4.1. The State-Of-The-Art
The studies presented below in chronological order refer to those shown in
Table 2 and address different aspects related to waterproofing, including sealing methods, slab waterproofing procedures, concrete admixtures, and environmental and economic impacts of different waterproofing options.
Alev et al. [
37] investigated different sealing methods to evaluate their effect on air leakage in construction joints. The research considered the air leakage rate of several commonly used foundation and slab-on-ground joints, such as limestone, external, and separation walls made of lightweight blocks. Different sealing materials were applied to these constructions, and it was found that the air leakage rate decreased between 1.3 and 86 times, depending on the method used. In addition, the researchers found that the quality of the constructions, such as the materials, method, and labor used, also significantly affected the air leakage rate.
Figueredo et al. [
38] analyzed the waterproofing procedure of a roof slab in development intending to achieve 100% water tightness. The study emphasized the importance of care in the preparation of the substrate, the knowledge of professionals, and the end user's attention regarding the use of the environment, maintenance, and periodic inspections necessary to maintain efficient waterproofing.
The research by Pinto and Aguiar [
39], in turn, aimed to clarify the importance of waterproofing and the relevance of well-executed projects. The researchers concluded that the correct execution of waterproofing, with adequate materials and qualified professionals, can avoid future inconveniences and high maintenance costs. Furthermore, it is important to point out that the cost of this measure is reasonable if executed during construction.
Sriravindrarajah and Tran [
40] point out that the successful waterproofing of a building depends on considering several factors, such as product selection, membrane detailing, drainage design, substrate preparation, design, installation, quality assurance, and maintenance. The authors conducted a study in Australia intending to discuss the standards and codes, membrane systems and performance, waterproofing practices, design and installation techniques, inspection and testing, and quality assurance adopted by the waterproofing industry. They stated that implementing proper design and installation techniques and performing maintenance procedures can significantly reduce the waterproofing failure rate and repair costs. Therefore, it is essential to consider all these factors to ensure the effectiveness of a building's waterproofing system.
In addition to waterproofing methods applied to surfaces, it is also possible to improve the water tightness of construction from an admixed concrete. In this sense, the study by Coppola et al. [
41] aimed to evaluate the performance of a carboxylic acid-based mixture added to concrete. The results obtained experimentally showed that adding the additive did not negatively affect the mechanical properties of concrete. It was observed that by adding 1% of the additive per mass of cement, there was a halving in water penetration under pressure compared to concrete without the waterproofing additive at 28 days. In addition, the mixture proved capable of sealing cracks resulting from plastic shrinkage, showing that the additive is a promising solution to ensure the water tightness of a construction.
The study by Gonçalves et al. [
42] compared different waterproofing options for various slabs, considering environmental and economic impacts. The authors analyzed the risk of global warming, consumption of non-renewable primary energy resources, and life cycle costs. After the analysis, it was concluded that bituminous membranes were the best option for all slabs, while synthetic EPDM (ethylene-propylene-diene) membranes showed the highest values.
Ribeiro et al. [
43], from another perspective, pointed out the lack of waterproofing as a significant flaw in daily construction, neglected by the lack of prioritization for the prevention of construction problems in the country. They pointed out that this practice can cause structural problems, resulting in much higher repair costs than prevention. In their case study, they used acrylic and flexible polymer-based products to waterproof the roof of a residential building, concluding that the roof infiltration was resolved and the products used ensured the desired service life of the building.
Meanwhile, Ksit and Plich [
44] presented liquid plastic films as a waterproofing solution composed of a mixture of polymers or polymers and bitumen. These authors' studies demonstrated that using these plastic films could provide a smooth and uniform surface, resulting in an excellent aesthetic result and even a "cool roof," capable of reducing the greenhouse effect in large cities.
Scheidegger [
19] conducted a literature review on the two main waterproofing products: asphalt blankets and polymeric mortar. It was concluded that polymeric mortar is easier to apply, but it is not recommended for structures subjected to thermal or settlement movements, which can compromise its water tightness. Asphalt blankets, on the other hand, are more resistant to thermal movements or settlements, but their application may be more complicated, generating possible complications later on.
In the work of Pinto et al. [
45], the infiltration process and its consequences were analyzed, concluding that the lack of adequate waterproofing is generally caused by the lack of specialization of professionals and the lack of standards for project preparation. The prioritization of cost over waterproofing can result in maintenance costs of up to 15% of the total value of the work. In contrast, if proper waterproofing is not performed during construction, the repair cost can reach up to 50% of the value of the work.
Considering green roofs, Pettersson et al. [
46] warn about the need for more data on their ability to retain and reduce stormwater under different climatic conditions. However, their study examined green roof water infiltration at the pore scale and evaluated the relationship between porous microstructure in thin substrate layers and water infiltration. Studies evaluating different microstructures and different heights of standing water on the porous medium surface were conducted, which demonstrated the relationship between microstructure and flow homogeneity by analyzing saturation, liquid-gas interfacial area, pore size distribution, porosity, and infiltration depth. Thus, the authors concluded that the knowledge of these relationships allows for optimizing the performance of the green roof concerning rainfall duration time from the material used in the substrate treatment.
