Browsing by Author "Anojan, T"

Now showing 1 - 4 of 4

item: Conference-Abstract
The effect of water to cement (w/c) ratio on workability of internal curing concrete in the development of high strength concrete with required workability and cement content (ICBP)
(Department of Civil Engineering, University of Moratuwa, 2018-09) Bandra, MMHW; Anojan, T; Mampearachchi, WK; Pasindu, HR
The escalating demand for highways and other related structure development of any country may lead to the introduction of fast and sustainable construction techniques and materials. Internal curing is an emerging technology in the cement concrete industry, and will outperform in the road construction industry than conventional curing methods, due to it being convenient to use under harsh envirpoonmental conditions. Generally, after the placement of concrete pavements, concrete is subjected to evaporation and hydration, which causes a significant loss of moisture. That will reduce the relative humidity of concrete and increase the internal stresses. This may form micro cracks throughout the concrete, subsequently, cementitious particles may not hydrate properly. As a result of that, the durability and strength of concrete will reduce significantly. Normally, external curing methods such as immersion, ponding, fogging and wet covering are used to provide excess water, to avoid the aforementioned problems. However, those external curing methods will be effective only up to a certain thickness from the concrete surface while internal curing provides water throughout concrete using prewetted aggregates. The water will distribute uniformly throughout the concrete and reduce the humidity drop and hydrate the cement paste. The main problem in internal curing concrete is that the water added through the aggregates will affect the water cement ratio and reduce the compressive strength. This study was conducted to investigate the effect of the water cement ratio of internal curing concrete on compressive strength and workability. Concrete is cured internally by providing the required amount of water using pre wetted aggregates. These pre wetted aggregate will spread all over the concrete and help to cure the cementitious matters uniformly. Here, pre wetted burnt clay chips (internal curing concrete aggregates) are used as water reservoirs which will provide water for cement hydration. Thus, additional water added through the fine aggregates will increase the expected workability. Results are obtained by adjusting the water content and then workability, and compressive strength values are compared. Results showed that water/cement ratio reduces, and compressive strength increases with ICCA for all grades of concrete, tested in the study.
item: Article-Full-text
Enhance the properties of concrete using pre-developed burnt clay chips as internally curing concrete aggregate
(Elsevier, 2019) Bandara, MMHW; Mampearachchi, WK; Anojan, T
Materials of internal curing concrete have been developed in many countries. Some of those materials are superabsorbent polymers, light weight aggregate (LWA), normal weight aggregate, recycled aggregate, bentonite clay, furnace slag and bottom ash. The most popular internal curing material is LWA. LWA are not available in most countries. Thus, the production of internal curing concrete (ICC) was limited for few countries. Consequently, this research was focused on the utilization of burnt clay chips as a new material to enhance the properties of ICC. Furthermore, water–cement (w/c) ratio and workability of ICC were investigated to develop high strength internal curing concrete (SICC). The water absorption and desorption capacity of porous aggregates are basically depends on the capillary interaction between water and the pore structure. Thus, formation of an effective pore structure within the burnt clay chips becomes the most important thing. Thus, Red clay was selected and different pore structures were developed within the clay mass by heating trough furnace. The heating temperature ranged from 800 to 1300 °C. The burnt clay chips produced at 900 °C was identified as an effective ICC aggregate. Afterwards, the pre-developed burnt clay chips (DBCC) were produced in larger scale. During the production of burnt clay chips, clay blocks (150 × 250 × 14 mm) were produced and heated at 900 °C using industrial furnace. Subsequently, heated clay blocks were crushed and sifted through 4.75 mm sieve to obtain fine clay chips. The water absorption capacity and the dry apparent density of DBCC was recorded as 15.5% and 1.8 g/cm3 respectively. Finally, grade 25, 30 and 35 concretes were prepared to study the effect of workability and w/c ratio. Moreover, three different concrete samples were prepared from each concrete grade; external curing concrete (ECC), ICC and SICC. ICC samples increased the slump value in 12%. Furthermore, the compressive strength of ICC and ECC were almost same for all three concrete grades. SICC sample increased the compressive strength in 9% while maintaining the required workability and same cement content of ECC sample. Thus, it is concluded that, DBCC can be used as an effective internal curing agent to increase the compressive strength and workability of ICC.
