Chemically resistant polymeric jointing grout with environmental impact

Chemically resistant polymeric jointing grout with environmental impact DROCHYTKA, R.; HODUL, J.; MÉSZÁROSOVÁ, L.; JAKUBÍK, A. Construction and building materials Volume 292, 19 July 2021, 123454, Pages 1-20 ISSN: 0950-0618 DOI: https://doi.org/10.1016/j.conbuildmat.2021.123454 Accepted manuscript © 2021. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ dspace.vutbr.cz 1 Chemically resistant polymeric jointing grout with environmental impact 1 2 Rostislav Drochytka, Jakub Hodul, Lenka Mészárosová, Aleš Jakubík 3 Abstract. This paper deals with the study of the chemical resistance of polymeric jointing grouts 4 intended for the jointing of elements that are permanently stressed by an aggressive chemical 5 environment, such as elements made of cast basalt, placed in the concrete structures of sewerages. 6 The paper researches three types of epoxy jointing grouts designed for conditions where there is a 7 chemically aggressive environment. The optimal amount of hazardous waste (end product and cement 8 bypass dusts) was incorporated in the developed jointing grouts. As part of chemical resistance 9 monitoring, changes in selected physical and mechanical properties of jointing grouts were monitored 10 and evaluated, including microstructure monitoring after chemical stress. The scanning electron 11 microscopy (SEM) was used for the explanation of bonding effects of the polymer matrix with the filler It 12 was found that the use of hazardous waste is highly effective in polymeric grouts with high chemical 13 resistance; there was no noticeable reduction in the chemical resistance of these jointing grouts 14 compared to the reference grouts. 15 1. Introduction 16 At present, there is a large demand for highly chemically resistant jointing grouts, intended primarily 17 for the reconstruction of sewerage networks. A large part of sewerage networks originated not only in 18 Europe, but also in the United States and Canada in the 1950s and 1960s. These sewerages, as well as 19 those that are only 30 years old and with a highly aggressive environment, are currently undergoing 20 extensive reconstruction [1],[2]. The environment in sewerage networks is very specific, and a number 21 of degradation processes take place in it. Biodegradation is one of various polymer degradation routes. 22 It is the process by which organic substances are broken down by microorganisms, such as bacteria, 23 fungi and algae. These microorganisms can degrade the polymers aerobically (producing carbon 24 dioxide and water) or anaerobically (producing carbon dioxide, water and methane) [3]. 25 The newly developed material based on epoxy resin is primarily designed for jointing sewerage pipes. 26 Corrosion of concrete pipes in sewerage networks is caused mainly by the action of hydrogen sulphide 27 (H2S). Hydrogen sulphide is formed by sulphate-reducing bacteria (SRB) in anaerobic sewer biofilms, 28 i.e. sewerage sediments. From the wastewater (WW), H2S is emitted into the free space and the level 29 of the WW in the sewerage pipe, where it is oxidised to sulphuric acid (H2SO4). This chemical reaction 30 can be described by the following equations [4]: 31 𝐻2𝑆+2𝑂2→𝑆𝑂4 2− +2𝐻+ (1) 32 2𝑆+3𝑂2+2𝐻2𝑂 →2𝑆𝑂4 2− +4𝐻+ (2) 33 H2SO4 causes biogenic sulphate corrosion of concrete remediation pipes (Fig. 1), which leads to 34 expansion, cracking and eventually the total disintegration of concrete sewerage pipes. This is because 35 the primary reaction of sulphate anions with calcium hydroxide present in the cementitious sealant 36 produces gypsum and ettringite at a substantially larger volume, which is the main cause of the 37 cracking and degradation of concrete [5]. Aggressive factors that cause unstable sulphur (sulphide) 38 compounds in sewerage systems are the composition of the WW (biochemical oxygen demand), 39 temperature, pH value, residence time of the water in the sewer network, car cleaners and detergents; 40 2 improper storage or disposal of substances, e.g. from industry, preparations for destroying weeds and 1 vermin (pesticides, herbicides and insecticides); fertilisers (nitrogen and sulphur) and de-icing salts. 2 Although the concentration of hydrogen sulphide in sewers varies across time and space (from units 3 to several hundred ppm), H2S is present everywhere in sewerage networks [6]. 4 The following types of WW located in sewers have been identified: sewage (from households, social 5 facilities, hostels, etc.), industrial (from production processes), urban (municipal; a mixture of sewage 6 and others, typically industrial water, which flows through public sewerage), agricultural (plant and 7 animal production, drainage waters from land improvement), rainwater (rainwater drained by the 8 sewer network) and others (e.g. hospital, cooling, mining). As raw WW is also a potential carrier of 9 pathogenic microorganisms, inhalation, contact and ingestion can endanger human health through 10 water or air pathways [7]. The pH values of municipal WW range between of 6.8–8.0 and contains a 11 wide variety of aggressive substances, such as dissolved inorganic salts, hydrocarbons, phenols, 12 polyphenols, ammoniacal nitrogen, mercury, lead, cyanides, surfactants, detergents and phthalates. 13 The sum of volatile fatty acids, soluble proteins and soluble sugars forms about 30% of the total 14 chemical oxygen demand (COD) of the WW [8]. 15 16 Fig. 1. Scheme of action of aggressive factors on the inner surfaces 17 of sewers [9]. 