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This research investigated the influence of adding cellulose nanofiber (CNF) on the rheology and hardened properties of self-compacting concrete (SCC). The CNFs were produced from wastepaper through chemical treatment and added as 0.25%, 0.50%, 1%, 2%, and 3% by weight of cement in SCC. The results revealed that the increase in the content of CNF caused the decrease in slump flow diameter (SFD), and the lowest SFD of 600 mm was achieved at 2% CNF. In addition, the T50 flow and unit weight increased with the increase in the content of CNF, and the maximum values of 5 s and 2.6 kg/m3 were achieved at 2% and 3% CNF, respectively. Furthermore, the compressive strength increased with an increase in curing age and CNF content (until 0.5%), and the maximum value of compressive strength was achieved as 89 MPa for 0.5% CNF at 28-days of curing. The dry density results increased with the increase in CNF contents at 7-days of curing. The ultrasound pulse velocity and strength ultrasound decreased with the increase in CNF contents. The results showed that the inclusion of CNF improved the microstructure and formed crack bridging. In conclusion, CNF (up to 0.5%) can be used for the production of SCC.

The absence of biodegradability exhibited by plastics is a matter of significant concern among environmentalists and scientists on a global scale. Therefore, it is essential to figure out potential pathways for the use of recycled plastics. The prospective applications of its utilisation in concrete are noteworthy. The use of recycled plastic into concrete, either as a partial or complete substitution for natural aggregates, addresses the issue of its proper disposal besides contributing to the preservation of natural aggregate resources. Furthermore, the use of agricultural wastes has been regarded as a very promising waste-based substance in the industry of concrete manufacturing, with the aim of fostering the creation of an environmentally sustainable construction material. This paper illustrates the impact of nano sunflower ash (NSFA) and nano walnut shells ash (NWSA) on durability (compressive strength and density after exposure to 800 °C and sulphate attack), mechanical properties (flexural, splitting tensile and compressive strength) and fresh characteristics (slump flow diameter, T50, V-funnel flow time, L-box height ratio, segregation resistance and density) of lightweight self-compacting concrete (LWSCC). The waste walnut shells and local Iraqi sunflower were calcinated at 700 ± 50 °C for 2 h and milled for 3 h using ball milling for producing NSFA and NWSA. The ball milling succeeded in reducing the particle size lower than 75 nm for NSFA and NWSA. The preparation of seven LWSCC concrete mixes was carried out to obtain a control mix, three mixtures were created using 10%, 20% and 30% NWSA, and the other three mixtures included 10%, 20% and 30% NSFA. The normal weight coarse aggregates were substituted by the plastic waste lightweight coarse aggregate with a ratio of 75%. The fresh LWSCC passing capacity, segregation resistance, and filling capability were evaluated. The hardened characteristics of LWSCC were evaluated by determining the flexural and splitting tensile strength at 7, 14 and 28 days and the compressive strength was measured at 7, 14, 28 and 60 days. Dry density and compressive strength were measured after exposing mixes to a temperature of 800 °C for 3 h and immersed in 10% magnesium sulphate attack. The results demonstrated that the LWSCC mechanical characteristics were reduced when the percentages of NWSA and NSFA increased, except for 10% NWSA substitution ratio which had an increase in splitting tensile strength test and similar flexural strength test to the control mixture. A minor change in mechanical characteristics was observed within the results of LWSCC dry density and compressive strength incorporating various NSFA and NWSA` contents after exposing to temperature 800 °C and immersed in 10% magnesium sulphate attack. Furthermore, according to the findings, it is possible to use a combination of materials consisting of 10-20% NSFA and 10-20% NWSA to produce LWSCC., (© 2024. The Author(s).)

In this work, carbon-based nanomaterials such as active carbon which is prepared from common sunflower (Helianthus annuus) seed shell, and the characterization of the activated carbon NPs were studied using FTIR (Fourier transform infrared spectroscopy), XRD, SEM, EDS, and DTA techniques. Activated carbon NPs have been used in the adsorption of Pb(II), Cd(II), and Cr(III) ions from the aqueous phase. The results showed the highest adsorption efficiency was 99.9%, 92.45%, and 98% for Pb(II), Cd(II), and Cr(III) ions respectively at a temperature of 25 °C, pH = 7-9, and a time of 60 and 180 min, in addition to the accordance of the adsorption models for activated carbon with the Freundlich isotherm model at the value of R 2 (0.9976, 0.9756, and 0.9907) and Langmuir isotherm model (0.966, 0.999, and 0.9873) of the Pb(II), Cd(II), and Cr(III) ions, respectively. We conclude the possibility of using activated carbon to have an extremely high sorption capacity across the conditions tested, with the highest adsorption efficiency having been >99% for Pb(II), Cd(II), and Cr(III) ions within the pH range 7-9 and a contact time of 60 to 180 min., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Environmental contamination and the massive high cost of waste disposal have been a huge concern for scholars throughout the globe, prompting them to alternatives of recycling waste materials in various implementation fields. The rising expenditure on disposal and the shortage of naturally main resources such as aggregate have increased interest in reusing recycled waste materials to manufacture concrete and mortar. The annual consumption of a country's population of hundreds of tons of black tea results in considerable numbers of discarded teabags. These huge quantities are disposed in landfills without being recycled or otherwise used. Moreover, such landfills are considered one of the country's biggest global issues. Therefore, the aim of this experimental work is to investigate the influence of nanocarbon tube produced from tea waste as cement replacement materials in mortar mixtures. Cement mortar mixes contain four replacement levels (1%, 2%, 3%, and 4%) of cement with nanocarbon tube produced from tea waste. The compressive strength, ultrasonic pulse velocity, and water absorption were tested to demonstrate the effect of the nanocarbon tube made from recycled tea waste on the mechanical properties of the mortar mix. The fresh properties such as flow rate were evaluated in accordance to specific standards. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDX) analyses were performed to demonstrate the microstructure of the mixtures. The results show that the fresh properties (flowability) of mortar containing nanocarbon tubes from tea waste were improved with the increase of the replacement ratio. In addition, the compressive strength was improved by substitution of up to 2%. For the other levels of substitution, it decreased with an increasing replacement percentage. In contrast, the density had increased with the increase of substitution levels of the tea waste. Based on the results of the experiments, it seems that the suggested biomixture could increase the compressive strength of the material by up to 2% of the replacement at 28 days of curing., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

