Browsing by Author "Kasthurirathna, KANS"

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item: Conference-Abstract
Estimation of penetration requirements for prime coat
(Department of Civil Engineering, University of Moratuwa., 2015-08) Kasthurirathna, KANS; Pasindu, HR; Pasindu, HR
Prime coat application is a necessary activity in road construction and it has a purpose in the pavement construction process, yet many times prime is misused during the project. The main function of prime coat is to prevent moisture infiltration to the base and underneath layers by sealing the road base. So the prime penetration into the road base is the most important consideration. When it comes to Sri Lankan context, the application of prime has been a common practice in road construction projects though there is no basis for penetration requirements. This is an issue of concern as there should be a basis for selecting the best type of prime coat in terms of the penetration and penetration requirement for respective type of processed bitumen as well. Commonly used types of processed bitumen for prime application in Sri Lanka are MC-30 (Medium Curing cut back bitumen) and CSS-1 (Cationic Slow Setting). The experimental research was done using both types of bitumen and the Aggregate Base Course (ABC) specified in the ICTAD-2009 specification as the road base. Specimens were casted in AASHTO specified CBR moulds at selected degree of compaction and sprayed each types of bitumen at selected rate under typical defined Sri Lankan conditions. Penetration requirement and required curing time were selected for each degree of compaction and rate of application, and then the penetration requirements for respective required curing time were plotted on a graph against the base compaction and rate of application. There is no significant difference of required penetration for both type of bitumen but MC-30 has shown a bit higher penetration at few time intervals to make it arguably the best to select in terms of the penetration into the base among the two types of bitumen tested. The penetration requirements for MC-30 and CSS-1 with the time are presented and can be used to make decisions on the best type of bitumen to use in terms of penetration and required penetration for a selected type of bitumen with curing time.
item: Thesis-Full-text
Estimation of penetration requirements for prime coat
Kasthurirathna, KANS; Pasindu, HR
Prime coat application is a necessary activity in road constructions. The main function of the prime coat is to seal capillary voids in the base course surface to prevent migration of moisture to the base course and underneath layers. However it is not carried out up to the required standards. The prime penetration into the road base is the most important consideration. In the local context, the application of prime coat has been a common practice in road construction projects though there is no specification for penetration requirements. This is an issue of concern as there should be a basis for selecting the best type of prime coat in terms of the penetration and penetration requirement for respective type of processed bitumen as well. Commonly used types of processed bitumen for prime application in Sri Lanka are MC-30 (Medium Curing cut back bitumen) and CSS-1 (Cationic Slow Setting). The experimental research was done using both types of bitumen and the Aggregate Base Course (ABC) specified in the Standard Specifications for Construction and Maintenance of Roads and Bridges [2nd Edition – June 2009] specification as the road base. Specimens were casted in AASHTO specified CBR moulds at selected degree of compaction and was sprayed at selected rates under typical defined Sri Lankan conditions. Penetration requirement and required curing time were selected for each degree of compaction and rate of application, and then the penetration requirements for respective required curing time were plotted against the base compaction and rate of application. There is no significant difference of required penetration for both type of bitumen but MC-30 has shown a relatively higher penetration for few time intervals to make it arguably the best to select in terms of the penetration into the base among the two types of bitumen tested. The penetration requirements for MC-30 and CSS-1 with the time are presented and can be used to make decisions on the best type of bitumen to use in terms of penetration and required penetration for a selected type of bitumen with curing time.
item: Conference-Full-text
Structural mitigation for stabilizing rock slope failure at Peradeniya on Colombo- Kandy Main Road: geotechnical and constructional aspects
(Department of Earth Resources Engineering, 2010-09) Premathilaka, KKW; Munasinghe, MPNJ; Kasthurirathna, KANS; Kumara, ALDP; Senapathi, LR; Abeysinghe, AMKB; Premasiri, HMR; Chaminda, SP; Puswewala, UGA; Wijewickrama, MIDH; Ratnayake, NP; Abeysinghe, AMKB; Premasiri, HMR; Karunaratne, S
Rock slope failure at Kandy -Colombo highway near Peradeniya town has been identified as a major threat to the highway as well as the people and properties of the vicinity. This study proposes a permanent mitigation plan for the rock slope failures at this site. Study was initiated with the analysis of similar case studies and field studies on the site area and mitigation options. Two level surveys were carried out to collect topographical data for preparation of a 3D model of the slope. Material identification was done by using particle size analysis and plasticity tests; direct shear tests were carried out to determine the friction angle, cohesion and density of the material. Mitigation plan was designed according to the site conditions. The design was analysed for nine sections on the slope for its stability with the test results by using Geo-studio 2004 software. Reinforcements were proposed to improve the stability whenever needed. An appropriate drainage system was also designed having analysed the past rain fall data of the area. The proposed mitigation plan in this study is a highly stable, safe, trouble-free and economically feasible one, and that can be implemented on this site.