The question asks about the aggregate impact value requirements for aggregates used in different types of concrete construction. The aggregate impact value is a measure of the toughness of an aggregate and its resistance to sudden shock or impact, which can cause failure by fracture.

Different concrete applications require aggregates with varying degrees of toughness depending on the stresses they will endure. For instance, concrete used in pavements and runways is subjected to significant impact loads from vehicles and aircraft, requiring aggregates with higher resistance to impact compared to concrete used in buildings, where impact loads are typically less severe.

The aggregate impact test is conducted using an impact testing machine. A sample of aggregate is placed in a mold and subjected to a series of blows from a standard hammer. The percentage of fines produced after the test relative to the original weight of the sample is the aggregate impact value. A lower aggregate impact value indicates a tougher aggregate.

Standard specifications provide limits for the aggregate impact value based on the intended use of the concrete. Let's examine the limits mentioned in the options:

• Building Concrete: Concrete used in various parts of buildings (excluding wear surfaces) generally does not require the same level of impact resistance as pavements. A higher aggregate impact value is permissible.
• Road Pavement Concrete: Concrete surfaces used for roads are subjected to frequent and significant impact loads from traffic. Aggregates used in road pavements must be sufficiently tough.
• Runway Concrete: Concrete runways in airports bear the impact of landing aircraft, which are extremely high impact loads. Aggregates for runway concrete need to be very tough and resistant to fracture under impact.

Based on common engineering standards (such as those from India, like IS 2386 Part IV), the typical limits for aggregate impact value are:

Now let's evaluate the given options based on these standard limits:

• Option 1: Building concrete is less than 45. According to standards, the limit for building concrete (non-wearing surfaces) is 45%. So, an aggregate impact value less than 45% is acceptable for building concrete. This statement is correct.
• Option 2: Road pavement concrete is less than 30. For concrete used in road pavements (a wearing surface), the limit is 30%. An aggregate impact value less than 30% means the aggregate is tough enough for road pavement concrete. This statement is correct.
• Option 3: Runway concrete is less than 30. Runway concrete is also a wearing surface subjected to heavy impact. The limit is 30%. An aggregate impact value less than 30% is required for runway concrete. This statement is correct.

Since Options 1, 2, and 3 are all correct statements regarding the permissible aggregate impact value for their respective applications, the statement that "All the options are correct" is the overall correct choice.

Aggregate Impact Value Testing and Significance

The aggregate impact value test is one of the important tests performed on aggregates to assess their mechanical strength properties, specifically toughness. Toughness is the resistance of a material to fracture under impact load. This property is crucial for aggregates used in pavement construction, railway ballast, and other applications where they are subjected to dynamic loads.

How Aggregate Impact Value Relates to Aggregate Quality

A lower aggregate impact value indicates that the aggregate is tougher and can better withstand sudden impacts without breaking down into smaller particles. This is particularly important for wearing courses of pavements, as breakdown under traffic loads can lead to rutting and surface distress.

Revision Table: Aggregate Properties for Concrete

Additional Information on Aggregate Testing

Besides the aggregate impact value, other tests are performed on aggregates to determine their suitability for concrete:

• Aggregate Crushing Value: Measures resistance to crushing under a gradually applied load.
• Los Angeles Abrasion Value: Measures resistance to wear, abrasion, and impact by a combination of attrition and impact in a rotating drum with steel balls.
• Specific Gravity and Water Absorption: Affect the weight and porosity of the aggregate.
• Shape Tests (Flakiness Index & Elongation Index): Measure the shape characteristics, which influence workability and interlocking.
• Soundness Test: Evaluates resistance to weathering actions like freezing and thawing, or wetting and drying.

All these tests together help determine the overall quality and suitability of aggregates for specific construction purposes like building concrete, road pavement concrete, and runway concrete, ensuring durability and performance.