Browsing by Author "Kumara, MAW"

Now showing 1 - 9 of 9

item: Conference-Abstract
Construction and demolition waste as a road construction material for flexible pavements
(2008) Jayasooriya, VWP; Kumara, MAW
This research is focuses on evaluating the physical properties and durability characteristics of both demolition and process waste for flexible pavement construction. The initial results showed that there is a possibility to replace aggregate base course using crushed concrete material of demolition waste Possibility to replace soil using construction and demolition waste as a stabilization agent are to be studied. This study included extensive laboratory and field testing. California bearing ratio (CBR), moisture susceptibility and abrasion evaluations tests are conducted. Effects of repeated load over the constructed pavement are evaluated using Nondestructive testing (falling weight deflectometer) on accelerated pavement testing facility.
item: Conference-Abstract
Construction and demolition waste as a road construction material in rigid pavement design
(2008) Gayani, JKU; Kumara, MAW; Nanayakkara, SMA
This paper focus on investigation of properties of recycled aggregate and use of recycled concrete aggregates to partially or fully replaced natural aggregates in the production of lower grade concrete. Recycled products may reduce the demands for new materials. Among which recycled aggregate (RA) is one of the major construction waste capable of being reused in the production of concrete. To evaluate the viability of this process, an experimental campaign was implemented in order to monitor the mechanical behavior of such concrete. With aim of that, the recycled aggregate properties were evaluated at the beginning before utilizing them in concrete application. The obtained test results in assessing properties of aggregate are reported in terms of (i) particle size distribution; (ii) particle density; (iii) porosity and absorption; (IV) particle shape; (v) strength and toughness.
item: Thesis-Abstract
Determination of optimum nominal aggregate size for single surface dressings
Wanigasekara, WMSB; Kumara, MAW
Surface dressings are used as a road maintenance activity as well as a surfacing of a newly constructed road. One of the main decisions to be taken in designing a dressing is the selection of appropriate aggregate size. Improper selection of aggregate size could tarnish the performance of a surface dressing. The aim of this study is to find the optimum size of aggregate for a single surface dressing especially in Sri Lankan Macadam roads. General size of aggregate for a particular surface dressing could be found using commercial traffic volume and surface hardness of the road based on TRRL method. But the aggregate sizes selected in above simple method have shown inconsistent results. Therefore tests should be carried out to find most appropriate size for the surface dressings. Three sizes of aggregate were selected using above simple check for the tests. Three different surface dressings from different aggregate sizes were done. Binder type kept constant and binder rate changed according to the chip size. The performances of these three surface dressings were evaluated by measuring aggregate removal rate and skid resistance of the seal. Digital photographs of demarcated locations in surface dressings of different chip sizes were taken at pre determined time intervals. The numbers of aggregate were counted in each photo after certain time interval and using this data, the behavior of each surface dressing over a period of time can be studied. The aggregate size that could keep highest area of aggregate intact in its dressing would be a more durable chip size. The next aspect of checking performance of the dressing is the skid resistance. The techniques utilized to measure this value are Locked wheel test and Sand patch method. The main- aim of skid resistance testing was to compare three sizes of aggregate and see how they respond to skidding. -It was found that 9.5mm nominal size performed better in durability aspect and 12.5mm performed better in skid resistance aspect.
item: SRC-Report
Development of a classification system for low volume roads : final report
Kumara, MAW; Bandara, JMSJ
Rural roads are an important sector in rural development, which deals in all aspects of development including agriculture, health, education, forestry, fisheries, small-scale industries, trade, commerce etc. that depends on good communication. Rural transportation network will give shape to the living environment of villagers; rather roads of rural transportation are the connectivity elements in our society. Appropriate combination of various links both technically and economically can generate rural traffic infrastructure, which should be prepared for the measure of land development
item: Thesis-Abstract
Effectiveness of traffic forecasting on pavement designs in Sri Lankan roads
Gunasinghe, PH; Kumara, MAW
Pavement design plays an important role in any improvement or rehabilitation of road. Therefore, it is a responsibility of the Road Design Engineer to ensure that he has come up with an effective design, so that it will last for the entire design life. This effectiveness or the optimization is very important as otherwise it could lead to financial implications. In this research study, Flexible Pavement Designs of recently rehabilitated or improved set of roads are analyzed to check the effectiveness of traffic forecasting on pavement design in Sri Lankan roads. It also demonstrates the suitability and the applicability of "American Association of State Highway and Transportation Officials" (AASHTO) flexible pavement design method for the Sri Lankan roads, as an alternative design method. This study also discusses the present practices of RDA in pavement design and finds a way forward to improve the system.
