Browsing by Author "Dedigamuwa, KV"

Now showing 1 - 4 of 4

item: Conference-Abstract
Analyzing the durability and the lateral drainage characteristics of open graded friction course pavement
(2019) Dedigamuwa, KV; Nawaz, RZ; Mampearachchi, WK
In Open Graded Friction Course (OGFC) is a thin permeable layer of special type Hot Mix Asphalt (HMA) which contains a combination of uniform size aggregate skeleton with minimum fines, and high asphalt content. OGFC is being used as an effective pavement material in many countries for expressway construction as it has many positive attributes in performing as a pavement material. During the operational stage of many expressways which were made out of dense asphalt, several issues were observed in wet seasons such as skidding, splash, hydroplaning. OGFC is a suitable solution as a pavement surfacing material for such existing drawbacks. Drainage characteristic of a pavement is one of the important parameters which dominantly contributes to the durability of a pavement. However, the inefficient water drainage due to the lack of drain-ability of vertical drainage caused by the clogging of OGFC lead to observe the properties of lateral drainage. Though, many studies had been carried out to address the clogging effect due to dust particles, no permanent rectification on this issue was found. Therefore, to investigate OGFC in a different way, the lateral drainage characteristics are analysed to identify the water movement on the surface of OGFC by comparing the capacities which can be endured by different types of OGFC. This study analyses the lateral drainage characteristics of OGFC pavement to find out the OGFC gradation which shows the optimum values for the combination of permeability and durability characteristics under the laboratory conditions. Further, the computer image analysis with the aid of MATLAB software is used to analyse the lateral drainage characteristics by identifying and calculating the areas of voids of cross sections captured as 2D photographs by a DSLR camera (Nikon- D3300). The proposed method is less time consuming, comparatively inexpensive and can be utilized to enhance OGFC by integrating with the traditional laboratory experiments.
item: Conference-Abstract
Development of a 3D model of open-graded friction course to evaluate the inter-connected air void with aggregate gradation
(Department of Civil Engineering, University of Moratuwa, 2020-12) Dedigamuwa, KV; Mampearachchi, WK; Perera, HLK
Open-Graded Friction Course (OGFC) is an asphalt material which has many advantages such as resistance to hydroplaning, low level of splash and spray, less headlight glare, improved visibility, a lesser number of accidents, reduced noise, and higher surface friction. OGFC is an advanced asphalt material which cannot thoroughly be understood by the results of traditional tests available. Though, OGFC consists of mastic, aggregate and air voids similar to hot mix asphalt, the porous structure of OGFC consists of a highly complicated interconnected void network. The number of voids and the void area of OGFC directly affects the durability and the permeability of the mixture. Therefore, it is necessary to increase the ratio of the area of interconnected voids to the area of total voids, in order to enhance the permeability of the OGFC mixture. A digital image analysis method has been introduced in this research in order to obtain different interconnected void structures for different gradations. This method consists of the identification of different properties such as number of void nodes, number of interconnected voids, areas of interconnected voids, reduction of interconnectivity with the depth, etc. An algorithm in “MATLAB” was developed to identify the properties of the crosssectional images obtained by the captured surfaces of the cut specimens of OGFC. The obtained cross-sectional data of aggregates, voids and mastic was used to create the plotting data of the 3D model using the algorithm developed in excel. Finally, the python tool “plotly” was used on the “Anaconda” platform to create the 3D model based on the data model created in Excel. The data of three different gradations were analyzed by the use of this method and the results were obtained. According to the pre-evaluated test data of three gradations on durability and permeability, the validity of the 3D models was analyzed. The developed 3D model from this study can be used to determine the optimum gradations of OGFC considering the durability and permeability, based on the analysis of the internal structure arrangement.
item: Thesis-Full-text
Estimate characteristics of open graded friction courses by digital image analysis
(2021) Dedigamuwa, KV; Mampearachchi, WK
The application of Open Graded Friction Courses (OGFC) as a pavement material has become a suitable solution for areas with high rainfall intensities. Since, OGFC material can act as a function-oriented pavement material to enhance permeability, reduce noise, and introduce more friction, improving the properties OGFC asphalt material to meet the requirements has drawn the attention of researchers in the last few decades. It is evident that the existence of a complex interconnected void network in OGFC has directly affected the durability and the permeability of the mixture. Further, the interconnected void network entirely depends upon the internal aggregate arrangement. Therefore, the identification of the internal arrangement of aggregates is very important to understand the void structure and improve the performance of designing OGFC. The lack of availability of quality controlling tools in the industrial construction stage leads to the occurrence of defects at the service stage and most of these issues can be minimized by investigating the internal structure of OGFC. This study presents a cost effective, rapid Digital Image Processing (DIP) method to determine the internal aggregate structure and the gradations of a core sample during the design and construction stages. Further, the proposed method enables the identification and quantification of segregation variation, internal voids and material distribution along the depth of the specimen. Experimental program of the study majorly included permeability test and durability test to compare the analytical results obtained for validation and justification. The internal aggregate structure data was collected by capturing cross section images in order to introduce a feasible way of implementing a gradation analysis. The cross sectional details were analysed to obtain details of areas, lengths and coordinates by developing an algorithm in MATLAB software. MATLAB was also used to obtain 2D aggregates structures and 3D models of specimens were constructed by using the python tool “plotly” on “Anaconda” platform. This research provides fundamentals to interpret and analyse data using DIP to construct the internal aggregate structure of OGFC specimens to identify and quantify deviations by the means of gradation, segregation and voids. Keywords: Digital Image Processing, Gradation, Internal Structure, MATLAB, OGFC
item: Article-Full-text
Performance of severely damaged reinforced concrete flat slab-column connections strengthened with carbon fiber reinforced polymer
(Elsevier, 2021) Silva, MAL; Dedigamuwa, KV; Gamage, JCPH
The punching shear failure of a slab‐column connection is a sudden catastrophic failure. The majority of studies have been focused on the strengthening aspects of non‐cracked slab‐column connections. However, the attention given to the retrofitting of heavily damaged slab‐column connections is comparatively less. Therefore, it is crucial to investigate the suitable damage repairing methods as well as post‐strengthening methods to enhance performance of damaged slab‐column connections. In this study, a total of twenty‐six heavily damaged medium‐scale flat slab‐column connections were repaired using an in‐situ chip concrete mixture. Then the damage repaired specimens were retrofitted using alternative arrangements of Carbon Fiber Reinforced Polymer (CFRP) in such a way to investigate the effects of sensitivity of bond parameters on punching shear performance. The punching shear capacity enhancements observed from retrofitted connections were in the range between 20% and 90%.