 wt.%, 4 wt.%, 6 wt.%, 8 wt.%, and 10 wt.% FGD to prepare the HAGM, respectively. The slurry was prepared with a water-solid ratio of 0.5. the slurry was made into 20 mm x 20 mm x 20 mm samples in a steel mould. After the samples were cured in a curing cabinet with a humidity of 95% and a temperature of 20 ^oC for 1 day, the samples were demoulded and left to cure to the corresponding age under the same curing conditions.

According to GB/T 749–2008, corrosion resistance testing was carried out. The samples were cured in water, seawater, Na₂SO₄ solution, NaCl solution, and MgSO₄ solution for 28 days. NaCl, Na₂SO₄, and MgSO₄ were purchased from Sinopharm Chemical Reagent Co., Ltd., and different erosion solutions were prepared according to mass ratio. The concentrations of Na₂SO₄ solution, NaCl solution, and MgSO₄ solution were set to 3%, 6%, and 9%. Seawater was taken from Qingdao, Shandong, and its chemical composition is shown in Table 3.

Table 3

Ions concentrations of seawater
Ion	Cl⁻	SO₄²⁻	Mg²⁺	Ca²⁺	Na⁺	K⁺
Concentration(g/L)	21.00	1.54	2.51	1.92	1.34	0.39

2.3. Characterisation method

The specific surface area of the HAGM matrix and that of PC was measured by MAC ASAP 2460 (according to the BET method). The particle size distributions were measured using a laser particle size distribution analyser by Malvern Mastersizer 2000. The chemical compositions were analysed using XRF (XRF-1800, Japan Shimadzu). The mineral composition was studied using XRD (Ultima IV from Rigaku, Japan) with Cu K-alpha radiation at a scanning rate of 5°/min from 5° to 90° (2-theta). In addition, the XRD data for the HAGM matrix were analysed by Rietveld quantitative phase analysis using Fullprof and TOPAS software, and the mineral phase content of the matrix was calculated.

The compressive strength, rheological behaviour, mineral composition, and microstructure of the matrix with the optimal amount of FGD were compared with the same properties of PC. The 1 day, 3 days, and 28 days compressive strengths of the samples were tested according to the ASTM C942-15 standard. The sample was broken, collected, placed, and soaked with anhydrous ethanol to prevent further hydration in the sample tube. The rheological behaviour was tested using the Haake Mars 60 from Thermo Fisher Scientific, America. The microstructure and mineral composition of the hydration products were studied using scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM-EDS, Thermo Fisher Quattro S) and XRD (Ultima IV), respectively.

The corrosion resistance of HAGM was evaluated by analysing the changes in its compressive strength, anti-erosion coefficient, microstructure, mineral composition, and pore structure after exposure to the different corrosion solutions. The ratio of the flexural strength of the sample soaked in the erosion solution for 28 days to that of the sample cured in water for the same length of time was regarded as the anti-erosion coefficient (K). According to the standard GB/T 31289 − 2014, the anti-erosion coefficient of PC for marine engineering should not be lower than 0.99, and the larger the value of K, the stronger the corrosion resistance of the test sample. The pore size distribution of the hardened paste structure of HAGM was analysed using solid-state nuclear magnetic resonance (NMR) of Suzhou Niumag Analytical Instrument Co., Ltd.

3.1. Characterisation of HAGM matrix

3.1.1 Chemical and physical characteristics

The chemical analysis and the particle size distributions of the of the synthesised HAGM matrix are given in Table 4 and Fig. 2, respectively. As Table 4 shows, the chemical composition of the synthesised HAGM matrix is like that of PC. The matrix contains more Fe₂O₃, than does PC which is in line with the purpose of the matrix design. As can be seen from Fig. 2, The particle size of the HAGM matrix is finer than that of PC. Using the BET method, the specific surface areas of the HAGM matrix and that of PC were found to be 2348.8 cm²/g and 1345.6 cm²/g, respectively.