18 19 Epoxy resin grouting material has been widely used in foundation treatment and concrete crack 20 treatment because of its good grouting ability and high mechanical strength. It penetrates effectively 21 into porous substrates in a way that provides an embedded network in the material. The main factors 22 that influence grouting quality include durability, permeability and physical and mechanical 23 compatibility. Excellent epoxy grouting materials must have high permeability, good durability and 24 good physical and mechanical compatibility with porous media [10]. The type of curing agent has a 25 significant effect on compressive and flexural strength [11]. The effect of fillers on the ageing of epoxy 26 adhesives has been studied by some authors [12],[13]. The environmental impact of polymer grouts 27 may be assessed by analysis of the life cycle. The environmental impact of polymer composites breaks 28 down to about 70–75% because of extraction, 10–15% because of processing, and 12–18% because of 29 the material itself [14]. However, the environmental impact of using epoxy resins, which exhibit 30 3 excellent properties and durability, is much reduced by using hazardous wastes as fillers that are firmly 1 incorporated in the polymer matrix. 2 In addition to conventional quartz sand or quartz flour, many authors have dealt with alternative 3 preparations of epoxy composite with used filler, e.g. based on kaolinite [15], bentonite [16] and 4 nanosilica [17]. 5 One way to use hazardous waste materials is through their solidification. The principle is to mix the 6 hazardous waste materials with an agent that will guarantee stabilisation. Of course, it is most 7 appropriate to use the maximum possible share of hazardous waste [18],[19]. For the perfect 8 incorporation of hazardous waste in the structure, it is possible to perform two-stage stabilisation. The 9 first step is to mix the waste with a solidifying agent. For the second step, the raw material thus 10 prepared is incorporated in a structure in which it is firmly enclosed. A very suitable material for this 11 purpose is epoxy resin [20]. The key technologies for harmlessly co-disposing and recycling municipal 12 solid waste incinerated fly ash, pickling sludge and waste glass were researched by Zhao et al. [21], and 13 eco-friendly materials using solid wastes as raw materials were formed. It was claimed by Erdoğan et 14 al. [22] that using slag reinforcement in the composite based on epoxy matrix is advantageous both in 15 terms of eliminating wastes that are harmful to the environment and in terms of preserving natural 16 reinforcement sources used in the production of the composite materials. 17 Stabilisation/solidification (S/S) is an efficient and reliable treatment technology for hazardous 18 materials [23]. The S/S processes can be driven by physical and chemical means, encapsulation, fixation 19 or adsorption with waste components [24]. S/S causes chemical changes in the hazardous components 20 in the waste; these changes reduce solubility, mobility and toxicity [25]. It was proven by Massardier 21 et al. [26] and Vipulanandan [27] that the S/S of hazardous waste by the use of polymeric 22 thermosetting materials is very effective, with the solidified waste having the potential to be used in 23 construction applications. 24 2. Materials 25 Three types of two-component epoxy resins (HRG-D, ERG-D, MRG-W) were selected as a binder, quartz 26 flour was used as the reference filler, and further solidified hazardous waste consisting of end product 27 (EP), cement dusts, fly ash and quartz flour. 28 2.1. Polymer binder 29 Three types of two-component epoxy resins were used: chemically resistant (HRG-D), highly chemically 30 resistant (ERG-D) and water-compatible resin with average chemical resistance (MRG-W). IN-CHEMIE 31 Technology, Ltd. supplied the HRG-D and ERG-D epoxy resins. The epoxy resin MRG-W was from 32 Redrock Construction, Ltd. The last type of resin (MRG-W) was examined due to the permanently 33 humid environment in the sewers due to the condensation of vapours on the inner walls (drying is 34 technologically and time-consuming). The composition of the resins used is given in Tables 1–3. 35 Densities of the polymer (epoxy) resins and the curing agents, including additives used for the 36 specimen's preparation, are stated in Table 4. The ambient and substrate temperature in the range of 37 10 ° - 25 ° C must be guaranteed to ensure the required curing of used polymer binders. When applying 38 the materials HRG-D and ERG-D, the maximum moisture content of the substrate must not exceed 5% 39 wt., and relative humidity (R.H.) must be ≤ 80%. For MRG-W resin, the substrate's maximum moisture 40 content must be ≤ 10% wt., and R.H. ≤ 95%. A curing time for the ERG-D and HRG-D binders is 20 hours 41 4 at temperature +20 °C, and for MRG-W, the time for complete curing is 24 hours. After mixing the two 1 components (A + B) of polymer binder, the temperature rises during the polymerisation due to the 2 exothermic reaction was: +2.5 ° C after 60 minutes (MRG-W), +10.1 °C (HRG-D), +13.2 °C (ERG-D) after 3 90 minutes. The filler did not significantly affect the temperature rise during polymerisation (heat 4 mechanism). Dynamic viscosities of used unfilled polymer resins at 23 °C (mixture of A+B components) 5 were 11,100 mPa·s (ERG-D), 5,900 mPa·s (HRG-D) and 1,900 mPa·s with MRG-W binder. The hardener 6 and the thermal curing procedure's type and concentration affect the curing process of epoxy resins. 7 The degree of cure has a high impact on epoxy systems' physical and mechanical properties [28]. Benzyl 8 alcohol (dynamic viscosity 5.84 mPa·s at 20 °C) and a petroleum solvent were present to adjust the 9 viscosity or catalyse the reaction. Benzyl alcohol was used as the solvent in the ERG-D curing agent 10 since it is soluble in the aromatic-containing epoxy resin and dissolves the hydrogen-bonded amine 11 [29]. Cyclohexylamine (dynamic viscosity 2.1 mPa·s at 20 °C) is an interesting compound that, due to 12 its ability as both proton donor and proton acceptor, is used in epoxy systems [30]. The morphology of 13 the epoxy blend cured by primary aliphatic amines, e.g., cyclohexylamine, is influenced by the curing 14 temperature. A higher temperature can reduce the blend viscosity and facilitate easier diffusion of all 15 components [31]. 