Evaluation of Type C Fly Ash in Cold In-Place Recycling

Abstract

The Kansas Department of Transportation has developed an innovative method of rehabilitating low-volume pavements using cold in-place recycling (CIR) and Type C fly ash. Previous field test sections have indicated that fly ash improves constructability and moisture sensitivity. However, the same field test sections have exhibited increased cracking with increased fly ash content and a drop in pavement modulus with time. A laboratory study was undertaken to evaluate the effect of fly ash content on CIR. Reclaimed asphalt pavement (RAP) was mixed with 3, 7, 11, and 15 percent Type C fly ash and the fatigue life, durability, freeze-thaw resistance, and thermal cracking potential of laboratory-compacted samples were evaluated. RAP mixed with asphalt emulsion and asphalt emulsion with hydrated lime were evaluated as well. The results indicated that 7 to 11 percent Type C fly ash provided optimal laboratory freeze-thaw and moisture sensitivity performance. Increasing the fly ash content resulted in a brittle fatigue behavior as well as an increased thermal fracture temperature. AASHTO T283 is recommended for selecting the optimum fly ash content.

Stabilization of recycled base materials with high carbon fly ash

“…Moreover, Cross and Young (1997) reported higher initial cracking of recycled pavement materials with increasing cementitious fly ash contents. On the other hand, the maximum LKD content was set at 5% in the current study solely considering the cost-effectiveness;…”

Effects of copper slag and recycled concrete aggregate on the properties of CIR mixes with bitumen emulsion, rice husk ash, Portland cement and fly ash

“…Various additives such as bitumen emulsion, cement, quick lime, coal waste (ash), silica fume or fly ash have been used during the compaction of the recycled mixtures [2,10,11,13,30,32]. Different factors such as cost, performance, and climate condition should be considered when choosing the appropriate type of additive [30].…”

“…Type of additives that is used in CIR mixtures has also been found as a factor that improves the mechanical properties and performance of these mixtures [10,11]. Various types of additives such as Portland cement, fly ash, and lime have been successfully used in CIR mixtures [2,[10][11][12][13].…”

“…Various types of additives such as Portland cement, fly ash, and lime have been successfully used in CIR mixtures [2,[10][11][12][13].…”

Field Performance Evaluation of Class C Fly Ash in Full-Depth Reclamation: Case History Study

“…However, additives are often used to stabilize the pulverized base course. The available additives in common practice include water, cement, asphalt emulsion, hydrated lime, and fly ash (3)(4)(5).…”