Building Construction 3 First Quiz

The explanation for the given correct answer is that the durability of the finish is indeed dependent on the material properties of the finish and the material it is applied to, as well as the bond between the two materials. This means that if the finish and the material it is applied to have compatible properties and a strong bond, the finish is likely to be more durable. On the other hand, if there is a mismatch in material properties or a weak bond, the finish may not last as long. Therefore, the statement is true.

The given statement is true. Admixtures, which are substances added to mortar to improve its properties, should be free from dirt and harmful chemicals. This is because any impurities or harmful substances in the admixtures can negatively affect the quality and performance of the mortar. Therefore, it is important to ensure that admixtures used in mortar are clean and safe to use.

Dry lining is a method of improving insulation and fire resistance values of a wall by adding suitable materials. By incorporating insulation materials such as foam boards or mineral wool between the existing wall and a new layer of plasterboard, the thermal efficiency of the wall can be enhanced. Additionally, fire-resistant plasterboards or intumescent coatings can be used to increase the fire resistance of the wall. Therefore, the statement that dry lining can improve insulation and fire resistance values of a wall is true.

The statement suggests that using materials with an inherent finish can help in reducing construction time and initial construction costs. This implies that these materials may require less additional work or finishing, resulting in time and cost savings. By carefully selecting such materials, construction projects can be completed more efficiently and cost-effectively. Therefore, the answer is true.

Surface finish is a crucial element in construction and interior design as it serves multiple purposes. It not only enhances the visual appeal of floors, walls, and ceilings but also provides durability and protection against wear and tear. Additionally, a good surface finish requires minimal maintenance, making it a practical choice for long-term use. Therefore, the statement that the primary function of a surface finish is to provide a durable, visually attractive, and low maintenance surface to floors, walls, and ceilings is true.

Portland Cement or other types of cements are used as binders in plaster mortars. Plaster mortars are a mixture of cement, sand, and water that are used for coating walls and ceilings. The cement acts as a binder, holding the sand particles together and providing strength to the plaster. Portland Cement is commonly used in plaster mortars due to its durability, strength, and ability to set and harden quickly. Therefore, the statement is true.

Finishes, such as flooring, wall coverings, and paint, play a crucial role in shaping our interaction and perception of the built environment. They form the interface between building users and the building itself, influencing the overall ambiance, aesthetics, and functionality of a space. The choice of finishes can affect the acoustics, lighting, temperature, and even the psychological well-being of occupants. Therefore, it is true that finishes have a significant impact on how we interact with and perceive our built environment.

The statement is true because in modern construction, plastering is being replaced by dry lining on interior surfaces and cladding on exterior surfaces. Dry lining involves fixing plasterboard or other board materials to the walls, providing a smooth and even surface for decoration. Cladding, on the other hand, involves adding a protective layer or decorative covering to the exterior walls. These methods are preferred over traditional plastering due to their ease of installation, versatility, and the ability to achieve a desired aesthetic without the need for wet plaster.

Lime pilaster has the ability to absorb humidity in the air, which ultimately provides better comfort to the occupants. This suggests that the statement is true. Lime pilaster is known for its moisture-absorbing properties, making it a suitable choice for creating a comfortable indoor environment by reducing excess humidity.

This statement is true because materials, such as furniture, carpets, and cleaning products, can release volatile organic compounds (VOCs) that produce scents or odors. These VOCs can contribute to indoor air pollution and can have negative effects on our health, such as respiratory problems, allergies, and headaches. Therefore, the scent emitted by materials can indeed influence our internal environment and potentially impact our well-being.

The statement suggests that undercoat mixes should have enough strength to provide a good grip on the surface but should not be stronger than the background. This means that the undercoat should not overpower the background layer, as it may result in unevenness or an unstable surface. Therefore, the statement is true as it emphasizes the importance of finding the right balance in strength between the undercoat and background.

Sand should be clean and free from clay when used with gypsum because clay particles can interfere with the setting and hardening process of gypsum. Clay contains impurities and can affect the chemical reactions that occur during the gypsum setting process, leading to weaker and less durable gypsum products. Therefore, it is important to use clean sand without clay to ensure the proper setting and strength of gypsum materials.