16 A more complex empirical model proposed by Kenny et al. [32] represents more comprehensively the 17 effect of the degree of cure on the resin viscosity by accounting for the degree of cure at gelation, 18 determined as: 19 𝜇 =𝐴𝜇𝑒𝑥𝑝(𝐸𝜇 𝑅𝑇)[𝛼𝑔 𝛼𝑔−𝛼](𝐴+𝐵𝛼) (3) 20 where Aμ, Eμ, A and B are experimentally determined constants, R is the universal gas constant, and αg 21 is the degree of cure at gelation. As α approaches αg, the resin viscosity increases dramatically as the 22 polymer system becomes a three‐dimensional network. 23 Table 1 24 Chemical composition of the chemically resistant epoxy resin HRG-D. 25 Component A Component B (curing agent) Mixing ratio A:B ER (average molar mass ≤ 700) (alkoxymethyl) oxirane (C12-C14 alkyl) formaldehyde; oligomeric reaction products with 1-chloro-2,3-epoxypropane and phenol 4,4-methylenebis (cyclohexylamine) Phenylmethanol, formaldehyde polymer with benzenamine 1.8:1 26 Table 2 27 Chemical composition of the chemically resistant epoxy resin ERG-D. 28 Component A Component B (curing agent) Mixing ratio A:B Polymer with formaldehyde, phenol glycidyl ether, 1- (2,3epoxypropoxy) -2,2-bis [(2,3epoxypropoxy) methyl] butane Benzyl alcohol, m-phenylenebis (methylamine) Phenol 4,4´ (1-methyletathylidene) bisoligomeric reaction product with 2- (chloromethyl) oxirane reaction product with 2.1:1 5 1,3-benzenedimethanamine 4,4´- methylenebis (cyclohexamine) 1 Table 3 2 Chemical composition of the water compatible epoxy resin MRG-W 3 Component A (curing agent) Component B Mixing ratio A:B Formaldehyde, polymer with N1- (2aminoethyl) -N2-[2-[(2-aminoethyl) amino]ethyl]-1,2-ethanediamine, 2,2´- [1,4-butanediylbis(oxymethyl), polyoxypropylenediamine, 3,6,9triazaundecane-1,11-diamine ER (average molar mass ≤ 700), polymer with formaldehyde, polymer with formaldehyde, (alkoxymethyl) oxirane (alkyl C12-C14) 1.16:1.93 4 Table 4 5 Densities of the epoxy resins and the curing agents including additives in kg/m3 6 Type of Polymer grout Epoxy resin Curing agent ERG-D 1,300 1,100 HRG-D 1,330 1,100 MRG-W 1,270 1,120 7 2.2. Filler component 8 Some hazardous wastes, quartz flour and fly ash were selected as by-products as input materials for 9 solidification. In regard to experimental secondary raw material, a mix was used, which was prepared 10 through the homogenisation of quartz powder, hazardous waste as a by-product of solid municipal 11 waste combustion – end product (EP) and cement bypass dust (CBD). Fly ash from fluidised bed 12 combustion (FBC) contaminated by the denitrification process from a thermal power plant in the Czech 13 Republic was used as a solidifying agent together with quartz flour. 14 2.2.1. Quartz flour 15 Silica powder is made by grinding dry quartz sand, followed by subsequent selection so that the highest 16 possible quality and low dust content is ensured. It has high mechanical and chemical resistance. The 17 quartz flour used contained SiO2 over 98.5% and Fe2O3 up to 10%, with grain sizes up to 0.2 mm, no 18 organic contamination, specific gravity of 2,680 kg/m3 and specific surface area of 4,660 cm2/g. For 19 water-compatible MRG-W grouts, black coloured quartz flour (specific gravity of 2,690 kg/m3) treated 20 with the addition of Fe2O3 (maximum amount 2.0%) was used, which is commonly utilised in practice 21 in these types of materials. 22 2.2.2. End product (EP) 23 The EP is a waste product from the II. stage of flue gas treatment of category HW – hazardous. Its 24 chemical composition depends on the composition of the flue gas, i.e. on the composition of mixed 25 municipal waste (MMW). It is separated on textile filters as the final reaction product of the 26 neutralisation reaction of acid components of flue gases and alkaline sorbent – lime wash. It is a very 27 fine dust of dark grey colour (due to the presence of activated carbon), odourless and strongly 28 6 hygroscopic due to unreacted Ca(OH)2. The experimentally determined specific weight of the used 1 material was 2,340 kg/m3, while the specific surface area was 5,190 cm2/g. The pH value of the aqueous 2 extract of the EP was 12.2. The X-ray diffraction pattern of the EP, with mineral peaks for defernite 3 (Ca6(CO3)2-x(SiO4)x(OH)7(Cl,OH)1-2x), cuspidine (Ca4(Si2O7)(F,OH)2), portlandite (Ca(OH)2), hannebachite 4 (2CaSO3·H2O), high-temperature polymorph of silica with a crystal structure (β-quartz), anhydrite 5 (CaSO4) and calcite (CaCO3), is stated in Fig. 2. The record of the differential thermal analysis (DTA) and 6 thermogravimetric analysis (TGA), with the indication of hydration products decomposition of the EP, 7 is presented in Fig. 3. The blue curve is the thermogravimetric (TG) curve, the red curve represents the 8 first derivative of the TG curve (DTG), and blue dashed curve represents the DTA curve. Table 5 displays 9 the content of minerals and phases calculated based on the DTA and TG record. Table 6 presents the 10 chemical composition of the hazardous waste and fly ash used, including the content of heavy metals 11 in dry matter. 12 13 Fig. 2. X-ray diffraction pattern of the end product (EP). 14 15 Fig. 3. Thermo-gravimetric and differential thermal analysis curves of the end product (EP) - red 16 curve (DTG), blue dashed curve (DTA) and blue curve (TG). 