Effect of Lime Powder and Metakaolin on Fresh and Hardened Properties of Self Compacting Concrete

This study investigated the fresh and hardened properties of Self-Compacting Concrete (SCC) with different types and amounts of admixtures. Six mixes were prepared by replacing 30% of cement with different percentages of fly ash (FA), lime powder (LP) and metakaolin (MK). Water- Cement ratio was kept constant at 0.41 and superplasticizer dosage of 1% by weight of cement. The filling and passing ability were investigated through Slump Flow, J-Ring, V-funnel and L-box test before filling the moulds. The compressive strength of hardened SCC cubes was also measured after specified days of curing (7, 14, 28, 60 90 days). The workability test results showed that as FA was replaced by increasing percentages of LP and MK, the mixes became dense and hence less workable. It was observed that the compressive strength showed an increase with increasing percentage replacement of FA with LP and MK. This increase was higher for mixes with MK than that of mixes with LP

Mechanical and Durability Characteristics of High Performance Concrete Using Copper Slag as Fine Aggregate

This paper reports the results of an experimental study on the high performance concrete made with copper slag as fine aggregate. The percentage of Copper Slag(CS) added by weight in a range viz. 0, 25, 50, 75 and 100% as a replacement of sand used in concrete and cement was replaced with 15% Metakaolin. The properties studied include compressive strength, splitting tensile strength, Sorptivity, Rapid Chloride Permeability Test (RCPT), Accelerated Carbonation test and Microstructural properties. The test results showed that the compressive strength increases up to 50% copper slag as replacement of sand, beyond which decrease in strength was observed. The results of RCPT and sorptivity with different proportions of copper slag at 28, 90, 120 days of curing period showed the lowest value for the mix containing 25%  and 50 % copper slag at each curing age. Carbonation results show that concrete mixes with 85% cement and MK 15% with increasing percentage of copper slag, the carbonation depth increases slowly especially for 75% and 100%. The microscopic view from Scanning electron microscopy (SEM) demonstrated more voids, capillary channels, and micro cracks with the increment of copper slag as substitution of sand as compared to the control mix, profoundly visible at 100% replacement of sand which is due to the presence of free water

Effect of Different Supplementary Cementitious Materials on Mechanical and Durability Properties of Concrete

Concrete is the most widely used composite in the world. Ordinary Portland cement (OPC) is the most commonly used binding material but the energy required for its production is large and its production leads to release of green house gases in the atmosphere therefore, the need for supplementary cementitious material is real. The utilization of Fly Ash (FA), Silica Fume (SF),Metakaolin (MK) and Ground Granulated Blast Furnace Slag (GGBS), as a pozzolanic material for concrete has received considerable attention in the recent years. This interest is a part of the widely spread attention directed towards the utilization of wastes and industrial byproducts in order to minimize the Portland cement consumption, the manufacture of which is being environment damaging. The paper reviews were carried out on the use of FA, SF, MK and GGBS as partial pozzolanic replacement for cement in concrete. The literature demonstrates that GGBS was found to increase the mechanical and durability properties at later age depending upon replacement level. Silica fume concrete performed better than OPC concrete even at early period for production of high strength concrete and high performance concrete. Fly ash increases the later age strength due to slow rate of pozzlanic reaction. Metakaolin was found to improve early age strength as well as long term strength but had poor workability

Investigating Relationships between locus of control and Emotional Intelligence on Reading Comprehension of Indian ESL Learners at Aligarh Muslim University

In recent years, locus of control and emotional intelligence abilities have increasingly attained attention in research correlated to students' achievement. A various body of educational study has reported the significance of locus of control ability and the constructive influence of locus of control and emotional intelligence on learners’ achievement. This study explored the predictability of locus of control and emotional intelligence (reality testing, social responsibility, Assertiveness) on reading comprehension. 200 Indian ESL learners participated in the study. For data collection, an emotional intelligence questionnaire (Bar-On's EQ-itest"), locus of control questionnaire (Levenson Multidimensional locus of control scale) and a version of TOEFL reading comprehension test (TOEFL, 2010) were used. The data were analyzed by using path analysis and Pearson correlation. The results of the study indicated that reading score has the highest positive correlation with reality testing (r = .31, p< 0.05), and the lowest correlation with Assertiveness (r = .05, p>0.05). In addition, there is a weak positive significant relationship between reading score and locus of control (r = .29, p<.05). Hence, emotional intelligence is better predictor for reading comprehension. Current study has focused on only three factor of emotional intelligence (reality testing, social responsibility, Assertiveness) which had the highest correlations with other skills like speaking

Durability Properties of Self Compacting Concrete containing Fly ash, Lime powder and Metakaolin

This paper investigates the durability properties of Self-compacting concrete (SCC), with different amounts of fly ash (FA), lime powder (LP) and metakaolin (MK). A total of 6 mixes were prepared that have a constant water-binder ratio (w/b) of 0.41 and superplasticizer dosage of 1% by weight of cement. In addition to compressive strength, the durability properties of SCC mixes were determined by means of Initial surface absorption test (ISAT) and Capillary suction test. The test results indicated that the durability properties of the mixes appeared to be very dependent on the type and amount of the mineral admixture used; the mixes containing MK were found to have considerably higher permeability resistance. Good co-relation between strength and absorption were achieved

