Forgotten Industrial Heritage: The Cement Factory from La Granja d’Escarp

Abstract

In the municipality of La Granja d’Escarp, for over thirty years, an important natural cement factory was in operation. In 1876, the Girona family, who were businessmen and bankers from Barcelona, opened the factory with modern industrial facilities. It included kilns, mills, and crushers, alongside warehouses, a small railway for internal transportation of the various materials used, and even a housing area for workers. The neighboring Ebro River allowed distribution by river transport at first. Later, with the use of railways, transport to consumption points was possible. This industrial complex became a center of significant importance in Catalonia in the production of cement, which was used for building hydraulic and civil works. During the first decade of the twentieth century, the factory stopped its activity and the facilities were abandoned. Nowadays, this industrial heritage site is in a state of neglect, without any kind of protection or maintenance. In turn, this has caused the collapse of some buildings in recent times and the loss of historical value of the architectural ensemble. We have carried out initial geomatic research, which has highlighted the constructive properties of the kilns. We have also tested five samples from different buildings using XRD and TGA/DSC, which showed the use of lime mortars in their construction. This is the first study to be carried out at this site, with the aim of showing the historical importance of the ensemble. The goal of the study was to highlight the value of this industrial heritage site and illustrate that it was once a pioneer in the production of natural cement and a driving force for Catalonia.

1. Introduction

During the nineteenth century, social, economic, and cultural changes occurred because of the industrialization process in the production sectors, driven by the industrial revolution. This historical change involved the transformation and loss of some traditional trades, mainly those related to agricultural work, in favor of the new opportunities offered by industry, resulting from the technological advances of the time. The emerging architecture in this historical context, as a reflection of the social and economic transformation, was also reinvented and evolved towards buildings that could host the new production systems [1].

This new industrial architecture was not limited to a single style, use, or construction typology. Consequently, both public and private architectural works varied widely. Some typological examples of this industrial architecture include the construction of mines, hydraulic canals, textile factories, hydroelectric power plants, steel complexes, cement factories, shipyards, warehouses, workers’ colonies, and wineries, among many others [2,3,4]. The value of industrial heritage is not only architectural. It goes beyond mere materiality and forms part of the collective memory of a never-before-seen historical moment [5]. These values surpass age, historical period, commemorative value, use, and newness [6]. They highlight the aspects that should be focused on and analyzed so that we can value heritage sites as places of influence, considering their building technology and the relationships between elements [7]. Historical issues bring into knowledge different layers of history that must overcome political issues [8]. These values must include ecological, social, economic, scientific, aesthetical, political, and other accepted social values [9].

In Europe, the first actions related to the protection and conservation of architectural heritage emerged in the mid-nineteenth century, led by architects such as Eugène-Emmanuel Viollet-le-Duc and John Ruskin, who took different approaches to the concept of restoration [10]. It was not until 1931 that guidelines for establishing the principles of conservation and restoration of historical monuments were set out in the Athens Charter [11,12]. Initially, the concepts of heritage protection and conservation were focused on material and immaterial cultural assets of cultural, historical, archeological, economic, social, and political significance for the people who inhabited a place [13]. Later, through the proposals of international organizations such as the International Committee for the Conservation of Industrial Heritage (TICCIH) (all the Acronyms are included in Appendix A) and the International Council on Monuments and Sites (ICOMOS), this concept was expanded and modified. This led to the current conception of protection, conservation, intervention, and enhancement of the architectural heritage of our environment [14]. Nevertheless, these terms have sparked debates in research fields, and studies have been needed to define them clearly and establish their limits [15,16]. The TICCIH has concluded that the remains of an industrial complex can contain historical, technological, social, architectonic, or scientific values, and all of them must be considered. The parameters of conservation have been widely discussed and improved over the years, and they must be continuously analyzed [17]. One aspect that should be carefully considered is the authenticity value of a heritage site [18]. The management of sites and the identification of approaches for improving their conservation for future societies are important factors in present conservation issues.

However, architectural heritage related to industrial architecture is still not sufficiently respected because its value is often intangible [19]. This impacts the protection, conservation, and recognition of industrial sites. To correctly identify the value of industrial heritage, proper studies must be carried out to help establish the right strategy [20]. Experiences of the valorization of industrial heritage vary throughout Europe [21]. To conserve industrial heritage sites, first, they must be correctly identified [22] and understood [23]. The recovery of sites that have been abandoned has been carried out through the conversion of existing spaces [24], to incorporate new functionalities [25,26]. Alternatively, such sites can be restored as places for the reinterpretation of industrial heritage [27]. The adaptation of existing buildings is a major strategy for the conservation of industrial heritage sites [28].

