Production and Flexural Behavior of Waste Glass Powder – Fibers Self Compacted Concrete

Abstract

In this research, a systematic investigation was performed into two stages to seek for the optimum benefits resulting from utilizing post consumed waste material (waste glass and RPET). Nowadays, we are meeting environmental protection problems especially after the appearance of virus-bio disease (covid-19). Several things that are designed for our luxurious lives are responsible for environmental pollution due to incorrect waste management technology. Glass and plastic are some of them that must be disposed of or reutilized properly to preserve our environment. To address this issue, the present work summarizes the most significant steps which have been considered in this direction. So the first stage focused on the study the possible influence of using glass powder material in concrete as a partial substitute for Portland cement and then specify the optimal content from performance state and sustainable aspect. Five self- compacting glass concrete (SCGC) have different replacement level of glass powder (0%, 10%, 20%, 30%, and 40%) were designed. Slump flow, blocking ratio, and sieve stability test were conducted to assess the rheological states of the designed mixtures. Mechanical and some related transport properties namely compression strength, splitting tensile strength, modulus of elasticity, ultrasonic pulse velocity, flexural strength, porosity, water absorption, bulk dry density. All tests were assessed on SCGC at 28 days except for the compressive test, which was examined at different ages 7, 28, 56 and, 90 days . In the second stage of this research study, A Recycled Polyethylene Terephthalate (RPET) fibers were selected to investigate its possibility of utilizing as fibers in SCGC mixes as well as assess its behavior on the key rheological, mechanical, durability states, flexural toughness, and static flexural tests. Nine design SCGC mixtures with different contents (0.25%, 0.5%, and .75%) of RPET fibers having various aspect ratios (15, 30, and 45), are cast in the desired size and shape as per the procedures of the tests. After the design process, all specimens were prepared to test the same characteristics in the first stage, in addition, to study toughness property and flexural behavior. Then, an analysis of variance based on the general linear model (GLM-ANOVA) was conducted using Minitab 2018 software package to descript statistical significance in a quantitative manner and to establish the binary effectiveness of volumetric proportions and length of plastic fiber on the SCGC states. Finally, Desirability function concepts were applied to simulate optimizing the target functions and to obtain an optimal mix percent that improving the performance of SCGC with RPET fiber. Test results clarify that the increased replacement of Portland cement in SCC by glass powder maintained the same filling ability value of reference concrete. There is small reduction in passing ability characteristic, all mixes exhibited good stability property compare to mixture without this powder. Compressive and tensile strengths in two type flexural and splitting shown gradually improvement up to the volumetric substitution of 30%, i.e. reduction in their values was more in mix included higher powder ratio. Results at 28 days also reported a substantial improvement in modulus of elasticity, ultrasonic pulse velocity, and dry density for all substitution patterns. Except for 40 % powder percentage caused a downhill almost 4.48%, 1.82%, and 0.79% respect to that noticed for the control blend. Empirical outcomes relative to absorption and porosity showed an increase and decrease in their results based on reference concrete. It is found that 20% glass powder adding can be more beneficial considering porosity response. At last, based on the desirability function technique, the optimum percent of glass powder needed to acquire the desirable properties in terms of performance and sustainability states was 24%. It is visible from data collected in second stage that incorporating RPET as reinforced material at different contents and aspect ratios have adversely affected the flow performance and passing ability property. Whereas increasing RPET contain and length resulted in an obvious improvement in stability property. The compression strength fluctuated with plastic fiber ratios while tensile characteristics in both types are in positive relation with increasing plastic aspect ratio based on fiber ratios and longer fiber showed best tensile strength. There was around 22.56%, 18.6%, and 16.8% reduction in modulus of elasticity, ultrasonic pulse velocity, and dry density with increasing RPET contents from 0 to 0.75% at 45 aspect ratio. Moreover, flexural toughness property illustrated that the use of discrete reinforcement fiber in concrete has positive affected in enhancing post – cracking resistance and enhanced SCGC ductility. An important enhancement in structural behavior of examined beams was observed with adding RPET. There was remarkable increase in load and deflection recorded at first flexural crack (Pcr, δcr) and ultimate deflection (δu) as well as strain corresponding to them. In spite of this, a small reduction was found in ultimate load based on RPET ratio and aspect ratio. Also, adding RPET fiber alters the beam’s failure mode and makes it failed in a more ductile manner after the initial flexural cracking occurred and improving concrete ductility. Finally, the linear regression model and deriving relationships among independent parameters and multiply response variables were established to fulfill the best properties. By adopting the desirability function concepts, the optimum aspect ratio of plastic fiber was 35.45 and volume fraction of this fiber was 0.697% for the best structural behavior.