Browsing by Author "Gopinath, K"

Now showing 1 - 6 of 6

item: Conference-Abstract
Effect of corrosion on compressive strength of structurally insulated panels
(2016-08-11) Baskaran, K; Gopinath, K
Demand for new construction methods are triggered due to post tsunami rehabilitations, recent landslides, floods and present developments in the North-East etc. Structurally insulated panels (SIPs) are one such system, which expedite and ease the construction work. In Sri Lanka major cities are located along the coastal belt where corrosion is inevitable. Though corrosion is not an uncommon event, effect of corrosion on load carrying capacity of SIP panels is not well documented in published literature yet. Hence, present study focused on finding the effect of corrosion on load carrying capacity and to propose durability enhancement methods of SIPs. Corrosion-induced damage was simulated in the cementitious structurally insulated panels (CSIPs) by reducing the reinforcing steel volume. Experimental investigations were carried out for SIP panels where three were having GI meshes and the other three were with chicken meshes (40% reduced steel volume) as reinforcement. All panels were testedfor compressive strength after 28 days. Durability enhancement (delaying or preventing corrosion) of CSIPs was tested by casting four panels. One panel was kept as reference panel and other three were sprayed with 0.1M Nacl solution to accelerate corrosion. Among these three panels, one panel was applied with water proofing agent and other was coated with weather shield paint and another was left uncoated. These panels were tested for compression after three months of periodic wetting and drying with salt water. 27.4% reduction in load carrying capacity was observed with chicken mesh. Moreover load carrying capacity of CSIPs were enhanced by 17.5% with weather shield paint coated and by 38.8% with water proofing agent with reference to not treated-but periodically salt sprayed panel. In this paper, in addition to comparing the durability enhancement techniques, there costs were also compared before concluding the paper with recommendations.
item: Conference-Full-text
Feasibility study of carbon black contaminated silica sand in the production of black blocks
(2013-11-26) Baskaran, K; Gopinath, K
Present study attempted to verify the feasibility of producing cement blocks by partially replacing fine aggregates with carbon black contaminated silica sand (CBCSS), which is a by-product of the tyre manufacturing process. In the present study performance tests such as compressive testing and flexural testing were conducted. In addition resistance against rain drops was measured and the quality of water, in case of inundation was also checked. As experimental investigations, eight individual black blocks were cast and tested for compressive strength and nine sample panels were made and tested for flexural and compressive strengths. In addition, pressurized drizzle test was conducted for individual blocks to study the erosion resistance characteristics against rain. Moreover, particularly in lower lands, during floods there is a room for these panels containing CBCSS being immersed under water for certain days. The present study accommodated the above through water quality test and the results were verified with drinking water specifications. Compressive strength of individual black blocks was 4.74 N/mm2, which is well above to that of the minimum requirement of 1.2 N/mm2 as per the SLS 855: Part 1: 1989. These blocks, according to the Sri Lankan Standard, could be used for both load bearing walls for up to two storeys and in any non-load bearing walls. The flexural strength parallel to the bed joint was 0.113 N/mm2, which is just below the recommended characteristic flexural strength of 0.2 N/mm2 as per the BS 5628. The flexural strength perpendicular to the bed joint was 0.61 N/mm2, which is higher than the recommended characteristic flexural strength of 0.4 N/mm2 as per the BS 5628. The pressure drizzle test being done to the black blocks was shown smaller indentation after one hour to that of a normal brick at 50 kPa pressure, which revealed a fact that black blocks are rather resistive in terms of indentation to rain to that of normal bricks. Water, in which the black blocks were immersed for three days, satisfied the standard levels for drinkable water, recommended by the SLS 614-1983, which implies the fact that black blocks would not release any additional pollutants to the existing water/flood. Hence, it shall be concluded that the black blocks could be used in constructing masonry walls.
item: Conference-Full-text
State of the art of concrete paving blocks in Sri Lanka (CPBs)
(Department of Civil Engineering, University of Moratuwa, 2011) Baskaran, K; Gopinath, K; Ratnayake, N
It is in the last five years that the stakeholders of concrete paving blocks (CPBs) are awakening to engineer the CPBs in Sri Lanka. Although large scale production of CPBs has already flourished in Sri Lanka, their adherence with stringent standards (both Sri Lankan and International) remains dubious. This reluctance to meet the performance and durability criteria according to codes of practices, curtails the life span of concrete block paved roads to a greater extent. The scope of the present paper is limited to verifying whether the local concrete paving blocks are made on par with international standards. Sample blocks were obtained from local CPB manufacturers and investigated.Though these blocks met the criteria in Sri Lankan Standard for CPBs for strength classes 2, 3, 4 roads, none of them met the compressive strength criteria for strength class 1 roads. Besides, tensile strength requirement specified in the BS EN 1338: 2003 was met by none of the blocks tested. Since, Sri Lankan Standard is planned to incorporate splitting tensile strength as the dominant measure to assess paving blocks in the near future, this study also attempted to identify a mix proportion to meet the splitting tensile strength requirement specified in BS EN 1338: 2003. When CPBs were casted using CPB making machine, an intolerable strength deviation was observed. A series of tests were conducted to explore the reasons for this.The outcome of which would help the small scale manufacturers to keep strength variations within a tolerable range, when they are using CPB making machines.