In Catalonia (Spain) and other countries, many industrial buildings have been converted into museums [29] or interpretation centers [30] to raise awareness, contextualize the buildings in their time, and maintain the historical, cultural, and technological legacy of previous eras. Some examples are the Museum of the Vidal y Sedó Workers’ Colony (Puig-Reig), the Museum of Science and Technology of Catalonia (Terrassa), the Cercs Thermal Power Station and Mining Museum (Cercs), and the Güell Colony (Santa Coloma de Cervelló). However, these initiatives are scarce, considering that there is extensive industrial heritage throughout the territory. Much of this heritage is still undervalued and requires urgent recognition and study by the administrations [31] to prevent its definitive loss [32,33].

Interventions in this type of building must consider various aspects [34], including the environment, for example, whether it is an urban, natural, mountainous, or fluvial setting [35]. Future uses and their sustainability [36] should be carefully studied, such as the impact of tourism on the area and its economic and cultural repercussions [37]. The productive role of the remains must be considered [38,39] and other uses, for example, housing [40]. Different strategies must be researched [41] and the creation of a database is fundamental [42]. Ultimately, in-depth research must be undertaken to develop the correct strategy to follow [43].

The use of digital tools [44] and other research technologies [45] to characterize a site will help to gain deeper knowledge of an area. Studies should consider the immediate surroundings and the surrounding area [46] to carry out a proper valuation. Inhabitants of the area must also be considered [47].

One industrial heritage site that we are aware of that is in a state of total abandonment is the natural cement factory in the Catalan municipality of La Granja d’Escarp, located in the region of Segrià (Lleida), bordering the Autonomous Community of Aragon (Figure 1). The location of the factory was no coincidence. It is in what was a highly rich coal mining area and it had a direct relationship with the river, which allowed transport of the product [48]. The factory helps to define the landscape of this important industrial area.

The industrial complex needs urgent intervention and action. Its study is justified by the following aspects:

• The territory where the remains of this industrial complex are located has historically been characterized by significant coal mining, which began in the mid-nineteenth century [49]. A unique feature of the lignite extracted from the mines was that it was accompanied by outcrops of clayey limestone (marl), an ideal stone for the manufacture of hydraulic binders [50];
• In 1876, the Barcelona banker Ignasi Girona Agrafel, owner for years of the concession of the Guadalupe mine in this coal area, began to manufacture natural cement in the factory. The two mining products were the reason for the considerable, growing economic progression of the territory [51]. Part of the coal extracted was used to calcinate limestone and operate machinery for its exploitation. The combination and links between the exploitation of both materials and the growth and expansion of the Girona family’s business allowed the construction of one of the most significant natural cement factories in Catalonia, which was in operation until 1920 [52];
• From the mid-nineteenth century (half a century earlier in England and France), natural cement, along with hydraulic lime, was the hydraulic binder par excellence to replace air lime mixed with pozzolans for hydraulic works or works that would be exposed to aquatic conditions. Subsequently, the latter was also replaced by Portland cement. However, for over a century, natural cement was the new paradigmatic binder not only for aquatic works but in all works where its performance, in terms of rapid setting time and resistance, was highly valued [53]. The production of this type of cement in Catalonia accounted for 60% of the total production in Spain for over a hundred years. This factory’s production was very important during the period that it was in operation [54];
• This natural cement became one of the main binders used in the development of most of the buildings constructed in and around Barcelona during the last decades of the nineteenth century and early twentieth century. This includes Antoni Gaudí’s Güell Palace, built in Barcelona between 1886 and 1890 [55].

The factory, which is the subject of this study, was the first to produce natural cement in the province of Lleida, and the first to appear in national mining statistics on cement production in 1877 [56]. The industrial complex is formed of several buildings and is fundamental to understand the typology of a cement and coal factory from the end of the nineteenth and start of the twentieth century. However, at present, this heritage is in a state of abandonment, without any kind of protection on maintenance, despite being included in the Archive of Architectural Heritage of Catalonia.

The aim of this study is to highlight the value of the industrial architectural heritage of the area and to provide the public administrations with the tools required to protect and preserve this industrial ensemble in the future. This is the first study of its kind to be carried out on this site. It is crucial to highlight the site’s important role in the history of construction in Catalonia. For this purpose, the existing built complex was studied using geomatic techniques applied to heritage (DP-UAV and TLS). The results were compared with the existing documentation, including historical sources and old photographs. In addition, we focused on the analysis of the site from the perspective of construction materials and analyzed some of the most representative mortars through mineralogical determination by DRX and TGA/DSC to enhance further detailed research [57,58] (Figure 2).