Table 4

Chemical analysis of the synthetic matrix (wt.%)
Chemical composition	CaO	Fe₂O₃	SiO₂	Al₂O₃	Na₂O	MgO	SO₃	K₂O	TiO₂	LOI
Matrix	62.10	11.08	17.17	6.09	0.88	0.60	0.29	0.03	1.29	0.47
PC	64.45	3.85	16.57	8.33	0.17	2.56	2.17	0.74	0.62	0.54

3.1.2 Mineralogical characteristics

The mineral composition and content of the HAGM matrix was obtained using Rietveld quantitative phase analyses, as shown in Fig. 3. It can be seen from Fig. 3 that the weighted profile R-factor (Rwp) is less than 5%, indicating that the refined structure is in high agreement with the measured XRD pattern [35] ccording to the results of the quantitative analysis, the contents of silicate minerals and solvent minerals in the HAGM matrix were 70.2 wt.% and 29.4 wt.%, respectively, which were close to the theoretical values for silicate minerals (69.71 wt.%) and solvent minerals (24.88 wt.%). However, the main phase of the HAGM matrix was 68.3 wt.% β-C₂S (PDF#33–0302), 21 wt.% C₄AF (PDF#71–0667), and 8.4 wt.% C₃A (PDF#32–0149), which deviates from the theoretical mineral composition design. This might have been due to the influence of impurity ions in solid waste, which changes the solid-state reaction of the system and inhibits the formation rate, development, and growth of C₃S to form a large amount of β-C₂S. The iron content of the matrix is higher than that of PC. The ƒ-CaO is relatively low in the HAGM matrix.

3.1.3 Microscopic characteristics

Figure 4 shows the microstructure and surface scan element distribution of the HAGM matrix. It can be seen from the micromorphology that the mineral crystals are well developed and closely arranged, and they show different forms of crystal in the HAGM matrix. Cobblestone-like β-C₂S was evenly distributed, and schistose-like C₄AF was present between the β-C₂S structures in a conglomeration state [36–37] It can be observed that each mineral has a corresponding element distribution in its respective position. The white regions (Al) and the blue regions (Fe) show the same distribution. Therefore, it can be concluded that the mineral in this area was C₄AF. Similarly, by observing the yellow area (Si) and green area (Ca), it can be judged that the minerals in this area were silicate minerals.

3.2. Synergistic effect of FGD

3.2.1 Compressive strength

The compressive strengths of the HAGM samples having different gypsum content are shown in Fig. 5. From Fig. 5, it can clearly be seen that the content of FGD has a great influence on the compressive strength of the HAGM. With the increase in FGD content, the 3 days, 7 days, and 28 days compressive strength of the stone body first increases and then decreases. The compressive strength of the HAGM prepared with 8 wt.% FGD is the highest, reaching 9.67 MPa, 12.65 MPa, and 16.70 MPa after curing for 3 days, 7 days, and 28 days. It can also be seen from the Fig. 5 that the compressive strength of the HAGM is lower than that of PC. Combined with the results of XRD quantitative analysis in section 3.1.2, this is because the mineral composition of the HAGM is mainly composed of β-C₂S, and the hydration rate of β-C₂S is much lower than that of C₃S in PC. Most of the hydration reactions for β-C₂S were carried out after 28 days. In a word, the compressive strength of the HAGM met the mechanical property requirements for grouting engineering [38].

