**6. Conclusions**

A new P&P technology, coupling a PAT and a pump, has been studied on the basis of the experimental data of the pump working in direct or in inverse mode. A P&P is suitable in all cases when a certain amount of the water at the end of a water supply system, presenting a residual energy, has to be pumped to a second network at a higher pressure level. In such a case, P&P is a low cost technology allowing the recovery of the residual energy of the water in the first network and the increase of the pressure level of the water in the second network. Equations for P&P design have been presented, allowing a simple analysis of the P&P working conditions. Depending on the number of stages of the pumping, different operating conditions in the ancillary supply network can be obtained, in terms of water demand and pressure level. For the pump model used in the simulation, up to 40% of the water can be transmitted by the P&P to a pressure level 20% higher than the initial level. If the water to be transmitted is limited to 20%, the pressure level can be increased by the P&P by more than three times. This high potentiality is determined by the total efficiency of the P&P, even greater than 40%. The case study shows the viability of the system in different scenarios, considering different supply conditions as well as different values of turbined discharge. The results, depending on the network configuration and the considered scenario, show that the P&P system can completely replace an ordinary pumping system or supply the network when the available hydraulic power is high. The calculated annual energy saving demonstrates the economic relevance of the P&P plant. As a future implementation of this study, an experimental investigation on a laboratory prototype could be undertaken and the results would be used for the design of a full scale plant, to investigate the interactions with a WDN in a real situation.

**Author Contributions:** Lauro Antipodi and Oreste Fecarotta performed the experiments on the PAT and on the pump. Armando Carravetta, Oreste Fecarotta and Umberto Golia developed the mathematical model. Umberto Golia ran the simulations. Armando Carravetta and Oreste Fecarotta wrote the paper.

**Conflicts of Interest:** The authors declare no conflict of interest.


**5. Conclusions**

The above elements presented in the tables are not, "in principle", smart, but they can successfully create a "physical" sustainable built environment, oriented on human needs (including the needs of seniors), which can be entwined by a network of "virtual" connections, offering various "smart" facilities. Such a more "analogue" approach should prevent the exclusion of some social groups, e.g., seniors due to their lower proficiency in the digital world, or poorer citizens—due to insufficient access to new technologies (e.g., smartphones). The most important role of an architect in this context is:

Creating innovative ideas, but also researching and recognizing user needs, reliable, knowledge-based co-creation and co-designing with local communities, educating and persuading to new solutions—these are the architect's main roles and tasks in the context of contemporary challenges of the architecture of elderly-friendly sustainable smart cities. The undertaken topic is very broad and the content presented is only a voice in the discussion on the development of modern cities and the role of the architect in this aspect. The list of tasks involving the creation of an image anew is certainly not closed. It presents a holistic approach and may be the nucleus of further in-depth research on each constituent. In the future, it could provide an opportunity to develop design guidelines for architects, indicating at the same time their important role, which has been so far insufficiently exposed in the designing process of elderly-friendly sustainable smart cities.

**Funding:** This research has received no external funding.

**Conflicts of Interest:** The author declares no conflicts of interest.


**2. Methods**

Our study took place at El Triunfo Biosphere Reserve (ETBR) in Chiapas, Mexico. El Triunfo lays on the Sierra Madre de Chiapas Mountain range (Figure 1), which runs parallel to the Pacific coast. ETBR has an extension of 119,177 ha and its altitudinal range goes from 450 to 3000 meters above sea level (Arreola-Muñoz et al., 2004). Along this range, several climates occur; from hot humid in the low parts to temperate humid in the high lands (García, 2004). Several vegetation types are present, but upper parts are dominated by Cloud Forest (Rzedowski, 1978).

Fig. 1. Map showing El Triunfo Biosphere Reserve boundaries in Chiapas, southern Mexico.

(20-25 years old, 30-35 years old, and mature forest), and to determine the floristic

Our study took place at El Triunfo Biosphere Reserve (ETBR) in Chiapas, Mexico. El Triunfo lays on the Sierra Madre de Chiapas Mountain range (Figure 1), which runs parallel to the Pacific coast. ETBR has an extension of 119,177 ha and its altitudinal range goes from 450 to 3000 meters above sea level (Arreola-Muñoz et al., 2004). Along this range, several climates occur; from hot humid in the low parts to temperate humid in the high lands (García, 2004). Several vegetation types are present, but upper parts are dominated by Cloud Forest

Fig. 1. Map showing El Triunfo Biosphere Reserve boundaries in Chiapas, southern Mexico.

composition, vegetation structure, and species replacement along this gradient.

**2. Methods**

(Rzedowski, 1978).

We selected three study sites at ETBR, all localized in the core zone I, based on accessibility and disturbance history. We established sampling plots in three different successional stages according to the time elapsed since disturbance: 1.- Early growth, 20-25 years old (n = 10); 2. old growth 30-35 years old (n = 7); and 3.- Mature forest (n = 10).

We modified the method proposed by Ramírez-Marcial et al. (2001) to describe the physiognomy and structure of plant communities. We used 0.1 ha circular plots, with a radius of 17.8 m. Inside each circular plot we set smaller circular sub-plots (Figure 2). To avoid border effect, plots were placed at least 50 meters from the border. We randomly selected a point to be used as the center of the plot, and then we placed four straight lines 17.8 m long to each cardinal direction with marks at 5.6, 12.6 y 17.8 m. Then, beginning from the plot center, we traced a circle at the 5.6 m mark (circle "A"), another at the 12.6 m mark (circle "B"), and finally one at the 17.8 mark (circle "C"). Then we measured different vegetation features in each circle. Circle A: all trees with DBH ≥5 cm and ≤ 10 cm; circle B: all trees with a DBH >10 cm and ≤ 30 cm; circle C: all trees with a DBH > 30 cm.