Section 2 of this paper describes the history of the site using historical sources and ancient photographs. Section 3 explains the tools used in this field research from a geomatic perspective. Section 4 identifies the analytical techniques used to characterize the samples obtained. Section 5 focuses on the limits of the study. Section 6 presents an analysis of the current situation of the case studied with the geomatic and material analysis tools. Section 7 presents proposals for future research and ongoing discussions about the site. Finally, Section 8 summarizes all the main aspects of the research and reflects on the loss of this industrial heritage.

2. History of the Factory

The industrial complex of La Granja d’Escarp is in the Mequinensa basin, a territory full of coal mines that were exploited through the granting of small concessions to industrialists and businessmen. Coal mining in this geographical enclave, which covered an area of approximately 500 km² between the territories of Catalonia and Aragon, continued for over 125 years.

Initially, the commercial interest of the businessman Ignasi Girona was only the lignite itself, but the presence of marlstone together with coal led to a new line of business. Consequently, part of the coal extracted was used as fuel for the natural cement calcination kilns and to feed the boilers of the steam engines that powered the grinding mechanism for the cement that was produced [60].

The factory facilities were built on the Catalan bank of the river Segre, just after the confluence of the Segre and Cinca rivers, and before flowing into the river Ebro [61,62]. The location was ideal. Clayey limestone was present, as was coal [63], which was confined between the layers of the extracted limestone. Both materials were of excellent quality.

In addition, the proximity of the River Segre, which was navigable all the way to the mouth of the River Ebro in the Mediterranean Sea, made up for the lack of good transport connections by land. To make it easier to bring the goods to the loading bay, a railway line of almost four kilometers was installed. This allowed wagons to travel from the limestone and coal extraction area to the river, passing through the kilns, milling, and sacking zones. The construction of this small transport system, using wagons, facilitated the dispatch of sacks or barrels of cement to the small boat that took the final product to the town of Tortosa in Tarragona. From there, the cement was transported by rail, heading south to Castellón and Valencia, or north to Tarragona and Barcelona [64,65].

In addition, the construction of a warehouse on the other side of the river allowed for local distribution of manufactured products in the Mequinensa region and nearby villages in Aragon by horse and carriage.

Alongside the installations for the manufacture of natural cement, other structures were built, including warehouses, stables for the animals, and a small building of the type traditionally known as “colonias”, with housing for up to 50 families of factory workers. In addition, a house was built for the engineer in charge of the operation (Figure 3 and Figure 4).

Internally, the factory site was organized on three levels, which were connected by the inclined planes of the small railway on which the wagons traveled. On the first level were the quarries and the mine, from where the wagons took the stone and coal to the loading mouth of the kilns. The second level was where the cooked stone came out, and this was taken to the third and final level, where the mill was located and the cement was put into sacks.

With the factory at full capacity, each kiln was unloaded twice a day and produced between 18 and 20 tons. For a long time, at least until 1885, only three kilns operated. However, it is known that at the beginning of the twentieth century, the factory had two batteries of four kilns each, placed in line. These batteries could all operate at the same time [66].

The furnaces were of the continuous vertical type, also known as vat furnaces. They were about five and a half meters high, and the ducts were about three meters in diameter, lined with refractory bricks (Figure 5). The batteries had a load-bearing structure of masonry made of masonry and ashlars, with slightly retaining walls. Each kiln had two unloading openings, except for the ends of the battery, which had three openings. There was a small roof on the front façade to protect the workers and the freshly fired material from the weather.

Initially, grinding was performed with vertical millstones moved by animals, but later a steam engine was installed, and the millstones were placed horizontally.

According to the data provided by the Estadística Minera yearbook, the cement produced at La Granja d’Escarp was a fast natural cement. Air lime was also produced, although the annual production quantities were small.

During the whole period of the factory’s activity, cement production fluctuated. It increased at times to coincide with the construction of important infrastructures in the territory, such as the railway link between Caspe and Reus, and it decreased notably at times of falling demand, when production barely reached a thousand tons a year. Even so, the factory was a benchmark in the manufacture of this binder for many years.

