Materials 4

The dimension of the concrete cylindrical sample is 6" in diameter and 12" in height.

Proper compaction of the fill materials is important because it has multiple positive effects. Firstly, it increases the shear strength of the materials, making them more resistant to sliding or deformation. Secondly, it decreases permeability, meaning that the compacted fill materials are less likely to allow water or other fluids to pass through them. Lastly, proper compaction helps minimize compressibility, ensuring that the fill materials settle and consolidate evenly, reducing the potential for future settlement or uneven subsidence. Therefore, all of the given options are correct.

Blue smoke is an indication that the asphalt mix is overheated. When the mix is overheated, the asphalt binder can start to burn, producing blue smoke. This can happen if the mix is heated at a temperature higher than the recommended range. The presence of blue smoke suggests that the asphalt mix may have undergone thermal degradation, which can affect its performance and durability. Therefore, it is important to monitor the temperature of the asphalt mix during the heating process to prevent overheating and potential issues with the final pavement quality.

The weight of the asphalt can be calculated by subtracting the weight of the dry aggregate from the weight of the sample. In this case, the weight of the asphalt is 1000 grams - 950 grams = 50 grams. To find the percentage of asphalt by weight of the mix, we divide the weight of the asphalt by the weight of the mix and multiply by 100. Therefore, the percentage of asphalt by weight of the mix is (50 grams / 1000 grams) * 100 = 5.0%.

The correct answer is atterberg device and glass plate. In the liquid limit and plastic limit test, the atterberg device is used to determine the moisture content at which soil changes from a liquid to a plastic state. It consists of a cup, a groove, and a crank mechanism. The glass plate is used to roll the soil into a thread-like shape during the test. Sieves and chisel are not used in this specific test, and mortar and pestle are typically used for grinding and mixing substances, not for the liquid limit and plastic limit test.

The contractor is required to submit a job-mix formula, along with laboratory test data and samples of resources, to the Engineer for testing and approval. This process takes a certain amount of time, and the contractor is given a deadline to submit these documents. In this case, the deadline is three weeks. This allows the Engineer enough time to review and test the mixture before approving it for use.

When cement comes into contact with the aggregate, a chemical reaction called hydration begins. This reaction causes the cement to harden and bind the aggregate particles together. If the cement and aggregate are not mixed within a certain timeframe, the hydration process may already be underway, leading to a weaker bond between the cement and aggregate. Therefore, if the mixing is not done within 1.5 hours of contact, the batches may be rejected to ensure the strength and quality of the final product.

A GI (Grading Index) value of 0 indicates good subbase materials. This means that the subbase materials have a well-graded particle size distribution, with a good balance of different sizes of particles. A well-graded subbase material allows for better compaction and stability, providing a solid foundation for construction or other applications.

Concrete that is not placed within 90 minutes from the time the ingredients were charged into the mixing drum should not be used. This is because concrete starts to set and harden after a certain period of time, known as the initial setting time. If concrete is not placed within this time frame, it may not have the desired strength and durability when it eventually hardens. Therefore, it is important to use concrete within the specified time limit to ensure the quality of the final product.

The higher the value of PI (Plasticity Index) of the soil, the weaker will be the soil performance as a construction material. This is because a higher PI indicates that the soil has a higher clay content, which leads to increased plasticity and reduced strength. Clay soils have a tendency to shrink and swell with changes in moisture content, causing instability and potential damage to structures built on them. Therefore, a higher PI value signifies weaker soil performance.

The penetration test is a method used to measure the consistency of asphalt. It involves measuring the depth in which a standard needle penetrates into the asphalt sample under specific conditions. The penetration value obtained indicates the consistency of the asphalt, with lower values indicating harder asphalt and higher values indicating softer asphalt. Therefore, the correct answer is consistency.

The concrete sample should be stored in a moist conditioned temperature within the range of 18 deg C to 24 deg C until the time of the test. This temperature range is ideal for maintaining the integrity and properties of the concrete sample. Higher temperatures can cause the concrete to cure too quickly, leading to potential strength and durability issues. Lower temperatures can slow down the curing process, resulting in delays in testing and potential variations in the final properties of the concrete. Therefore, the specified temperature range ensures optimal conditions for accurate and reliable test results.