Fig. 2. Plot sampling layout (modified from Ramírez-Marcial et al., 2001)


**3.5 Summary and perspectives**

With the development of nanotechnology, CP nanostructures integrated into advanced electronics have pursuit of better sensing systems during the past decade for fabricating miniaturizing state-of-the-art sensor devices, due to their continuously discovered unique chemical and physical characteristics, such as reversible signal transduction processes, low operating temperature, tunable sensitivity, and design flexibility. However, sensing technologies based on CPs still require significant incubation and device development. From the viewpoint of sensing activity, control over CP characteristics is necessary to improve sensitivity, selectivity, and stability to design advanced detection sensors. The desired set of physicochemical properties can be introduced into the CPs through the rational molecular design of specific receptors or judicious functionalization of the CP surface with a molecular recognition, leading to enhanced specificity via covalent attachments and reproducibility in response. Also, for large-scale synthesis, it is important to develop reliable routes to synthesize CP nanostructures and nanocomposites with controlled morphology. Of the exciting synthetic methods, the soft template approach is somewhat advantageous in both large-scale synthesis and size/shape control. Such improvements in their molecular structure and crystallinity and an increase in conjugation length are crucial for increasing room temperature conductivity. Another concern is that CPs are also susceptible to environmental perturbations such as moisture, heat, and light, which may degrade over time, even in dry, oxygen-free environments, and thus much attention must be paid to improving their long-term stability that is considered to be an important factor in pursuing high sensor reliability for an ever-increasing role in online environmental monitoring, industrial safety control, and security. Since the fabrication of nanostructured CPs, response time and sensitivity have experienced impressive improvements with great advances in sensor nanotechnology. However, selectivity is still a challenging task for detecting specific target analyte in a multi-analyte environment which hindered the widespread application of CP-based sensors. Besides, the demand for miniaturization has encouraged for designing portable sensor devices, lower power dissipation, and better device integration. In this sense, nanostructured CPs have considerable potential for fabricating miniaturized multi-sensing arrays by using microcontact printing, surface-directed assembly, site-specific polymerization, inkjet printing, etc. Interestingly, CPs are highly compatible with a flexible substrate, which opens up the possibility of realizing all-polymer electronics. From viewpoint, we believe that nanostructured CPs still have many unexplored potentials and will definitely play an expanding role in future sensor technology for exclusively designing of next-generation sensors involving high sensitivity, high reliability, multi-analyte determination, miniaturization, and structural flexibility due to their fascinating chemical/physical properties that are not available in other materials. Thus, it is anticipated that extensive future research studies into the development of flexible high-performance sensors by utilizing CPs will be expected in the near future.

**141**

**Author details**

Nagy L. Torad1

and Mohamad M. Ayad1,2\*

Technology (E-JUST), New Borg El-Arab City, Alexandria, Egypt

\*Address all correspondence to<EMAIL_ADDRESS>
and<EMAIL_ADDRESS>
provided the original work is properly cited.

1 Chemistry Department, Faculty of Science, University of Tanta, Tanta, Egypt

2 Institute of Basic and Applied Sciences, Egypt-Japan University of Science and

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

*Gas Sensors Based on Conducting Polymers DOI: http://dx.doi.org/10.5772/intechopen.89888* *Gas Sensors Based on Conducting Polymers DOI: http://dx.doi.org/10.5772/intechopen.89888*

*Gas Sensors*

**3.5 Summary and perspectives**

Novel low-humidity sensors were investigated by the in situ photopolymerization of PPY/Ag/TiO2 nanoparticle composite thin film coating on QCM [224]. Room temperature highly sensitive sensors with short response/recovery time for humidity based on GO/SnO2/PANI and PANI-GO coating on QCM were explored by Zhang et al. [225, 226]. The adsorption process of water molecules on QCM senor was carefully discussed using Langmuir adsorption isotherm model.

With the development of nanotechnology, CP nanostructures integrated into advanced electronics have pursuit of better sensing systems during the past decade for fabricating miniaturizing state-of-the-art sensor devices, due to their continuously discovered unique chemical and physical characteristics, such as reversible signal transduction processes, low operating temperature, tunable sensitivity, and design flexibility. However, sensing technologies based on CPs still require significant incubation and device development. From the viewpoint of sensing activity, control over CP characteristics is necessary to improve sensitivity, selectivity, and stability to design advanced detection sensors. The desired set of physicochemical properties can be introduced into the CPs through the rational molecular design of specific receptors or judicious functionalization of the CP surface with a molecular recognition, leading to enhanced specificity via covalent attachments and reproducibility in response. Also, for large-scale synthesis, it is important to develop reliable routes to synthesize CP nanostructures and nanocomposites with controlled morphology. Of the exciting synthetic methods, the soft template approach is somewhat advantageous in both large-scale synthesis and size/shape control. Such improvements in their molecular structure and crystallinity and an increase in conjugation length are crucial for increasing room temperature conductivity. Another concern is that CPs are also susceptible to environmental perturbations such as moisture, heat, and light, which may degrade over time, even in dry, oxygen-free environments, and thus much attention must be paid to improving their long-term stability that is considered to be an important factor in pursuing high sensor reliability for an ever-increasing role in online environmental monitoring, industrial safety control, and security. Since the fabrication of nanostructured CPs, response time and sensitivity have experienced impressive improvements with great advances in sensor nanotechnology. However, selectivity is still a challenging task for detecting specific target analyte in a multi-analyte environment which hindered the widespread application of CP-based sensors. Besides, the demand for miniaturization has encouraged for designing portable sensor devices, lower power dissipation, and better device integration. In this sense, nanostructured CPs have considerable potential for fabricating miniaturized multi-sensing arrays by using microcontact printing, surface-directed assembly, site-specific polymerization, inkjet printing, etc. Interestingly, CPs are highly compatible with a flexible substrate, which opens up the possibility of realizing all-polymer electronics. From viewpoint, we believe that nanostructured CPs still have many unexplored potentials and will definitely play an expanding role in future sensor technology for exclusively designing of next-generation sensors involving high sensitivity, high reliability, multi-analyte determination, miniaturization, and structural flexibility due to their fascinating chemical/physical properties that are not available in other materials. Thus, it is anticipated that extensive future research studies into the development of flexible high-performance sensors by utilizing CPs will be expected

**140**

in the near future.


**1. Introduction**

Polymeric composites are all around us. The addition of nanofillers to polymers has opened pathways for designing materials with improved functionalities. The synergistic effects of each component can result in better mechanical properties, thermal or electrical conductivity, and enhanced optical properties. The wide range of applications, spanning diverse fields such as civil engineering (building and constructions), electronics, biomedical materials, etc.,

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

renders this kind of materials essential for our daily life. The simplest structure of a composite is the one consisting of a polymeric matrix in which a solid filler is dispersed. The logic behind this combination is the ability to manipulate the composite properties as function of those of the individual components and the interfacial bonding [1]. However, even at this very simple level, the system can be considered as quite complex. In particular, the geometrical shape of the filler as fibers, platelets, and particles (respectively approached as 1-, 2-, and 3-dimensional objects) is pivotal in determining the final properties. Many studies have been dedicated in the past to understand these features and to develop physical models that are able to predict the properties as a function of the structure [2–8].