In 1906, the Guadalupe mine was exhausted. Consequently, for the calcination of the stone, waste coal was used from some new exploitations that the Girona family had in the province of Zaragoza. In 1908, the company, Carbonífera del Ebro, founded some thirty years earlier, became the property of the sons of the Barcelona industrialist Girona. It was then that this company took control of the La Granja d’Escarp mine and the Serós and Almatret mines, while the cement factory continued to operate.

3. Documents and Geomatic Works

3.1. Available Data and Techniques Applied

For this study, geomatic documents were used that were obtained from the web application of the Institut Cartogràfic i Geològic de Catalunya (ICGC) and other sources. In the first case, historical orthophotographs were used, as well as vector maps of the study area. In addition, a photogrammetric survey was carried out from an unmanned aerial vehicle (UAV) or a remotely piloted aerial vehicle platform (remotely piloted aircraft system, RPAS) and using a large-scale terrestrial laser scanner, with the support of terrestrial support points by means of a global navigation satellite system (GNSS). In summary, the following were used:

• Historical digital orthophotographs 1945 and 1956 (known as American flights), orthophoto 1945 (100 cm/px), and orthophoto 1956 (50 cm/px);
• Current orthophotography in force (2021), scale 1:2500 (25 cm/px);
• Vector mapping of the area, topographic base 1:5000;
• Terrestrial LiDAR scanning (TLS);
• Digital orthophotography from UAV (DP-UAV), scale 1:200 (2 cm/px).

A fundamental aspect of the correct use of cartographies is georeferencing, which must be the same for all documents. In our case, all documents use the official geodetic reference system, the European Terrestrial Reference System 1989 (ETRS89), and are represented in UTM 31N projection (EPSG: 25831) and orthometric altitudes.

The models derived from TLS and DP-UAV were georeferenced using control points from the bases of the local topographic network established by GNSS observations and adjusted from the network of permanent stations of the ICGC (CATNET stations). The equipment used was a Topcon Hiper Pro model. The accuracy of the base coordinates was better than 2 cm in planimetric coordinates and 5 cm in elevation.

3.2. Digital Photogrammetry (DP-UAV)

For the photographic coverage, we used a modified commercial DJI multicopter, model Phantom2 (Zen-muse H4-3D gimbal), and a GoPro Hero4 (GoPro. Inc., San Mateo, CA, USA) digital camera, with 12 Mpx resolution (4000 × 3000, RGB) and a focal point of 3 mm, flying at an average height of 30 m above the ground. This allowed us to achieve a photographic scale of 1:10,000 and a ground resolution of less than 2 cm (Ground Sampling Distance, GSD). The photographs were taken vertically and obliquely, depending on the slope of the ground in the corresponding study area. Four support points and nine ground control points were used for photogrammetric adjustment and georeferencing, using identifiable elements in photographs and artificial signs, such as checkerboard targets with dimensions of 20 cm × 20 cm. A total of 282 aerial photographs were taken and photogrammetrically adjusted using Agisoft Metashape Professional software (software developed by Agisoft LLC, St. Petersburg, Russia).

The products obtained from the photogrammetry were a 3D point model of the area (DTM) and an orthophotography of 2 cm resolution.

3.3. Terrestrial Laser Scanner (TLS)

In the case of the model generated by terrestrial laser scanner, a Trimble instrument model TX5 (Trimble Navigation Limited, Westminster, CO, USA) was used to obtain a total of 34 stations, with a resolution of 10 mm in 10 m, and an average of six million points per station. They were adjusted using FARO’s Scene software (software developed by FARO Technologies, Inc., Lake Mary, FL, USA), to create a single 3D model of points, with a maximum point error of 15 mm, and an average point error of 5.5 mm.

These products were used to obtain plans, elevations, and sections of elements of interest such as the furnaces.

4. Mortar Testing Methodology

The mortars extracted from different structural elements of the factory were disaggregated using mechanical means and in dry conditions.

From the fine fraction (<0.063 mm) of each sample, the binder composition was analyzed using X-ray diffraction (XRD) and thermogravimetry-differential scanning calorimetry (TGA/DSC). The XRD analysis was performed with a PANalytical X’Pert PRO MPD Alpha1 (Malvern Panalytical Ltd., Almelo, The Netherlands) powder diffractometer in Bragg–Brentano ϕ/2ϕ geometry with a radius of 240 mm (CuKα1 radiation, λ = 1.5406Å). X’Pert HighScore software (software developed by Malvern Panalytical Ltd., Almelo, The Netherlands) was used for the data interpretation.