Van Linden and Van Den Bossche [
47] conducted an experimental study in Belgium to evaluate the performance of different joint sealing materials for the water tightness of constructed buildings. The materials evaluated were tapes, silicone, base materials, coatings, foam sealing tapes, and polyurethane foams, which were subjected to different parameters. The study's results indicated that the choice of waterproofing materials should be made carefully, as all tested materials performed well in waterproofing. However, it was observed that the labor skill used in applying the materials had a significantly more significant impact on the materials' performance than the life cycle. Therefore, it was concluded that skilled labor is critical to ensure the proper performance of joint sealing materials in buildings.
Neves et al. [
48] developed a guide to detect and solve the main pathological manifestations in Brazilian residences related to moisture. The guide was created from a literature review of the leading causes of pathology and included the types, manifestations, origins, risks, and a repair guide. The material also contains information about the leading suppliers of products for these repairs and a study of the processes to be carried out. Although the valuable life of a repaired construction does not compare with one well-developed, made compatible, and executed, the authors indicated, among other aspects, that the Brazilian market has quality brands that offer good services and provide assistance to their consumers.
Silva et al. [
49] conducted a case study evaluating pathological manifestations due to infiltrations in a Salvador, Bahia, Brazil building. Diagnostic techniques were used to identify the primary damage and determine the appropriate repair methodologies. It was concluded that the investigation methods were essential to identify the risk in each pathology found in the building and find the necessary repair method to prevent degradation.
Reis et al. [
50], in turn, investigated the leading causes of pathology and moisture damage to enable better health and mobility conditions for the elderly at the Carlos Romeiro Asylum, located in Conselheiro Lafaiete, Minas Gerais, Brazil. On-site inspections were conducted to identify and analyze the damage and define the appropriate repairs in each case. The authors concluded that in addition to repairs, repairs to leaking pipes, improving the water-tightness of the reservoirs, and cleaning and unblocking surface drainage devices would be necessary. Installation of roofing and/or application of waterproofing blankets was raised as ways to treat the damage.
According to Heinlein et al. [
51], waterproofing membranes have grown in recent years, evidenced by the increase in the number of manufacturers, patents, and on the market. However, it is essential to note that these membranes are only efficient if installed by qualified professionals due to possible adhesion problems that can arise in the application and preparation of the surface to be waterproofed.
The study by Maj and Ubysz [
52] finally analyzed the use of polyurea coating to protect concrete surfaces, intending to reinforce waterproofing in water and other liquid tanks. To ensure water-tightness, it is essential to pay attention to the phenomena of diffusion and osmosis and to take prudent measures in preparing the substrate, using primers, adequate coating thickness, and avoiding micropores and holes. In addition, the authors state that it is essential to schedule periodic coating inspections.
The analysis of the articles mentioned above reveals several relevant types of research on the application of surface waterproofing blankets, covering a broad theme. These studies address water infiltration in constructions, the importance of waterproofing forecasting, analysis of existing techniques, and the feasibility of new approaches. The diversity of studies on the subject highlights the importance of waterproofing in civil construction, with the growing need to improve construction quality and increase structures' life span.
4.2. Case Study
A case study was conducted in residence located in Nova Lima, Minas Gerais, Brazil. The construction in question comprises structural masonry, two floors (
Figure 12 and
Figure 13), and a waterproofed slab roof. The project included solar and photovoltaic heating, air conditioning infrastructure, a sound system, an electric car charging point, a swimming pool, and a fireplace.
Next, the waterproofing methods used in this residence are presented, divided into different areas: floors and external areas; Slab and water tank; bathrooms; swimming pool, fireplace, and deck. An analysis of the chosen waterproofing method and its application techniques was performed based on the NBR 9574 standard [
21].
4.2.1. Floors and External Areas
The floors were waterproofed from the beginning of the project in different stages and methods, according to the infiltration risks and use of the area.
When the first Slab was made, supported on the ground at the beginning of the project, it was necessary to waterproof the contact between the concrete and the soil to avoid the capillarity phenomenon. The first waterproofing was done using a 150-micron tarp (
Figure 14), thicker than the ordinary tarp, usually with 50 to 100 microns, and, therefore, has a better performance and useful life. After applying the tarp, EPS (expanded polystyrene) sheets were also placed over it (
Figure 15) to increase the distance between the ground and the concrete and take advantage of the characteristics of EPS, which is highly resistant to mold and moisture. The tarp method was also used under the concrete ramp for vehicle access to the upper garage (
Figure 16) to avoid capillarity between soil and concrete.