Furthermore, the same kind of reversible chemistry can be also applied in solution [20–22] where the crosslinking yields gels of different nature finding applications in very popular fields such as biomedical products. It must also be stressed that very recently particular attention has been paid to a new research field, still in its infancy, dealing with the use of supramolecular polymer in composites [23, 24]. The overall concept, stemming from the use of reversible interaction for the polymer backbone, nicely fits in the thermally reversible context although with even more remarkable loss of properties at relatively high temperatures. In the present chapter, we focus on the use of the Diels-Alder (DA) reaction as a modification toolbox for nanocomposites. While presenting a general overview of the recent literature, we aim to highlight the strategic chemical modification routes and, whenever possible, the added value of such strategy for the properties of the final composite. Other kinds of "click"

Thermoreversible Polymeric Nanocomposites http://dx.doi.org/10.5772/intechopen.80218 147

reactions are also possible, the reader being referred to recent works in the field [25].

The use of Diels-Alder chemistry as a modification tool for composite materials stems from the peculiar characteristics of this reaction. The choice to proceed with or without catalyst at relatively mild temperatures as well as the intimate connection between the forward (DA) and reverse, i.e., retro Diels-Alder (rDA) reactions and the structure of the diene and dienophile render this reaction ideal in terms of being able to control its decrosslinking as a function of temperature. As a consequence, many efforts have been reported in the use of DA to decorate various types of fillers including carbon nanotubes (CNT) [20, 26] and silica [27, 28]. In particular, CNT represent a popular choice (**Figure 2**) in view of their increasing availability and the kaleidoscopic variety of properties they potentially endow the composite with (electrical

Functionalization of CNT improves their dispersion in polymer matrices and also improves the processability of the nanocomposites. The DA reaction has a clear effect on the debundling of CNT [29] and also on their dispersion in polymeric matrixes [33]. The mechanical property enhancement is due to two mechanisms: the fillers act as (additional) crosslink points while also serving as stress-transfer points, distributing the stress to the polymer matrix uniformly. In both cases, the key feature is the improved adhesion at the interface between filler and matrix [34]. It is also noteworthy how CNT can act as both diene and dienophile in the DA reaction, respectively, with maleimide and furan groups [30]. As these reactions are mainly aimed at introducing functional groups on the CNT surface, this testifies the versatility of the approach even if in some cases side reactions might be present [19] and there is no mention of the reversibility or its use [31]. Some of the reported approaches towards incorporation of

In the present case, functionalized CNT and furfuryl amine are simply mixed with di-glycidylbisphenol A, yielding in one step, a multifunctional monomer that can be subsequently crosslinked via addition of a bis-maleimide. In this case, the self-healing behavior can be induced by near-infrared (NIR) irradiation (**Figure 4**). Scratch healing was demonstrated in the vicinity of the

CNT via DA clearly indicate relatively easy synthetic routes [35] (**Figure 3**).

**2. Chemical strategies for the insertion of DA groups in**

**nanocomposites**

conductivity, strength, and shape memory).

One of the challenges in nanocomposites is the nanoscale dispersion and distribution of the filler, which can be achieved by chemical modification of the filler surface. During the last three decades, many works have been focusing on a relatively novel concept, i.e., on the use of a covalent, yet thermally reversible, linkage between the filler and the matrix. On the one hand, this fits the general idea that (thermally) reversible linkages between the components could significantly improve some mechanical characteristics, such as impact properties. This can be achieved also by using relatively weaker interaction forces, such as hydrogen bonding. On the other hand, the use of covalent, and yet reversible bonds, might significantly help in achieving the same goal while avoiding any significant compromise on the strength of the final material [9, 10]. Indeed, among all possible thermoreversible interactions, only covalent bonds can be defined as relatively strong (more than a few kcal/mol) and metal free (**Figure 1**).

Hydrogen bonding [11–14] and ionic interactions [9] have been often used as thermally reversible interactions for composites of different kinds. One of the main driving forces behind the use of such a strategy is the presence of special end properties. For example, the dynamic nature of thermally reversible interactions (as a function of temperature) endows composites with self-healing behavior [11, 13, 15–17] and shape-memory characteristics [18, 19].

**Figure 1.** Schematic representation of different kinds of thermally reversible interactions.

Furthermore, the same kind of reversible chemistry can be also applied in solution [20–22] where the crosslinking yields gels of different nature finding applications in very popular fields such as biomedical products. It must also be stressed that very recently particular attention has been paid to a new research field, still in its infancy, dealing with the use of supramolecular polymer in composites [23, 24]. The overall concept, stemming from the use of reversible interaction for the polymer backbone, nicely fits in the thermally reversible context although with even more remarkable loss of properties at relatively high temperatures. In the present chapter, we focus on the use of the Diels-Alder (DA) reaction as a modification toolbox for nanocomposites. While presenting a general overview of the recent literature, we aim to highlight the strategic chemical modification routes and, whenever possible, the added value of such strategy for the properties of the final composite. Other kinds of "click" reactions are also possible, the reader being referred to recent works in the field [25].


Distal obstruction is diagnosed by probing and then syringing, and if it refluxes through the other punctum, it indicates that there is distal obstruction. If there is reflux through the same punctum, then there is canalicular or common canalicular stenosis which can be confirmed by gentle probing. Where the sac becomes the duct, is the site most common for distal obstruction. EDCR may be offered to patients with a functional blockage where there is free flow on syringing but a nonfunctioning pump system on scintigraphy. Lester-Jones Pyrex tube is required only in extensive bi-canalicular obstruction on failure of forced probing and silicone intubation.

## **10. Surgical technique**

**Figure 11.** A diagrammatic sagittal section showing the anatomy of the lacrimal sac in relation the frontal process of the

sac is drawn open. The lacrimal sac then contracts to its original volume, and the tears are

Topical local anesthetic drops are placed in the eye followed by dilatation of the upper and lower puncta with punctum dilator followed by passage of Bowman probe through the dilated punctum and angled medially (**Figure 12**). A slight resistance may be felt as a "soft stop" when the probe enters the common canaliculus, and there is a "hard stop" when it touches the medial wall of the sac. Subsequently, the probe is angled vertically down to feel whether there is any sac pathology or distal obstruction. Fine obstructing membranes causing proximal obstruction can be found at the medial aspect of the upper and lower canaliculi when viewed with rigid

maxilla anteriorly and the uncinate process posteriorly.

132 Endoscopy - Novel Techniques and Recent Advancements

pushed down the nasolacrimal duct.

**9. Preoperative assessment**

**Figure 12.** Picture of Bowman probes.

Nasal decongestion is performed with neuropatties and infiltration with lidocaine and adrenaline, and then, a 15 scalpel blade is used for mucosal incisions horizontally 1 cm superior, commencing 3 mm posterior to axilla of the middle turbinate and moving forward 1 cm onto the frontal process of maxilla. The blade is then turned vertically and incision is made about two thirds of the vertical height of middle turbinate, stopping above the insertion of inferior turbinate into lateral nasal wall. The blade is then turned horizontally, and the inferior insertion commenced at the insertion of the uncinate process and brought anteriorly to meet the vertical incision (**Figure 14**).