17 7 2.2.3. Cement Bypass Dust (CBD) 1 CBD is a by-product of the production of cement in cement plants. Due to the high circulation of 2 pollutants (chlorine, alkalis and, to a lesser extent, sulphur), it is important to include a gas bypass at 3 the entrance to the cement kiln. Bypass dusts make up 5–20% of the clinker produced. Typical bypass 4 components are chlorine bypass (up to 15%) and sulphur bypass (up to 70%). The bypass is an exhaust 5 of a part of furnace gases from the transitional part of the rotary cement furnace, rapid cooling of this 6 part of furnace gases and their diverting into an independent filter. These gases are not led to the 7 exchanger before the furnace where partial calcination in the raw material mix takes place. The 8 percentage of coarse fraction is 85–90%, and it can be returned to the cement production process - 9 reduced concentration of chlorides, and fine fraction presents 10–15% of the total amount of dust. 10 The fine fraction used in the research contained a larger amount of chlorides and also contained heavy 11 metals, such as lead, copper and cadmium [33], which is evident from their chemical composition 12 (shown in Table 6). The specific weight was 2,790 kg/m3, while the specific surface area was 6,440 13 cm2/g. The pH value of the aqueous extract of CBD was 12.8. The X-ray diffraction pattern for the CBD, 14 with mineral peaks for syngenite (K2Ca(SO4)2·H2O), portlandite (Ca(OH2)), belite (2CaO·SiO2), calcite 15 (CaCO3), hydrogrossular (Ca3Al2(SiO4)3−x(OH)4x) and sylvine (KCl), can be seen in Fig. 4. The record of the 16 DTA and TGA of CBD is presented in Fig. 5., and the content of minerals and phases calculated based 17 on the DTA and TG record is stated in Table 5. 18 19 Fig. 4. X-ray diffraction pattern of the cement bypass dust (CBD). 20 21 8 1 Fig. 5. Thermo-gravimetric and differential thermal analysis curves of the Cement Bypass Dust (CBD). 2 Table 5 3 Results of DTA – mass loss and mass content. 4 Hazardous waste Mass loss corresponding to decomposition [%] Mass Content [%] C-S-H C-A-H Ca(OH)2 CaCO3 Ca(OH)2 CaCO3 End Product (EP) 5.62 0 2.47 15.3 10.2 34.8 Cement Bypass Dust (CBD) 0 0.25 2.07 3.32 8.5 7.5 2.2.4. Fly Ash from Fluidized Bed Combustion (FBC) 5 The fly ash from FBC, which was contaminated due to selective non-catalytic reduction (SNCR) 6 technology, is a by-product of a lignite-burning thermal power plant in the west part of the Czech 7 Republic. The specific weight of this material was experimentally determined to be 2,872 kg/m3, the 8 specific surface area was found to be 627 m2/kg and the concentration of ammonia ions (NH3) = 30.11 9 ppm. As it can be seen from the Table 6, this fly ash contained significant amounts of vanadium (242 10 mg/kg dry matter) and chromium (91.9 mg/kg dry matter). 11 Table 6 12 Chemical composition of hazardous waste and fly ash. 13 Parameter Unit EP CBD FBC Dry matter (105 °C) % 99.6 99.7 99.8 Chlorides mg/ kg dry matter 151000 117000 76 Sulphates (SO42-) % dry matter 4.20 8.02 5.88 SiO2 % dry matter 3.81 9.39 35.2 Al2O3 % dry matter 1.86 2.13 19.8 CaO % dry matter 37.8 32.5 18.5 Free CaO % dry matter 26.9 9.81 8.74 P2O5 % dry matter 0.40 0.14 0.18 Fe2O3 % dry matter 0.65 1.33 5.80 K2O % dry matter 5.52 22.7 0.63 Na2O % dry matter 3.29 0.93 0.31 MgO % dry matter 0.74 0.71 1.05 15 inhomogeneous film structure, due to insufficient coalescence during the curing process, also leads to 1 poor resistance [42]. Generally, room temperature-cured epoxy resins have poor resistance to organic 2 acids. However, at lower concentrations, the resistance is much improved [43]. The oxidation 3 degradation of epoxy-based materials only occurs within the surface layer, effectively reducing oxygen 4 diffusion and finally reaching a limited thickness to protect the inner cores from further oxidation. High 5 temperatures can catalyse the formation of the oxidised layer [44]. Oxidation and hydrolysis can occur 6 after the ageing of polymer grouts and are irreversible [45]. For the reference sample filled with quartz 7 flour, no spots formed, but a colour change occurred. However, no colour changes resulting from the 8 effect of the simulated WW transpired. From the point of view of visual assessment, FHW2 appears to 9 be the most suitable filler out of those examined. A 30% acetic acid solution led to significant 10 degradation and total decomposition of all samples (Fig. 12c). The action of a 10% acetic acid solution 11 on the water-compatible MRG-W jointing grout resulted in the total decomposition of the structure 12 only in the reference sample with quartz flour (Fig. 12d). The decomposition of the sample was caused 13 by the Fe2O3 content of the pigment, which reacted with acetic acid according to the following 14 equation: 15 𝐹𝑒2𝑂3+6𝐶𝐻3𝐶𝑂𝑂𝐻→2(𝐶𝐻3𝐶𝑂𝑂)3𝐹𝑒+3𝐻2𝑂 (4) 16 17 (a) (b) (c) (d) Fig. 12. Grout samples after exposition to chemical aggressive media: a) samples ERG-D after exposition to 60% H2SO4 (grooves are after strength tests); b) samples ERG-D after exposition to 10% CH3COOH, (c) samples ERG-D after exposition to 30% CH3COOH, (d) sample MRG-W after exposition to 10% CH3COOH. 4.2. Hardness 18 A graphical evaluation of the results of the hardness testing is presented in Fig. 13. In the lower part of 19 the graph, the percentage changes in hardness due to aggressive environment are shown in 20 comparison with reference samples stored only in a laboratory environment. Samples with the HRG-D 21 and MRG-W binders increased their hardness when exposed to a sulphuric acid solution (this could be 22 due to the formation of sulphate neoplasms that filled the pores of the grout). Compared to the 23 reference filler, the samples with the newly formed solidification products (FHW1 and FHW2) achieved 24 higher hardness due to the higher degree of hardness of the filler component. Due to the more suitable 25 