Q and ans is right. concrete pavement resisting load by bending within it self and very low amount of load is transfered to the lower level(base, sub-base...etc).therefore, bending strength( flexural strength) is one of the citical design parameter in rigid pavement design.

The mix design for pavement concrete is based on flexural strength.

Flexural strength is the measure of a material's ability to resist bending or cracking under load. In the case of pavement concrete, it is crucial to ensure that the concrete can withstand the stresses and loads imposed by traffic and environmental conditions without experiencing excessive cracking or failure.

Importance of Flexural Strength in Pavement Concrete:

1. Durability: Pavement concrete is subjected to repeated loading from vehicles, which can cause flexural stress. A concrete mix with sufficient flexural strength will be able to resist these stresses and maintain its structural integrity over time.

2. Crack Resistance: The flexural strength of concrete is directly related to its ability to resist cracking. Cracks in pavement concrete can allow water and other harmful substances to penetrate, leading to further deterioration of the pavement. By designing the mix for adequate flexural strength, the risk of cracking can be minimized.

3. Load Distribution: Flexural strength is essential for ensuring that the load from vehicles is distributed evenly across the pavement surface. A concrete mix with inadequate flexural strength may lead to localized stress concentrations, resulting in premature pavement failure or uneven wearing.

4. Design Life: The design life of pavement concrete is an important factor to consider. By specifying a mix with appropriate flexural strength, the pavement can be designed to meet the required service life without significant maintenance or repairs.

Mix Design Process:

The mix design process involves determining the proportions of various concrete ingredients to achieve the desired flexural strength. This process typically includes the following steps:

1. Target Flexural Strength: The design engineer determines the required flexural strength based on factors such as traffic loadings, environmental conditions, and pavement design life.

2. Material Selection: The engineer selects suitable materials, including aggregates, cement, water, and admixtures, that can collectively provide the desired flexural strength.

3. Proportioning: The engineer determines the optimal proportions of each material to achieve the target flexural strength. This is done through trial mixes and laboratory testing.

4. Testing and Validation: The designed mix is tested for its flexural strength through standardized tests such as the three-point bending test or the four-point bending test. The test results are compared to the target flexural strength to validate the mix design.

5. Adjustment and Optimization: If the tested flexural strength is not within the desired range, adjustments can be made to the mix proportions to optimize the flexural strength while considering other factors such as workability and durability.

In conclusion, the mix design for pavement concrete is based on flexural strength to ensure the durability, crack resistance, load distribution, and design life of the pavement. The mix design process involves selecting suitable materials and determining their proportions to achieve the desired flexural strength.