3.2.2 Rheological characteristics

The pumping, fluidity, and rheological properties of grouting materials in engineering are often directly related to the rheological characteristics of the materials. The rheological characteristic parameters guide the determination of on-site grouting parameters. The rheological characteristics of HAGM with different gypsum contents are shown in Fig. 6, and the fitted rheology characteristic parameters according to the Herschel–Bulkley model are shown in Table 5. It can be seen from Fig. 6 that the shear stress of HAGM is always less than that of PC, indicating that the HAGM has better fluidity. This characteristic determines that the HAGM is suitable for long-distance pumping. As can be seen from Table 5, the correlation coefficients (R) between the fitted curve equation and the Herschel-Bulkley model are all above 0.98, which indicates that they have a high correlation. Under the different gypsum contents, the flow coefficient (n) of HAGM is greater than 1, indicating that all samples show a shear thickening behaviour. The yield stress decreases with the increase in FGD content, which shows that gypsum can improve the rheology of HAGM. This is because FGD generates ettringite with very low solubility on the surface of the matrix particles and forms a thin film that further hinders the reaction of matrix particles. The increase in free water in the system enhances the lubrication between slurry particles, resulting in a decrease in frictional resistance, an increase of slurry fluidity, and a decrease in yield stress. Combined with the results of compressive strength analysis in section 3.2.1, 8% FGD was selected as the content of the HAGM.

Table 5

Fitting results for the Herschel–Bulkley model
	Fitting results	n	τ₀/Pa	η/(Pa·s)	R
PC	y = 29.51 + 1.07·γ^0.96	0.96	29.51	1.07	0.9964
2%FGD	y = 23.23 + 0.45·γ^1.03	1.03	23.23	0.45	0.9933
4%FGD	y = 19.22 + 0.27·γ^1.13	1.13	19.22	0.27	0.9930
6%FGD	y = 14.11 + 0.08·γ^1.40	1.40	14.11	0.08	0.9921
8%FGD	y = 13.66 + 0.09·γ^1.38	1.38	13.66	0.09	0.9886
10%FGD	y = 11.83 + 0.11·γ^1.32	1.32	11.83	0.11	0.9892

3.2.3 Mineralogical characteristics

Figure 7 shows the XRD pattern of the hydration products of the HAGM and PC after they were cured for 3 days. According to the XRD pattern, the hydration products of the HAGM with a curing age of 3 days are mainly ettringite, C₃(A, F)H₆, aluminum gel, and unreacted β-C₂S, whereas the hydration products of PC mainly consist of CH, ettringite, unreacted β-C₂S, and C-S-H gel. The C-S-H gel is amorphous, so it can’t be characterised by XRD. By comparing the hydration products of the HAGM and PC, it can be seen that the diffraction peak of CH in the HAGM is much lower than that in PC, while the diffraction peak of C₃(A, F)H₆ and aluminum glue are opposite. This is due to the mineral composition characteristics of the HAGM having a low C₃S content and a high C₄AF content. The hydration reaction equation for the mineral phase involved is as follows (Eqs. (8)–(11)).

C₄AF + nH₂O→C₃(A, F)H₆ + FH₃ (> 20 ^oC) (8)

C₃A + 21H→C₄AH₁₃ + C₂AH₈ (9)

C₄AH₁₃ + 3CŜH₂ + 14H→C₃A·3CŜ·H₃₂ + CH (10)

C₃S + nH→C-S-H+(3-x)CH (11)

3.2.4 Microscopic characteristics

We observed the microstructure and element composition of the hydration products of HAGM and PC after 3 days of curing. The results are shown in Fig. 8. As can be seen from the microstructure of the hydration products for HAGM in Fig. 8 (top), sheet-like hydration products and gels appear in the gaps between unreacted particles, and needle-like hydration products are embedded in the gels. Flocculent gel and thin film hydration products appear on the surface of the unreacted particles. This proves that there is a film on the surface of the particles, which hinders the further reaction of the particles. Combined with EDS analysis of the hydration products for HAGM, it was speculated that the sheet-like hydration product should be C_x(A, F)H_y, the unreacted particles should be β-C₂S, the gel hydration product should be aluminum gel, and the needle-like hydration product should be ettringite. As can be seen from the SEM-EDS image of the hydration products for PC in Fig. 8 (bottom), the hydration products of PC are mainly ettringite, CH, and C-S-H gel. In conclusion, the SEM-EDS analysis results for the hydration products are consistent with XRD analysis results.

