Influence of Recycled Concrete Aggregate and Crushed Clay Brick on Mechanical Properties of Concrete

Concrete is regarded as the most used construction material and natural aggregates used in concrete must be preserved by any acceptable means. This paper presents the results; compressive strength and tensile strength, of using Recycled Concrete Aggregate (RCA) and Crushed Clay Brick (CCB) as partial replacements for coarse and fine aggregates respectively in concrete. Three factors: RCA, CCB and CD were considered and combined at different levels of replacement in the determination of the compressive and tensile strength of concrete. The Response Surface Methodology (RSM) was used to determine the combination of these factors. RCA was used at 30%, 22.5% and 15% representing the high, middle and low replacement levels. Similarly, CCB was replaced at 20%, 15% and 10% which represents the high, middle, and low level respectively. CD was set to 28, 18 and 7 days representing the high, middle and low level. 20 combination set was generated using the RSM. It was found that RCA and CCB included concrete gains compressive strength faster within the first 7 days than the Normal Aggregate Concrete (NAC) but may not gain much more strength afterwards. Keywords: Concrete, Recycled Concrete Aggregate, Crushed Clay Brick, Compressive Strength, Tensile Strength, Response Surface Methodology

A Prediction Of Welding Process Control Variables By Prediction Of Weld Bead Geometry Using Factorial Design Approach

Plasma Enhanced Shielded Metal Arc Welding (PESMAW) is a modified version of the age old manual metal are welding (MMA) where the cellulose based flux coated solid wires are replaced by tubular low hydrogen flux coated electrodes. PESMAW process is aimed to eliminate the usage of cellulose in the electrode coating so as to save some trees and hence make the welding process partially green. The high heat content of the cellulose supported arc is achieved by controlled supply of auxiliary plasma gas through the tubular wire directed into the arc. This paper discusses the influence of the welding process parameters to the weld bead characteristics of weldments made by PESMAW process using mild steel as base metal. Two level fractional factorial design was adopted to investigate and quantify the direct and interactive effects of four major control parameters. “Bend on plate” technique was used to lay weldments and bead geometry was measured using standard metallurgical procedures. Statistical models were made from the obtained results and were analyzed and tested by using analysis of variance technique and students’t’ test. The main and interactive effects of control parameters were studied and presented in graphical form

An investigation on relationship between process control parameters and weld penetration in robotic CO2 arc welding using factorial design approach

Weld penetration is an important physical characteristic of a weldment that affects the stress carrying capacity of the weld joint. Several welding parameters seem to influence weld penetration. This paper presents the relationship between weld penetration and four direct welding process parameters of robotic CO2 arc welding process on structural carbon steel. Two level, full factorial design was applied to investigate and quantify the direct and interactive effects of four process parameters on weld penetration. The upper and lower limits of the process control variables were identified through trial and error methodology, and the experiments were conducted using ‘bead on plate’ mode. The performance of the model was then tested by using analysis of variance technique and the significance of the coefficients was tested by applying student’s‘t’ test. Commercial computer programs were used for statistical analysis. The main and interactive effects of different welding parameters are studied by presenting it in graphical form

Prediction and measurement of weld dilution in robotic CO2 arc welding

Weld dilution is an important feature of weld bead geometry that determines the mechanical and chemical properties of a welded joint. For robotic CO2 arc welding, several welding process parameters are reported to be controlling the dilution. This paper investigates the relationship between four of these process parameters and dilution by depositing ‘bead on plate’ robotic CO2 arc welds over mild steel plates. Two level four factor full factorial design method was used for conducting the experimental runs and linear regression models were developed accordingly. The adequacy of the models were tested by applying students ‘t’ test and the predicted values from the models were plotted against the observed values through scatter diagram. Results showed that the proposed two level full factorial empirical models could predict the weld dilution with reasonable accuracy and ensure uniform weld quality. It can be concluded that robotic CO2 arc welding is a very simple and effective tool for quantifying the main and interactive effects of welding parameters on dilution. Future works should focus in analyzing the influence of variable pure gasses as well as the gas mixture on dilution percentage in robotic arc welding

An Investigation On Relationship Between Process Control Parameters And Weld Penetration For Robotic CO2 Arc Welding Using Factorial Design Approach

Weld penetration is an important physical characteristic of a weldment that affects the stress carrying capacity of the weld joint. Several welding parameters seem to influence weld penetration. This paper presents the relationship between weld penetration and four direct welding process parameters of robotic CO2 arc welding process on structural carbon steel. Two level, full factorial design was applied to investigate and quantify the direct and interactive effects of four process parameters on weld penetration. The upper and lower limits of the process control variables were identified through trial and error methodology, and the experiments were conducted using ‘bead on plate’ mode. The performance of the model was then tested by using analysis of variance technique and the significance of the coefficients was tested by applying student’s‘t’ test. Commercial computer programs were used for statistical analysis. The main and interactive effects of different welding parameters are studied by presenting it in graphical form