The mucosal flap is elevated using a Freer's dissector suction (Storz, Germany) to expose and identify the junction hard frontal process of maxilla and the soft lacrimal bone. The thin

avoided by using a diamond burr that may cause light contact with it as compared to a cutting

Endoscopic Dacryocystorhinostomy http://dx.doi.org/10.5772/intechopen.81831 135

Next, the inferior punctum is dilated with a punctum dilator, and a Bowman's canalicular probe is passed into the sac (**Figure 16**). If the tip of the probe is not seen to move behind the thin sac wall, the probe is not in the lumen. For complete marsupialization of the sac, it is exposed and incised vertically with a DCR mini-sickle knife (Medtronic Xomed, USA) and eventually an upper and lower releasing incisions made with Bellucci scissor (Storz, Germany) on the posterior flap which is rolled out flat on the lateral nasal wall. To avoid secondary intention healing and reduce the formation of granulation tissue and scarring,

**Figure 16.** Intraoperative endoscopic view showing a right dacryocystorhinostomy and wide exposure of the nasolacrimal sac with visible end of Bowman's canalicular probe with removal of agger nasi cell exposing the frontal recess.

**Figure 17.** Intraoperative endoscopic view showing right dacryocystorhinostomy with stent and ligar clips in situ in an

adult patient presenting with unresolving tearing.

burr that will remove the bone faster but with significant damage to the wall.

**Figure 14.** A zero degree endoscopic view of the left lateral nasal wall showing the maxillary line and uncinate process (A) and a diagrammatic illustration (B) showing the anatomical relationship of lacrimal sac to the maxillary line, uncinate process, and middle turbinate.

lacrimal bone is 2 to 5 mm wide anterior to the insertion of the uncinate process where the dissection ends. The soft lacrimal bone is elevated and removed away from the posteroinferior region of the sac using a round knife (Storz, Germany) [11].

The lower portion of the frontal process of the maxilla is removed using a forward-biting Hajek Kofler punch (Storz, Germany; **Figure 15**). During the removal of the hard lacrimal bone, the tip of the punch is used carefully to push the lacrimal sac away from it to expose the anteroinferior portion of the lacrimal sac. Bony removal is performed as far superiorly as possible until it becomes too thick for the punch to engage. The rest of the thick bone up to the superior mucosal incision is removed using a 15-degree curved 2.9 mm rough diamond burr (Medtronic Xomed, Jacksonville, Florida, USA) attached to the micro-debrider (Jones, 1998). Eventually as the sac is followed superiorly above the axilla of the middle turbinate, an agger nasi cell is approached and the frontal recess is exposed on removing it. Damage to the lacrimal sac wall is

**Figure 15.** Intraoperative endoscopic view showing right DCR with initial removal of the thin frontal process of maxilla with Hajek Kofler sphenoid punch and subsequently the superior hard bone with a microdrill.

avoided by using a diamond burr that may cause light contact with it as compared to a cutting burr that will remove the bone faster but with significant damage to the wall.

Next, the inferior punctum is dilated with a punctum dilator, and a Bowman's canalicular probe is passed into the sac (**Figure 16**). If the tip of the probe is not seen to move behind the thin sac wall, the probe is not in the lumen. For complete marsupialization of the sac, it is exposed and incised vertically with a DCR mini-sickle knife (Medtronic Xomed, USA) and eventually an upper and lower releasing incisions made with Bellucci scissor (Storz, Germany) on the posterior flap which is rolled out flat on the lateral nasal wall. To avoid secondary intention healing and reduce the formation of granulation tissue and scarring,

**Figure 14.** A zero degree endoscopic view of the left lateral nasal wall showing the maxillary line and uncinate process (A) and a diagrammatic illustration (B) showing the anatomical relationship of lacrimal sac to the maxillary line, uncinate

lacrimal bone is 2 to 5 mm wide anterior to the insertion of the uncinate process where the dissection ends. The soft lacrimal bone is elevated and removed away from the posteroinferior

The lower portion of the frontal process of the maxilla is removed using a forward-biting Hajek Kofler punch (Storz, Germany; **Figure 15**). During the removal of the hard lacrimal bone, the tip of the punch is used carefully to push the lacrimal sac away from it to expose the anteroinferior portion of the lacrimal sac. Bony removal is performed as far superiorly as possible until it becomes too thick for the punch to engage. The rest of the thick bone up to the superior mucosal incision is removed using a 15-degree curved 2.9 mm rough diamond burr (Medtronic Xomed, Jacksonville, Florida, USA) attached to the micro-debrider (Jones, 1998). Eventually as the sac is followed superiorly above the axilla of the middle turbinate, an agger nasi cell is approached and the frontal recess is exposed on removing it. Damage to the lacrimal sac wall is

**Figure 15.** Intraoperative endoscopic view showing right DCR with initial removal of the thin frontal process of maxilla

with Hajek Kofler sphenoid punch and subsequently the superior hard bone with a microdrill.

region of the sac using a round knife (Storz, Germany) [11].

process, and middle turbinate.

134 Endoscopy - Novel Techniques and Recent Advancements

**Figure 16.** Intraoperative endoscopic view showing a right dacryocystorhinostomy and wide exposure of the nasolacrimal sac with visible end of Bowman's canalicular probe with removal of agger nasi cell exposing the frontal recess.

**Figure 17.** Intraoperative endoscopic view showing right dacryocystorhinostomy with stent and ligar clips in situ in an adult patient presenting with unresolving tearing.

**12. Revision EDCR**

**13. Postoperative care**

**14. Outcome of surgery**

**Figure 19.** Endoscopic view of a patent left DCR at 6 months postsurgery.

**14.1. Complications**

Since the bone along the lateral nasal wall has already been removed in primary DCR, revision EDCR is therefore much easier procedure to perform. The size of the lacrimal duct is of importance in revision EDCR. For a normal sized sac, the success rate is high (89%) compared to low rates in scared condition where limited amount of lacrimal mucosa can be marsupialized. The agger nasi mucosa can be utilized as free graft functional mucosa to surround the

Endoscopic Dacryocystorhinostomy http://dx.doi.org/10.5772/intechopen.81831 137

The nasal spacer is removed the following morning. Patients must irrigate their nose with saline at least twice a day, and clinic visit was scheduled 1 week later and intranasal debris was removed then. The silastic tubing is removed in about 4 weeks postsurgery. Exposed tubing at the medial canthus is cut with scissors and the stent is withdrawn through the nose.