Effect of Different Supplementary Cementitious Materials on Mechanical and Durability Properties of Concrete

Concrete is the most widely used composite in the world. Ordinary Portland cement (OPC) is the most commonly used binding material but the energy required for its production is large and its production leads to release of green house gases in the atmosphere therefore, the need for supplementary cementitious material is real. The utilization of Fly Ash (FA), Silica Fume (SF),Metakaolin (MK) and Ground Granulated Blast Furnace Slag (GGBS), as a pozzolanic material for concrete has received considerable attention in the recent years. This interest is a part of the widely spread attention directed towards the utilization of wastes and industrial byproducts in order to minimize the Portland cement consumption, the manufacture of which is being environment damaging. The paper reviews were carried out on the use of FA, SF, MK and GGBS as partial pozzolanic replacement for cement in concrete. The literature demonstrates that GGBS was found to increase the mechanical and durability properties at later age depending upon replacement level. Silica fume concrete performed better than OPC concrete even at early period for production of high strength concrete and high performance concrete. Fly ash increases the later age strength due to slow rate of pozzlanic reaction. Metakaolin was found to improve early age strength as well as long term strength but had poor workability

Mechanical and Durability Characteristics of High Performance Concrete Using Copper Slag as Fine Aggregate

This paper reports the results of an experimental study on the high performance concrete made with copper slag as fine aggregate. The percentage of Copper Slag(CS) added by weight in a range viz. 0, 25, 50, 75 and 100% as a replacement of sand used in concrete and cement was replaced with 15% Metakaolin. The properties studied include compressive strength, splitting tensile strength, Sorptivity, Rapid Chloride Permeability Test (RCPT), Accelerated Carbonation test and Microstructural properties. The test results showed that the compressive strength increases up to 50% copper slag as replacement of sand, beyond which decrease in strength was observed. The results of RCPT and sorptivity with different proportions of copper slag at 28, 90, 120 days of curing period showed the lowest value for the mix containing 25%  and 50 % copper slag at each curing age. Carbonation results show that concrete mixes with 85% cement and MK 15% with increasing percentage of copper slag, the carbonation depth increases slowly especially for 75% and 100%. The microscopic view from Scanning electron microscopy (SEM) demonstrated more voids, capillary channels, and micro cracks with the increment of copper slag as substitution of sand as compared to the control mix, profoundly visible at 100% replacement of sand which is due to the presence of free water

Mechanical and durability performance of concrete incorporating graphene oxide

This current investigation was conducted to explore the influence of graphene oxide (GO) on the mechanical and durability properties of normal concrete. A total of five mixes were prepared in addition of laboratory synthesized GO ranging from 0-0.8% with an increment of 0.02% by weight of cement. The synthesized GO was characterized using SEM, FT-IR and XRD techniques.  The workability, initial surface absorption and sorptivity values were observed to have reduced with increase in GO content in the cement matrix. Whereas, the ultrasonic pulse velocity (UPV), compressive and tensile strength were observed to enhance with percentage increment of GO in the concrete compare to control mix. The microstructural analysis was performed using SEM/EDX at 90 days curing age. The mix with 0.08% GO showed better result compared to rest of the mixes with GO and control mix

Mechanical and durability performance of concrete incorporating graphene oxide

This current investigation was conducted to explore the influence of graphene oxide (GO) on the mechanical and durability properties of normal concrete. A total of five mixes were prepared in addition of laboratory synthesized GO ranging from 0-0.8% with an increment of 0.02% by weight of cement. The synthesized GO was characterized using SEM, FT-IR and XRD techniques.  The workability, initial surface absorption and sorptivity values were observed to have reduced with increase in GO content in the cement matrix. Whereas, the ultrasonic pulse velocity (UPV), compressive and tensile strength were observed to enhance with percentage increment of GO in the concrete compare to control mix. The microstructural analysis was performed using SEM/EDX at 90 days curing age. The mix with 0.08% GO showed better result compared to rest of the mixes with GO and control mix

The Effect of Task Planning and Genderon Writing Fluency: A Case Study of Undergraduate Students at AMU

Tasked Based Language Teaching (TBLT) has widely provided learners with some opportunities to learn spoken and written language through learning activities in the major of English Language Teaching (ELT). It offers the student an opportunity to be taught more naturally. In the recent years, that there is a massive growth of interest in examining differential effects of task planning conditionson fluency, accuracy and complexity in English as a second language (ESL) context but, the present study explored the impacts of task planning and gender on ESL learners’ written performance in terms of fluency. To this end, five-hundred undergraduate English Language Learners, both male and female (within the age range of 18-24) have been recruited from Aligarh Muslim University. Two tasks were chosen as instruments for data collection. One is a narrative task (as a pre-task for five-hundred) and the other is an argumentativeessay (for two-hundred one) to measure the fluency of the participants’ written production, under different planning conditions (pre-task planning, within-task planning, and no planning). One-way MANOVA was employed as the statistical means of analysis. The findings revealed a significant effect of task planning and gender under different planning conditions inwords per minute (the number of words produced by the participants divided by the time they spent on each assignment) and syllables per minute (The number of syllables that the participants produced divided by the minutes they spent on production) regarding fluency