3.3. Performance effects of different erosion solutions

3.3.1 Anti-erosion coefficient and compressive strength

The anti-erosion coefficient (left) and compressive strength (right) for HAGM exposed to different erosion solutions are shown in Fig. 9. As Fig. 9 (left) shows, after the HAGM samples have been soaked in different erosion solutions for 28 days, the anti-erosion coefficient K is greater than the 0.99 required for the standard GB/T 31289 − 2014 marine PC, indicating that the HAGM has better corrosion resistance than PC, especially for the corrosion resistance to Na₂SO₄ solution. As shown in Fig. 9 (right), the compressive strengths of HAGM after curing in 6% MgSO₄, 6% NaCl, 6% Na₂SO₄, and seawater, respectively, are 23.21%, 21.47%, 35.89%, and 14.56% at 28 days. This also indicates that the HAGM has poorer resistance to NaCl erosion than to other erosion solutions.

3.3.2 Mineralogical characteristics

The hydrate phase compositions of the HAGM under the action of 6% MgSO₄, 6% NaCl, 6% Na₂SO₄, distilled water, and seawater were analysed, and the results are shown in Fig. 10. It can be seen from Fig. 10 that the hydration products of the HAGM all have ettringite, C₃(A, F)H₆, aluminum gel, unreacted β-C₂S, and gypsum. The difference is that CH exists in the hydrate phase under distilled water curing, and Friedel’s salt exists in the hydrate phase under seawater and NaCl solution curing. No diffraction peak for CH was found in the hydrate phase under the action of different erosion solutions, which is because sulphate and chloride can consume CH. The Friedel’s salt is from the reaction between Cl^-, C₃A, and CH in the systems to produce chloroaluminate compounds. The corresponding reaction equation is shown in Eqs. (13)-(16). The existence of C-S-H and CH is the cause of material erosion. It can be seen from Sections 3.2.3 and 3.2.4 that the content of CH and C-S-H in the hydrate phase of HAGM is much less than that in PC, so the HAGM has excellent erosion resistance.

MgSO₄ + Ca(OH)₂+2H₂O→CaSO₄·2H₂O + Mg(OH)₂ (13)

3CaO·2SiO₂·(aq) + 3MgSO₄ + nH₂O→3(CaSO₄·2H₂O) + 3Mg(OH)₂+2SiO₂(aq) (14)

Na₂SO₄·10H₂O + Ca(OH)₂→CaSO₄·2H₂O + 2NaOH + 8H₂O (15)

C₃A + Ca(OH)₂+2Cl^-+10H₂O→C₃A·CaCl₂·10H₂O + 2OH^- (16)

3.3.3 Microscopic characteristics

The hydration product microstructures of the HAGM cured using different erosion solutions are shown in Fig. 11. It is evident that the morphology of the hydration products of the HAGM under erosive solution curing did not change much, and the hydration products is still the product of gel, unreacted particles, and needle-like or rod-like hydration products. This shows that the erosion solution has little effect on the hydrate phase of the HAGM. It can also be concluded that the slurry structure of the HAGM cured using erosion solution is denser than that cured using distilled water. Especially under curing with Na₂SO₄ solution, many of the hydration products generated partially fill in the slurry holes, making the slurry structure more compact. Other hydration products form a stable network structure, covering the surface of unreacted β-C₂S particle. This is one of the reasons for the increase in the compressive strength of the HAGM cured by erosion solution. According to the EDS image results, the hydrated products of the corroded HAGM were ettringite solid solution, iron (aluminum) gel solid solution, and unreacted β-C₂S. The appearance of ettringite solid solution is because some of the Al in ettringite was replaced by Fe in the presence of adequate gypsum. In addition, it is evident that the peak intensity of S and Cl elements in iron (aluminum) gel solid solution (Point 2) under the action of different corrosion solutions is higher than that under distilled water curing, indicating that the hydrated product gel of C₄AF can adsorb SO₄^2- and Cl^-.