4.2.2. Slab and Water Tank
Using waterproof slabs for the conventional roof has become more common in high-end residences. The conventional roof demands more time to build and requires frequent maintenance. On the other hand, the waterproofed Slab requires an advanced waterproofing system because it is directly exposed to rain and humidity, and concrete is not a waterproof material.
The method chosen to waterproof the Slab in this study was aluminized asphalt blanket. Despite the high cost of the material and labor, the material was chosen due to its high waterproofing capacity. In addition, as the Slab is a non-traffic area, no additional coating (mechanical protection) is required, which avoids extra costs. The same material was used to waterproof the water tank, an area with a high risk of infiltration due to possible leaks.
A specialized team should apply asphalt blanket on the Slab due to the complexity of the service, handling, and adherence of the blanket. The professional must be careful when joining blanket rolls, dealing with corners, and, especially, when making the necessary holes in the Slab, such as drains for drainage and air conditioning pipes.
The application method consists of preparing the Slab by applying a layer of mortar to make the surface smooth and free of imperfections to receive the blanket. This mortar layer is also essential to ensure the water drainage, foreseen at the moment of the Slab's concreting, directing it to the drains and avoiding the accumulation that could damage the Slab. Next, general cleaning is done on the surface to be waterproofed, using a broom and a powerful vacuum cleaner.
After this process, a primer composed of polycondensed asphalt cement diluted in solvents is applied (
Figure 17a and
Figure 17b), which increases the adhesion between the asphalt-based waterproofing system and the surface. With the primer applied, modified asphalt sheets are heated to dissolve and apply them, thus beginning the process of adherence of the asphalt mats to the surface (
Figure 17c and
Figure 17d). The professional distributes the roll of the mat on the Slab and uses a blowtorch to ensure the adherence of the mat and the modified asphalt to the surface (
Figure 17e).
After the blanket application is completed on the entire Slab (
Figure 17f), it is necessary to wait for drying time and perform the water tightness test. This test aims to verify the effectiveness of the blanket applied and correct any details, if necessary. The water tightness test consists in filling the Slab with water and checking whether any leakage will occur. If any leakage is found, it will be evident by moisture stains under the Slab, and the responsible team must correct this failure and perform the test again, ensuring no more leaks.
4.2.3. Bathrooms
As this is an environment with much contact with humidity, it is also necessary to worry about infiltration in this area. In the building under study, the method used for waterproofing the bathrooms was the application of polymeric mortar. This material was chosen mainly due to its easy application, not requiring specialized labor, and low cost. The product used, the waterproofing material "tec plus top" by Quartzolit, is intended for use in humid areas such as bathrooms, kitchens, service areas, walls, baseboards, and planters.
Applying the waterproofing material followed the manufacturer's recommendations and the NBR 9574 standard [
21]. First, the liquid component was mixed with the powder component using a metal rod attached to a drill. Then, using a brush, the first layer of the mixture was applied on the floors and walls (up to a height of approximately 1.80 m) of the bathrooms (
Figure 18) and then reapplied after drying in the opposite direction to the application of the first coat. This way, the bathrooms were released for the finishing stage, covering floors and walls with ceramic tiles and protecting them from humidity.
4.2.4. Pool, Fireplace, and Deck
The pool, fireplace, and deck waterproofing were done using a polyethylene asphalt blanket. This type of blanket is chosen for these areas due to its greater flexibility, resistance, and durability. Unlike other surfaces, the pool, the fireplace, and the deck are subject to a much higher volume and time of exposure to humidity, besides being places with foot traffic, which require mechanical protection on the asphalt membrane.
The waterproofing process of the deck, pool, and fireplace surfaces started with verifying the drainage system and testing the water flow toward the area's drains. After this verification, these areas were cleaned using brooms and vacuum cleaners. Then the primer was applied to the pool, fireplace, and deck surfaces (
Figure 19a), preparing them to receive the asphalt. Then, a layer of modified asphalt was applied and melted with a blowtorch to adhere the mat to the surface (
Figure 19b).
Then, applying the polyethylene asphalt blanket on the surfaces was started, using a blowtorch to melt the modified asphalt and ensure the adherence of the blanket (
Figure 20a). After finishing the application of the blanket on the pool surfaces (
Figure 20b), deck, and fireplace, the water-tightness test was performed, as was done on the Slab, to verify the waterproofing guarantee. Next, the pool, fireplace, and deck were filled with water up to the limit of the edges (
Figure 21).
As proven to be watertight after the test, the next step would be plastering the pool and fireplace and the counter flooring of the deck to apply the lining later. For this type of blanket used, before receiving the lining, the chicken wire was applied to the entire surface of the pool and fireplace (
Figure 22a) using mortar to facilitate the adherence of the plaster to the blanket and prevent future detachment of the ceramic linings. After the preparation with the chicken wire and the mortar on the polyurethane asphalt blanket, the pool and the fireplace were plastered, and the counter-flooring was done on the deck. Then these surfaces were covered with porcelain tiles or ceramic pieces (
Figure 22b).