Browsing by Author "Mampearachchi, W"

Now showing 1 - 12 of 12

item: Conference-Abstract
Analysis of suitability of dry-back process in Sri Lankan road pavement construction
(Department of Civil Engineering, University of Moratuwa, 2022-12) Vasavan, V; Mampearachchi, W; Perera, HLK
Moisture content is an important component in the Compaction of pavement layers in road construction. Moisture content in pavement layers is varied by precipitation and environmental factors in the construction and operational stages. If the measured moisture content of the pavement layers exceeds the optimum moisture content, it causes premature pavement failures, such as traffic compaction in the wheel path. Also, this excess moisture content leads to the formation of undulation in the pavement. Therefore, the Dry-back process is widely used in Australia and New Zealand to prevent such pavement failures. The dry-back process is required to prevent the pavement from moisture-related failures. Water is added to the pavement material to achieve a specified density in the construction stage. If the moisture content of the pavement layer exceeds the optimum moisture content, pavement material must be allowed to dry to a certain level below the optimum moisture content. It is known as the dry-back process. Before laying one pavement layer over the other, the water content of the laid pavement must be checked. This is the quality measurement activity for the dry-back process. This research mainly focuses on the dry-back Requirement in Sri Lankan Road pavement construction. The research was carried out using four methods such as survey, material comparison, case study, and practical analysis. First, based on carried out industrial surveys, it was found that the dry-back method is followed in Sri Lankan pavement construction practices without understanding the exact process of it. Second material comparison, In Australia, higher quality materials are allowed for pavement construction when compared with the Sri Lankan Standards. In Australia, field compaction is maintained at a higher value, whereas California Bearing Ratio (CBR) is kept lower than the Sri Lankan materials specification. Various testing methods are practised in Australian Construction processes to ensure the quality of materials compared to Sri Lanka. The third Case study, weather reports, and testing summaries were interpreted to identify the pavement layers with high moisture content, specifically during the rainy season. On the other hand, failures on the pavement surface were identified. Professionals were interviewed regarding these pavement failures, while weather reports and material testing-related data were analyzed. Both approaches clearly illustrate that high moisture content might increase the possibilities of reconstruction of layers, obstruction in the pavement compaction, and pavement failures. Further, this finally practical analysis was carried out in the road sections where cracks are formed on pavements due to moisture content above the optimum moisture content. The moisture content of the pavement layer should be below 60% degree of saturation is preferable for the Sri Lankan pavement condition. This condition is derived from the literature survey and practical analysis of this research. Hence it can be concluded that the dry-back process is a primary requirement in Sri Lankan Road pavement construction.
item:
Axle load distribution characterization for mechanistic pavement design
(Department of Civil Engineering, University of Moratuwa, 2020-12) Sumanasekara, S; Mampearachchi, W; Perera, HLK
As per the World Bank records of the year 2018, Sri Lanka had the highest road density among the South Asian countries with 173.9 km of roads per 100 square kilometres of land. Sri Lankan government reserves a considerable amount of finance in every year for developing and maintaining the existing road infrastructure, which is a well-recognized national priority. Currently, in local road designs, the Overseas Road Note 31 and AASHTO method are the most frequently used design references. However, in these methods, the consideration given for utilization of readily available in-situ materials and incorporating characteristics of substandard materials into the designs is not significant. Therefore, in most of the occasions, the economics of the construction processes are adversely affected due to overdesigns. The AASHTO Mechanistic-Empirical (M-E) method of pavement design combines the physical causes such as stresses, strains, and deflections within a pavement structure and the empirical mathematical models. It also allows the designer to utilize in-situ materials and allows to optimize the pavement design to suit the conditions at the site. Although attempts had been made to adopt M-E design method in Sri Lanka, since the M-E design process requires a lot of data input, the preference of local practitioners in using the M-E method is not satisfactory. Out of the input parameters required for M-E design, traffic volume and axle load distribution data are crucial parameters. This study aimed at identifying trends in axle load group type distributions in different regions and to establish a classification for the pavement loading in regions throughout the island. It has been found that there are similar patterns in the distribution of axle group types throughout the island. Accordingly, on average the total axle counts in different regions constitutes of 57% single axles with single tires, 38% single axles with dual tires, 5% tandem axles with dual tires, and 0.1% tri axles with dual tires. Further, in this study, hierarchical clustering techniques have been utilized to identify geographical regions with similarities in pavement loading conditions. An attempt for zoning traffic load distributions for selected geographic areas has been presented in this study. Comparative for the resource utilization in obtaining axle load distributions, obtaining manual classified counts for a road is convenient. With the aid of the identified traffic load zones, this study will be useful for determining the traffic data input for M-E design, with a degree of accuracy level 2 as defined in the M-E design method.