The shrinkage limit refers to the point at which further loss of water due to evaporation will not result in a reduction of volume. In other words, it is the minimum moisture content at which a soil will not shrink any further. This limit is important in determining the soil's ability to retain water and its susceptibility to shrinkage and cracking.

The correct answer is grading, LL and PL test. These tests are commonly used for soil classification. Grading refers to the analysis of particle size distribution in the soil sample. LL (Liquid Limit) and PL (Plastic Limit) tests determine the plasticity characteristics of the soil, helping to classify it into different groups. These tests provide valuable information about the behavior and suitability of the soil for various engineering applications.

The submission of a sample for testing for cement typically requires a small amount, usually around 10 kg. This quantity is sufficient for conducting various tests to determine the quality, strength, and other properties of the cement. It is important to use a representative sample to ensure accurate and reliable test results.

Raveling refers to the wearing away of the pavement surface caused by the dislodging of aggregate particles. This occurs when the bond between the aggregate particles and the asphalt binder weakens, leading to the loss of aggregate and the formation of loose debris on the pavement surface. Raveling can result from various factors such as aging, traffic loads, and environmental conditions, and if left untreated, it can lead to further deterioration of the pavement.

The correct answer is pile load test. This test is used to determine the bearing capacity of a pile by loading it with one or more weights and measuring the settlement or deformation of the pile under the applied load. This test helps in assessing the load-carrying capacity and performance of the pile in different soil conditions. It is an essential test in the design and construction of deep foundations.

The correct answer is 0.5%. This means that the scales used for weighing aggregates and cement must be accurate within 0.5% throughout their entire range of use. It is important to regularly inspect and seal the scales to ensure that they maintain their accuracy.

The answer is 0.5% because when weighing aggregates and cement, it is important to have accurate measurements to ensure the proper ratio and consistency of the mixture. A tolerance of 0.5% allows for a small margin of error while still maintaining the overall accuracy of the weighing process. This ensures that the final product meets the required specifications and quality standards.

Excessive asphalt content in bituminous mixes can lead to bleeding. Bleeding occurs when the excess asphalt rises to the surface of the pavement, creating a shiny, sticky film. This can result in reduced skid resistance, making the road slippery and unsafe for vehicles. Additionally, the excess asphalt can attract dirt and debris, leading to poor aesthetics and reduced visibility of road markings. Overall, bleeding can negatively impact the performance and durability of the pavement.

The basis for acceptance of material in a small project where the quantity of steel bars is 10,000 kg or less is the mill certificate. A mill certificate is a document provided by the manufacturer of the steel bars, which certifies that the material meets the required specifications and standards. It includes information such as the chemical composition, mechanical properties, and testing results of the steel bars. This certificate ensures that the material is of acceptable quality and can be used in the project without the need for additional testing.

Weathering is the correct answer because it refers to the process of breaking down rocks into smaller pieces of various sizes. This process can occur due to various factors such as temperature changes, water, wind, and biological activity. Weathering can result in the formation of different types of sediment, including large boulders, gravel, sand, and clay particles. It is an essential step in the formation of soil and plays a crucial role in shaping the Earth's surface over time.

If the strength control specimen does not meet the requirement and obtaining cores is not feasible due to structural considerations, the Material Engineer's decision would be to make payment at an adjusted price. This means that the payment for the area will be adjusted based on the strength deficiency of the specimen, rather than completely withholding payment or paying only a percentage of the original amount. This decision takes into account the limitations of obtaining cores and allows for a fair adjustment in payment based on the quality of the material.

Hygroscopic moisture content refers to the moisture present in an air-dried soil. This moisture is absorbed from the surrounding air by the soil particles due to their hygroscopic nature. It represents the water content that is held tightly by the soil particles and is not easily available for plant uptake. The hygroscopic moisture content is important in determining the soil's ability to retain water and its overall moisture-holding capacity.