During surgery, sufficient opening from the lacrimal sac into the nose is made but the final

Complications of EDCR can be divided into intraoperative and early or late postoperative. Early postoperative (up to 1 month) complications include hemorrhage, crusting, perirhinostomy granuloma, transnasal synechia, and periorbital emphysema (**Figure 20**). Most of the

size of the healed surgical ostium is 1 to 2 mm in diameter on average (**Figure 19**).

common canaliculus-sac junction in severe lacrimal sac stenosis and scarring.

In revision cases with scarring, the stent can be left in place even longer.

the lacrimal sac lining and nasal mucosa are approximated well. Silastic lacrimal intubation tubes (O'Donoghue tubes) are placed through the upper and lower puncta and retrieved endonasally and secured with ligar clips (**Figure 17**) [3]. A loop of tubing is pulled in the medial canthus of the eye to ensure that the tubes are not tight before placing the ligar clips (**Figure 18**). Tight tubing loops at the medial canthus can cheese-wire through the punctum [5]. To hold the flaps in position intranasally, a square of Gelfoam (Pharmacia NSW, Sydney, Australia) or Merogel (Medtronic Xomed) is slid up the tubing and placed over the flaps [12].

Saline irrigation is commenced within 3 to 4 hours postsurgery, and broad spectrum antibiotics started for 5 days and eye drops for 3 weeks. Removal of the O'Donoghue tubes is performed in clinic at about 4 weeks postsurgery. Stents can be used for small fibrotic lacrimal sacs to make sure that the neo-ostium remains patent. The patient is reviewed for a further 18 months before discharge.

## **11. Laser-assisted DCR**

Laser was used exclusively in the early part of 1990s, and the site for osteotomy was the thinnest bone in the inferoposterior parts of the lacrimal fossa, corresponding to the brightest area in the nasal cavity by the transilluminator. Laser-assisted DCR success rate was around 78%, which was well lower than that of conventional technique. In late 1990s, osteotomy was performed with either a drill or a punch or both, and subsequently with time, the site moved to the level of medial canthus, which was anterior and superior to that of previous surgeries (**Figure 2**). When completed, the common internal punctum was visible on endoscopy, and the success rate improved to 92% [10].

In 65 patients with a mean follow-up of 74 months, it was reported that the success rate of endoscopic laser-assisted DCR has gradually declined over the years to 56%. Umapathy et al., in 2006, did not encourage the use of laser in endonasal DCR with epiphora [13].

## **12. Revision EDCR**

Since the bone along the lateral nasal wall has already been removed in primary DCR, revision EDCR is therefore much easier procedure to perform. The size of the lacrimal duct is of importance in revision EDCR. For a normal sized sac, the success rate is high (89%) compared to low rates in scared condition where limited amount of lacrimal mucosa can be marsupialized. The agger nasi mucosa can be utilized as free graft functional mucosa to surround the common canaliculus-sac junction in severe lacrimal sac stenosis and scarring.

## **13. Postoperative care**

the lacrimal sac lining and nasal mucosa are approximated well. Silastic lacrimal intubation tubes (O'Donoghue tubes) are placed through the upper and lower puncta and retrieved endonasally and secured with ligar clips (**Figure 17**) [3]. A loop of tubing is pulled in the medial canthus of the eye to ensure that the tubes are not tight before placing the ligar clips (**Figure 18**). Tight tubing loops at the medial canthus can cheese-wire through the punctum [5]. To hold the flaps in position intranasally, a square of Gelfoam (Pharmacia NSW, Sydney, Australia) or Merogel (Medtronic Xomed) is slid up the tubing and placed

**Figure 18.** Picture showing looping of the O'Donoghue tubing placed through the upper and lower puncta and retrieved

Saline irrigation is commenced within 3 to 4 hours postsurgery, and broad spectrum antibiotics started for 5 days and eye drops for 3 weeks. Removal of the O'Donoghue tubes is performed in clinic at about 4 weeks postsurgery. Stents can be used for small fibrotic lacrimal sacs to make sure that the neo-ostium remains patent. The patient is reviewed for a further

Laser was used exclusively in the early part of 1990s, and the site for osteotomy was the thinnest bone in the inferoposterior parts of the lacrimal fossa, corresponding to the brightest area in the nasal cavity by the transilluminator. Laser-assisted DCR success rate was around 78%, which was well lower than that of conventional technique. In late 1990s, osteotomy was performed with either a drill or a punch or both, and subsequently with time, the site moved to the level of medial canthus, which was anterior and superior to that of previous surgeries (**Figure 2**). When completed, the common internal punctum was visible on endoscopy, and

In 65 patients with a mean follow-up of 74 months, it was reported that the success rate of endoscopic laser-assisted DCR has gradually declined over the years to 56%. Umapathy et al.,

in 2006, did not encourage the use of laser in endonasal DCR with epiphora [13].

over the flaps [12].

endonasally.

18 months before discharge.

136 Endoscopy - Novel Techniques and Recent Advancements

**11. Laser-assisted DCR**

the success rate improved to 92% [10].

The nasal spacer is removed the following morning. Patients must irrigate their nose with saline at least twice a day, and clinic visit was scheduled 1 week later and intranasal debris was removed then. The silastic tubing is removed in about 4 weeks postsurgery. Exposed tubing at the medial canthus is cut with scissors and the stent is withdrawn through the nose. In revision cases with scarring, the stent can be left in place even longer.

During surgery, sufficient opening from the lacrimal sac into the nose is made but the final size of the healed surgical ostium is 1 to 2 mm in diameter on average (**Figure 19**).

**Figure 19.** Endoscopic view of a patent left DCR at 6 months postsurgery.

## **14. Outcome of surgery**

#### **14.1. Complications**

Complications of EDCR can be divided into intraoperative and early or late postoperative. Early postoperative (up to 1 month) complications include hemorrhage, crusting, perirhinostomy granuloma, transnasal synechia, and periorbital emphysema (**Figure 20**). Most of the

**Author details**

**References**

25-27

Balwant Singh Gendeh

2006;**61**(3):274-277

Surgery. 2010;**62**:S 68-S 80

of North America. 1994;**7**:393-406

Thieme Medical; 1989. pp. 99-102

Prague, Bangi, Selangor: Maxdorf; 2003

Butterworth Heinemann; 2004. pp. 123-133

Address all correspondence to<EMAIL_ADDRESS>
Pantai Hospital Kuala Lumpur, Kuala Lumpur, Malaysia

[1] Farahani F, Hashemian F, Fazlian MM. Endoscopic dacryocystorhinostomy for primary

Endoscopic Dacryocystorhinostomy http://dx.doi.org/10.5772/intechopen.81831 139

[2] Gendeh BS. Minimally invasive surgical approaches to the sphenoid sinus, sell, parasellar and clival region. Current and future perspectives. The Medical Journal of Malaysia.