item: Conference-Abstract
Axle load distribution for mechanistic-empirical pavement design in Sri Lanka
(Department of Civil Engineering, University of Moratuwa, 2022-12) Sumanasekara, S; Mampearachchi, W; Perera, HLK
The AASHTO Mechanistic-Empirical (ME) method of pavement design seeks to combine physical causes such as stresses, strains, and deflections within a pavement structure and empirical mathematical models. The pavement responses under the ME method are computed using detailed traffic loading, material properties, and environmental data and are used to predict incremental damage over time. The design of pavements under the ME method is an iterative process using analysis results based on trial designs postulated by the designer. The basic advantage of the combined ME method over a purely empirical method is the ability to accurately characterize in-situ material. Hence it can be used for both existing pavement rehabilitation and new pavement construction, and also, the ME method accommodates changing load types and allows the designers to optimize the pavement designs. However, in Sri Lanka, the design references frequently used for local road designing purposes are the Overseas Road Note 31 and AASHTO method, which do not allow the designers to utilize the in-situ material characteristics in the design process in order to utilize the readily available materials effectively. Therefore, in most scenarios, the economy of road construction is affected detrimentally. Therefore attempting to adopt the ME design method in Sri Lanka is worthwhile investigating. For the pavement design using the ME method, the axle load spectrum data is required. In general, traffic volume is more convenient to obtain than load spectrum, considering the time and resource consumption in gathering data. The historical traffic counts and vehicle classifications are more likely to be available on many existing routes. However, for a new route, historical traffic data may not exist at all. Under these circumstances, it is necessary to estimate load spectra based on indirect information. Therefore, there is a need to develop default or representative axle load spectra that can be used with some level of confidence in the design process. Therefore, this research is aimed at deriving region-specific axle load spectra that will allow the generation of more appropriate inputs for pavement designs from the ME method. This study uses hierarchical clustering methodology and Euclidean distance matrix to identify geographical zones having similar characteristics in axle load frequency distributions. For single axle/ single tires axle loads, three geographical zones and for single axle/dual tires axle loads, four geographical zones have been identified for having similar characteristics in axle load frequency distributions. The axle load zones derived in this research will allow the estimation of traffic input to the ME pavement design approach from limited site-specific traffic data and will support the implementation of the ME design method in Sri Lanka.
item: Conference-Abstract
Comprehensive review on performance of internal curing aggregates
(Transportation Engineering Group, Department of Civil Engineering, University of Moratuwa, 2023-12-08) Dilsara, S; Ekanayake, S; Jayantha, N; Mampearachchi, W; Jayantha, WRAN
The curing of concrete is essential for cement hydration, which is a series of chemical reactions that require an adequate, constant water supply and stable, proper temperatures over time. Curing is maintaining moisture and temperature conditions in a freshly placed concrete mixture in order to allow hydraulic cement hydration. External curing techniques are frequently used to cure conventional concrete. In that method, external curing water is applied at the surface, and the quality of the concrete governs the depth of penetration. As a result, external curing may not satisfy demand since external curing water is only able to act on the surface layer of concrete and cannot reach the inside of the concrete. As a result, external treatment is ineffective in preventing the ongoing reduction of interior humidity. Therefore, Internal curing is used as a method of maintaining the relative humidity within the concrete. Internal curing allows the water to be spread more evenly throughout the cross section by releasing water eventually into the concrete mixture. This literature review provides a comprehensive examination of internal curing methods, mechanisms, and their impact on the properties of concrete. Internal curing is the technique of introducing curing elements that act as a curing agent, to the concrete mixture to serve as a water reservoir. It is a viable method for providing additional water for curing cement-based materials with low water-cement ratios, and it does not adversely affect the fresh or hardened properties of concrete mix. It differs from the externally applied curing. In the internal curing process, once the concrete is hardened, the water intended for internal water curing is dispersed within the concrete mixture and