A rapid curing cutback is a type of liquid asphalt that is made by mixing asphalt cement with gasoline. This mixture allows the cutback to cure quickly, making it suitable for applications where a fast curing time is desired.

The specific gravity of sodium sulfate used in the soundness test for aggregates should be within the range of 1.151 to 1.174. This range is important because it ensures that the sodium sulfate solution has the correct density to accurately measure the potential for volume changes in the aggregates. If the specific gravity is outside of this range, it could result in inaccurate test results and potentially lead to incorrect conclusions about the soundness of the aggregates.

The Atterberg limit is a measure of the water content at which a soil transitions from a liquid to a plastic state, and from a plastic to a solid state. It consists of three tests: the liquid limit, the plastic limit, and the shrinkage limit. The Atterberg limit helps determine the consistency and behavior of a soil, which is important in various engineering applications such as foundation design and slope stability analysis. Therefore, the Atterberg limit is a key indicator of the composition and properties of soil.

The correct answer is 50 seconds nor more than 90 seconds. This means that when mixing concrete at the site or in a central mixing plant, the mixing time should be at least 50 seconds but should not exceed 90 seconds. However, if mixer performance tests demonstrate that adequate mixing can be achieved in a shorter time period, then the mixing time can be adjusted accordingly.

The core test is used to determine the thickness and density of compacted asphalt pavement. This test involves extracting a cylindrical sample (core) from the pavement and analyzing it in a laboratory. By measuring the dimensions and weight of the core, the thickness and density of the pavement can be calculated. This information is crucial for assessing the quality and performance of the asphalt pavement, as well as for making necessary adjustments or repairs if needed.

The extraction test is used to determine the asphalt content in the bituminous mix. This test involves extracting the asphalt from the mix using a solvent, such as trichloroethylene or methylene chloride. The extracted asphalt is then weighed to determine its percentage in the mix. This information is important for quality control purposes, as it helps ensure that the correct amount of asphalt is present in the mix, which is crucial for its performance and durability.

When the GI (Group Index) is equal to 20, it indicates very poor subbase materials. The Group Index is a measure used in geotechnical engineering to assess the quality of subgrade soils. A higher GI value suggests a weaker and less stable subbase. Therefore, a GI of 20 signifies extremely poor subbase materials, indicating that the subgrade is highly susceptible to deformation and may require significant improvements or reinforcement.

A medium curing cutback is a type of liquid asphalt that is made by mixing asphalt cement with kerosene. This mixture has a moderate rate of curing, meaning it takes a moderate amount of time for the cutback to harden and set. This type of cutback is commonly used for various applications such as road construction and maintenance, as it provides a good balance between curing time and durability.

Magnesium chloride is used in soil stabilized road surfaces due to its high absorbent property, meaning it has the ability to absorb and retain water. This property helps to prevent the soil from becoming too dry or too wet, which can lead to instability and damage to the road surface. Potassium chloride, calcium chloride, and sodium chloride do not possess the same absorbent property as magnesium chloride, making them less suitable for this purpose.

The given answer range of 0-20 is the correct one because it encompasses the entire range of possible values for the empirical number used in evaluation for GI. This means that any value within this range can be considered when evaluating GI.

The correct answer is 60 cm. This means that the maximum spacing between the vibrations should be 60 cm. Vibration is expected to operate at a frequency of 8,300 to 9,600 impulses per minute under load. This information suggests that the vibrations should be evenly spaced apart by a maximum distance of 60 cm.

The correct answer is "approximately quarter points." When measuring the cored sample of asphalt pavement, it is done at approximately quarter points. This means that the sample is measured at four equidistant points along its circumference, dividing it into quarters. This method helps ensure that the measurements are taken evenly across the sample, providing a representative analysis of its properties and characteristics.

In asphalting work, there are three phases of rolling. This means that during the process of laying asphalt, there are three distinct stages where rolling is done to compact the asphalt and ensure a smooth and durable surface. Rolling helps to remove air voids and achieve proper density, which is crucial for the longevity and performance of the asphalt pavement.