The spattering of a cement/sand slurry dash coat increases the bond between the cement and sand. This means that when the slurry is applied to a surface, it helps to create a stronger bond between the surface and the subsequent layers of cement or plaster that are applied. This can be useful in various construction or renovation projects where a strong bond is desired for durability and longevity.

Gypsum is a material commonly used in construction due to its unique properties. One of its advantages is that it expands slightly when it sets and dries. This expansion helps to prevent cracking, making gypsum a preferred choice for applications where cracking is a concern. Therefore, the statement that the advantages of gypsum include expansion on setting and drying to prevent cracking is true.

The statement states that sand used in plaster mixes can be obtained from rivers, the sea, or by crushing stones. This implies that there are multiple sources of sand for plaster mixes, including natural sources like rivers and the sea, as well as artificial sources like crushed stones. Therefore, the statement is true.

The statement "it is important that the aggregate shouldn't be clean" is false. This implies that it is not important for the aggregate to be clean. However, in many cases, it is important for the aggregate to be clean in order to ensure accurate and reliable data analysis. Clean aggregates help to eliminate any errors or inconsistencies in the data, leading to more meaningful insights and conclusions.

All of the problems mentioned (cracking, bonding failure, and crazing) can arise in plastering. Cracking refers to the development of cracks in the plaster surface, bonding failure occurs when the plaster does not adhere properly to the substrate, and crazing refers to the formation of fine cracks on the plaster surface. Therefore, all of these issues can occur when plastering, making the answer "all above" correct.

The given statement is true. The coating of plastic material can indeed be referred to as "plaster." Plaster is commonly used to describe a material that is applied to a surface to create a smooth and even finish. In this case, plastic material is being used as a coating to achieve the desired result.

To prevent cracking, natural or synthetic fibers are used in lime pilasters. This is because fibers provide added strength and stability to the lime mixture, making it less prone to cracking. The fibers act as reinforcement, helping to distribute stress and prevent the formation of cracks. Therefore, it is true that natural or synthetic fibers are used in lime pilasters to prevent cracking.

The statement is false because the plaster mixes and application techniques on the outside surface should not necessarily be the same in interior applications. The exterior surface of a building is typically exposed to harsher weather conditions and requires more durable materials and techniques, whereas the interior surface may prioritize aesthetics and ease of application. Therefore, the plaster mixes and application techniques can vary between the two surfaces.

The statement suggests that applying materials like plaster to a wall or paint to timber is considered an inherent finish. However, this is not true. Applying materials to existing backgrounds is a process of adding a finish to the surface, not an inherent finish itself. Inherent finishes are those that are naturally present in the material, such as the natural color or texture of wood.

The given statement is false. Generally, the mix proportion of 1 volume of cement to 6 or 7 volumes of sand is not used. The correct mix proportion for cement and sand can vary depending on the specific application and requirements. It is important to consider factors such as the type of cement, desired strength, and the intended use of the mixture when determining the appropriate mix proportion.

If the background does not completely dry before the undercoats are applied, it can lead to all of the mentioned problems. Cracking can occur when the moisture trapped in the background expands and contracts, causing the paint to crack. Bond failure can happen when the wet background prevents proper adhesion between the layers of paint, leading to peeling or flaking. Crazing refers to the formation of small, interconnected cracks on the surface, which can also result from inadequate drying. Therefore, all of the mentioned problems can arise if the background is not allowed to dry properly before applying undercoats.

The statement "Internal plasters shall be 20 mm" is false. Internal plasters are generally not required to be 20 mm thick. The thickness of internal plasters can vary depending on the specific requirements of the project, such as the type of wall and the desired finish. It is important to follow the guidelines and specifications provided by architects and engineers when determining the appropriate thickness for internal plasters.

Class B type b gypsum pilaster has a usual setting time in the range of 1-1.5 hours.

The usual thickness of a finishing coat is not 5-7 mm.