facilitates the hydration process. Internal curing is used to minimize autogenous, plastic, and drying shrinkage, which increases the probability of shrinkage cracking of the concrete, to reduce the permeability of concrete and the modulus of elasticity, to improve the strength and permeability at the interface transition zone (ITZ), to obtain reduced moisture gradient along the concrete section results in less warping in concrete pavements and reduced coefficient of thermal expansion (CTE) and thermal conductivity, resulting in lower temperature gradients across the concrete section and less curling in concrete pavements etc. In past studies, internal curing methods are explored in detail, ranging from techniques like pre-soaked lightweight aggregates such as crushed clay brick waste, and ceramic tile waste to more recent innovations such as superabsorbent polymers, which act as internal reservoirs, supplying an internal source of water needed to replenish moisture lost due to chemical shrinkage and self-desiccation in various concrete types such as normal weight concrete, high- performance concrete, Roller compacted concrete etc. A wide variety of studies have been done to check the potential of different kinds of material to use as internal aggregates to replace conventional aggregates. Also in some studies, the effect of the particle size of internal curing aggregates on the performance of concrete has been checked. Practical applications of each method are critically evaluated, offering insights into their effectiveness and feasibility in different construction scenarios. The optimum amount of each internal curing aggregate and the impact of internal curing methods on various concrete parameters such as strength development, shrinkage, cracking, and durability characteristics such as chloride penetration, air permeability, and water absorption are investigated in this paper. A thorough examination of laboratory results 31 and real-world case studies demonstrates the practical advantages that internal curing can impose on concrete performance. In a nutshell, this literature review synthesizes the wealth of information available on internal concrete curing, offering a thorough understanding of its concepts, methods, mechanisms, and impacts. Internal curing emerges as a possible option for improving the durability and performance of concrete structures while reducing their environmental imprint as infrastructure demands continue to rise. This review's information and insights contribute to a better understanding of internal curing's potential and pave the way for its wider implementation in the building sector.
item: Conference-Abstract
Development of a guideline to determine structural capacity of demolition waste as a road construction material
(Department of Civil Engineering, University of Moratuwa, 2021-10) Jayasooriya, W; Mampearachchi, W; Jayantha, N; Perera, HLK
The use of demolition waste as pavement base material is a promising but unproven technique for road rehabilitation and construction. The scarcity of natural resources for construction industry-related activities was rising over the past few years. However, demolition waste is not frequently being used in pavement construction, primarily due to a lack of knowledge about the engineering properties of the material used. This research study focuses on evaluating the strength and durability characteristics of such waste in Sri Lanka and determining the applicability of crushed concrete material (CCM) in pavement base construction. Laboratory testing component in the study includes preliminary material tests including flakiness index, elongation index, Los Angeles abrasion value (LAAV), aggregate impact value (AIV), and unconfined compressive strength (UCS). In addition, a laboratory-scale prototype model testing was carried out to compare the characteristics of CCM with respect to conventional base materials. This setup was subjected to a plate load test and a dynamic cone penetration test to determine its properties. The results of the prototype model testing demonstrated that the CCM base layer was susceptible to stiffness changes due to the changes in moisture levels. The layer coefficient of CCM was calculated using deflection data and it was equal to 0.134. However, the variability of material properties was significant in the case of CCM compared to conventional dense graded aggregate bases (DGAB). Therefore, the authors recommend using CCM as a base material for the pavements where light wheel loads operating, preferably 20kN or less. The present practice of flexible pavement design in Sri Lanka is based on the Transport Research Laboratory method (RN31-1993) but modified to suit local conditions. Even though RN31 provides different aggregate base layer types, DGAB is the common practice of base construction. Therefore, a guideline and a design chart have been developed for the process of replacing DGAB with CCM. The equivalent thickness of CCM required for DGAB thicknesses varying from 4-10 inches could be obtained from the developed design chart.
