CDC 3e251 Set-a Vol. 2

The numerical value of pi is 3.14. Pi is a mathematical constant that represents the ratio of a circle's circumference to its diameter. It is an irrational number, meaning it cannot be expressed as a simple fraction or a finite decimal. The value of pi is approximately 3.14159, but it is commonly rounded to 3.14 for simplicity in calculations.

A sounding rod is the most common tool used to detect unsound pavement. This tool is typically a long, slender rod that is inserted into the pavement and then tapped or struck with a mallet. By listening to the sound produced when the rod hits the pavement, experienced professionals can determine if the pavement is solid and in good condition or if there are voids or areas of deterioration beneath the surface. The sound produced by the rod can indicate the presence of cracks, delamination, or other issues that may require repair or replacement of the pavement.

A French drain is a type of structure that is constructed by filling a ditch or trench with crushed or broken rock. The purpose of a French drain is to redirect water away from an area, preventing waterlogging and potential damage. The crushed or broken rock allows water to flow through easily while filtering out debris. This type of drain is commonly used to alleviate drainage issues in yards, gardens, and basements.

Subsurface drainage is a method used to manage water levels in the ground. Lowering the water table is one of the functions of subsurface drainage as it helps to prevent waterlogging and increase soil productivity. Draining underground lakes is another function, as it helps to remove excess water and prevent flooding. Intercepting seepage or underground springs is also a function of subsurface drainage, as it helps to redirect water away from structures or areas where it may cause damage. Therefore, all of the given conditions are functions of subsurface drainage.

Treating the bottom of vertical dry wells with calcium chloride or hay helps prevent freezing. Calcium chloride is commonly used as a de-icing agent because it lowers the freezing point of water, preventing the formation of ice. By applying calcium chloride or hay at the bottom of the wells, the water inside the wells is less likely to freeze during cold temperatures. This prevents the wells from being blocked or damaged by ice, ensuring proper drainage and functionality.

The first centerline stake for concrete should be placed at the beginning of the project. This is because the centerline stake helps to establish the reference point for the project and ensures that the concrete is poured accurately along the desired path. Placing it at the beginning allows for proper alignment and measurement of subsequent stakes and ensures that the project starts off on the right track.

A line composed of a series of short dashes on a drawing represents a hidden line. Hidden lines are used in technical drawings to represent features that are not visible from a particular viewpoint. These features are typically obscured by other parts of the object or are located inside the object. The dashed line helps to differentiate hidden lines from other types of lines on the drawing, such as visible lines or center lines.

When ordering concrete, it is recommended to order 5 percent excess. This is because there can be unexpected factors that may result in the need for additional concrete, such as spillage, uneven surfaces, or mistakes in measurement. Ordering a 5 percent excess ensures that there is enough concrete to complete the project without running out. Ordering a higher percentage of excess may lead to unnecessary wastage and increased costs, while ordering a lower percentage may result in insufficient concrete and the need for additional deliveries, causing delays in the project.

During or immediately after a rainstorm, it is important to perform an operational drainage inspection. This type of inspection focuses on assessing the functionality and performance of the drainage system. It involves checking if the drains are properly functioning, if there are any blockages or clogs, and if the water is being effectively directed away from the desired areas. This inspection helps identify any issues or potential problems in the drainage system that may have arisen due to the rainstorm, allowing for timely maintenance and repairs if needed.

When setting forms, it is important to use a strong and durable string that can withstand tension and pressure. Nylon is a suitable type of string for this purpose as it is known for its strength and resistance to stretching. It is commonly used in construction and carpentry projects where forms need to be securely set in place. Cotton, yarn, and thread are not as strong or durable as nylon, making them less suitable for this task.

GPS operates off of a radio signal. Radio waves are used to transmit the signals from GPS satellites to GPS receivers on the ground. These signals contain information about the satellite's location and the time the signal was transmitted. The GPS receiver uses this information to calculate its own location. The radio signal is essential for the functioning of GPS as it allows for accurate positioning and navigation. Microwave, TV, and electric signals are not used in GPS operation.

If a subsurface drain becomes clogged, it can be cleaned by flushing it with high-pressure water. This method is effective because the force of the water can dislodge and remove any debris or blockages that may be causing the clog. The high-pressure water can create enough force to push the debris through the drain and clear the pathway for proper drainage. This method is commonly used in drain cleaning as it is efficient and does not require the use of chemicals or manual labor to remove the clog.

