Indian Concrete Journal

Influence of numerical modelling techniques in the estimation of seismic demands on non-structural elements S. Saranya, P. Sunitha

Non-Structural Elements (NSEs) in buildings are expected to remain operational after earthquakes. But, numerical models of Structural Elements (SEs) (buildings) seldom include NSEs, thereby ignoring dynamic interaction between SE-NSEs, resulting in unrealistic earthquake demands. This study aims to quantify these earthquake demands, especially in accelerationsensitive NSEs, by using Floor Response Spectrum (FRS) approach, and employing Decoupled & Coupled Models during Nonlinear Response History Analysis. Results are examined for effectiveness and accuracy in predicting acceleration demands. The findings emphasize importance of incorporating coupled SE-NSE behavior, for improved seismic design and behavior of buildings and NSEs during earthquake events

Comparison of different rates of cooling on the properties of flyash concrete on exposure to different sustained elevated temperatures Shweta Patil, K. B. Prakash

Flyash is gaining popularity as it is used to partially replace cement. Good quality of flyash is being obtained from thermal power plants because of improved technology in collection system of flyash. Fire represents one of the most severe conditions to which structures might be subjected. As the most utilized material in the construction industry, concrete is generally known to have good fire resistance. Most studies involving ordinary Portland cement (OPC) based concrete emphasize thermal properties and the addition of reinforcement to improve fire resistance; however, the concrete still cannot withstand high temperatures. Many recent studies have shown extensive damage or even catastrophic failure at high temperatures. This paper presents the results of experimental investigation carried out to evaluate the strength performance of concrete by replacing cement by fly ash in various percentages when subjected to elevated temperature with gradual, sudden and Intermittent cooling. The replacement of 0, 5, 10, 15, 20, 25 and 30 %, of cement with fly ash is considered and the concrete is exposed to elevated temperature of 200, 400, 600, 800, and 1000^o C for 4 hours. The various strength parameters studied are compressive strength, tensile strength, flexural strength and impact strength as per the relevant IS standards. It is observed that all the strength properties of fly ash concrete when subjected to sustained elevated temperature with sudden cooling have drastically reduced as compared to that of gradual cooling and intermittent cooling. The gradual cooling has less deteriorating effect on the strength properties of fly ash concrete when subjected to sustained elevated temperatures

Experimental investigations on glass and polypropylene fiber reinforced pervious concrete Sabahat Ahmad Khan, Mohammed Arif

Pervious concrete, known for its high porosity and stormwater management benefits, typically has lower compressive strength, limiting it to low-traffic areas. This study explores enhancing its strength using glass and polypropylene fibers. Mix design was done according to IRC 044, with 63 batches made with varying fiber contents (0.2 %-0.6 %), a 0.38 water-cement ratio, and 20 % target porosity. Optimal glass fiber content was 0.4 %. For polypropylene fibers, the optimal content was 0.2 % for 22 % paste volume (V_p) and 0.4 % for both 24 and 26 % V_p. The results highlight the potential for high-performance, sustainable pervious concrete mixes.

Static response of high-strength concrete beams with hybrid fibrere inforced polymer (HyFRP) laminates P. Somiyadevi, V. Ramasamy

This study aims to evaluate the static behavior of externally bonded Hybrid Fibre Reinforced Polymer laminates in High Strength Concrete beams with various layer combinations. This research article is mainly focused experimental and analytical investigations on the strengthening of High Strength Concrete beams with hybrid Fibre Reinforced Polymer laminates under flexural loading. This current research work intends to study how alternative sequences of carbon FRP (CFRP) and glass FRP (GFRP) laminates with the combined effect of hybrid FRPs affect the enhancement of the reinforced cement concrete beams. For this research investigation, a total of 17 rectangular beams were cast and strengthened by using GFRP and CFRP. Out of the seventeen cast beams, one beam was the control concrete beam, and the remaining sixteen beams were strengthened with hybrid Fibre Reinforced Polymer laminates which consist of glass and carbon Fibre. The arrangements, which are hybrid FRP laminates, are attached, and they are attended as the main variables in the current research test. Concrete with reinforcements after laminating beams with two, three, and even four layers of hybrid FRP laminates, a static load was given to the beams until they failed. The conclusion of the test results shows that the strength and ductility value of High concrete beams were increased depending on different layers of Hybrid FRP laminates.

Investigative analysis on mechanical and durability properties of concrete mixed and cured with different construction water sources Bhanupriya Sharma, Nisheeth Agnihotri

The quality of concrete for construction activity is governed by the ingredients and construction water used for mixing and curing. In densely populated cities like the national capital region (NCR) in India, the availability of construction water is indeed a significant challenge due to high urbanization and the associated strain on water resources.

The present study encompasses utilization of construction water from alternate sources and comprises a comparative analysis of their effects on durability of concrete. Furthermore, the study also determines the corrosivity behavior of concrete in terms of larson-skold index (LS), aggressivity index, ryznar index (RI) and puckorius index (PI). For experimental examination water samples were collected from different sources to understand the effects associated with mixing and curing of concrete and in the process primarily physio-chemical analysis has been performed to determine the parameters for all the water sources. The properties of concrete specimen prepared and cured with different water sources were investigated at different ages. Investigations such as compressive strength (CS), ultrasonic pulse velocity (UPV), Rebound Hammer, rapid chloride permeability test (RCPT), and water permeability test (WPT) were carried out to establish a comparative analysis. The investigations showed that the concrete made with river water exhibits lower compressive strength, higher RCPT value and greater water penetration depth. In addition, it also demonstrates the upper corrosion tendency. The LS index is also analyzed with respect to RCPT and WPT values, to determine the effect of sulphate and chloride on concrete durability. The study presents a way forward towards utilization of alternate construction water sources such as surface water and river water etc.