3.3.4 Pore structure characteristics

Figure 12 shows the pore size distribution curve of the hardened slurry structure of the HAGM after 28 days of erosion in different erosion solutions. According to previous work, the pore size can be divided into three categories: small gel pores (3.5–10 nm), large gel pores (10–100 nm), and capillary pores (greater than 0.1 µm) [39] It can be seen from the diagram that, compared with pure water curing, the number of capillary pores in the pore structure of the hardened paste in different erosion solutions decreases, and the pore size distribution is more concentrated in gel pores. The results show that the slurry structure of the eroded HAGM is more compact, the strength is higher, and the erosion resistance is better, which is consistent with the analysis results for the microstructure and compressive strength.

The synthesis, characterisation, and properties of HAGM were analysed in this paper. According to the test results obtained, the main conclusions are as follows:

(1) This investigation proved the feasibility of using solid waste to prepare HAGM. It was prepared using 18.16 wt.% of RM, 64.56 wt.% of CS, and 17.28 wt.% of SF to produce an HAGM matrix that contained approximately 68.3 wt.% β-C₂S, 21 wt.% C₄AF, and 8.4 wt.% C₃A at a calcination temperature of 1400 ^oC. The key difference is that the HAGM matrix had an excessive content of C₄AF compared with that of the PC clinker, and it contained a small amount of C₃S. The mineral crystals of the HAGM were well developed and closely arranged: cobblestone-like β-C₂S was evenly distributed, and schistose-like C₄AF filled the voids between the β-C₂S structures. Compared with the chemical composition, particle size distribution, and specific surface area of PC, in the HAGM matrix there was more Fe₂O₃, and there were finer hydrated particles.

(2) With the increase in FGD content, the compressive strength of the HAGM first increased and then decreased, and the yield stress of the HAGM decreased gradually, indicating that gypsum can improve the compressive strength and rheology properties of HAGM. The action mechanism of the FGD is to form a film on the surface of hydrated particles, increase the number of water molecules, and weaken the friction resistance between the particles. The compressive strength of the HAGM prepared with 8 wt.% FGD was the highest, reaching 9.67 MPa, 12.65 MPa, and 16.70 MPa after curing for 3 days, 7 days, and 28 days. XRD and SEM-EDS showed that hydration of the HAGM led to the formation of ettringite, C₃(A, F)H₆, aluminum gel, and unreacted β-C₂S. Compared with PC, there was less CH and C-S-H in the hydrated phase of the HAGM.

(3) The anti-erosion coefficient K of the HAGM samples that were soaked in different erosion solutions for 28 days was greater than 0.99, indicating that the HAGM has better corrosion resistance than PC. The erosion solution promoted the development of compressive strength in the HAGM and improved its corrosion resistance. This mechanism is related to the high C₄AF and low C₃S content in the mineral composition of the HAGM, which leads to the formation of a very small amount of CH and C-S-H and a large amount of iron (aluminum) gel solid solution during the hydration process, providing an environment with a compact microstructure and the ability to adsorb erosive ions, thus improving the erosion resistance.

Acknowledgements

This work was supported by the Major Scientific and Technological Innovation Projects in Shandong Province (Grants Nos. 2020CXGC011405 and Grants Nos. 2021CXGC010301) and the Key Projects of Natural Science Foundation of Shandong Province (No. 2020KE006).

Data Availability

Some or all data, models, or code that support the findings of thisstudy are available from the correspond-ing author upon reasonablerequest. Some data are openly available as part of a Masters thesis, published openly by Shandong University.

We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled “Preparation, characterization and properties of high anti-erosion grouting materials from industrial solid waste. The authors declare no conflict of interest.