The TGA analysis was conducted in an air atmosphere at a heating rate of 10 °C/min using a NETZSCH STA449 F5 JUPITER instrument (NETZSCH-Gerätebau GmbH, Selb, Germany). The data obtained were interpreted using NETZSCH-PROTEUS-80 software (software developed by NETZSCH-Gerätebau GmbH, Selb, Germany).

These tests were used to determine the mineralogical composition of the mortars analyzed and to identify the construction typology used for some of the buildings in the complex.

5. Limitations of the Study

The study encountered some limitations in access to the site. The geomatic research was restricted by the state of the site, due to the undergrowth in the surroundings, the accumulation of waste in some areas, and the collapse of some of the buildings. For future investigations, the site will have to be cleared. Once this previous work has been completed, new surveys of the complex with greater definition can be carried out, and a non-destructive testing campaign can be undertaken by means of ground investigation with a thermal camera, metal detector, or ground-penetration radar (GPR). A further study could combine the cloud points used with other modern technologies, such as Building Information Modeling (BIM) [58] and the creation of interactive 3D models.

The material analysis was carried out using only five samples from different buildings of the ensemble because access to some buildings is difficult and dangerous due to their state of conservation. For future research on the materials and construction systems used, it will be necessary to first carry out some structural consolidation.

6. Current Situation

6.1. Description of the Complex

The industrial buildings of the La Granja d’Escarp industrial complex are of great heritage importance, as the entire Ebro coal basin was significant for the development of the cement industry during the period between the late nineteenth and early twentieth centuries. The La Granja d’Escarp factory fell into disuse when the production of natural cement was discontinued in favor of other industries, especially those dedicated to producing the new artificial Portland cement. From that moment, the structures of the industrial complex began a process of degradation that continues today.

The elements or constructions of the complex have been classified or divided into four large groups of structures or buildings. The first is made up of the two batteries of calcining kilns, the second corresponds to the actual factory buildings for grinding, bagging, and dispatching the cement. A third group consists of all the installations, basically the rail tracks and wagons, for the transfer and movement of the material before and after calcination. Finally, a fourth group includes the residential buildings in the colony and the factory manager’s house.

Structurally, the buildings are made up of masonry walls with occasional incorporation of stone blocks, all of which are held together by mortar joints and topped with sloping roofs covered with ceramic tiles. Both the horizontal structure and the various roofs of the buildings were built with wooden beams. Almost all the roofs have collapsed, leaving the interior of the buildings exposed to the elements. This situation promotes the rapid degradation of the remains that are still standing. If this situation is not remedied, the total collapse of the buildings is foreseeable, as has already happened with the building intended for the workers’ residence. The windows are completely devoid of frames, but the ceramic surrounds are generally in good condition. Some better-preserved interior partitions of the buildings are still standing, so the spaces that made up these constructions can be identified. There is no machinery, although the fastenings for the millstones, rails, etc., have been identified.

Another aspect to consider is the external elements of the complex, which have practically disappeared. They include the railway that connected the spaces and elements that made up the factory (kilns, mills, and warehouses), and the wharf. This structure was on the riverbank for the transport of cement downstream. Among all the buildings, there is a large amount of undergrowth and geo-anthropological material that has accumulated over 100 years of neglect.

The kilns deserve special mention, as they can be identified immediately, forming an essential and characteristic element of this factory complex. There are two groups of batteries with four kilns each. One of them has completely collapsed, leaving only the remains of the furnaces’ inner conduit. The other battery, the one that is furthest south in the complex, is almost intact. We can provide construction data on the latter. The kilns are connected by their mouths to each other. The structure’s plan is rectangular with chamfered corners. The walls are made of bricks joined by mortar. The lower mouth of the duct is topped by a semicircular arch made of stone voussoirs. The openings are formed on all four sides. The interior structure is cylindrical and a bit coniform. Of the two battery sets of kilns in the factory, only the one closest to the buildings remains standing. In the one at a higher level, only the kilns’ ducts remain partially, with the rest of the structure destroyed or semi-buried. All these elements highlight the heritage value of this site from different historical, economic, and technical perspectives [6].

In the interior shape of the kilns, two geometric figures are found: a cylinder and a truncated cone, with the latter corresponding to the area of maximum temperatures for cement cooking. This duct is lined with a refractory ceramic coating. (Figure 6, Figure 7 and Figure 8).