Plastering is the correct answer because it involves applying a thin layer of plastic material to rough surfaces to create a smooth and durable finish. This process helps to cover imperfections and create a jointless surface, enhancing the aesthetic appeal and longevity of the surface. Plastering is commonly used in construction and renovation projects to achieve a polished and professional look.

The main binding agent in "Rendering" is not portland lime.

Class A gypsum pilaster sets in 5-10 minutes by regaining the lost molecular water. This means that when the gypsum pilaster is mixed with water, it quickly hardens and sets within a short period of time. This is due to its ability to absorb the water molecules and form a solid structure. Class A gypsum pilaster is known for its fast setting time, making it suitable for applications where a quick setting is required.

Class B Type A gypsum pilasters have a usual setting time of 2-3 hours. The setting time refers to the time it takes for the gypsum to harden after it has been mixed with water. This specific type of pilaster is known for its relatively quick setting time, making it suitable for applications where a shorter setting time is desired.

The statement is false because mortar mixes should not be made stronger than the background. In fact, the mortar mix should be slightly weaker than the background to allow for expansion and contraction. Additionally, the finishing coat does not need to be stronger than the undercoat. Both coats should have similar strength to ensure a cohesive and durable finish.

The statement is false because class B of gypsum pilaster is suitable for plasterboards and other soft backgrounds.

Plasterboards typically have one surface that is ivory colored and the other surface that is gray colored. Contrary to the statement, both surfaces of the plasterboard are suitable for different applications. The ivory colored surface is suitable for the application of board plasters, while the gray colored surface is ready for direct decoration. Therefore, the correct answer is False.

Gypsum pilaster class D should not be mixed with lime. Mixing gypsum pilaster class D with lime can result in a chemical reaction that may affect the strength and durability of the material. It is important to follow the recommended guidelines and instructions provided by manufacturers to ensure proper usage and performance of the product.

Crazing refers to the formation of irregular surface cracks on a material, typically caused by the rapid evaporation of water from its surface. This phenomenon is commonly observed in ceramics, pottery, and glazes. The evaporation of water causes the material to contract, leading to the development of fine cracks or lines on the surface. Therefore, the correct answer for the given question is "crazing."

Lime plaster does not harden quickly. In fact, it is known for its slow drying and hardening process. Lime plaster requires a longer period of time to fully dry and harden compared to other types of plaster, such as gypsum plaster. This slow drying process allows lime plaster to have certain advantages, such as better breathability and flexibility, making it suitable for historic buildings and environments with high moisture levels.

An accelerator is added to class C gypsum pilaster to improve the setting time.

The functional requirements for materials to use in internal finishings include aesthetics, durability and flexibility, ease of maintenance and cleaning, strong mechanical or chemical bond, expelling water from the surface that forms as condensation, preventing and resisting mold growth or insect attack, providing a visual finish, and offering a tactile or touch-sensitive finish as an aid to those with visual difficulties. These requirements ensure that the materials used not only enhance the visual appeal of the space but also withstand wear and tear, are easy to clean and maintain, and provide necessary protection against moisture, mold, and insects. Additionally, the inclusion of a tactile finish helps individuals with visual impairments navigate the space effectively.

The functional requirements for materials to use in external finishes include aesthetic appeal, durability, strong mechanical or chemical bond, flexibility, health and safety considerations. Aesthetic appeal is important to ensure that the external finish enhances the overall look of the building. Durability is necessary for the material to withstand harsh weather conditions and maintain its appearance over time. A strong mechanical or chemical bond is crucial to ensure that the material adheres well to the surface it is applied to. Flexibility is important for the material to accommodate movement and prevent cracking. Health and safety considerations are necessary to ensure that the material does not pose any risks to the occupants or the environment.

The given correct answer for this question is "inherent finishes". This refers to materials such as timber, stone, brick, and glass that already have a natural finish and do not require any additional work or treatment. These materials possess inherent qualities that make them suitable for use in their natural state, without the need for further finishing processes.

Gypsum is a common mineral found in nature as calcium sulphate dehydrate, which is represented by the chemical formula CASO4 2H2O.