[3] Gendeh BS. Advances in technology and its application to rhinology. In: Gendeh BS, editor. Clinical Atlas of Nasal Endoscopy. UKM Publication; 2009. pp. 114-117

[4] Gendeh BS. Extended applications of endoscopic sinus surgery and its reference to cranial base and pituiatary fossa. Indian Journal of Otolaryngology and Head & Neck

[5] Anuwar K, Gendeh BS. Tube extrusion and cheese wiring: Five years post dacryocystorhinostomy. Philippine Journal of Otolaryngology Head and Neck Surgery. 2011;**26**(2):

[6] Hurwitz JJ, Molgat Y. Nasolacrimal drainage system evaluation. Ophthalmology Clinics

[8] Kominek P, Cervenka S, Mullner K. The Lacrimal Diseases: Diagnosis and Treatment.

[9] Lang J. Clinical Anatomy of the Nose, Nasal Cavity and Paranasal Sinuses. New York:

[10] Lee TS, Shin JC, Woog JJ. Endoscopic dacryocystorhinostomy: An eastern perspective. In: Woog JJ, editor. Manual of Endoscopic Lacrimal and Orbital Surgery. Philadelphia:

[12] Trisbas A, Wormald PJ. Mechanical endonasal dacryocystorhinostomy with mucosal

[11] Olver J. Colour Atlas of Lacrimal Surgery. Oxford: Butterworth-Heinemann; 2002

flaps. Otolaryngologic Clinics of North America. 2006;**39**:1019-1036

[7] Hurwitz JJ. The Lacrimal System. Philadelphia: Lippincott-Raven Publishes; 1996

nasolacrimal duct obstruction. Saudi Medical Journal. 2007;**28**(10):1633-1613

**Figure 20.** Left periorbital emphysema postpowered endoscopic sinus surgery which resolved spontaneously.

later complications occur between 1 and 3 months of surgery and include surgical failure from impacted tubes, rhinostomy scarring, granuloma, synechia, and cheese wiring.

In inexperienced hands, the rate of complications from EDCR is greater and similar to those of endoscopic sinus surgery (ESS). Poor visualization during surgery due to excessive bleeding can result in major intraoperative complications namely blindness and CSF leak. In such circumstances, it is better to convert to an open technique. A branch of the sphenopalatine artery supplying the remnant of a partially resected middle turbinate can cause bleeding within 1 week of surgery.

Sometimes during bone removal to expose the lacrimal sac, orbital fat may be exposed, and in such situations, the orbital fat should be left alone to avoid injury to orbital contents namely blood vessels, nerves, and medial rectus muscle. Nasal or orbital infection following DCR is rare, and perioperative antibiotics are administered to avoid this complication.

The most common causes of surgical failure for EDCR are postoperative adhesions, which can result in obstruction of new ostium. Surgical insult to the middle turbinate mucosa should be avoided, and the anterior end of the turbinate resected to avoid it from nearing to the ostium. Postoperative adhesions are reduced by prior septal corrections.

## **Acknowledgements**

I wish to acknowledge with gratitude the co-operation of the Departments of Otorhinolaryngology Head Neck Surgery and Ophthalmology of the National University Malaysia Medical Faculty (UKMMC) and Pantai Hospital Kuala Lumpur (PHKL).

## **Author details**

Balwant Singh Gendeh

Address all correspondence to<EMAIL_ADDRESS>
Pantai Hospital Kuala Lumpur, Kuala Lumpur, Malaysia

## **References**

later complications occur between 1 and 3 months of surgery and include surgical failure

In inexperienced hands, the rate of complications from EDCR is greater and similar to those of endoscopic sinus surgery (ESS). Poor visualization during surgery due to excessive bleeding can result in major intraoperative complications namely blindness and CSF leak. In such circumstances, it is better to convert to an open technique. A branch of the sphenopalatine artery supplying the remnant of a partially resected middle turbinate can cause bleeding within 1

Sometimes during bone removal to expose the lacrimal sac, orbital fat may be exposed, and in such situations, the orbital fat should be left alone to avoid injury to orbital contents namely blood vessels, nerves, and medial rectus muscle. Nasal or orbital infection following DCR is

The most common causes of surgical failure for EDCR are postoperative adhesions, which can result in obstruction of new ostium. Surgical insult to the middle turbinate mucosa should be avoided, and the anterior end of the turbinate resected to avoid it from nearing to the ostium.

I wish to acknowledge with gratitude the co-operation of the Departments of Otorhinolaryngology Head Neck Surgery and Ophthalmology of the National University Malaysia Medical

rare, and perioperative antibiotics are administered to avoid this complication.

Postoperative adhesions are reduced by prior septal corrections.

Faculty (UKMMC) and Pantai Hospital Kuala Lumpur (PHKL).

from impacted tubes, rhinostomy scarring, granuloma, synechia, and cheese wiring.

**Figure 20.** Left periorbital emphysema postpowered endoscopic sinus surgery which resolved spontaneously.

week of surgery.

138 Endoscopy - Novel Techniques and Recent Advancements

**Acknowledgements**

[13] Umapathy N, Kalra S, Skinner DW, Dapling RB. Long-term results of endonasal laser dacrocystorhinostomy. Otolaryngology and Head and Neck Surgery. 2006;**135**(1):81-84

[14] Woog JJ. Endoscopic dacryocystorhinostomy and conjunctivodacryostorhinostomy. In: Woog JJ, editor. Manual of Endoscopic Lacrimal and Orbital Surgery. Butterworth

[15] Wormald PJ. Powered endoscopic dacryocystorhinostomy. The Laryngoscope. 2002;

[16] Wormald PJ. Powered endoscopic dacryocystorhinostomy. Otolaryngologic Clinics of

Heinemann; 2004. pp. 105-121

140 Endoscopy - Novel Techniques and Recent Advancements

North America. 2006;**39**:539-549

**112**(1):69-72

*Edited by Costin Teodor Streba, Dan Ionut Gheonea and Cristin Constantin Vere*

Endoscopic techniques are widely used for screening, diagnostic and therapeutic maneuvers in all groups of patients and for a large spectrum of complaints. The availability of basic iterations of endoscopic techniques made screening programs for various diseases viable in most parts of the world, while the advent of modern techniques opens new perspectives for rapid and correct diagnosis.

Going beyond normal human vision, innovative techniques opened the prospect of in-situ pathology. Endoscopic ultrasound has made incredible progress in recent years. Reaching the smaller orifices by endoscopy was a major step forward in the surveillance of previously inaccessible lesions.

Investigatory techniques were complemented by advances in therapy, with novel applications in many major areas of medicine.