6.2. Results and Evaluation of Mortar Tests

To better understand the construction systems of the industrial complex, samples of the binders used in the elements were collected (Figure 3). These samples were taken in March 2024. It was decided to test the most representative of all the samples collected. This could provide complementary information to understand the various construction elements. The condition of the buildings and structures in the complex at the time of the sample collection visit was extremely precarious. Except for the southern kiln battery, the rest of the buildings had lost both their roofs and the upper sections of their interior and façade walls.

Each sample underwent X-ray diffraction to determine its composition and thermogravimetric analysis to assess its hydraulic capacity.

• Sample of the exterior plaster of the Engineer’s House building.

The minerals detected by X-ray diffraction (XRD) are as follows (Figure 9):

The main composition consists of gypsum and anhydrite. The remaining minerals, such as muscovite and chlorite, are clays, while quartz and calcite are minerals associated with gypsum.

The black line represents weight loss over time. The blue dashed line represents the derivative of the weight loss at each temperature (TGA), and the red dashed line represents the calorimetric variation associated with each mineralogical decomposition (DSC) (Figure 10).

The most significant peak occurred at 180 °C, which corresponds to the loss of water from dehydrated gypsum, generating the hemihydrate phase. This reaction took place as an endothermic process. At 370 °C, an exothermic peak was observed, related to the transformation of anhydrite from the hexagonal to the orthorhombic system [67].

Around 700 °C, weight loss occurred, accompanied by an endothermic peak, which corresponded to the loss of structural water from the clays (muscovite and chlorite–serpentine). A smaller weight loss occurred around 750 °C, associated with the release of CO₂ from calcite in an endothermic reaction. Overall, there was a total weight loss of approximately 20%.

Based on this information, the sample can be identified as a gypsum mortar containing associated minerals such as clays (muscovite and chlorite–serpentine), calcite, and a very small proportion of quartz.

• Sample of the interior plaster of the Engineer’s House building.

The minerals detected by X-ray diffraction (XRD) are as follows (Figure 11):

In this mortar, the decomposition of gypsum was clearly observed at 180 °C, with an endothermic peak. The exothermic peak was not observed, and the largest weight loss occurred between 700 and 800 °C, which corresponded to the loss of structural water from the clays (chlorite–serpentine and muscovite) and the decomposition of calcite, to release CO₂. Overall, a weight loss of 23% was observed (Figure 12).

This mortar is a mixture of gypsum and lime, with the presence of clays and feldspars (albite and microcline). Such mortars are described as traditional gypsum mortars [68].

• Sample mortar from the structure of the southern kiln battery.

The minerals detected by X-ray diffraction (XRD) are as follows (Figure 13):

The most significant peak occurred at 180 °C, which corresponds to the loss of water from dehydrated gypsum, generating the hemihydrate phase. This reaction takes place as an endothermic process. At 370 °C, an exothermic peak was observed, related to the transformation of anhydrite from the hexagonal to the orthorhombic system (Figure 14).

Around 700 °C, weight loss was observed, accompanied by an endothermic peak, corresponding to the loss of structural water from the clays (muscovite and chlorite–serpentine). Another smaller weight loss occurred around 750 °C, associated with the release of CO₂ from calcite in an endothermic reaction. Overall, a total weight loss of approximately 22% was recorded.

Based on this information, the sample can be identified as a gypsum mortar containing associated minerals such as clays (muscovite and chlorite–serpentine), calcite, and a very small proportion of quartz.

• Sample mortar from the joints of the brick masonry of the main factory building.

The minerals detected by X-ray diffraction (XRD) are as follows (Figure 15):

A peak was observed at 180 °C, which corresponds to the loss of water from dehydrated gypsum, generating the hemihydrate phase. This reaction occurred as an endothermic process. The most significant peak occurred at around 800 °C, which corresponded to the decomposition of calcite and the loss of structural water from the clays (muscovite and clinochlore), accompanied by an endothermic peak (Figure 16).

Overall, a total weight loss of approximately 30% was observed.

This is a lime mortar, which is completely carbonated (no presence of portlandite was detected), and the aggregates consist of quartz (the predominant mineral), feldspars such as anorthite, and clays such as muscovite and clinochlore.

Considering the location of the sample, gypsum could be a contaminant mineral from the factory’s coating, like the gypsum in the house building.

• Sample mortar from the masonry (stonework) of the kiln structure.

The minerals detected by X-ray diffraction (XRD) are as follows (Figure 17):

A small peak was observed at 180 °C, which corresponds to the loss of water from dehydrated gypsum, generating the hemihydrate phase. This reaction occurred as an endothermic process. The most significant peak occurred at around 800 °C, which corresponded to the decomposition of calcite and the loss of structural water from the clays (muscovite and chlorite–serpentine). In both cases, the decomposition was endothermic (Figure 18).