item: Conference-Abstract
Development of construction standard for semi-rigid pavement construction
(Department of Civil Engineering, University of Moratuwa, 2021-10) Dahanayaka, I; Mampearachchi, W; Perera, HLK
The drawbacks of the conventional Asphalt and concrete pavement mixtures such as rutting, cracks formation in modern construction practices have been given the tendency to discover an excellent composite mixer that achieves the required properties to increase the life cycle of the roads due to continuous loading. This research mainly focuses on developing construction standards to prepare a project specification to comply with every stage of the preparation of the mixtures up to laying the mix at the site. The report involves the literature review on the research, all material selection, and their methodology to prepare the proper gradations and grout mixture, data collection, and analysis of pavements mixtures properties, compressive strengths of cement grout, and comply the results. Here, two paving tests were conducted subjected to different gradations and different site environmental conditions. Paving operations were observed closely with the different rolling patterns to monitor the range of Air voids of 20%-30% under certain conditions. The data were kept finalizing the temperature ranges, both mixing and paving, no of roller passes and type of roller specified, compaction factor, etc. The final results of the experimental studies were tabulated in the graphs, especially with the field density vs. passes, void in field sample vs. passes. Then it compared the difference of gradation in field samples and design and their impact on void and other parameters of specific limits, which have to be incorporated into the final specifications. As laboratory experiments, the marshal mixtures were conducted with 20 No of blows of compaction as many researchers done, to obtain the density, voids to compare with field data. Here, the air voids calculations were done by applying the formula of Ï€r2h as cylindrical volume calculation for core samples and as well as using the Core lock method, which gives more accurate values for void ratio than depending on the other current calculation process. The grout was prepared using 150mg Silica fume, 0.45 water/cement ratio, and 2.58ml/kg admixture to adhere to the semi-rigid mixture design criteria. Also, this approach involves not only technical evaluation but also the study of the possibility to adapt to the local construction field, which gives more benefits to the country economy such as reduce the cost of mixed production and paving, time-saving and locational demands of optimal usage, mitigation of environmental impact, increases durability, etc.
item: Conference-Abstract
Evaluate the effect of segregation in road materials on performance of a road
(Department of Civil Engineering, University of Moratuwa, 2021-10) Senavirathna, B; Mampearachchi, W; Perera, HLK
Gradation is a key parameter when selecting a suitable road material for sub-base, base, and asphalt courses. Selected gradation of the pavement material considerably affects the performance and service life of a pavement. Even though many studies had focused on the effect of segregation in asphalt mix; only few studies found the evaluation of sub-base and base materials. This paper presents research aiming to evaluate the effects of gradation segregation on individual properties in base, sub-base, and asphalt wearing coarse materials. Since segregation in each material may possible in different forms and due to difficulties in simulating in a laboratory as it is to site condition; segregation levels are defined as the difference between segregated and controlled gradations. For sub-base soil; center, lower limit (coarser mixtures), upper limit (fine mixtures), 5% coarse and 5% fine gradations are selected while for base material (Aggregate Base Coarse-ABC) 10% coarse and 10% fine gradations are also selected than that of sub-base. Since simulating of gradual change in segregation of asphalt is difficult; total mix separated through each sieve and individual asphalt coated aggregates blended for Marshall specimens. Then the levels of segregations are found by bitumen extraction tests and those are from fine side 56%, 44%, 34% and from coarse side 15%, 7%, and 6% relative to the trial mix gradation. Based on those segregation levels; California Bearing Ratio (CBR) values and Maximum Achievable Degree of Compaction (DOC) values are observed for sub-base and base materials while cantabro loss and Marshall properties are observed for asphalt wearing coarse. The results are compared to requirements stipulated in Standard Specifications for Construction and Maintenance of Roads and Bridges (ICTAD, 2009). CBR values are gradually decreased from coarse segregation to fine and at 5% fine segregation; CBR drop from the required limit of 30% for sub-base soil. For ABC; CBR values drop from both coarse and fine sides than the center and at 5% fine segregation drops from minimum limit of 80%. Maximum achievable degree of compaction drops from both fine and coarse segregations of ABC; while gradually increase from coarse side to fine side than that of for sub-base. In the case of asphalt, cantabro loss increases from fine to coarse segregation on average. Bitumen content increases gradually from coarse to fine segregation and at both ends exceeds the minimum and maximum requirements respectively. Marshall stability increases at coarse segregation than that of fine segregation and vice versa in the case of Marshall flow values. According to this study; fine segregation (increase of fines) of sub-base and base materials negatively effect to the layer strength. Fine segregation of asphalt leads to corrugation and coarse segregation leads to raveling during the service.