The leveling screw is used to center the bubble on the bull eye of a self-leveling level. By adjusting the leveling screw, the user can ensure that the level is perfectly leveled and the bubble is centered. This allows for accurate measurements and leveling of surfaces. The compensator, azimuth clamp, and tangent screw are not specifically used for centering the bubble on the bull eye.

When computing base course materials, it is necessary to compensate for low spots in the subgrade by adding a certain percentage of the computed volume to the order. In this case, the correct answer is 5 percent. Adding 5 percent to the order ensures that there is enough material to fill in the low spots and create a level and stable base for construction.

When time is a critical factor, conducting a walking inspection may not be feasible or efficient. In such situations, it is important to prioritize time-sensitive tasks and opt for alternative inspection methods that are quicker and more effective. Conducting a walking inspection would require more time and may delay other essential activities that need to be completed urgently. Therefore, when time is a critical factor, it is best to choose a different inspection method that can be completed more swiftly.

The strength of concrete is primarily influenced by the water-cement ratio and the hydration process that takes place. The water-cement ratio determines the amount of water used in the mixture, which directly affects the hydration reaction and the overall strength development. If the ratio is too high, the concrete may be weak and prone to cracking. On the other hand, if the ratio is too low, the mixture may be too dry and difficult to work with. Additionally, the hydration process refers to the chemical reaction between water and cement, which leads to the formation of hardened concrete. The extent of hydration directly impacts the strength and durability of the concrete.

When transporting concrete, it is important to prevent segregation. Segregation refers to the separation of the components of concrete, such as the cement, aggregates, and water. This can occur due to improper handling or excessive vibration during transportation, leading to an inconsistent mixture and reduced strength. To prevent segregation, proper techniques should be followed, such as using appropriate equipment, avoiding excessive pouring heights, and ensuring a consistent and uniform mix.

Vibration is the most widely used mechanical method for consolidating concrete. When concrete is poured into a form, it contains air voids and pockets of excess water that can weaken the structure. Vibration helps to remove these air voids and excess water by causing the concrete to settle and compact. This process improves the strength and durability of the concrete, making it more resistant to cracking and other forms of damage. Vibration can be achieved through the use of vibrating tools or machinery, which are commonly used in construction projects to ensure the quality and integrity of the concrete.

Angular aggregates in a concrete mixture produce a stronger mix because their irregular shape allows for better interlocking and bonding between the particles. This results in a denser and more compact concrete structure, enhancing its strength and durability. On the other hand, uniform, square or oval, and round or sub-round aggregates have smoother surfaces and do not interlock as effectively, leading to a weaker mix.

Work drawings usually begin by showing boundaries. This is because boundaries define the limits and extents of the project area. By showing the boundaries on the drawing, it allows the viewer to understand the exact area where the work will take place. This information is crucial for contractors, engineers, and other stakeholders involved in the project to have a clear understanding of the project's scope and to avoid any encroachment or confusion with neighboring properties. Additionally, showing boundaries helps in coordinating and planning the project effectively.

Physically checking the construction site should be the first step when preparing a sketch for a sidewalk because it allows the person to assess the actual conditions and constraints of the site. This step helps in understanding the terrain, any existing structures, and potential obstacles that may affect the design and construction of the sidewalk. By physically inspecting the site, one can gather accurate information and make informed decisions regarding the placement and design of the sidewalk.

A dowel is a cylindrical rod that is used to connect two components or structures. When a dowel is placed across an expansion joint, it needs to be smooth in order to allow for movement and prevent any obstruction or resistance. A smooth dowel will ensure that the joint can expand and contract freely without causing any damage or hindrance. Grooved, stamped, or deformed dowels would create friction and restrict the movement of the joint, which is undesirable in this context. Therefore, a smooth dowel is the most suitable choice for placing across an expansion joint.

Oiling and grooving with a saw kerf can prevent wooden keyways from cracking. Oiling the keyway helps to keep the wood moisturized and prevents it from drying out and cracking. Grooving with a saw kerf creates channels in the wood, allowing for expansion and contraction without causing cracks. This combination of oiling and grooving helps to maintain the integrity of the wooden keyway and prevent cracking.