Overall, a total weight loss of approximately 27% was observed.

This is a lime mortar, which is already fully carbonated (no presence of portlandite was detected), and the aggregates consist of quartz (the predominant mineral), feldspars such as albite, and clays such as muscovite and chlorite–serpentine [69].

6.3. Recovery of the Complex

In the works to recover the value of these buildings, a multidisciplinary team will be needed. Our team includes specialists in the disciplines of construction materials, geomatic techniques, traditional construction systems, the history of industrial construction, and archeology. To this team and collaborators, with a cross-cutting vision of this type of industrial heritage, we should add the technical guidelines of governmental institutions (town councils, provincial councils, and regional councils). In addition, local associations provide a vision that is closer to the territory and has the special aim of conserving and disseminating local architectural heritage and promoting the value of social, cultural, and historical memory. This team will help to understand and enhance the various aspects of the complex that need to be highlighted (material, archeological, territorial, social, cultural, productive-industrial, and historical factors) to recover the complex from its ruinous current state (Figure 19).

In the recovery of the complex, the needs and specificities of the immediate environment must be considered. This privileged enclave is geographically at the meeting point of two rivers. Here, the past activity was mining and industry, while the current activity is agriculture. Both must be combined to obtain the best results. Therefore, interventions on these buildings must recover the memory of the place and consider the future use of the complex that facilitates its conservation and maintenance.

The restoration works must respect what exists and avoid, as far as possible, the complete restoration of the buildings. Therefore, the works should consist of recovering the built elements that remain and providing new elements for those that have disappeared, mainly the roofs (Figure 20). All the works that are carried out must be sufficiently documented, so that this new intervention can be well differentiated from the previous works.

The works must be performed as soon as possible to prevent any more information from disappearing. The decay of some of the buildings in the ensemble has already led to the loss of some information. Because of this urgency, this paper is the first step in the recovery of this important site.

7. Discussion

There remain numerous uncertainties to be resolved in the industrial complex of Granja d’Escarp. The study brought together the scarce bibliographic documents that record the events and evolution of the Granja d’Escarp factory during its productive life. The information was obtained from the archives of the National Museum of Science and Technology of Catalonia and the Excursionist Club of Catalonia. In addition, various visits were carried out by the authors of this article to inspect the site and verify the data obtained. In these visits, geomatic data were gathered, with which the survey of the constructed elements was carried out. In addition, characterization tests were undertaken on samples of the buildings to determine the materials used in their construction. These data helped us to produce a reliable document on the current state of the complex, its situation, and its deterioration. They are a source of knowledge that remains for the future.

Based on the data and the research carried out, various uncertainties emerged, especially about the functioning of the complex. It is known that there was a train track that connected the factory’s buildings, and there was also a wharf. However, only a few remains of these important routes for the transport of manufactured materials and raw materials have been detected. It is very likely that these infrastructures have been preserved, or at least enough traces of them have remained to interpret them. However, they may be hidden under the dense vegetation and the accumulation of earth deposited after the closure of the complex. Therefore, there are still some doubts about the factory’s operation. With the planning of a new field campaign, the study can be completed and the questions answered.

To be able to fully discover the productive complexity of the factory and the uses of the infrastructure in the built complex, it is essential to carry out an exhaustive campaign to clear the existing vegetation. Excavation work should be performed at the entrances to the tunnels of the wagon circuit and work should be undertaken to remove rubble and earth in the areas adjacent to the buildings, the areas near the furnaces, and in the hidden sections of track. To locate the hidden tracks, non-destructive tests can be carried out using ground investigation with a thermal camera, metal detector, or ground-penetration radar (GPR). Once the work has been completed, the terrain can be re-mapped. The data obtained can be compared with that of this preliminary study, to obtain new probabilistic mapping. Based on this information, it will be possible to locate with greater precision some of the areas that have not been found yet [70]. When the land has been cleared, we can assess the use of various destructive and non-destructive tests that are adapted to the needs of each study area.