Shucai, L., Yanhai, Q., Zhaofeng, L., Haiyan, L., Jian, Z.: A novel treatment method and construction technology of the pipeline gushing water geohazards in karst region. Tunn. Undergr. Sp Tech. 113, 103939 (2021). https://doi.org/10.1016/j.tust.2021.103939
Haiyan, L., Yuchuan, Z., Jing, W., Xiangyu, Z., Lewen, Z., Zhaofeng, L.: Grouting sealing mechanism of water gushing in karst pipelines and engineering application. Constr. Build. Mater. 254, 119250 (2020). https://doi.org/10.1016/j.conbuildmat.2020.119250
Xintong, W., Shucai, L., Zhenhao, X., Xiaozhao, L., Peng, L., Chunjin, L.: An interval risk assessment method and management of water inflow and inrush in course of karst tunnel excavation. Tunn. Undergr. Sp Tech. 92, 103033 (2019). https://doi.org/10.1016/j.tust.2019.103033
Qinglong, C., Huaina, W., Shuilong, S., Yeshuang, X., Guanlin, Y.: Chinese karst geology and measures to prevent geohazards during shield tunnelling in karst region with caves. Nat. Hazards. 77(1), 129–152 (2015). https://doi.org/10.1007/s11069-014-1585-6
Fulin, Q., Wengui, L., Wenkui, D., Vivian, W.Y.T., Tao, Y.: Durability deterioration of concrete under marine environment from material to structure: A critical review. J. Build. Eng. 35, 102074 (2021). https://doi.org/10.1016/j.jobe.2020.102074
de Medeiros-Junior, R.A., de Lima, M.G., de Brito, P.C., de Medeiros, M.H.F.: Chloride penetration into concrete in an offshore platform-analysis of exposure conditions. Ocean. Eng. 103, 78–87 (2015). https://doi.org/10.1016/j.oceaneng.2015.04.079
Junsheng, Y., Cong, Z., Jinyang, F., Shuying, W., Xuefeng, O., Yipeng, X.: Pre-grouting reinforcement of underwater karst area for shield tunneling passing through Xiangjiang River in Changsha, China. Tunn. Undergr. Sp Tech. 100, 103380 (2020). https://doi.org/10.1016/j.tust.2020.103380
Shucai, L., Jian, Z., Zhaofeng, L., Yifan, G., Yanhai, Q., Haiyan, L., Qingsong, Z.: Investigation and practical application of a new cementitious anti-washout grouting material. Constr. Build. Mater. 224, 66–77 (2019). https://doi.org/10.1016/j.conbuildmat.2019.07.057
Jinquan, L., Kaveng, Y., Weizhong, C., Xiaosheng, Z., Wei, W.: Grouting for water and mud inrush control in weathered granite tunnel: A case study. Eng. Geol. 279, 105896 (2020). https://doi.org/10.1016/j.enggeo.2020.105896
Zijie, H., Jianping, Z., Zishan, Z., Chang, L., Lei, L., Haiyan, L.: Effects of nano-clay on the mechanical and microstructural properties of cement-based grouting material in sodium chloride solution. Constr. Build. Mater. 245, 118420 (2020). https://doi.org/10.1016/j.conbuildmat.2020.118420
Kaiyue, Z., Yun, Q., Peng, Z., Jiuwen, B., Yupeng, T.: Experimental and numerical study on chloride transport in cement mortar during drying process. Constr. Build. Mater. 258, 119655 (2020). https://doi.org/10.1016/j.conbuildmat.2020.119655
Weerdt, K., De, Justnes, H., Geiker, M.R.: Changes in the phase assemblage of concrete exposed to sea water. Cem. Concr Compos. 47, 53–63 (2014). https://doi.org/10.1016/j.cemconcomp.2013.09.015
Guoxin, L., Ai, Z., Zhanping, S., ChenShi, Y., Wang, J.: jie Z.: Study on the resistance to seawater corrosion of the cementitious systems containing ordinary Portland cement or/and calcium aluminate cement. Constr. Build. Mater. 157, 852–859 (2017). https://doi.org/10.1016/j.conbuildmat.2017.09.175