French drains are not recommended for permanent construction due to their tendency to silt up. This means that over time, the drains can become clogged with sediment, reducing their effectiveness in draining water. As a result, the drains may not be able to effectively remove water from the surrounding area, leading to potential flooding or water damage. Therefore, alternative drainage systems that are less prone to silt buildup are typically preferred for permanent construction projects.

The correct answer is B. The B horizon, also known as the subsoil, is the base for all types of pavement construction. This layer is typically composed of compacted soil with good load-bearing capacity, which is essential for supporting the weight of pavement materials and vehicles. The B horizon is located below the topsoil (A horizon) and above the parent material (C horizon). It provides a stable foundation for the pavement and helps prevent settling or cracking.

The only real difference between laying out a large area and a small area is the amount of work involved. When working on a large area, there will be more materials, measurements, and overall effort required compared to a small area. The size of the area directly affects the amount of work needed to complete the task, while factors such as terrain, weather conditions, and equipment available may vary but do not necessarily differentiate between laying out a large or small area.

The base course is a layer of material that is placed on top of the subgrade, which is the natural soil or prepared earth beneath the road. The purpose of the base course is to distribute the wheel loads, or the weight of vehicles, evenly across the subgrade. This helps to prevent excessive stress on the subgrade, which could lead to deformation or failure of the road. The base course also provides a stable and uniform surface for the pavement to be constructed on. The insulating course and shoulder are not directly involved in distributing wheel loads to the subgrade.

The area of a rectangle is calculated by multiplying its length by its width. In this case, the length is 8 feet and the width is 12 feet. Multiplying 8 by 12 gives us 96, so the area of the rectangle is 96 square feet.

The class of pneumatic hammer most commonly used for breaking concrete slabs is in the range of 30-90 pounds. This weight range is suitable for the task as it provides enough force to effectively break the concrete without being too heavy or difficult to handle. Pneumatic hammers within this weight range are commonly used in construction and demolition work for their ability to efficiently break through concrete surfaces.

Coarse-grained soil classification is made up of sand and gravel in the "B" horizon and has 50% or less material passing the No. 200 sieve. This means that the soil particles are larger in size and have less fine material. It is important to note that fine-grained soil would have more fine material and smaller particle sizes. Therefore, the correct answer is coarse-grained.

The correct answer is Rodman. A Rodman is the person who takes the rod reading when using a target.

Chemical membranes are applied to concrete surfaces to provide protection against moisture penetration and to enhance durability. Applying the membranes as soon as the concrete is finished ensures that the surface is adequately protected from the beginning. This allows the membrane to effectively prevent moisture from entering the concrete and causing damage. Applying the membranes after floating or edging may not provide the same level of protection, as the concrete may have already been exposed to moisture during these processes. Similarly, waiting until the joints are installed may result in moisture ingress before the membranes are applied.

The bottom of the trench needs to be shaped to fit the pipe because this will ensure proper alignment and support for the pipe. If the bottom of the trench is not shaped to fit the pipe, it may result in misalignment or instability of the pipe, leading to potential leaks or damage. Shaping the bottom of the trench to fit the pipe allows for a secure and stable installation, ensuring the proper functioning of the subsurface structure.

To determine the height of the instrument, you add the benchmark elevation to the backsight reading taken from the leveling rod. The backsight reading is the measurement taken from a point of known elevation (benchmark) to the instrument. Adding this reading to the benchmark elevation allows for the calculation of the instrument's height above the benchmark, which is necessary for accurate leveling measurements.

A blanket or insulating course helps reduce frost action. In cold climates, frost action can cause the ground to freeze and expand, leading to heaving and damage to the pavement or structure above. By providing insulation, the blanket or insulating course helps to minimize the penetration of cold temperatures into the ground, reducing the potential for frost action and its negative effects.

The approximate area of a circle can be found using the formula A = πr^2, where r is the radius of the circle. In this case, the diameter is given as 18 feet, so the radius is half of that, which is 9 feet. Plugging this value into the formula, we get A = 3.14 * 9^2 = 3.14 * 81 = 254.34 square feet. Since the options are rounded, the closest approximation is 254 square feet.

