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Go to Editorial ManagerThis study was conducted to examine the impact of plastic fibers (WPFs) in an effort to improve some of the features of self-compacting concrete (SCC) using Iraqi raw materials. Waste polyethylene terephthalate fibers (waste PET fibers) from used beverage bottles were added. Some tests were carried out to determine the effects of adding WPFs on the fresh properties of new concrete, while additional tests examined the mechanical properties of hardened concrete. Because of this, self-compacting concrete blends were created with a constant water-to-binder ratio of 0.32 and a binder content of 525 kg/m3. The designated plastic fiber percentages contents were 0%, 0.5%, 0.75%, and 1% of mix volume. Self-compacting concrete mixtures' fresh characteristics were assessed for slump flow diameter, T50 slump flow concurrently, V-funnel flow concurrently, and L-box height ratio. The 28-day density, compressive strengths and flexural strength of self-compacting concretes were also measured. The use of plastic waste fibers had a slight effect on reducing the density of the produced concrete and a negative effect on the fresh properties. The compressive strengths were improved by using WPFs, with the maximum improvement equal to (11.065%) when compared to those made from the reference mix
This main aim of this study is evaluate wide range of fresh and hardened properties of sustainable self-compacting concrete containing various types of Cement Replacement Materials with optimum contents of Polyethylene Terephthalate PET waste plastic as fibers and fine aggregate replacement. This is to evaluate effect of the two forms of PET and to determine the best CRMs could be used with sustainable SCC. such as limestone, glass powder and fly ash with high replacement rate of 70% by weight of cement were used while fourth one (kaolin) was used with replacement rate of 20%. PET fibers were added to SCC with an aspect ratio of 24.4 and 0.7% volume fraction whereas fine aggregate partially replaced by 4% of waste plastic. Four reference mixtures contained FA, LP, GP and KA only, same four mixtures contained 0.7% PET fibers by volume, and the other same four mixtures contained 4% PET fine aggregate by volume. The obtained results all tested fresh properties, which include slump flow, T500, L-Box and segregation resistance were within the limits of the specification reported in EFNERC guidelines. Further, the forms PET have an adverse effect fresh properties of SCC. As for hardened properties (compressive strength, splitting tensile strength, flexural strength and impact strength). Further, this produced type of SCC showed an range of compressive strength (15.2-31.64 MPa) at 28 days. It can be from the current study the best CRMs to be used in SCC containing PET wastes was FA in terms of most tested properties.
This paper presents and discuses some properties of self-compacting concrete SCC containing optimum contents of different types of cement replacement materials CRMs like fly ah, silica fume and limestone powder. The purpose is to evaluate the performance of SCC mixtures to choose the best one for strengthening purposes of corroded reinforcement concrete beams. In a preliminary work, the theoretical optimum contents of the above materials were specified using statistical program (Minitab) and they were verified experimentally. This verification based on checking fresh properties such as slump flow, T500, L-box and segregation resistance as well as compressive strength. The optimum contents of CRMs: 14% fly ash, 19% limestone, 18% silica fume plus fly ash and 11% silica fume were selected and studied. Compressive, tensile, and flexural strengths were examined, as well as the modulus of elasticity, water absorption and porosity (which reflect the related durability properties) were examined. Test results show that the optimum verified theoretical percentage of a combination of fly ash and silica fume, at 18% by weight of cement with a fixed water-binder ratio of 0.33 showed the best overall performance. It was deduced that this SCC mix gave the highest mechanical properties and the lowest porosity and water absorption. For example, the compressive strength increased by 36.25% as compared to SCC mix containing limestone powder. Further, the porosity and water absorption decreased by 120.8% and 164% respectively as compared to the above same SCC mix. Thus, it could be used for strengthening purpose of corroded RC beams.
Adding fibers to the shotcrete concrete mixes is very important to increase the load carrying capacity, toughness, and reducing crack propagations by bridging the cracks. On the other hand, this fiber has an effect on the fresh and hardened properties of shotcrete. In this study, fresh properties evaluated by using slump flow, , and segregation resistance tests. Hardened properties included testing of air voids, dry density, water absorption, ultrasonic pulse velocity (UPV), compressive strength, and flexural strength. This works including two types of fibers in three forms (waste plastic (PET)fibers only, polypropylene fibers (PP) only, and hybrid fiber (PET and PP)), each form added by three percentages (0.35%, 0.7%, and 1%) by volume.The results showed that the addition of 1% of all types of fiber has a negative impact on fresh properties. Especially in shotcrete containing waste plastic fiber. Also, all specimens containing fibers showed a decrease in the ultrasonic pulse velocity (UPV) and an increase in air voids and water absorption compared to the reference specimens. Also, the results clarify that the addition of waste plastic fiber to shotcrete led to a slight decrease in dry density. The highest increasing in compressive strength of shotcrete recorded by about 8.2% with using 0.35% PP fiber and highest decreasing was 20.9% with using 1% waste plastic fiber. the highest increasing in flexural strength was 62 with using 1% PP fibers.