Schneider, M.: Process technology for efficient and sustainable cement production. Cem. Concr Res. 78, 14–23 (2015). https://doi.org/10.1016/j.cemconres.2015.05.014
Nidheesh, P.V., Suresh Kumar, M.: An overview of environmental sustainability in cement and steel production. J. Clean. Prod. 231, 856–871 (2019). https://doi.org/10.1016/j.jclepro.2019.05.251
Schneider, M.: Process technology for efficient and sustainable cement production. Cem. Concr Res. 78, 14–23 (2015). https://doi.org/10.1016/j.cemconres.2015.05.014
Yonggang, Y., Wenlong, W., Zhi, G., Changzai, R., Xingliang, Y., Shuang, W.: Hydration study and characteristic analysis of a sulfoaluminate high-performance cementitious material made with industrial solid wastes. Cem. Concr Compos. 112, 103687 (2020). https://doi.org/10.1016/j.cemconcomp.2020.103687
Wei, G., Beidou, X., Caihong, H., Jiaxi, L., Zhurui, T., Wei, L., Caiyun, M., Weixia, W.: Solid waste management in China: Policy and driving factors in 2004–2019. Resour. Conserv. Recy. 173, 105727 (2021). https://doi.org/10.1016/j.resconrec.2021.105727
Changzai, R., Wenlong, W., Yanpeng, M., Xueliang, Y., Zhanlong, S., Jing, S., Xiqiang, Z.: Comparative life cycle assessment of sulfoaluminate clinker production derived from industrial solid wastes and conventional raw materials. J. Clean. Prod. 167, 1314–1324 (2017). https://doi.org/10.1016/j.jclepro.2017.05.184
Rahimi, S., Hafezalkotob, A., Monavari, S.M., Hafezalkotob, A., Rahimi, R.: Sustainable landfill site selection for municipal solid waste based on a hybrid decision-making approach: Fuzzy group BWM-MULTIMOORA-GIS. J. Clean. Prod. 248, 119186 (2020). https://doi.org/10.1016/j.jclepro.2019.119186
Shucai, L., Jian, Z., Zhaofeng, L., Chao, L., Jingpeng, C.: Feasibility study on grouting material prepared from red mud and metallurgical wastewater based on synergistic theory. J. Hazard. Mater. 407, 124358 (2021). https://doi.org/10.1016/j.jhazmat.2020.124358
Xiaobin, W., Xiuying, L., Xiang, Y., Cheng, T., Zhaoguo, Y.: Environmental risks for application of iron and steel slags in soils in China: A review. Pedosphere. 31(1), 28–42 (2021). https://doi.org/10.1016/S1002-0160(20)60058-3
Junjie, Z., Hongbo, T., Xingyang, H., Wei, Y., Xiufeng, D.: Utilization of carbide slag-granulated blast furnace slag system by wet grinding as low carbon cementitious materials. Constr. Build. Mater. 249, 118763 (2020). https://doi.org/10.1016/j.conbuildmat.2020.118763
Mehta, A., Ashish, D.K.: Silica fume and waste glass in cement concrete production: A review. J. Build. Eng. 29, 100888 (2020). https://doi.org/10.1016/j.jobe.2019.100888
Król, A., Mizerna, K., Bożym, M.: An assessment of pH-dependent release and mobility of heavy metals from metallurgical slag. J. Hazard. Mater. 2020, 384, 121502 (2020). https://doi.org/10.1016/j.jhazmat.2019.121502
Xiaoming, L., Na, Z., Henghu, S., Jixiu, Z., Longtu, L.: Structural investigation relating to the cementitious activity of bauxite residue-red mud. Cem. Concr. Res. 2011, 41: 847–853 (2011). https://doi.org/10.1016/j.cemconres.2011.04.004
