Faculty of Engineering

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Author: search.filters.author.Perera, J

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Now showing 1 - 3 of 3
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    PublicationOpen Access
    The Properties of Lime/Soil Concrete
    (SLIIT, 2022-02-11) Perera, J; Chandrasiri, J
    The investigation of materials for replacing cement in concrete manufacturing has garnered steady interest from experts in recent years. However, the majority of past researches have only focused on the use of lime as a cement substitute in producing Lime Concrete. The reason for this is that lime concrete can be made easily and cheaply while still providing a durable material that can minimize negative environmental impacts. Even though lime is used as an alternative material the integration of a new material as a replacement for conventional aggregates has been limited. As a result, this study will attempt to examine the various compositions of hydraulic lime as a partial replacement of cement while completely replacing the coarse and fine aggregate with a soil to find the influence on the physical characteristics of Lime/Soil concrete. This will also help in decreasing the ecological imbalance caused due to the excess use of conventional aggregates. Locally available reddish-brown laterite soil was used in this study without any modifications. C30 concrete mixes containing 0%, 10%, 15% of hydraulic lime replaced with OPC and complete replacement of aggregate with laterite soil were casted before subjected to water curing. Workability, compressive strength, splitting tensile strength and water absorption test were conducted in accordance with the existing standard. Based on the results obtained from the study it has shown that even with complete replacement of aggregate with laterite soil it was able to produce workable concrete with satisfactory strength that can be employed for ground improvements in pavement design and to manufacture economical non-load bearing concrete blocks. The targeted strength still can be achieved with replacement of 15% hydraulic lime for a lower cost. With the accomplishment from the composition, future studies will be able to better assess the long-term effects of construction operations on the environment.
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    PublicationOpen Access
    Effects of Manufactured Sand on the Properties of Normal and High Strength Concrete
    (SLIIT, 2022-02-11) Perera, J; Premadasa, R
    Manufactured Sand (MS) has been introduced as a very effective fine aggregate and is being widely used in various construction activities. Large amounts of Manufactured Sand Fines (MSF) that are less than 75 µm in particle size, are produced during the production process. Costs are incurred in separating these fines from the crushed stone and are then dumped in landfills, thus causing serious environmental issues. Studies on MSF are not well established and a handful has been done on High Strength Concrete (HSC). The key objectives of this study were to study and compare the effects that MSF have on the properties of Normal Strength Concrete (NSC) and HSC and to propose effective fines percentages that could be incorporated in them. Tests were carried out by partial replacement of MS with fines in proportions of 10%, 15% and 20% for C30 and C60 concrete and were compared with the control mixes that contained 3.36% MSF. It was identified that a 15% replacement of MSF produced effective results with the highest compressive, splitting tensile and flexural strength results and minimum water absorption in both NSC and HSC. At 15% fines content, a strength of 35.3 MPa and 63.3 MPa was achieved by the C30 and C60 concretes respectively. However, the increment of fines decreased the workability significantly. The microstructure analysis proved the densification of the microstructure at 15% MSF content. The cost analysis showed that the availability of high fines content can deduct the cost of NSC by 1.8% and HSC by 1.6%. The 10% - 15% range was identified as the most effective fines content range that can be incorporated in NSC and HSC. Results of this study can contribute to develop concrete with better performance while addressing several environmental and cost issues related to the concrete industry.
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    PublicationEmbargo
    A gyroscopic data based pedometer algorithm with adaptive orientation
    (IEEE, 2018-06-12) de Silva, R; Perera, J; Abeysingha, C. P; Abhayasinghe, N
    Orientation of an Inertial Measurement Unit (IMU) relative to earth is a critical factor to the step detection in gyroscopic data based pedometer algorithm. The orientation of the IMU will be often subjected to change while using the small scale electronic pedometers. Existing fixed axis gyroscopic data based pedometer algorithm may not be suitable to implement in the modern small scale embedded pedometer applications. In this paper we have developed an advanced version of the gyroscopic data based pedometer algorithm which can dynamically adjust for the changing orientation of the IMU. Step detection component of the proposed algorithm is based on the gyro readings and the orientation detection is based on accelerometer readings. The algorithm employs the gravity vector and linear acceleration vector of the pedestrian to identify the orientation of the IMU. The active gyroscopic data axis for the pedometer algorithm is chosen based on the orientation.