Published in London, UK © 2019 IntechOpen © Bogdanhoda / iStock

Endoscopy - Novel Techniques and Recent Advancements

Endoscopy

Novel Techniques and Recent Advancements

*Edited by Costin Teodor Streba,*

*Dan Ionut Gheonea and Cristin Constantin Vere*


*4.3. Solution of the Multi-Period Design Problem and Final Feasibility Check*

In the final step, the multi-period design problem was solved. In order to calculate the TAC of the different design proposals, representative operating points and their respective normalized duration factors were defined. For the illustrative example, 11 representative operating points were assumed. Furthermore, it was assumed that each operating point had the same normalized duration factor. The different representative operating points and their normalized duration factors are given in Table A4 in Appendix B. As can be seen in Table A4, extreme values (which can be calculated with the values given in Table 3) were not considered as representative operating points since these values represent extreme situations, which are usually not representative for longer operating periods.

To reduce the computational complexity, the multi-period design problem was solved individually for each retrofit proposal. The problems were solved using the global solver BARON. Table 6 shows the TAC for the proposals in the reduced superstructure, the annual net savings (difference between the annual operating cost of the initial HEN and the TAC of the proposals), and the flexibility index. The annual operating cost of the initial HEN was used as a benchmark for the TAC of the different retrofit proposals and was calculated considering the cost data presented in Section 4.2. The annual operating cost of the initial network is 314,600 €/y. Additionally, the derived design values of the process-to-process HEXs of the different retrofit design proposals are shown in Tables A6–A10 in Appendix B. The results in Table 6 indicate that proposal MER is the most cost efficient.

**Table 6.** Total annualized cost, annual net savings, and flexibility index of the different retrofit design proposals in the reduced superstructure.

The flexibility index was calculated using the active set approach developed by Floudas and Grossman [39] and the results were verified by searching for the minimum direction matrix using simulated annealing as it is reported in [40]. In contrast to [40], the subproblem to find the maximum value for δ (maximum feasible variation of the uncertain parameters) in a given direction was obtained by utilizing BARON. The parameters that were used for the simulated annealing algorithm are shown in Table A11 in Appendix B.

Introducing different representative operating points to the problem increases the problem size and complexity, which may cause longer CPU times to guarantee the globality of the obtained solution. The solutions presented above were obtained on an Intel i7-6600 2.6 GHz processor with 16.0 GB RAM in 1800 s. It is worth mentioning, that globality (within default EpsA range of BARON: 1e-6) could be achieved in the case of proposals 2, 3, and 4. However, it should be mentioned that the optimality gap for proposal 1 was less than 500 €/y while the largest remaining optimality gap was 37,000 €/y in case of proposal MER. Although the remaining optimality gap of the proposal MER is considerable in comparison to the possible savings, the found local solution was considered satisfactory as it indicates that proposal MER is the most cost efficient.


*3.2. The Results of the Study of Leaching Mineral Wool-Based Geopolymer*

Similar studies of the leachability of geopolymers made from mineral wool have not been carried out. This is the first study to assess the environmental effects of mineral wool-based geopolymer. The leachability of metals depends on the pH of the material in which they are immobilised. The paper [58] presents the results obtained in the pH leaching test. It assesses the influence of pH changes and occurring processes on releasing heavy metals (Cd, Ni, Cr total, Pb, Cu and Zn) from metallurgical slag in a zinc smelter. Based on test results obtained in the pH test, a strong dependence of heavy metals leaching on the pH was found. The highest concentrations of the analysed elements were observed in an acidic environment. For most metals, except for lead, an increase in the pH of the solution caused a decrease in their concentration. Lead showed an upward trend of release under alkaline conditions. A sharp increase of copper leaching at pH 10.5 was also observed. Based on the study results, cadmium can be considered the most mobile element from metallurgical slag. Chromium indicated the lowest degree of release.

The results of the leachability test (Table 6) were compared to the highest permissible rates of pollution in sewage discharged into water or soil. The water extract of geopolymer binders (SG\_B and SG\_Al2O3) was characterised by a strongly alkaline pH value, exceeding the permissible values. The remaining ions are eluting themselves in amounts lower than the limit values. The analysis of the test results presented in Tables 7 and 8 proves that the geopolymer made of mineral wool meets the requirements in terms of chloride, sulphate, phosphorus, potassium, calcium, lithium, and barium concerning pollution indicators in wastewater discharged into water or soil. Unfortunately, the pH value and sodium content exceed the acceptable environmental standards.

Table 8 summarises the results of studies on the leachability of heavy metals from the geopolymer. The research results on the content of heavy metals in water extracts showed that the rock wool geopolymers in the comminute form meet all the requirements in this regard.

Table 9 shows the leachability of harmful substances from the monolithic geopolymer mortar. The obtained results were related to the leachability of monolithic cement mortars based on Portland cement. The geopolymer mortar was characterised by a high reaction value (pH > 11). The exceedance was also noted for barium, and its content exceeds four times the permissible value. However, the remaining substances do not exceed the allowable values of water and soil.

**Table 7.** Leachability of pollutants from ground rock wool-based geopolymer binders expressed as mg/L dry weight (except for pH).

BLQs \*—below the limit of quantification.

**Table 8.** Leachability of heavy metals (mg/L) from geopolymer rock wool binders in a comminated form.

**Table 9.** Leachability of harmful substances for monolithic rock wool geopolymer mortar, expressed in mg/L dry weight (except for pH).

The leachability of heavy metals from the monolithic form of geopolymers is presented in Table 10. The content of heavy metals in water extracts from geopolymer mortar did not exceed the permissible values. Therefore, it can be said that they do not pose a threat to the natural environment.

The rock wool and glass wool show different leachability performances for each ion because their base composition is very different [7]. Table 11 The chemical composition of rock wool and glass wool, determined by ICP-OES.

**Table 10.** Heavy metal content (mg/L) in water extracts for monolithic rock wool geopolymers.

**Table 11.** The chemical composition of rock wool (RW) and glass wool (GW), determined by ICP-OES [7].

Note: CVAAS represents "cold-vapor atomic absorption spectrometry".

The presented test results proved that it is possible to store rock wool in a landfill for non-hazardous and inert waste. However, too much barium in glass wool discriminates against it for storage in such landfills; therefore, it should be stored in a hazardous waste landfill. Moreover, the geopolymer is characterised by too high alkalinity due to the environmental requirements.

The proposed reuse of waste mineral wool in the form of a geopolymer is a solution that is beneficial for the environment, climate, human health, and economic reasons.

The results of the research on the quality of water extracts made of comminute geopolymer binders based on rock wool show that:

• sodium content was at the level of 2700 mg/L.