Zhaofeng, L., Jian, Z., Shucai, L., Chunjin, L., Yifan, G., Chao, L.: Feasibility of preparing red mud-based cementitious materials: Synergistic utilization of industrial solid waste, waste heat, and tail gas. J. Clean. Prod. 285, 124896 (2021). https://doi.org/10.1016/j.jclepro.2020.124896
Shiyu, Z., Lei, Y., Fengyu, R., Jingping, Q., Hangxing, D.: Rheological and mechanical properties of cemented foam backfill: Effect of mineral admixture type and dosage. Cem. Concr Compos. 112, 103689 (2020). https://doi.org/10.1016/j.cemconcomp.2020.103689
Haiqiang, J., Mamadou, F., Erol, Y., Yuanhui, L., Lei, Y.: Effect of mineral admixtures on flow properties of fresh cemented paste backfill: Assessment of time dependency and thixotropy. Powder Technol. 372, 258–266 (2020). https://doi.org/10.1016/j.powtec.2020.06.009
Bernal Camacho, J., Mahmoud Abdelkader, S., Reyes Pozo, E., Moragues Terrades, A.: The influence of ion chloride on concretes made with sulfate-resistant cements and mineral admixtures. Constr. Build. Mater. 70, 483–493 (2014). https://doi.org/10.1016/j.conbuildmat.2014.07.109
Seungwon, K., Y. k., Muhammad, Cheolwoo, U., Asad, P. H.: Durability of slag waste incorporated steel fiber-reinforced concrete in marine environment. J. Build. Eng. 33: 1–12: (2021). https://doi.org/10.1016/j.jobe.2020.101641
Jianming, Y., jie, Z., Shucong, Z.: Experimental research on seawater erosion resistance of magnesium potassium phosphate cement pastes. Constr. Build. Mater. 2018, 183: 534–543 (2018). https://doi.org/10.1016/j.conbuildmat.2018.06.136
Zhaofeng, C.: Inorganic nonmetallic materials. Northwest University of Technology Press, Xi'an (2016) Zhejiang, China
Tsakiridis, P.E., Papadimitriou, G.D., Tsivilis, S., Koroneos, C.: Utilization of steel slag for Portland cement clinker production. J. Hazard. Mater. 152, 805–811 (2008). https://doi.org/10.1016/j.jhazmat.2007.07.093
Yifan, G., Zhaofeng, L., Jian, Z., Chen, Z., Jingpeng, C.: Synthesis, characterization and properties of solid waste based high belite cement. Chem. Lett. 2021, 50(1): 128–130 (2021). https://doi.org/10.1246/cl.200662
Jinzhen, L., Yulei, Y., Shaowen, H., Chao, W.: Effect of Na₃AlF₆ on the chroma and mineral compositions of the interstitial phase in white Portland cement clinker. Constr. Build. Mater. 308, 125034 (2021). https://doi.org/10.1016/j.conbuildmat.2021.125034
Žibret, L., Ipavec, A., Dolenec, S.: Microstructural characteristics of belite–sulfoaluminate cement clinkers with bottom ash. Constr. Build. Mater. 321, 126289 (2022). https://doi.org/10.1016/j.conbuildmat.2021.126289
Chunjin, L., Wenjie, D., Zhaofeng, L., Yansheng, W.: Study on the inorganic synthesis from recycled cement and solid waste gypsum system: Application in grouting materials. Constr. Build. Mater. 251, 118930 (2020). https://doi.org/10.1016/j.conbuildmat.2020.118930
Jian, Z., Guang, Y., Breugel, K.: Characterization of pore structure in cement-based materials using pressurization depressurization cycling mercury intrusion porosimetry (PDC-MIP). Cem. Concr Res. 40(7), 1120–1128 (2010). https://doi.org/10.1016/j.cemconres.2010.02.011

Preparation, characterization and properties of high anti-erosion grouting materials from industrial solid waste

Status:

Version 1

Abstract

Figures

Statement of Novelty

1. Introduction

2. Experimental Procedure