item: Conference-Abstract
An experimental study to evaluate the effective specific gravity estimation on percent air voids of asphalt mixture design
(Department of Civil Engineering, University of Moratuwa, 2021-10) Chamodya, H; Mampearachchi, W
Asphalt concrete is one of the most widely used surfacing compounds consisting of mineral aggregates with asphalt (Bitumen) binder. Various types of bituminous mixtures such as cold mix asphalt, hot mix asphalt, plant mix, and warm mix asphalt are used with relevance to the environment while tropical countries like Sri Lanka use hot mix asphalt mixes for surfacing. In hot mix asphalt mixes, the theoretical maximum specific gravity (Gmm) value plays a significant role when considering the performance and durability. The impact of theoretical maximum specific gravity (Gmm) can be noticed directly on properties of paving mixtures like bleeding, rutting, raveling, and fatigue. Precise calculation of Gmm is critical in the mix design process in determining exact values of percent air voids in a compacted mix (VIM), percent voids filled with bitumen (VFB), and optimum asphalt binder content in a compacted mix. Manual Series-2 published by Asphalt Institute recommends determining Gmm directly by performing the standard test method called RICE method (AASHTO T209, ASTM D2041) for every binder content or by performing the RICE test for a selected binder content around optimum binder content to obtain effective specific gravity (Gse) of aggregate mix and then to calculate Gmm for other binder contents using a back-calculation method as an indirect method. Sri Lankan road industry used to determine Gmm for every binder content using the effective specific gravity (Gse) which is pre estimated as the average of apparent and bulk specific gravities of the aggregate mix. It has been found that the measured air voids content using the Gmm value measured by rice test is lower than the average estimated method used in Sri Lanka in about 20% and 9% for limestone and basalt, respectively. This research aims to study the impact of the effective specific gravity estimation method for asphalt mixture on the percent air voids and other characteristics of asphalt mixes when using granite as the aggregate. To achieve this objective, an extensive experimental program was designed using 10 different sample projects. Maximum theoretical densities of the samples were determined using the rice method according to ASTM D2041, while bulk and apparent specific gravities were taken from the mix designs which were done for the same hot bin and bitumen samples. Based on the results, the impact on percent air voids and optimum binder content was evaluated to determine the accuracy of the average estimated method compared to the standard rice test method.
item: Conference-Abstract
Implementation of warm mix asphalt in Sri Lanka: case study
(Department of Civil Engineering, University of Moratuwa, 2022-12) Gunarathna, S; Mampearachchi, W; Langappuli, S; Hettiarachchi, C; Weerakoon, J; Ranasoma, I; Perera, HLK
Warm Mix Asphalt (WMA) is the technology that allows a reduction in the production and paves temperature of Asphalt. WMA can be produced using four different technologies; chemical additives, organic additives, water-bearing additives and water-based processes. Adaptation of WMA may reduce the production cost, paving cost, and emission of greenhouse gases and allow longer paving season. Therefore, implementation of WMA in Sri Lanka is vital as WMA can be an answer to the economic crisis and has been recognized as the future of Asphalt. Organic additive technology or chemical additive technology was decided to select for the implementation of WMA in Sri Lanka as the minimum plant modifications in these technologies. Sasobit®, which is an organic WMA additive, was selected for the implementation as it is available in the south Asian region, and further, this was successfully implemented in India. Sasobit® is a synthetic wax which decreases the viscosity of the bitumen in lower temperatures. However, below 900C, Sasobit® creates a crystalized lattice structure allowing the modified bitumen to stiffen and increase the rutting resistance. The optimum Sasobit® percentage was determined as 2.5% by mass of binder by analyzing the results of viscosity against the Temperature curve. A Series of samples with bitumen modified by optimum Sasobit® percentage shall be prepared in different mixing temperatures and different compaction temperatures falling under the WMA temperature range. The mixing temperature and compaction temperature shall be selected where the optimum density was achieved, and results are within the limitations stated in ICTAD specifications for Marshal Test. The mixing temperature was found as 1400C, and the compaction temperature was 1300C. The section selected for the study is 500m in Mawanella. A paving trial was conducted near the selected study area for 57 m, and it was observed that the required degree of Compaction was achieved with lower roller compaction coverage. The bitumen decentering plant was modified to achieve the modification by Samsonite®. Bitumen was circulated through the plant for 2 hours after Sasobit® was added, and the temperature was maintained at 1400C. The mixing of Asphalt was maintained at 1400C, and the Compaction at the field was started when the temperature was 1300C. One breakdown roller coverage was able to be reduced, and four intermediate roller covers were ably reduced from typical roller coverage, and still, the required degree of Compaction was achieved. Further, it was observed that the temperature drop to 600C in the WMA is 120 minutes (2 hours). Temperature is lowered in WMA bitumen production by 10- 150C allowing cost saving duet lowered use of fuel in heating of materials. Further, the required degree of Compaction was achieved by lower roller coverage. Moreover, the road can be open to traffic less than 2 hours from the time of the paving. Therefore, the paving season can be increased /which is beneficial for roads with heavy traffic flow. Implementation of WMA in Sri Lanka is vital at this stage, and it is evident WMA can be used as absolution for the current economic crisis. However, there are more options for modification methods, and the use of recycled Asphalt is more feasible in WMA. Hence, it is recommended to study more along these avenues.