shape index of the particles, a better homogenisation of the mixture and, therefore, better 26 incorporation of the filler component in the polymer matrix was possible. It can be observed that the 27 action of both vapours and sulphuric acid solution increased the surface hardness of most grouts. This 28 is likely caused by the reacted surface layer, which filled the surface pores and thus increased the 29 surface hardness; this layer was evident in visual evaluation. When the epoxy specimen is dried 30 completely and reach a mass stabilization, a little amount of acid solution still remains in the specimen 31 16 [46]. For the sample with the reference binder exposed to acetic acid, the structure was completely 1 decomposed, and the hardness could not be determined at all. Surface hardness is important for 2 jointing grouts in chemically aggressive environments, as it can be concluded from higher hardness 3 values that the material will withstand mechanical stress when mechanical resistance is high. 4 Hardness, as well as abrasion resistance (especially in the lower part of the profile, see below 4.3), is 5 especially important for jointing grouts in sewer environments (which must withstand mechanical 6 cleaning, scrapers, water jets, damage caused by an introduced foreign sharp element, etc.) and 7 ensures they will not be damaged. It was showed by Zhang et al. [47] that hardness depends not only 8 on the degree of cure but also on the thermal history during curing process. Fillers that increase the 9 elastic modulus of epoxy composites increase the hardness of the composite – hardness is a function 10 of the relative filler or fibre volume and modulus [48]. 11 12 Fig. 13. Evaluation of the influence of a chemically aggressive environment on the surface hardness 13 of jointing grouts. 14 15 4.3. Abrasion resistance 16 Abrasion resistance was determined before and after exposure to a chemically aggressive 17 environment. The results of the determination of abrasion resistance show that the abrasion 18 resistance deteriorated due to the action of a chemically aggressive environment. From Fig. 14, it can 19 be seen that the greatest deterioration in abrasion resistance occurred in the HRG-D samples using 20 the reference quartz flour filler. The MRG-W sample with the reference filler was completely 21 degraded in the CH3COOH solution as described above, so the abrasion resistance could not be 22 determined at all. The results of all samples show that the exposure of the grouts to chemically 23 aggressive environments led to the deterioration of abrasion resistance. This is caused by the 24 degradation of surface layers due to surface damage, which became less resistant to abrasive stress; 25 thus, there was greater volume loss for the grouts. 26 17 Fig. 14. Evaluation of the influence of a chemically aggressive environment on the abrasion resistance of jointing grouts. 1 4.4. Flexural and compressive strength 2 Due to the direct action of the 60% solution and the vapours of the 96% sulphuric acid solution, the 3 three-point flexural strength increased in all samples (the most significant increase was recorded for 4 grouts with highly chemically resistant epoxy resin ERG-D). The grouts with the ERG-D and HRG-D 5 binders achieved strengths comparable to the reference filler when using solidification products as 6 filler (Fig. 15 and Fig. 16). The CH3COOH solution had a negative effect on the flexural strength of all 7 samples examined. The excellent parameters of epoxy adhesives may be modified by the 8 environment which often acts as a degrading agent [49]. The effect of sulphuric acid on epoxy resin 9 composites was also researched by Ribeiro et al. [50], who found that the flexural strength of epoxy 10 polymer concrete was only slightly affected by immersion in this solution, indicating good chemical 11 resistance to this type of aggressive environment. Mebarkia et al. [51] found that after one-month 12 immersion in chemical solutions with different pH levels, the flexural and compressive strength of 13 polymer concrete decreased with higher pH levels. The affecting of flexural strength and modulus 14 due to ageing was showed in the previous study [52], where both properties had an initial, steeper 15 decay and tended to stabilise later. 16 Epoxy is inherently brittle, and it has a low fracture toughness [37]. The load-deflection diagram from 17 the bending test is presented in Fig. 17 and the compressive strength test in Fig. 18. A depression to 18 the deflection of 0.5 mm was noted for all samples, except the sample MRG-W_REF. Region of 19 reduced tangent stiffness was recorded only with MRG-W grouts. The ultimate strength of ERG-D 20 and HRG-D specimens was recorded at the end of the linear part of the curve. Under compressive 21 stress, the loading of ERG-D and HRG-D samples were linear until the failure. For MRG-W samples, 22 nonlinearity was recorded in the area of maximum strength. Subsequently, the deformation 23 increased, while the force decreased until the sample's failure, in this case, the maximum strength, 24 did not correspond to the sample's failure. It is also evident from the diagrams that the MRG-W 25 jointing compound showed a lower modulus of elasticity. The stress concentration plays a major role 26 18 in the type of fracture. It may overshadow the strain rate effect on modulus of rupture in flexure, the 1 degree of nonlinearity, and the epoxy grout's overall response [53]. The elastic modulus and tensile 2 strength of epoxy-based adhesives decrease with the number of ageing cycles [54]. Previously, the 3 epoxy systems were exposed to 50 °C for 28 days, and this exposure led to a 15% increase of Tg, and 4 the flexural strength increased 32% due to the density increase of crosslinking [55]. Due to the direct 5 action of the 60% sulphuric acid solution, the compressive strength of the samples ERG-D and HRG6 D increased (the most significant increase occurred in the grouts with highly chemically resistant 7 epoxy resin ERG-D with a reference filler made of quartz flour). This increase, noticeable form Fig. 8 16, is due to the formation of small crystalline neoplasms in the porous structure resulting from the 9 direct action of H2SO4 on silicate compounds, which filled the pores and thus created a more compact 10 structure. The negative effect of 10% acetic acid solution on compressive strength was not 11 demonstrated. In the samples with the MRG-W resin used with the reference filler, the structure was 12 completely decomposed due to the action of CH3COOH (see Fig. 12d). 