item: Conference-Abstract
State of the art of concrete paving blocks Sri Lanka (CPBs)
(2016-08-11) Baskaran, K; Gopinath, K
It is in the last five years that the stakeholders of concrete paving blocks (CPBs) are awakening to engineer the CPBs in Sri Lanka. Although large scale production of CPBs has already flourished in Sri Lanka, their adherence with stringent standards (both Sri Lankan and International) remains dubious. This reluctance to meet the performance and durability criteria according to codes of practices, curtails the life span of concrete block paved roads to a greater extent. The scope of the present paper is limited to verifying whether the local concrete paving blocks are made on par with international standards. Sample blocks were obtained from local CPB manufacturers and investigated. Though these blocks met the criteria in Sri Lankan Standard for CPBs for strength classes 2, 3, 4 roads, none of them met the compressive strength criteria for strength class 1 roads. Besides, tensile strength requirement specified in the BS EN 1338: 2003 was met by none of the blocks tested. Since, Sri Lankan Standard is planned to incorporate splitting tensile strength as the dominant measure to assess paving blocks in the near future, this study also attempted to identify a mix proportion to meet the splitting tensile strength requirement specified in BS EN 1338: 2003. When CPBs were casted using CPB making machine, an intolerable strength deviation was observed. A series of tests were conducted to explore the reasons for this. The outcome of which would help the small scale manufacturers to keep strength variations within a tolerable range, when they are using CPB making machines.
item: Thesis-Abstract
Study on applicability of ACI and DOE mix design methods for paving blocks
(2015-01-06) Gopinath, K; Baskaran, K
Presently local manufacturers select the initial mix proportions for CPBs in a random basis and improve it through several trials to attain the final mix. Whereas either identification of new mix proportioning method or modification of existing mix design methods yet remains to be researched. In view of the above, applicability of contemporary mix design methods such as American Concrete Institute (ACI) Method and Department of Environment (DoE) Method to mix proportion the concrete paving blocks (CPBs) were studied experimentally in the present study. In line with both mix design methods, constituents of CPBs were estimated for characteristic compressive strengths, from 15 N/mm2 to 50 N/mm2, a range that approximately satisfies the requirements of the Sri Lankan Standard for CPBs. Based on the estimated proportions, trial mixes were cast and tested for compression at 7 and 28 days and from the experimental observations, some suggestions are made in this thesis. Moreover, adoptability of ACI mix design method with local materials is experimentally verified with limited number of test samples and it can be concluded that many sand samples being tested failed to fall within the fineness modulus range specified in ACI method, leaving local sand to be unsuitable in many cases. Hence, a method of combining sand samples is identified in the literatures and presented in the thesis, using which sand samples can be made suitable for ACI Method of mix proportioning. Further, effect of fine aggregate proportions on compressive strength was studied through set of experiments. Mix proportions were estimated using DoE method for Grade 15 and Grade 50 for finer and coarser sands (94% and 34 % passes through 600 μm sieves respectively) and cubes were cast. They were tested on 7 and 28 days and the test results have shown that the cubes cast with fine sand have attained slightly higher compressive strength to that of coarser sand.
item: Article-Abstract
Study on applicability of ACI and DoE mix design methods for paving blocks
Baskaran, K; Gopinath, K
Applicability of either ACI or DoE mix design method for paving blocks is limited in the published literature. Further, small scale paving block manufacturers struggle at the initial stages to come up with mix proportions. In view of the above, a comparative study on both ACI and DoE mix design methods, to select the initial mix proportion for the paving blocks was carried out in the present study. Quantities of constituents were estimated for characteristic compressive strengths (cylinder strength for ACI method and cube strength for DoE method), from 15 N/mm2 to 50 N/mm2. Based on the estimated proportions, trial mixes were cast and tested for compression at 7 and 28 days. When paving blocks are mix proportioned as per ACI mix design method, the achieved compressive strengths are higher than the compressive strength requirements of Sri Lankan Standard for paving blocks. Whereas a correlation being observed between the achieved compressive strength of paving blocks and the grade designation. Similarly, when paving blocks are mix designed as per the DoE mix design method, the achieved compressive strengths satisfied the compressive strength requirements of Sri Lankan Standard for Classes 2, 3 and 4 roads.