item: Conference-Abstract
Study of driver behavior at entrance ramps of expressways in Sri Lanka
(Department of Civil Engineering, University of Moratuwa, 2022-12) Ratiyala, D; Mampearachchi, W; Perera, HLK
Driver behaviour characteristics have a significant influence on the design of an expressway interchange ramp terminal in relation to traffic safety. In general, ramp terminals are more prone to accidents because of their function, which includes traffic merging, diverging, and changing lanes more frequently. These factors increase driving anxiety and lead to more accidents. In addition, due to the adoption of various design standards in various projects, the ramp terminal lengths of Sri Lankan expressways differ from one to another. The primary goal of this research is to examine how drivers behave at the entrance ramp terminal in relation to crucial influencing elements such as vehicle entry speed, ramp terminal entry zone, and expressway through traffic speed at the proximity of the entrance ramp terminal, as well as to examine ways to enhance drivers' behaviour there. Six interchanges, Kerawalapitiya, Kothalawala, Kottawa, Galanigama, Pinnaduwa, and Godagama, were selected for further study based on the variation in acceleration lane lengths among them. The study was conducted utilizing video data from a CCTV camera installed at the Kottawa Interchange on 27th February 2020, and since there was no CCTV camera available at the other five Interchanges, a drone survey was carried out in other places on 14th October 2020. The analysis was carried out based on two important parameters, which were identified through the literature survey: 1. Vehicle entering speed to the expressway and 2. Vehicles entering the zone to the expressway through the entrance ramp terminal. The speed of the vehicles as they enter the expressway is significantly lower than the speed of expressway vehicles, except at Godagama Interchange, according to the analysis. The entry speed into the expressway is 60 kmph on average for all six interchanges. This necessitates a larger space between oncoming expressway traffic and entering traffic using the acceleration lane. Another significant aspect was that the vehicles entering the expressway did not use the expressway acceleration lane as anticipated. At the Kottawa Interchange, a higher percentage of vehicles entering the expressway (20%) was observed beyond the ramp's tapering. In violation of the safety regulations, 27% of vehicles at the Godagama Interchange entered the expressway in the chevron area. When all interchanges are considered, only 50% of the vehicles entered the expressway through the designated zone, while the remaining 50% used the ramp taper, the chevron region, or beyond the ramp taper. The research results support the conclusion that drivers lack the necessary knowledge to use the expressway ramp terminal based on a careful investigation of driver behaviour, including how they enter the expressway and at what speed. In order to educate the drivers before they enter the expressway, The phrase "Prepare for the Expressway Speed" has been selected as the appropriate wording for the signboard as a result of a survey that was conducted among design engineers and experts involved in the field of geometric design of roads in Sri Lanka. Additional variable speed signboards displaying ramp speed to expressway speed along the ramp have been identified as a secondary measure to promote uniform speed at the expressway entrance. Based on the research results, it is recommended to notify drivers of the expected way to enter the expressway through the entrance ramp terminal by signboards, publicity through television programs, or printed media.