13 Fig. 15. Evaluation of the influence of a chemically aggressive environment on the flexural strength of jointing grouts. 19 Fig. 16. Evaluation of the influence of a chemically aggressive environment on the compressive strength of jointing grouts. 1 2 Fig. 17. Load-deflection diagram from the bending test. 3 4 20 1 Fig. 18. Load-deflection diagram from the compressive strength test. 2 3 4 4.5. Glass transition temperature 5 As can be seen from Fig. 19, it is clear that the type of filler used does not have a significant effect on 6 the glass transition temperature (Tg). Only the type of resin used has a fundamental influence. The 7 highest Tg values (approx. 70 °C) were reached by the water-compatible epoxy resin MRG-W, while 8 the lowest values were reached by the chemically resistant resin HRG-D (approx. 60 °C). As HRG-D 9 grouts can withstand temperatures of 60 °C, their use in sewers and chemical plants is therefore 10 possible. Lesser et al. [56] stated that reactions of epoxide groups with primary and secondary amines 11 are more favoured than the base catalysed epoxide etherification reaction. 12 13 Fig. 19. Glass transition temperature. 14 15 16 4.6. Dynamic viscosity 17 The results of dynamic viscosity are presented in Fig. 20. The highest value of the viscosity (149,000 18 mPa·s) was achieved with the mixture ERG-D containing a 40% solidification product FHW2 as the filler. 19 ERG-D resin also exhibited the highest viscosity of the three used. The reference grouts, in which the 20 quartz flour was used, showed the lowest viscosity due to the particle size, the specific surface area, 21 21 and the filler's shape index. The type of solidification products (FHW1, FHW2) did not significantly 1 affect the mixture's viscosity. It can also be seen from the results that the epoxy resins used influenced 2 the viscosities of the jointing grouts, the highest being achieved with ERG-D binder. The polymer 3 binders' viscosity is determined primarily by their composition (type of ER, type and number of 4 solvents, hardeners, and other additives). The rheology of epoxy resins was also investigated [57],[58], 5 providing information on viscosity changes along with the curing process. During the ER curing, the 6 molecular size increases, as does the crosslinking density, decreasing mobility and increasing the resin 7 system's viscosity [58]. 8 9 10 Fig. 20. Dynamic viscosity of the fresh polymer grouts 11 12 13 4.7. Study of microstructure 14 In the hardness test, the sample was loaded until the test tip of the cone was pressed into a depth of 15 2 mm. Subsequently, the created indentation was examined microscopically. By observing the 16 microstructure after pilot plant verification of the properties, it was proven that even with the action 17 of aggressive substances, there were no major changes compared to the reference sample. The 18 indentation profile of the test cone in the surface sample after the chemical resistance test in the 3D 19 model can be observed in Fig. 21 and Fig. 22. Regarding the evaluation of the acquired images, it can 20 be stated that the type of filler also influenced the shape of the indentation of the pressed cone in the 21 jointing grout. The type of aggressive medium also had an effect on the way the cone penetrated the 22 surface of the grout. The effect of the microstructure on the diffusion rate depends on the type of 23 epoxy composite: the type of epoxy resin and hardener, the epoxy to hardener ratio, and the type of 24 filler [59],[60]. 25 22 Fig. 21. Indentation profile of the test cone to the HRG-D REF sample surface after the chemical resistance test due to the action of CH3COOH in the 3D model. Fig. 22. Indentation profile of the test cone to the HRG-D FHW2 sample surface after the chemical resistance test due to the action of CH3COOH in the 3D model. The diameters of the indentation passing through the centre of the interleaved circle were measured 1 (Fig. 23). The picture also shows the method of failure near the indentation, around which small cracks 2 23 formed, which could be a source of further propagation of defects in the future due to the cyclic 1 mechanical stress of the grout. 2 Fig. 23. Measurement of test cone indentation diameters (HRG-D FHW2) after H2SO4 immersion. Fig. 24 shows the diameters and surface areas of indentation of the test tip into the surface of the test 3 sample for surface hardness determination after pilot plant verification in a chemically aggressive 4 environment. When the samples with the ERG-D resin were exposed to sulphuric acid and acetic acid, 5 the diameter of the test cone indentation increased for all types of fillers used in this test. Samples 6 with the HRG-D binder and reference filler behaved similarly. The FHW2 filler used in combination with 7 the HRG-D binder caused the indentation to have a smaller diameter compared to the sample not 8 exposed to aggressive media. Samples with the MRG-W binder, which were exposed to sulphuric acid, 9 had a larger indentation diameter compared to the reference sample. The MRG-W FHW2 sample had 10 a smaller indentation diameter compared to the reference sample. The sample with the reference 11 binder, exposed to acetic acid, experienced total decomposition of the structure; thus, the hardness 12 could not be determined at all. 13 24 1 Fig. 24. Diameters and areas of the indentation of the test cone tip into the surface of the examined 2 sample during the test of surface hardness determination – determined microscopically. 