On the other hand, geopolymer products are used in the industry, such as PCI-Geofug geopolymer grout by Basf [59], GeoLite geopolymer mortar by Kerakoll [60], ASTRA GKB geopolymer concrete [61], also the geopolymer injection as a quick and non-invasive method of strengthening the ground. It is used in linear (infrastructure) and cubature construction (industrial, commercial, and residential). It has been successfully used in Western Europe and Scandinavia for over 40 years. Geopolymer is gaining popularity due to its exceptional performance parameters and convenience of use: speedy repair time and minimal nuisance during geoengineering works. Unfortunately, the results of the leachability test of hazardous substances and heavy metals do not pose a potential threat to the environment. However, a strongly alkaline reaction and the excess sodium content are open for further consideration. The authors will lower the alkaline reaction of geopolymer binders in further research steps. The geopolymerisation process requires the dissolution of the starting material in a high pH (alkaline) solution, and thus, pH values of fresh geopolymer pastes are usually 11.2–13.2 [37,38]. Like products based on Portland cement, the pH must not be too low due to reinforcement corrosions [55]. The concrete is acceptable for use, although the pH of the water extract is from 9 to 11 (Table 9). Due to environmental requirements, the value of the concrete solution is also too high, but not as high as in the case of the geopolymer solution. The authors do not know the pH of the mentioned above geopolymer products. The authors want to check out it is possible to lower the pH geopolymer add an acid component to it, but this will drastically reduce its strength. The authors will analyse this problem in the future. The problem is very significant in terms of the environment. In the future, the authors will decrease the alkalinity of wool-based geopolymers to 11.2 according to the suggestion of publication [25,42].

#### *3.3. The Fresh and Mechanical Results of Wool-Based Geopolymer*

The slump-flow of glass wool-based geopolymer fresh mortar with Al2O3 or bauxite was comparable and was about 13 cm (Figure 8). Whereas the slump flow of geopolymer mortar with rock wool was more significant by up to 3 cm. thus, the type of wool is essential for the rheological properties of fresh geopolymer. It has been noticed that geopolymers, due to their high viscosity value, are very resistant to segregation, which is undoubtedly their great advantage.

**Figure 8.** The view of slump-flow of glass wool-based geopolymer fresh mortar with Al2O3.

The geopolymer was characterised by high adhesion strength to the forms in which they stayed. The phenomenon of geopolymer adhesion was mentioned in the publication [18]. It was noticed that geopolymers show more adhesion than materials at the entrance to cement. This phenomenon may be due to work with the fibres or reinforcement of the geopolymer. Moreover, the geopolymers were highly viscous, especially with sodium-potassium water glass, which requires careful mechanical concentration. In Figure 9, pores in the structure of wool-based geopolymers are presented, probably from under dumping the sample. Despite this, geopolymers glass wool-based mortars with

Al2O3 (Figure 9) obtained an average compressive strength of 59 MPa and tensile strength of 4.5 MPa. The geopolymer with bauxite achieved about 51 MPa, and flexural strength 4.1 MPa. Thus, Al2O3 is a better additional glass wool-based geopolymer than bauxite.

**Figure 9.** The view of pores of glass wool-based geopolymer mortar with Al2O3.

The average compressive strength of their binders (tested on 20 mm × 20 mm × 160 mm samples, Figure 10) was about 20 MPa (in the case of glass wool-based geopolymer with bauxite). It was observed that samples of geopolymeric binders without aggregate participation are characterised by cracking and deformation of samples due to shrinkage. The reason was that the samples were too slender. The shrinkage value is greatly influenced by the geometry of the samples, especially without aggregate. The compressive strength of binders with AL2O3 was about 25 MPa.

**Figure 10.** The view of pores of glass wool-based geopolymer mortar with bauxite.

The average compressive strength of rock wool-based geopolymer mortar was about 62 MPa, and their compressive strength of binder was about 25 MPa and flexural strength 4.8 MPa. It was also noticed that the rock wool thickens better in the moulds, which translated into a higher value of their strength.

The studies [6,7] show that maximum compressive strengths of 48.7 and 30.0 MPa were measured for wool-based binders. The binder matrix consisted of aluminosilicate gel with partly dissolved mineral wool fibres. The maximum flexural strength was 13.2 MPa for GW and 20.1 MPa for RW. This study shows that high strength can be obtained without additional co-binders by activating alkali with sodium aluminate solution. Furthermore, the research carried out by the authors of this publication proved that it is possible to obtain the strength of the geopolymer, resistant to shrinkage deformation, but after modification of its composition. The latest achievement of the authors is a wool-based geopolymer with a strength of 100 MPa, which will be the subject of the following publication.

#### **4. Conclusions**

Due to the increasing necessity to reduce CO2 emissions and the energy consumption of buildings, the consumption of mineral wool in construction is increasing. Mineral wool is a waste material that meets the requirements for storage; however, it is not the direction to be followed when considering the future. In line with the closed-loop policy and the increasing need to reuse materials, the goal is to recycle them, also due to the decreasing availability of the waste storage area.

The carried-out research results proved that:

The compressive strength of geopolymer results [37] showed that the optimum NaOH concentration is 8 M. The geopolymer strength decreases with NaO concentration in the NaOH solution. As mentioned in the article, the geopolymerisation process requires the dissolution of the starting material in a high pH (alkaline) solution. Thus, the pH values of fresh geopolymer pastes are usually 11.2–13.2 [37,38]. Therefore, an attempt will be made to lower the wool-based geopolymer alkalinity to 11.2. Although it still does not meet the environmental requirements [1,57]. However, the problem needs future research.

In the following research steps, Al2O3 will be replaced with a waste material that predominantly contains the same compound to create a glass wool geopolymer from waste materials only.

Further modifications aim to replace the sand of geopolymer mortar with material derived from waste, in line with the goals of sustainable development and the protection of natural resources.

**Author Contributions:** Conceptualisation, B.Ł.-P., M.C. and D.S.; Methodology, B.Ł.-P., M.C. and D.S.; validation B.Ł.-P., M.C. and D.S.; formal analysis, B.Ł.-P., M.C. and D.S.; writing—original draft preparation, B.Ł.-P., M.C. and D.S.; writing—review and editing, B.Ł.-P., M.C. and D.S. All authors have read and agreed to the published version of the manuscript.

**Funding:** Publishing supported by the pro-quality grant: 03/030/RGJ21/0122; The Silesian University of Technology, Department of Building Processes and Building Physics, Faculty of Civil Engineering: BK-223/RB3/2022; The research of publication was funded by a subsidy allocated for 2021. The research reported in this paper was co-financed by the European Union from the European

Social Fund in the framework of the project "Silesian University of Technology as a Centre of Modern Education based on research and innovation" POWR.03.05.00-00-Z098/17.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest. The funders did not play any role in the design of the study plan; in collecting the resulting data, analysing its results, or interpreting data, and formatting the content of the manuscript or in the decision to publish the results of the study.