item: Conference-Abstract
Using clay tile waste as an internal curing aggregate (ICA) to replace aggregates in roller-compacted concrete (RCC)
(Transportation Engineering Group, Department of Civil Engineering, University of Moratuwa, 2023-12-08) Ekanayake, S; Dilsara, S; Jayantha, N; Mampearachchi, W; Jayantha, WRAN
The high demand for natural resources has become a significant problem in the construction industry. Therefore, the construction industry is searching for sustainable and eco-friendly alternatives, leading to a burgeoning interest in incorporating waste materials into concrete production. Considering the strength gained from concrete, proper curing is a crucial aspect. Lack of proper curing causes disturbances to the hydration process of cement, and it leads to a lot of problems such as reduction in strength, shrinkage cracks, and durability issues. Conventional curing methods have some weaknesses in providing uniform curing throughout the full depth of concrete. Therefore, the industry is moving towards alternative methods. Among those alternatives, using an internal curing agent is an innovative approach being researched widely, especially for concrete with a low water/cement ratio. Roller compacted concrete (RCC) is a type of concrete that has a low water/cement ratio, and it is gaining prominence as a durable and cost-effective construction material for a wide range of applications, including pavements, dams, and industrial floors. Its composition typically comprises coarse aggregates, cementitious materials, and fine aggregates. Since it has a low water/cement ratio, curing is vital to the hydration process of cementitious materials. Considering the water absorption and desorption capacity of materials, attention has been focused on the use of waste materials as internal curing agents. This study explores the feasibility of utilizing clay tile waste as an internal curing aggregate (ICA) in roller-compacted concrete (RCC). The aim is to investigate the potential of clay tile waste as an ICA and evaluate its effect on the properties of RCC. Since the particle size of the clay tile waste can affect the concrete properties, two studies have been done. One study investigates the use of clay tile waste to replace fine aggregates in RCC, and another investigates the use of clay tile waste to replace coarse aggregates. In both studies, a series of experiments are done to check the potential of clay tile waste to be used as an internal curing aggregate. The physical properties of clay tile waste, such as water absorption and desorption capacities, specific gravity, pore structure, and chemical properties, are studied in these experiments. After checking the potential to use as an ICA, RCC mixtures are prepared with different clay tile waste replacement ratios. Then, the mechanical properties of concrete, such as compressive strength, splitting tensile strength, and durability properties, are checked using laboratory experiments. Finally, all the results will be analyzed and compared with the control mixture that does not contain clay tile waste. The optimum replacement ratio for fine and coarse aggregates will be determined using analyzed results. With the positive results of the study, the construction sector will significantly improve sustainability by replacing either fine or coarse aggregate with clay tile waste material. Additionally, the possibility of early-age cracking owing to autogenous shrinkage is addressed using clay tile waste as an internal curing agent in RCC construction. This inherent quality of the waste material increases the durability and service life of the RCC structures, enabling long-term performance and cost-effective maintenance and repair. In the broader context of sustainable construction practices, integrating clay tile waste into RCC applications is a significant stride toward achieving environmental, economic, and performance-related objectives.
item: Conference-Full-text
Utilization of bottom ash on thin asphalt surfaced pavements for low volume roads
(IEEE, 2020-07) Moses, JA; Bandara, RWDK; Mampearachchi, W; Edussooriya, C; Weeraddana, CUS; Abeysooriya, RP
More than 65% of the entire road network of Sri Lanka consists of low volume roads with AADT of 1000 vpd or less. The provision of better surfacing for these roads has become one of the main needs nowadays and traditional asphalt pavements are not recommended due to their higher layer thicknesses; thus, higher cost. Therefore, an adaptation of thin surfaced asphalt pavements can yield favorable solutions and this research was carried out to develop mixture design and check the suitability of utilizing bottom ash, to achieve durable, economical and sustainable thin asphalt pavements while reducing the environmental issues associated with the waste generated from the coal power plant. Marshall samples were prepared for DG 7 mixtures with the replacement of 0%, 10%, 20%, and 25% of fine aggregates with bottom ash. The Marshall properties of the specimens were examined and concluded that only DG 7 mixtures with 0% and 10% of bottom ash replacements attained the required Marshall criteria to be used in low volume roads. Even though the mixtures without bottom ash are determined as more economical, mixtures with 10% of bottom ash are recommended as the voids in mineral aggregates criteria were well established in them.