Spalling is the correct answer because it refers to the defect where concrete chips or breaks away at joints, cracks, or edges. This can occur due to various reasons such as freeze-thaw cycles, corrosion of reinforcing steel, or poor construction practices. Spalling can lead to further deterioration of the concrete structure if not addressed in a timely manner.

Depth is generally considered to be the third dimension in a measurement. While width, length, and height are all measurements that describe the size or extent of an object in two dimensions, depth adds the aspect of the third dimension, which is the measurement of how far an object extends or penetrates into space. Therefore, depth is the correct answer for the third dimension in a measurement.

The correct answer is 24. The GPS system consists of a constellation of 24 satellites that orbit the Earth. These satellites work together to provide accurate positioning, navigation, and timing information to GPS receivers on the ground. Each satellite continuously broadcasts signals that allow GPS receivers to determine their precise location. Having 24 satellites ensures that at least four satellites are always visible from any point on Earth, ensuring reliable and accurate GPS positioning.

A backhoe is not recommended for excavating large areas because it is primarily designed for digging small trenches and holes. It has a limited reach and capacity compared to other equipment like a dozer, scraper, or clamshell. These other equipment options are better suited for large-scale excavation projects as they have larger capacities, longer reach, and can move more material efficiently.

When excavating, it is important to completely remove the parent material, which refers to the original material from which the soil has developed. The parent material can vary and may include rocks, minerals, or organic matter. By removing the parent material, the excavation process ensures that only the desired soil is left behind. The A horizon soil, also known as topsoil, is the uppermost layer of soil that is rich in organic matter and nutrients, making it essential for plant growth. Therefore, it is not necessary to remove the A horizon soil during excavation.

The most important part of landscaping is drainage. Proper drainage ensures that water is effectively directed away from the landscape, preventing issues such as pooling, erosion, and damage to plants. Without proper drainage, the landscape can become waterlogged, leading to poor plant health and potential structural damage. Additionally, drainage helps to maintain the overall appearance of the landscape by preventing water accumulation and maintaining a clean and well-maintained look.

When the structure is to be placed along the side of the pavement, it is important to have the holes in the perforated pipe placed upwards. This is because placing the holes upwards allows the water to drain away from the structure and towards the side of the pavement, preventing any accumulation of water near the structure. This helps in maintaining the stability and integrity of the structure and prevents any potential damage that could be caused by water accumulation.

Symbols are used by engineers to convey ideas and thoughts. Symbols are visual representations that can represent complex concepts or objects in a simplified manner. They are commonly used in engineering drawings, diagrams, and schematics to communicate information quickly and effectively. Symbols can convey specific meanings and are universally understood within the engineering community, making them a valuable tool for expressing ideas and thoughts in a concise and standardized way.

In a working sketch, it is important to include special instructions. These instructions provide specific details or requirements that need to be followed while working on the sketch. By including special instructions, it ensures that the person working on the sketch understands any specific guidelines or directions that need to be followed to complete the task accurately. This helps to avoid any confusion or mistakes during the process. Including special instructions in the working sketch improves communication and ensures that the desired outcome is achieved.

When setting up a tripod on steep surfaces, it is important to place the third leg uphill. This is because positioning the leg uphill provides stability and prevents the tripod from sliding or tipping over. Placing the leg downhill or to the left/right may cause the tripod to be unbalanced and increase the risk of it falling. Therefore, placing the third leg uphill ensures the tripod is securely positioned and minimizes the chances of any accidents or damage.

Once a pneumatic drill has begun to break pavement, slowly increasing the speed is the correct action to take. Increasing the speed gradually allows the drill to effectively break through the pavement without causing excessive damage or creating safety hazards. It allows for better control and precision in the drilling process.

Expansion joints are installed in slabs to release the compressive stresses that occur due to temperature changes and moisture variations. These joints allow the slab to expand and contract freely without causing any damage or cracking. By providing space for movement, expansion joints help to maintain the integrity and stability of the slab and prevent any potential structural issues.

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Adding calcium chloride to a concrete mixture increases the concrete's early strength. Calcium chloride acts as an accelerator, speeding up the hydration process of cement. This results in faster setting and hardening of the concrete, allowing it to gain strength more quickly. This can be beneficial in situations where early strength development is desired, such as in cold weather conditions or when a quick construction schedule is required.