3 4 Fig. 25 shows the connection of the grout of the reference sample without chemical stress to the 5 underlying cat basalt (darker part). A strong contact zone between the basalt and the grout was 6 observed, with no larger air pores visible at the interface that could impair the cohesion between these 7 materials. 8 (a) (b) Fig. 25. The connection of the HRG-D grout to the cat basalt element: (a) magnification 6.4×; (b) magnification 16×. With SEM analysis, the filler (solidification products) was found to be evenly dispersed in the polymer 9 matrix. No clumps of filler or segregation were visible, and the contact zone between the filler and the 10 polymer matrix was cohesive. Images (Fig. 26) show the crystals in the filler and neoplasms formed by 11 acid and silicate-based filler's reaction. In Figures 26a and 26b, the grains of quartz flour, which 12 increase the chemical resistance, are marked in yellow. The degree of penetration of hydrochloric acid 13 into the grout's surface is shown with a red line. These images clearly show the unaffected and affected 14 part of the grout with HCl. Fig. 26c shows pores in the grout whose size is between 10-80 μm. Some 15 31 [18] M. Safiuddin, M.Z. Jumaat, M.A. Salam, M.S. Islam, R. Hashim, Utilization of solid wastes in 1 construction materials, Int. J. Phys. Sci. 5 (13) (2010), pp. 1952–1963. 2 [19] B. Vacenovska, V. Cerny, R. Drochytka, B. Urbanek, E. Vodickova, J. Pavlikova, V. Valko, Verification 3 of the possibility of solidification product made of neutralization sludge use in the building industry, 4 Procedia Engineering 57 (2013), pp. 1192–1197, https://doi.org/10.1016/j.proeng.2013.04.150. 5 [20] T. Žlebek, J. Hodul, R. Drochytka, Polymer based grout with specially treated hazardous waste, IOP 6 Conference Series: Materials Science and Engineering 549 (2019) 12030, https://doi:10.1088/17577 899X/549/1/012030. 8 [21] S. Zhao, B. Liu, Y. Ding, J. Zhang, Q. Wen, C. Ekberg, S. Zhang, Study on glass-ceramics made from 9 MSWI fly ash, pickling sludge and waste glass by one-step process, J. Clean. Prod. 271 (2020) 122674. 10 https://doi.org/10.1016/j.jclepro.2020.122674. 11 [22] A. Erdoğan, M.S. Gök, V. Koç, A. Günen, Friction and wear behavior of epoxy composite filled with 12 industrial wastes, J. Clean. Prod. 237 (2019) 117588, https://doi.org/10.1016/j.jclepro.2019.07.063. 13 [23] H.M. Jafer, W. Atherton, M. Sadique, F. Ruddock, E. Loffill, Development of a new ternary blended 14 cementitious binder produced from waste materials for use in soft soil stabilisation, J. Clean. Prod. 172 15 (2018), pp. 516–528, https://doi.org/10.1016/j.jclepro.2017.10.233. 16 [24] Y. Pan, J. Rossabi, C. Pan, X. Xie, Stabilization/solidification characteristics of organic clay 17 contaminated by lead when using cement, J. Hazard Mater. 362 (2019), pp. 132–139, 18 https://doi.org/10.1016/j.jhazmat.2018.09.010. 19 [25] B. Dohnálková, R. Drochytka, J. Hodul, New possibilities of neutralisation sludge solidification 20 technology, J. Clean. Prod. 204 (2018), pp. 1097-1107, https://doi.org/10.1016/j.jclepro.2018.08.095. 21 [26] V. Massardier, P. Moszkowicz, M. Taha, Fly ash stabilization-solidification using polymer-concrete 22 double mastrices, Eur. Polym. J. 33 (7) (1997), pp. 1081–1086, https://doi.org/10.1016/S001423 3057(96)80250-3. 24 [27] C. Vipulanandan, S. Krishnan, Solidification/Stabilization of phenolic waste with cementitious and 25 polymeric materials, J. Hazard. Mater. 24 (2-3) (1990), pp. 123–136, https://doi.org/10.1016/030426 3894(90)87004-2. 27 [28] R.J.C. Carbas, E.A.S. Marques, L.F.M. Da Silva, A.M. Lopes, Effect of cure temperature on the glass 28 transition temperature and mechanical properties of epoxy adhesives, The Journal of Adhesion 90 29 (2014), pp. 104-119, https:// 10.1080/00218464.2013.779559. 30 [29] S. Le Craz, R.A. Pethrick, Solvent effects on cure 1-benzyl alcohol on epoxy cure, Int. J. Polym. 31 Mater. 60 (7) (2011), pp. 441-455. 32 [30] J. Ding, G. Sun, B. Liu, Synthesis of rubber vulcanization accelerator n-cyclohexyl-233 benzothiazolesulphenamide with crude 2-mercaptobenthiazole, Speciality Petrochem. 25 (2008), pp. 34 47-50 35 [31] J.L. Chen, F.C. Chang, Phase separation and melting behavior in poly(ε-caprolactone)-epoxy blends 36 cured by 3,3′-dimethylmethylene-di(cyclohexylamine), J. Appl. Polym. Sci. 89 (2003), pp. 3107-3114, 37 https://doi.org/10.1002/app.12499. 38 [32] J.M. Kenny, A. Apicella, L. Nicolais, A model for the thermal and chemorheological behavior of 39 thermosets. I: Processing of epoxy‐based composites, Polym. Eng. Sci. 1989 29 (1989), pp. 973-983. 40 32 [33] C. Lanzerstorfer, Residue from the chloride bypass de-dusting of cement kilns: Reduction of the 1 chloride content by air classification for improved utilisation, Process Saf. Environ. Prot. 104 (A) (2016), 2 pp. 444–450, https://doi.org/10.1016/j.psep.2016.06.010. 3 [34] J. Hodul, L. Mészárosová, T. Žlebek, R. Drochytka, Z. Dufek, Impact of Aggressive Media on the 4 Properties of Polymeric Coatings with Solidification Products as Fillers, Coatings 9 (12) (2019) 793, 5 https://doi.org/10.3390/coatings9120793. 