• Prabhat Ranjan Prem

      Articles written in Sadhana

    • Influence of curing regimes on compressive strength of ultra high performance concrete

      Prabhat Ranjan Prem B H Bharatkumar Nagesh R Iyer

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      The present paper is aimed to identify an efficient curing regime for ultra high performance concrete (UHPC), to achieve a target compressive strength more than 150 MPa, using indigenous materials. The thermal regime plays a vital role due to the limited fineness of ingredients and low water/binder ratio. By activation of the reaction kinetics, the effectiveness of the binder is enhanced which leads to improvements in mechanical as well as durability properties. The curing cycle employed are ambient air curing, water curing and hot air curing. The specimens were exposed to thermal regime at (90°C/150°C/200°C) for duration of 24, 48 or 72 hours at the age of 3rd and 7th day followed with air curing or water curing till 28 days. The results showed a marked difference in compressive strength ranging from 217 to 142 MPa with change in curing regimes. The samples when thermally cured at the age of 3rd and 7th day produced an average ultimate strength of 217–152 MPa and 196–150 MPa, respectively.

    • Low velocity impact behaviour of ultra high strength concrete panels

      Smitha Gopinath R Ayashwarya V Ramesh Kumar Prabhat Ranjan Prem A Rama Chandra Murthy C K Madheswaran R Nagesh Iyer

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      This paper presents the results of an investigation carried out on Ultra High Strength Concrete (UHSC) panels subjected to low velocity projectile impact to assess impact resistance. UHSC panel of size 350 × 350 mm and thickness 15 mm is studied under drop weight impact loading for three different pre-determined drop heights ranging from 100 mm to 300 mm. The response of UHSC panel in terms of acceleration vs time is obtained experimentally. Numerical model has been developed to simulate the impact behaviour of UHSC panel. The Brittle cracking model is used to simulate the behaviour of UHSC panel under impact loading and to perform parametric studies by varying the volume fraction of steel fibres.

    • Development of concrete mixes for 3D printing using simple tools and techniques


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      3D concrete printing is an avant-garde building process with the potential to revolutionise the construction industry by automating construction procedures, reducing material consumption, lowering formwork costs, and optimising structural elements. The current study proposes a methodology for developing plain and fibered 3D printable concrete mixes using locally available binders (cement, silica fume, fly ash, and limestone powder), fine aggregate, water, admixtures, polypropylene fibers, and steel fibers. The study presents the results of 24 trials conducted to develop mixes for concrete 3D printing. According to the present studies, the recommended flow for the mix to be extrudable, printable, and buildable is between 19–21 cm and the open time is 45–60 min. The printed specimens under bending failed monolithically with a single dominant crack. Theplain and fibered 3D printed specimens possessed greater flexural strength than the in-situ cast specimens. The increase in flexure capacity is found to be in the range of 07–22%.

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