The required strength in the absence of a beam mold on-site is 3,500 psi. This means that the concrete used in the construction should have a compressive strength of at least 3,500 pounds per square inch. This specification ensures that the concrete is strong enough to withstand the intended load and perform well in the structure.

Based on the given information, if no core had been taken at the end of each day of operation and the project has already been completed, a core shall be taken for every 100 l.m./lane. This means that for every 100 linear meters per lane, a core sample should be taken.

When concrete is delivered in truck mixers, there may be instances where the slump of the concrete needs to be increased to meet the specified requirement. In such cases, the Engineer permits the addition of additional water to the batch and additional mixing to be performed. However, these operations must be completed within a certain timeframe after the initial mixing operation. The correct answer of 45 minutes indicates that the additional water and mixing can be done within this time limit, as long as the water and cement ratio is not exceeded.

After concrete has been placed, it is advisable to maintain it fully wetted and in position for 72 hours. This is because during this time, the concrete undergoes a process called hydration, where it reacts chemically with water to harden and gain strength. Keeping the concrete wet during this period helps to prevent it from drying out too quickly, which can result in shrinkage cracks and reduced strength. Therefore, it is important to maintain the concrete's moisture content for the full 72-hour period to ensure proper curing and achieve the desired strength and durability.

When the value of GI (Group Index) is negative, it indicates that the soil has very good properties. This means that the soil has a high bearing capacity, good drainage, and is generally stable. Therefore, the soil performance would be classified as "very good subgrade".

The correct answer is 50 mm and 6 mm. This means that the depth of the weakened joints should be at least 50 mm and the width should be 6 mm. This is important to ensure that the joints are strong enough and can withstand the required load or stress. A depth of 50 mm provides enough material for the joint to resist bending or breaking, while a width of 6 mm allows for sufficient bonding area between the joint components.

The length of the Shelby tube of an undisturbed sample is 18" long.

The retarder is a chemical additive used in concrete to slow down the setting time. It can delay the setting time of concrete for up to 4 hours. This is beneficial in situations where there is a need for extended workability or when the concrete needs to be transported over long distances. By extending the setting time, the retarder allows for better placement and finishing of the concrete, resulting in a higher quality end product.

The prime coat needs to be undisturbed for at least 24 hours to allow it to fully dry and cure. This time period ensures that the prime coat forms a strong bond with the surface and provides a stable base for the subsequent layers of coating or paint. If the prime coat is disturbed before it has fully cured, it may not adhere properly and could result in a compromised finish or reduced durability. Therefore, it is important to wait for the recommended 24 hours before proceeding with any further work or application on top of the prime coat.

The correct answer is 15. This means that all the water should be in the drum by the end of the first 15 seconds of the mixing period. This indicates that the flow of water should be consistent and evenly distributed throughout the mixing process. If all the water is not in the drum by this time, it may affect the quality and consistency of the mixture being produced.

A slow curing cutback is a type of liquid asphalt that is made by mixing asphalt cement and oil. It is called "slow curing" because it takes a longer time to cure or harden compared to other types of cutbacks. This type of cutback is often used for road construction and maintenance projects where a slower curing time is desired.

Bulk cement is the correct answer because it refers to a type of cement that is transported and stored in large quantities, typically in silos or bins. It is specifically mentioned in the question that the cement needs to be transferred to an elevated, air tight, and weatherproof storage, which aligns with the characteristics of bulk cement storage. Portland cement and pozzolan cement are types of cement, but they do not necessarily require the same storage conditions mentioned in the question. Therefore, the correct answer is bulk cement.

The consolidation test is usually performed on undisturbed samples. This is because undisturbed samples represent the natural state of the soil, without any disturbance or alteration to its structure. By testing undisturbed samples, the true behavior and properties of the soil can be accurately determined, allowing for more reliable analysis and predictions of its consolidation characteristics. Disturbed samples, on the other hand, have been altered or disturbed during sampling, which may affect their behavior and not provide an accurate representation of the soil's actual properties. Therefore, undisturbed samples are preferred for consolidation testing.