Durability of steel reinforced concrete in chloride environments: An overview

Tribology of electroless nickel coatings – A review

A design scheme for self-reinforced cementitious composites to be used for building-scale 3D printing processes is introduced. The design is based on that of engineered cementitious composites, which include dispersed short polymer fibers to generate robust tensile strain-hardening. The mechanical property profile of these printable ECC materials is meant to eliminate the need for steel reinforcement in printed structures, providing more freedom and efficiency for building-scale 3D printing processes. The fresh state rheological properties have been systematically manipulated to allow printability. Effects on fresh state workability of several compositional ingredients and processing parameters are investigated herein. To maintain consistent printing performance with a batch mixing approach, thixotropy in the fresh state is exploited to temporarily decouple hardening behavior from the processing timeline. Minimal workability loss under continued shear agitation is achieved. Mechanical properties of the printable materials are characterized and the printability of the materials is demonstrated.

A self-reinforced cementitious composite for building-scale 3D printing

On the rheology of using geopolymer for grouting: A comparative study with cement-based grout included fly ash and cold bonded fly ash

A scientometric review of geopolymer concrete

This paper about the experimental investigations on the study of bottom ash concrete by replacing river sand with lignite based bottom ash. Bottom ash is a coarser material, which falls into furnace bottom in modern large thermal power plants and constitute about 20% of total ash content of the coal fed in the boilers. Bottom ash, which is rarely used in concrete due to its inactive pozzolanic reaction, improved its quality of concrete. Since fine collection is completely replaced with bottom ash. The effect of mechanical properties on bottom ash has to be studied. This project will give a clear idea of sustainable effect of bottom ash concrete. The strength development for various percentages (0‐ 40%) replacement of cement with fly ash has to be studied at various stages.

bottom ash concrete

Corrosion fatigue crack growth studies were conducted on eccentrically-loaded single edge notch tension specimens made of SA 333 Gr. 6 and SA 516 Gr. 70 carbon steels in water environment. The experiments were conducted using a ±250 kN capacity Universal Testing Machine under constant amplitude sinusoidal loading at a test frequency of 0.50 Hz and stress ratio of 0.1. The fabrication of test specimens and the experiments were carried out based on ASTM E 647 and ASTM E 1820. The crack initiation and growth were monitored and images were captured by using a digital camera at regular intervals of fatigue cycles. By using these images, the length of crack was measured. The tests were terminated when the uncracked portion of the specimens was insufficient to take further load. Crack growth rate and stress intensity factor range values were evaluated at incremental values of loading cycles and crack length. Using the crack growth rate vs. stress intensity factor range plots, best fit curves following power law in the form of Paris’ equation were obtained.

/pdf/corrosion-fatigue-crack-growth-studies-on-pressure-vessel-3rb2ihf6u2.pdf

Corrosion Fatigue Crack Growth Studies on Pressure Vessel and Piping Steels in Water Environment

The waste and by–products from industries, thermal plants, and recycled materials have been used historically in cement, concrete and other constructional activities. By–products such as fly ash, bottom ash, silica fume, etc., gains its utilisation owing to their physical, chemical and engineering properties when used either by processing or directly on concrete. This paper was aimed in making concrete green and durable by utilisation of bottom ash as sand replacement material in concrete that can conserve river sand from exploitation and also prevents environmental pollution caused by bottom ash which is dumped in the form of slurry as ash ponds. Bottom ash is replaced for river sand for 30%, 60%, and 100% in concrete. The strength and durability of concrete was evaluated to find its potential application in concrete. Experimental results show that 30% bottom ash can beneficially be added to the concrete to produce 40–50 MPa without affecting the strength. The durability of bottom ash exhibited superior and better performance than reference concrete.

Strength and durability of green concrete

The development of a linear numerical model of flat-plate to predict shear stress distribution around slab column connection is presented in this paper. An attempt is made to model the slab, flexural reinforcement and shear reinforcement using three dimensional solid elements. The proposed finite element model has been proved to be capable of simulating the shear behavior of slab-column connection and to be suitable for analysis of structural performance of flat plate structures. Numerical results obtained from this model have good agreement with the available results of other researcher’s numerical model with one dimensional rebar element. Keywords: Flat plate, ABAQUS, shear reinforcement, slab-column connection. 1. Introduction Flat-plate slab system is widely adopted by engineers as it provides many advantages such as reduction of floor height, more spatial planning due to no beams present. These advantages further results in reduction in material cost. In the flat plate slab-column connection is always subjected to combination of high bending moments and shear stresses, which develop a punching, shear failure. This failure is undesirable as it occurs without warning and may lead to progressive collapse of slab. Due to large tensile stresses, the potential diagonal crack in the form of truncated cone or pyramid is formed around the column. The failure surface extends from bottom of the slab at the support, diagonally upward up to the top surface. The angle of inclination with the horizontal depends on slab reinforcement. Hence, designing of flat-plate requires a special attention for both strength and ductility when punching shear being consider. The punching shear capacity of the slab-column connection is affected by the size of the column, the depth of slab, flexural reinforcement and compressive strength of slab etc. The punching shear capacity can be increased by using a larger column diameter, larger effective depth, more flexural reinforcement, higher concrete compressive strength or by shear reinforcement. Among these methods, the most effective way to enhance the slab-column connection is to use shear reinforcement at the punching shear zone (ACI 421 R-99), which is permitted by most of the building codes. The provision of punching shear reinforcement in various forms help in increasing the shear and ductility of the concrete. The various forms of shear reinforcements include stirrups, shear studs, bend up bars, shear heads (placed above the column), etc. According to ACI 318-05, the shear strength is a function of compressive strength of concrete and geometrical condition. The provision given in EC2 also includes the size effect and the effect of the flexural reinforcement ratio. Allowable shear strength of concrete with shear reinforcement is calculated as 0.125 √f

Shear stress distribution of flat-plate using Finite Element Analysis

Three reinforced cement concrete (RCC) flat plate panels, namely interior, edge, and corner panels, were considered for evaluating the deflection and crack development from the column. In this study, a numerical analysis was conducted for a steel fibre-reinforced flat plate with steel fibre volumes of 0.3% and 0.4%. The study was conducted on real- and scaled-sized flat plates. We used the ABAQUS software to model and evaluate the deflection and crack patterns. An experimental study was conducted on the scaled-sized specimens to validate the finite element analysis (FEA) results. This study presents the punching shear behaviour of various panels of a flat plate with and without steel fibres. The deflection values obtained from the FEA and experiment were compared, and we found that the interior panel exhibited better results when compared to edge and corner panels. A minimum of three sided support is preferred for the stability of a larger-sized flat plate. The interior panels provided better strength and load-bearing capacity when compared to edge and corner panels. Crack patterns for different panels of a flat plate with different steel fibre volumes were analysed by comparing the FEA and experimental results. The development of cracks moved away from the column face on addition of steel fibres and changed its brittle nature. The results indicate that the crack developed from the column face is away from the critical distance d/2 from the slab-column junction (specimens with fibre), further demonstrating the stability of the structure. Doi: 10.28991/CEJ-2022-08-03-05 Full Text: PDF

/pdf/a-material-model-approach-on-the-deflection-and-crack-2reswa8n.pdf

A. S. Santhi

Papers

bottom ash concrete

Corrosion Fatigue Crack Growth Studies on Pressure Vessel and Piping Steels in Water Environment

Strength and durability of green concrete

Shear stress distribution of flat-plate using Finite Element Analysis

A Material Model Approach on the Deflection and Crack Pattern in Different Panels of the RCC Flat Plate using Finite Element Analysis