An effort is being conducted to enhance some characteristics of self-compacted concrete (SCC) and clean the environment through the addition of waste plastic fibers resulting from the cuts of waste medical radiology. A number of tests were carried out to examine the impact of waste medical radiology (WMR) fiber additions with various aspect ratios and various percentages on SCC characteristics. Thus, various SCC mixes were designed at a constant water-to-binder ratio of 0.33 and 550 kg/m 3 of binder content. The four groups of WMR fiber content were specified with different aspect ratios of (0, 40, 50, and 60) with various ratios of (1%, 1.25, and 1.5%) by volume of concrete. The workability characteristics of SCC mixes were determined by fresh density, segregation resistance, L-box height ratio, T50 slump with V-funnel flow time, and slump flow diameter. Also, the measurement of thermal conductivity, compressive, flexural, and splitting tensile strengths were performed at 28 days for SCC mixtures. The findings revealed that WMR fibers have a negative impact on the fresh characteristics of SCC except for segregation resistance, which improved. However, the results of splitting tensile and compressive strengths were enhanced at 1% WMR fiber content with various aspect ratios then decreased. However, all results of flexural strength were reduced in comparison with the control mixture excluding samples containing 1% WMR fibers with an aspect ratio of 50 which showed a higher result. The outcomes of thermal conductivity were reduced with the usage of various WMR fiber percentages and various aspect ratios in comparison with the control mixture, and the best result was obtained at 1.25% WMR fiber with an aspect ratio of 50., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The increasing cost of landfills, and lack of natural large aggregates observing interests for using wastes to produce concrete and mortar materials. Utilizing plastic waste and crushed ceramic waste not only save the landfills cost but also reduce the cost of using natural aggregates. Secondly, tea is the second most consumed beverage at world level and resulted huge amount of waste. Thus, this article attempts to develop the appropriate characteristics of self-compacting concrete (SCC) by adding plastic waste, tea waste, and crushed ceramics. The fresh and hardened properties of the SCC were investigated to examine the addition of waste plastic, whereas the content of tea waste and crushed ceramic was kept constant. The results revealed that the addition of plastic waste caused to reduce SFD, L-Box, segregation, and fresh density, and obtained maximum values as 765 mm, 0.94, 19, and 2382 kg/m 3 for PP5 and RP5, respectively, whereas T500 and V-funnel flow gradually increased with increasing waste plastic, and the maximum values were obtained as 3.44 and 16 for RP25 and PP+RP25, respectively. Further, compressive and flexural strengths were decreased with increasing content of waste plastic, and the maximum values were obtained as 55 MPa and 6.5 MPa for PP5 and PP+RP5 at 28 days, respectively. The results proved the possibility of using plastic waste, tea waste, and crushed ceramics in SCC., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Reusing the industrial waste materials is one of the main aims of sustainability and achieve the environmental protection. However, concrete is the main production for recycling waste materials and cleaning the climate. The utilization of self-consolidating lightweight concrete (SCLC) can achieve two important advantages of the structure self-weight reduction and improving workability. This paper examined the effect of waste expanded polystyrene (EPS) beads on the workability and hardened characteristics of sustainable SCLCs. Six different EPS volume fractions up to 80% replaced with normal coarse aggregate to produce SCLC mixtures with water to binder (w/b) ratio of 0.35. A total binder content of 500 kg/m 3 by including 20% waste ceramic powder with 80% Portland cement and fine aggregate consist of river sand and fine ceramic with 1:1 ratio in all SCLC mixes. The workability of SCLCs was examined by slump flow time and diameter, L-box height ratio, V-funnel flow time, and segregation resistance. Moreover, the hardened properties tested at different curing periods such as compressive strength at 7, 28, and 90 days; flexural strength at 28 and 90 days; and splitting tensile strength, dry density, voids percent, water absorption, ultrasonic pulse velocity (UPV); and scanning electron microscope (SEM) at 28 days. The results verified that workability of SCLCs enhanced as EPS incorporation increased and achieved the limitations required for self-compacting concrete (SCC) while the strengths value curtailed but the compressive strength satisfied the lower value indicated by ACI for structural purposes. Depending on the water absorption and UPV, results illustrated that all produced sustainable SCLC mixtures had a good durability. Furthermore, a high linear correlation was noticed between the results., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)