Technical Report Oral Exam - CE 2030

CIR

Cold In-Place Recycling

What is CIR?

a pavement rehabilitation method that reuses existing asphalt material to restore road performance

What are the benefits of CIR?

Minimizes environmental impact and costs and construction time

What is the first step of the CIR process?

Milling

What happens during the milling step of the CIR process?

The damaged asphalt layer is milled to the desired depth to prepare for recycling.

What is the second step of the CIR process?

Mixing

What is the third step of the CIR process?

Re-laying

What is re-laying?

The mixture is re-laid and compacted using specialized equipment to ensure proper bonding and structural integrity.

What is Marshall Hammer Compaction?

A method used to compact CIR samples using a Marshall hammer to simulate field conditions and achieve target density.

What are the key components of CIR?

RAP, cement, water, and emulsion

What temperature is the Marshall Stability and Flow test conducted at?

60°C

Proper aggregate gradation ________

Enhances load distribution, reduces voids, and leads to more durable pavement.

Implementation of standardized test methods ________

Ensures repeatability, accuracy, and relevance to pavement performance objectives.

Reuse of existing asphalt materials ________

Lower environmental impact and preservation of natural resources.

Use of CIR in pavement rehabilitation

Cost savings and reduced construction time compared to traditional methods.

What is G_mb?

Bulk specific gravity

What is SSD?

Saturated surface dry condition, a state where aggregate surface moisture is balanced with internal moisture content.

How do you find bulk specific gravity (G_mb)?

Dry Mass / (SSD Mass - Underwater Mass)

Why is Bulk specific gravity important?

It helps calculate for air voids and ensure proper density in the mix

Describe the purpose and procedure of the sieve analysis test.

used to determine the particle size distribution of aggregates by passing them through a series of sieves with different mesh sizes

What is the fineness modulus?

Indicates the fineness or coarseness of an aggregate which affects the workability and texture of the concrete mix

How do you find the fineness modulus?

Adding the cumulative percentages of material retained on set of sieves and dividing by 100

What is the slump test?

Measures the consistency and workability of freshly mixed concrete

What is the concrete compression test?

measure the compressive strength of cured concrete cylinders where an increasing compressive load is applied until failure. The maximum load is then recorded and used to calculate the compressive strength.

What does the concrete beam flexural test measure?

The tensile strength of concrete by determining its ability to resist bending forces.

What is the relationship between w/c ration and the flexural strength of concrete?

A lower w/c ratio generally leads to higher flexural strength, as it results in a denser and stronger concrete mix.

What factors contribute to higher compressive strength in concrete?

lower w/c ratios and longer periods of hydration

What is nominal maximum aggregate size?

The largest sieve size that retains no more than 10% of the aggregate

What is the relation between dry stability (lb) and emulsion content % ?

Dry stability decreases as emulsion content increases in percentage.

What is stability?

measures the resistance of the mix to deformation under load

What is flow?

Indicates flexibility and deformation capacity of the concrete mix.

What is the relation between retained stability % and emulsion content % ?

retained stability increases with increasing emulsion content percentage

How do you find dry stability?

The load peak in LBS

How do you find the flow?

Displacement peak in IN

How do you find the retained stability?

100 * (Wet Stability/Dry Stability) = %

What is the relation between emulsion content % and flow (in.)?

Flow increases with emulsion content increasing

What does the semi-log gradation chart show?

Sieve size vs Percent passing (particle size distribution)

What does the 0.45 power chart show?

Represents aggregate gradation if used for asphalt and displays the max density line used to determine optimum grading.

How do you calculate Apparent specific gravity?

Dry Mass / (Dry Mass - Water Mass)

How do you calculate for Absorption?

[(SSD Mass - Dry Mass) / Dry Mass] * 100 = %

How do you determine if an aggregate is fine or course?

Aggregates that pass through #4 sieve are fine aggregate

How do you calculate for compressive strength (f primec) ?

Max load / area

Why does a shorter slump test better when performing the slump?

It correlates to higher compressive strength of concrete

What is specific gravity?

It measures the density of aggregate compared to water

What is the relationship of the slump and w/c ratio?

Inches of slump increase as the w/c ration increases

What does RAP stand for?

Reclaimed Asphalt Pavement

How do you determine bulk specific gravity in the lab?

Weighing compacted samples in three conditions: dry weight, submerged weight, and SSD weight.