The accumulation of large amounts of construction and demolition waste in Iraq, especially after the 2014 conflicts, has created a serious environmental problem. To achieve sustainable goals, recycling these materials in the construction sector supports the principles of the circular economy and reduces the demand for natural aggregates, as recycling represents one aspect of crisis recovery. This study investigates the mechanical performance and bond strength of Self-Compacting Concrete (SCC) containing demolition brick aggregate (DBA) and discarded brick aggregate (CBA) at 100% replacement ratios for fine and coarse aggregates, with and without 10% crumb rubber (CR) as a volumetric replacement for fine aggregate. Ten SCC mixes were designed and experimentally evaluated after 28 days. The results showed that adding 10% rubber to the reference mix resulted in a 13.5% decrease in compressive strength and a 16.8% decrease in bond strength. Complete replacement of natural aggregate with recycled brick aggregate resulted in significant decreases in compressive and bond strengths of up to 60% and 50%, respectively. Furthermore, incorporating crushed rubber into the recycled brick aggregate further decreased the compressive and bond strengths. The predominant failure patterns observed in the bond strength test were splitting and sliding failure. The combination of these two types of waste aggregate could promote the use of sustainable SCC in practical applications
AbstractThis study aims to investigate the properties of SCC produced by locally availablematerials , and attempts have been made to increase the range of grading of fineaggregate, with fineness modulus ranging from (1.5 to 4.1) , and to study the effect of themaximum size of coarse aggregate . It also aims to study the influence of High ReactivityMetakaolin (HRM) as a partial replacement by weight of cement on the properties of freshand hardened SCC, 24 different mixes of SCC are prepared .8 mixes are considered asReference mixes which are used for comparison purposes. To determine the workability,different test methods were adopted such as slump flow, V-funnel, and L-box tests. Whenfineness modulus of fine aggregate and maximum size of coarse aggregate increase,flowability, passing ability and segregation resistance decrease as compared with smallmaximum size of aggregate and other fineness modulus. Further more, the inclusion of10% HRM as a partial replacement by weight of cement leads to decrease flow ability andincrease of viscosity. The fineness modulus (3.1) of fine aggregate gives better resultsthan other fineness modulus. The results obtained from this study, also show that it ispossible to produce SCC from local available materials which satisfy the requirement ofthis type of concrete. Moreover, the results show the possibility of using different gradingof fine aggregate with fineness modulus ranging from (1.5 to 4.1) and the effect ofchange in fineness modulus is not significant on hardened concrete properties , while it ismore significant on fresh concrete properties .
Self-Compacting Concrete (SCC) is a pioneering concrete that can gush beneath its own load, filling the formwork, and achieving full consolidation while maintaining sufficient cohesion to handle the concrete without segregation or bleeding issues. To develop EPS- fiber reinforced SCC, waste materials such as Expanded Polystyrene Beads (EPS) and waste plastic fibers (Polyethylene terephthalate (PET)) were incorporated. This study investigated the response of SCC to the incorporation of different ratios of PET fibers (0.35%, 0.5%, and 0.75%) and 10% of EPS particles and its impact on fresh and mechanical properties of SCC mixtures. Five SCC mixtures were designed, including the reference mixture, 10% EPS mixture, and three volume fractions (Vf) of PET mixtures. Test results indicated that EPS particles had an optimistic effect on fresh properties and a slight negative effect on mechanical properties. While PET fibers revealed a slight negative impact on fresh properties, they also improved mechanical properties. The highest and lowest values in fresh properties tests, including slump flow, T50, V-funnel, L-box, and sieve segregation were (780mm for (E %10) mix, 5.4 seconds for (0.75% f) mix, 19 second for (0.75% f) mix, 0.85 for (E %10) mix, and 10.77% for (R) mix), respectively and (670mm for (0.75% f) mix, 1.8 second for (E %10) mix, 6 seconds for (E %10) mix, 0 for (0.75% f) mix, and 3.28% for (0.5% f) mix), respectively. While, the highest and lowest values in mechanical properties tests, including density, ultrasonic pulse velocity (UPV), compressive strength, and splitting tensile strength were (2305 kg/m3 for (R) mix, 4.2 km/s for (R) mix, 48 MPa for (0.5% f) mix, and 3.66 MPa for (0.5% f) mix), respectively and (2170 kg/m3 for (0.5% f) mix, 4.03 km/s for (0.75% f) mix, 31 MPa for (E %10) mix, and 2.33 MPa for (E %10) mix), respectively
The problem of discarded tires has received a lot of attention from many authors. Incorporation of rubber aggregate recycled from waste tires is one of the solutions to this issue. This research is based on evaluating fresh and hardened properties such as slump flow, T500, segregation resistance, and L-box tests, compressive strength, impact resistance, and flexural toughness. Rubber aggregate replacements in the self-compact concrete mixes was 10% by volume of fine aggregate. Additionally, both PET and steel fibers are utilized at a volume rate of 0.25%.The outcomes indicate that introducing rubber declines rheological and hardened properties, whereas incorporating hybrid fibers enhances hardened properties such as compressive strength, impact energy, and flexural toughness. The best increase impact energy was obtained at roughly 166.6% when 0.25% hybrid fibers and 10% rubber were used. 74.21 was the greatest increase in flexural toughness when 0.25% hybrid fibers (SCCH3) were used. As for the compressive strength, it was the highest by about 11%.