6 [35] K. Shi-Cong, P. Chi-Sun, A novel polymer concrete made with recycled glass aggregates, fly ash and 7 metakaolin, Constr. Build. Mater. 41 (2013), pp. 146-151, 8 http://dx.doi.org/10.1016/j.conbuildmat.2012.11.083. 9 [36] K.T. Varughese, B.K. Chaturvedi, Fly ash as fine aggregate in polyester based polymer concrete. 10 Cem. Concr. Compos. 18 (1996), pp. 105–108, https://doi.org/10.1016/0958-9465(95)00006-2. 11 [37] S. Sugiman, I.K.P. Putra, P.D. Setyawan, Effects of the media and ageing condition on the tensile 12 properties and fracture toughness of epoxy resin, Polymer Degradation and Stability 134 (2016), pp. 13 311-321, https://doi.org/10.1016/j.polymdegradstab.2016.11.006. 14 [38] M. Vyšvařil, M. Rovnaníková, Sulfuric acid attack on various types of fine grained concrete, Adv. 15 Mat. Res. 1100 (2015), pp. 101–105, https://doi.org/10.4028/www.scientific.net/AMR.1100.101. 16 [39] EN 13892-3:2014, Methods of test for screed materials - Part 3: Determination of wear resistance 17 – Böhme, European Committeefor Standardization (CEN), Brussels, Belgium, 2014. 18 [40] EN 12808-3, Grouts for tiles. Determination of flexural and compressive strength, European 19 Committee for Standardization (CEN), Brussels, Belgium, 2008. 20 [41] P. Kalenda, Chemical-resistance values of epoxy resins hardened with polyamines, Pigment & 21 Resin Technology 30 (3) (2001), pp. 150–158, https://doi.org/10.1108/03699420110390797. 22 [42] A. Wegmann, Chemical resistance of waterborne epoxy/amine coatings, Prog. Org. Coat. 32 (1–4) 23 (1997) 231–239, https://doi.org/10.1016/S0300-9440(97)00062-3. 24 [43] H.G. Cooke, A.R. Strohscher, W.F. McWhorter, Chemical resistance of epoxy resins, Industrial and 25 Engineering Chemistry 56 (5) (1964), pp. 38–41, https://doi.org/10.1021/ie50653a005. 26 [44] M. Zhang, B. Sun, B. Gu, Accelerated thermal ageing of epoxy resin and 3-D carbon fiber/epoxy 27 braided composites, Composites Part A : Applied Science and Manufacturing 85 (2016), pp. 163-171, 28 https://doi.org/10.1016/j.compositesa.2016.03.028. 29 [45] G.L. de Oliveira, A.J.A. Gomez, M. Caire, M.A. Vaz, M.F. da Costa, Characterization of seawater and 30 weather aged polyurethane elastomer for bend stiffeners, Polym. Test. 59 (2017), pp. 290–295, 31 https://doi.org/10.1016/j.polymertesting.2017.02.012. 32 [46] M. Mozzami, M.R. Ayatollahi, A. Akhavan-Safar, L.F.M. da Silva, Experimental and numerical 33 analysis of cyclic aging in an epoxy-based adhesive, Polymer Testing 91 (2020) 106789, 34 https://doi.org/10.1016/j.polymertesting.2020.106789. 35 [47] J. Zhang, Y.C. Xu, P. Huang, Effect of cure cycle on curing process and hardness for epoxy resin, 36 eXPRESS Polymer Letters 13 (9) (2009), pp. 534-541, 37 https://doi.org/10.3144/expresspolymlett.2009.67. 38 33 [48] C.V. Srinvasa, K.N. Bharath, Impact and Hardness Properties of Areca Fiber-Epoxy Reinforced 1 Composites, J. Mater. Environ. Sci. 2 (4) (2011), pp. 351-356. 2 [49] M. Lettieri, M. Frigione, Effects of humid environment on thermal and mechanical properties of a 3 cold-curing structural epoxy adhesive, Constr. Build. Mater. 30 (2012), pp. 753-760, 4 10.1016/j.conbuildmat.2011.12.077. 5 [50] M.C.S. Ribeiro, C.M.L. Tavares, A.J.M. Ferreira, Chemical resistance of epoxy and polyester 6 polymer concrete to acids and salts, Journal of polymer engineering 22 (1) (2002), pp. 27–44, 7 https://doi.org/10.1515/POLYENG.2002.22.1.27. 8 [51] S. Mebarkia, C. Vipulanandan, Mechanical properties and water diffusion in polyester polymer 9 concrete, J. Eng. Mech. 121 (12) (1995), pp. 1359–1365, https://doi.org/10.1061/(ASCE)073310 9399(1995)121:12(1359). 11 [52] J.M. Sousa, J.R. Correia, S. Cabral-Fonseca, Durability of an epoxy adhesive used in civil structural 12 applications, Constr. Build. Mater. 161 (2018), pp. 618-633, 13 https://doi.org/10.1016/j.conbuildmat.2017.11.168. 14 [53] M.Y. Fard, Nonlinear inelastic mechanical behaviour of epoxy resin polymeric materials, A 15 dissertation presented in partial fulfilment of the requirements for the degree doctor of philosophy, 16 Arizona state university, August 2011, p. 192. 17 [54] M. Mozzami, M.R. Ayatollahi, A. Akhavan-Safar, L.F.M. da Silva, Experimental and numerical 18 analysis of cyclic aging in an epoxy-based adhesive, Polymer Testing 91 (2020) 106789, 19 https://doi.org/10.1016/j.polymertesting.2020.106789. 20 [55] P. Nogueira, C. Ramírez, A. Torres, M.J. Abad, J. Cano, J. López, et al., Effect of water sorption on 21 the structure and mechanical properties of an epoxy resin system, J. Appl. Polym. Sci. 80 (2001), pp. 22 71–80. 23 [56] A.J. Lesser, E. Crawford, The role of network architecture on the glass transition temperature of 24 epoxy resin, Journal of Applied Polymer Science 66 (1997), pp. 387-395. 25 [57] G. Liang, A. Garg, K. Chandrashekhara, K., V. Flanigan, S. Kapila, Cure characterization of pultruded 26 soy-based composites, J. Reinf. Plast. Compos. 24 (2005), pp. 1509-1520, 27 https://doi.org/10.1177/0731684405050387. 28 [58] G. Liang, K. Chandrashekhara, Cure kinetics and rheology characterization of soy‐based epoxy 29 resin system, Journal of Applied Polymer Science 102 (4) (2006), pp. 3168-3180, 30 https://doi.org/10.1002/app.24369. 31 [59] L. Li, M. Liu, S. Li, Morphology effect on water sorption in a thermoplastic modified epoxy system, 32 Polymer 45 (2004), pp. 2837-2842, https://doi.org/10.1016/j.polymer.2004.02.002. 33 [60] L. Li, Y. Yu, Q. Wu, G. Zhan, S. Li, Effect of chemical structure on the water sorption of amine-cured 34 epoxy resins, Corros. Sci. 51 (2009), pp. 3000-3006, https://doi.org/10.1016/j.corsci.2009.08.029. 35 [61] W.K. Loh, A.D. Crocombe, M.M.A. Wahab, I.A. Ashcroft, Modelling anomalous moisture uptake, 36 swelling and thermal characteristics of a rubber toughened epoxy adhesive, Int. J. Adhes. Adhes. 25 37 (2005), pp. 1-12. 38 39