item: Thesis-Abstract
Effects of superpave specifies aggregate gradation on marshall mix parameters
Fernando, PRD; Kumara, MAW
The purpose of this study is to evaluate the effect of the Superpave aggregate gradation on Marshall Parameters. The Superpave Specifies aggregate gradation was used to select aggregate gradation as such blending of available aggregate was carried out and that the gradations were above, through and below the Superpave restricted zone. The Marshall method was used to design the asphalt mixtures. Asphalt concrete mixes were designed for 28 numbers of Superpave aggregate gradations and were tested in the laboratory to evaluate their stability and flow value. In addition, density - void analysis was carried out to find Marshall Parameters. Statistically, all type of mixes (over, through and above the restricted zone) did not show any significant difference on Marshall Stability and Void in Mineral aggregate (VMA) in this study. The gradation pass below the restricted zone, those mixes showed higher Va and lesser Flow value than the gradation pass above / through the restricted zone. Based on the testing perfonned In this study, following recommendations can be made; 1. Superpave specifies aggregate gradation could be used as a guide to develop 100 percent crushed granite aggregate blends for wearing course. 2. Superpave coarser aggregate gradation (gradation that pass through or below the Superpave restricted zone) could be used as wearing courses with local conditions (still not use such a gradation for wearing coarse in Sri Lankan specifications) .
item: Conference-Extended-Abstract
Evaluating suitability of soil stabilization methods for local road construction industry
(2009) Herath, HMSM; Kumara, MAW
Soil stabilization is not using in local roads construction industry in major scale. Various reasons effects to non popularity and initial part this paper presents the result of questionnaire survey among the professionals who practice in road construction industry. Soil Sample collected from different places, used to determine the engineering 'properties (Sieve Analysis, Liquid Limit (LL), Plastic Limit (PL), California Bearing Ration (CBR) and Unconfined Compressive Strength (UCS)). Same soil has being used to determine the properties after stabilizing according to the mailable guideline, with locally available stabilizers ( Cement and Lime). Laboratory test results indicates that both Stabilizer improve soil properties in considerable amount. Suitable stabilized criteria and quality controlling measures is to be established.
item: Thesis-Abstract
Evaluation of feasibility of composite pavements for resurfacing intersections/pedestrian crossings in Sri Lanka
Kosgolla, JV; Kumara, MAW
Intersections, pedestrian crossings and their approaches are more susceptible to cause distresses due to often decelerating and accelerating effects of vehicles. Frequent maintenance of asphalt concrete pavements at intersections and pedestrian crossings create severe traffic delays in metropolitan regions. Therefore in essence a long lasting pavement rehabilitating method has to be adopted for intersections and pedestrian crossings. This study attempts to reveal the feasibility of whitetopping for resurfacing of such vulnerable places. A three-dimensional (3-D) finite element model was developed for stress analysis of whitetopping pavements with SAP2000 structural analysis software in order to simulate field conditions of a whitetopping pavement constructed in the pavement testing facility, at Florida Department of Transportation and it was verified with field strain data. The verified software model was used to perform a parametric study in with the ultimate goal of revealing applicability of whitetopping concept to resurfacing intersections and pedestrian crossings. A software model for a ramp was also developed and parametric study was conducted in order to develop a ramp for raised pedestrian crossings. Throughthe study, it could be revealed that the software models developed can be used to estimate the maximum anticipated stresses. In whitetopping pavements while emphas,izing the significance of using accurate design parameters and material properties. High performance concrete mix design was performed to reveal a proper concrete mix and a suitable admixture with available materials in Sri Lanka. Applicable curing method was also revealed to reduce early age cracking. Maturity test was performed to verify the field strength gain. A life cycle cost analysis was performed to compare the cost' of whitetopping and asphalt concrete. The cost comparison shows that whitetopping overlaying saves significant amount of maintenance cost.
item: Thesis-Abstract
Finite element model approach to determine an effective layout and suppport conditions for concrete block paving
Gunarathna, WPH; Kumara, MAW
There has been an intensive process of urbanization which has brought about need for rapid construction of roads and related infrastructure during the end of the last century. Therefore development of economical road construction methods is a high priority for a developing country like Sri Lanka. Concrete block paving is one of the predominant road construction method used in most of the developing counties due to economic adaptability. This method has also been emerged as a cost effective road construction method suitable for certain local conditions. But in Sri Lanka this technique is yet to be developed to a fully fledge road construction method. This can be attributed to a dearth of the technical expertise and knowledge. As a result, there is a great need to develop knowledge and establish proper methods of block paving suitable for local conditions. The aim of this research is to evaluate the state of support conditions and effective block laying patterns which can be used to improve concrete block paving technology. Prototype concrete block paving model development, support conditions and their improvements were mainly considered in the development stage of this study. Laboratory scale prototype concrete block pavement model was developed and their surface deflection basin was measured with four different arrangements. A three dimensional (3-D) finite element model was developed to measure elastic deflection behavior of concrete block pavement ,with SAP2000 structural analysis software. This Finite Element Model (FEM) was used to simulate field conditions of a concrete block pavement and it was verified with the deflection values observed in the prototype model. The verified software model was used to perform a parametric study in order to determine necessary improvements for weaker support conditions and find effective laying arrangement in the concrete block paving. . Developed design charts and field observations are used to propose subgrade improvement methods for weaker support conditions. Therefore it's recommended' to introduce concrete block laying work for low volume roads which are having subgrade strength higher than 10% (CBR). FEMs were developed to evaluate performance of the laying patterns. Four different block laying patterns were tested against breaking action and vertical loading. Finally it was possible to conclude that herring bond pattern is more suitable for road construction work with better performance.