item: Conference-Full-text
A study to investigate the factors affecting construction worker performance
(IEEE, 2021-07) Anojan, T; Siriwardana, CSA; Adhikariwatte, W; Rathnayake, M; Hemachandra, K
Worker performance is highly significant in the construction industry since it affects the productivity, safety, and quality level of the project. Construction activities are considered labour-intensive as they heavily rely on human effort. This study aims to evaluate and rate the impact of the factors affecting construction worker performance in the Sri Lankan construction industry. The factors identified through the literature review were categorized into different 11 groups by their nature. The most suitable factors were selected and grouped by using a specific structured approach. Structured questionnaires comprising all the selected factors were used to gather the relevant data from directors, managers, technical officers, engineers, and other professionals. All the gathered data were analysed and were ranked using the Relative Important Index (RII). Improvement strategies were also proposed, and a framework had been developed for improving worker performance. The results of this study will be worthwhile information to improve the performance of the project as part of the research was involved in investigating the interaction relationship of the key factors affecting worker performance to improve the labour productivity in the Sri Lankan construction industry.
item: Conference-Abstract
A study to investigate the factors affecting construction worker performance
(Department of Civil Engineering, University of Moratuwa, 2021-11) Anojan, T; Siriwardana, CSA; Hettiarachchi, P
Worker performance is highly significant in the construction industry since it affects the project's productivity, safety, and quality level. Construction activities are considered labour-intensive as they heavily rely on human effort. This study aims to evaluate and rate the impact of the factors affecting construction worker performance in the Sri Lankan construction industry. After the construction worker performance background study, 25 research papers were chosen based on the number of citations, number of factors and categories, and applicability, yielding more than 200 factors. A structured approach was then used to narrow down the factors. The appearance and relevance of each criterion were used to narrow down the list to 123 factors. A factor was chosen if it appeared in more than one paper. The number of factors was then reduced by considering their ranking in the research paper and the frequency which they featured in research articles. i.e., For factor selection, a ranking below 40 was chosen. Eighty-seven factors were selected from this process. Certain factors were merged because of their similarities, resulted in 67 factors of 13 categories. A questionnaire was developed for a pilot survey to reduce the factors further. Fortytwo (42) responses were collected from various construction industry professionals, including directors, managers, engineers, engineering assistants, technical officers, quantity surveyors, etc. The Relative Importance Index technique was used to analyse the responses independently, and based on the total results, 44 factors were chosen for the final questionnaire survey. According to the responses, the final questionnaire was designed with the corrections. A total of 108 responses were obtained, 47 via site visits and 61 from an online survey. There were 29 firms and 13 professions represented in the responses. The online survey was conducted using the Lime survey platform. All the gathered data were analysed and were ranked using the Relative Important Index (RII). Based on overall ranking and category ranking, labour and management factors play a significant role in worker performance. Experience of workers, manpower skills, and training and skill improvement are the most critical relating to labour factors, while leadership skills and site management are the most vital within the management factors. Supervisor experience also affects the worker performance. Lack of experience reduces performance. Technical factors such as rework, application of technology, and construction methods also impact the performance. So, the utilisation of new methods and techniques can improve worker performance and productivity; however, they should be very convenient for the workers. Design and drawings issues should be considered for better performance of the workers. Since the material and equipment factors are next to the labour and management factors, better equipment and material management can improve the performance. A framework for the improvement has been developed based on these findings. Improvement strategies were also proposed, and a framework was developed for improving worker performance. The results of this study will be valuable information to enhance the performance of the project as part of the research was involved in investigating the interaction relationship of the critical factors affecting worker performance to improve the labour productivity in the Sri Lankan construction industry.