In the case of the wharf, prospecting work will have to be carried out on the riverbank to help detect its exact location. There are no data on this wharf, other than the fact of its existence. This archeological survey work could include underwater observations, and soundings to assess the nature of the terrain and the presence of possible traces of the foundations of the wharf. As for the furnaces, there are not many doubts about their operation, given the simplicity of the system and the information obtained from other studies of similar structures that we have carried out before. After cleaning and clearing the land, an initial exploration of the interior of the galleries could be carried out [71] and a terrestrial laser scanner survey could be undertaken. The internal connections could be mapped and samples of the materials (stone, ceramic bricks, mortar, wood, etc.) that form part of the architectural complex could be obtained. A structural assessment is also necessary to carry out consolidation and stabilization to ensure the preservation of the furnaces.

All this information will help us to expand our current knowledge of the industrial complex, and to formulate verifiable hypotheses to understand their operation. It will provide the necessary information to carry out an intervention that respects the environment and is highly compatible with the traditional materials used in this industrial heritage.

The geometry of the remaining buildings in the complex is not known with precision, since several of them have collapsed. Of these buildings, only two old photographs have survived and are included in this article. The buildings’ foundations also remain. Therefore, a survey of these archeological building remains must be carried out to be able to elaborate constructive and functional hypotheses that help understand the complex.

Once the working hypotheses have been formulated and verified, it will be possible to advance with work on the recovery and enhancement of the complex.

The geomatic methodologies employed, such as UAV photogrammetry and terrestrial laser scanning, could serve as a model for initial site assessments in other abandoned industrial complexes. These methodologies provide highly valuable preliminary information for the conservation of industrial heritage. Additionally, the historical and cultural evaluation framework applied here may be adapted for sites with similar architectural and economic significance. Finally, laboratory tests using XRD and TGA on the materials that are found help verify historical studies of the site where the heritage is located.

8. Conclusions

The industrial complex of La Granja d’Escarp is an industrial monument that was of great importance in the nineteenth century when the industrialization of Catalonia began. As mentioned throughout the article, the production of natural cement in the late nineteenth century had a great impact on the construction of infrastructure during that time. The development of this cement factory and its proximity to river transport routes facilitated the popularization of the new hydraulic binder and its use in infrastructure and buildings. Cement improved setting times, and its application in elements that were in contact with water made it particularly appealing.

In the second decade of the twentieth century, the production of cement at this factory declined in favor of other factories with greater production capacity that were closer to Barcelona.

Currently, this complex is completely unused and abandoned, in a state of great deterioration. Over the years, various collapses have occurred in the buildings, gradually leading to their near disappearance. The communication galleries between the kilns are filled with material. Due to the geomatics research carried out, we can clearly identify the buildings that formed part of the industrial complex. Some of them are partially hidden, missing, or even in a serious state of structural collapse. We can also observe the overall infrastructure. In addition, due to this technique, we could undertake a survey of one of the two batteries of furnaces and make an interior section of one of the furnaces. This information is very important as it allows us to observe the internal structure and visually identify some of the materials and construction systems used in the construction of this site, for example, the refractory ceramic coating used in the kilns. The geomatic research carried out represents the documentation of great importance because it helps to identify the magnitude of the factory, locating those places of greatest interest, and is the first step to highlight the imperative need for future interventions aimed at the recovery of the site.

Based on the results obtained in the study of the mortars that were analyzed, we can confirm that the binders used in the construction of the buildings and the kilns of the factory were not composed of natural cement. Therefore, the material manufactured in the factory was not used for its own construction. Instead, it was made with the traditional binders used in the region’s constructions.

Of the five samples analyzed by DRX and TGA/DSC, it was determined that their mineralogical composition was mainly lime mortars with gypsum impurities but we also found some traditional gypsum mortar.

The article aims to focus on this factory, firstly, as a reliable document of knowledge that enables future research, and secondly, to emphasize its conservation and recovery. No other studies have been carried out on this site or on sites of similar importance in the region. Therefore, the work that has already been started should be advanced and the various administrations should be involved, to highlight the importance of this industrial establishment for Catalonia as a whole. La Granja d’Escarp Town Council is willing to preserve heritage but has significant management limitations due to its small size. It will need help. The first action to be carried out should be the cleaning of the site and securing of the structures to avoid any further decay.

There are still numerous questions to be answered about the functioning and configuration of this factory, but these questions cannot be answered until further work is carried out.

Currently, the cement factory complex of La Granja d’Escarp is a group of abandoned buildings, but the relationships between them can still be recognized. This factory had a vital influence on the development of Catalonia in the late nineteenth and early twentieth centuries, due to the use of natural cement in construction in those years. The factory played an important role in this process because of its considerable production of natural cement and its ability to transport it to the building sites where it was needed. However, if this complex is not recovered, it could disappear soon, resulting in a significant loss in the history of construction.