Experimental Study on Bond Behavior between Heat-Damaged Recycled
|نوع نگارش مقاله||
scopus – master journals – JCR
۴٫۲۷۶ در سال ۲۰۲۰
۲۶ در سال ۲۰۲۱
۰٫۹۰۱ در سال ۲۰۲۰
|شاخص Quartile (چارک)||
Q1 در سال ۲۰۲۰
خرید محصول توسط کلیه کارت های شتاب امکان پذیر است و بلافاصله پس از خرید، لینک دانلود محصول در اختیار شما قرار خواهد گرفت و هر گونه فروش در سایت های دیگر قابل پیگیری خواهد بود.
فهرست مطالب مقاله:
In this work, the effect of high temperature on the bond behavior between Recycled Asphalt Pavement (RAP)
concrete and Fiber Reinforced Polymer (FRP) was studied. The use of RAP in concrete construction has been developed and utilized recently due to its various economic and environmental features. Nevertheless, very few studies have examined the bonding performance and failure mode between RAP concrete and FRP. A total of 46 asphalt pavement concrete specimens with three different concrete compressive strength were cast and tested under pullout test. The specimens were prepared using different RAP aggregate content and were subjected to elevated temperatures within a range from 23 °C to 600 °C. The heat damaged specimens were repaired using two Near-Surface Mounted Carbon Fiber Reinforced Polymer (NSM-CFRP) strips spaced at 50 mm with three different bonded lengths. According to the experimental results of the pullout test, RAP concrete specimens showed lower bonding strength and slippage than Natural Aggregate (NA) concrete specimens. Furthermore, specimens exposed to elevated temperatures showed a significant decrease in bonding strength and a significant increase in slippage. Results also indicated that as the temperature increased, specimens with high RAP aggregate content failed at higher slippage compared to specimens with low RAP aggregate content with the same compressive strength. Moreover, the relationships between bond load and strain of (CFRP) strips were established and discussed in the results. The failure mode in all specimens was concrete separation.
Keywords: Recycled Asphalt Pavement (RAP), Bond behavior, NSM-CFRP strips, Heat-damage, pullout test, Repair
|بخشی از متن مقاله:|
Using Recycled Aggregate (RA) is a new, promising technique used in the concrete industry for constructing civil structures with less environmental impact. Large amounts of recycled aggregates can be generated from crushing parent concrete produced from the construction industry, referred to as Recycled Concrete Aggregate (RCA), or from demolished asphalt pavement materials from road reconstruction projects, referred to as Recycled Asphalt
Pavement (RAP) aggregate. Thus, Recycled Aggregate Concrete (RAC) is an alternative concrete material that can be produced by partially or totally replacing Natural Aggregate (NA) with RA. Very few studies have
investigated the effect of employing RAP aggregate in concrete mechanical properties. Okafor , showed that
RAP aggregate has lower specific gravity and lower water absorption compared to Natural Aggregates (NA) due to the asphalt coating, which inhibited the full absorption of water by the aggregates. It was also reported that the
splitting tensile strength of the concrete made with RAP aggregate decreased as compared with concrete made
with NA. The strength reduction was due to the existence of the asphalt film around the aggregates. However, Huang et al. , found that RAP aggregate improved the toughness. The modulus of elasticity of RAC decreased with the increase of the RA content [3,4]. Many researchers studied the influence of elevated temperature on the RAC. Zega and Miao , reported more degradation of the mechanical properties of RAC with 75% RCA replacement ratio compared to concrete with natural aggregate exposed to an elevated temperature of 500 °C. Parameters included in the study were compressive strength, static, and dynamics modulus of elasticity. Salahuddin et al. , examined the influence of high temperature on the behavior of concrete with varying RCA percentage. Replacement contents used were 30%, 60%, and 100%. Although experimental results showed a significant decrease in the mechanical properties of RAC, the residual compressive strength of RA concrete at high temperature was comparable with NA concrete, which is the same conclusion reached by Govindagowda et
- al. . Khan et al.  and Varona et al. , reported that the elastic modulus and Poisson’s ratio of RAC significantly affected the high RA replacement ratio under high temperatur RA concrete has a higher degree of properties degradation compared to NA concrete. Xiong et al.  studied the dynamic performance of RAC double-skin tubular columns (DSTCs) subjected to cyclic axial compression. The experimental results showed that the RA replacement percentage and the loading rate played an important rule on the stress–strain relationship and the mechanical properties of the RAC-filled DSTCs.
Currently, Fiber Reinforced Polymers (FRPs) are commonly utilized for strengthening and the rehabilitation of concrete structures. Near Surface Mounted–Carbon Fiber Reinforced Polymer (NSM-CFRP) is widely used for
this purpose due to its efficiency in minimizing damage caused by harsh environmental conditions, the minimal
installation time, and low labor cost. In this method, CFRP strips are placed in a groove cut inside the concrete cover and bonded to concrete with epoxy. The high tensile strength of FRP materials contributes to protecting the FRP material from an unexpected hazardous effect and therefore, plays an important role in delaying the de- bonding of NSM-CFRP strips . Teng et al. , reported interfacial de-bonding at the FRP–epoxy interface for the NSM CFRP strips strengthening technique. Xiong et al.  investigated the bond behavior between RAC and basalt fiber-reinforced polymer bars, including the failure modes, bond mechanism, bond load, and slip. A
new model was proposed to simulate the bond stress‐ slip relationship. The impact of elevated temperature on the
FRP has been considered by a number of studies. Jadooe et al. , indicated that for an elevated temperature
below 600 °C, the bond load of specimens repaired with CFRP strip–epoxy adhesive is higher than the bond load of specimens repaired with cement-based adhesive. The cement-based adhesive showed a lower bond load at
temperatures higher than 600 °C. Meanwhile, Yu and Kodur , reported that CFRP strip or CFRP rod maintained its initial mechanical properties up to a temperature of 200 °C. On the other hand, fast degradation of
FRP properties was reported beyond 300 °C due to the decomposition of polymer resin. Yang et al. , showed an inverse relationship between the temperature and both tensile strength and elongation of CFRP strips in which the increase in temperatures led to a decrease in the tensile strength and elongation of CFRP strips while the
elastic modulus showed negligible change. However, the above research served to examine the bond behavior between NA concrete and CFRP strips but not for RAC strengthened with FRP. Obaidat et al. , reported lower
bonding load between NSM-CFRP strips and RAC at high RA content and high temperature.
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