Papers by Keyword: Curing

Abstract: In today's contemporary world, concrete is a top choice, but curing issues persist due to water scarcity. Civil engineering offers alternatives like polyethylene and self-curing concrete, but they are costly. Over the past two decades, wastewater recycling for purposes like concrete curing has gained attention after treatment. The aim of this literature review is to thoroughly assess the viability of using treated wastewater, particularly sewage water, for the curing process. It focuses on articles from reputable journals published over the last decade. The review begins by examining concrete curing and its techniques and insufficiency cause. Subsequently, it delves into the philosophy of wastewater treatment need, source and the treatment process itself. Consequently, waste water treatment is suggested as an affordable and eco-friendly solution for concrete curing. Lastly, the feasibility of adopting treated waste water in developing nations is scrutinized, with an emphasis on its real-world applicability following comprehensive analysis of its overall performance. Membrane filtration technique is preferred for treatment of waste water due to its reasonable results.

Abstract: Fly ash is a material suitable for making concrete because of its silica, alumina, and calcium contents, which can improve the compressive strength of concrete. In this study, the researcher tried to renew a mixture that is resistant to corrosion using fly ash and calculating the powder in an oven at 200°C for 60 min to change the nature of the shell powder to become reactive in a concrete mixture. Using experimental methods and supported by previous studies. In this experiment, normal concrete (Fc' = 30 MPa. In this study using 6 formulations, with Fly ash 10%, 10%, 15%, 10%, 5%, and 13% of cement and clamshell power 10%, 20%, 20%, 20%, 20%, and 17%, respectively) from sand. The influence of seawater on salty materials, such as shells, and pozzolanic materials, such as fly ash, during drying affects the compressive strength of concrete. The addition of 20% shellfish powder as a substitute for river sand and a combination of 15% fly ash as a substitute for cement (code. C3-SC) greatly affected the performance of concrete for application in marine areas, with the result that the compressive strength of this composition did not decrease. With a curing experiment using seawater, the compressive strength results at the age of 7 days were 23.93 MPa, at the age of 14 days were 33.55 MPa, and at the age of 28 days were 34.02 MPa. These results indicate that the compressive strength of concrete with this mixture does not decrease. From the research results, it can be concluded that calcined shellfish and fly ash powder materials can be applied to concrete in seawater areas.

Abstract: In this study, the blast furnace slag (BFS) was used to replace 30% cement (weight replacement), freshwater, and saltwater (half, same, and twice the concentration of seawater) used to produce the cement mortar. Then, these four types of mixing water were used to cure the mortar till the test ages (7 days and 28 days). The test results show that, at 7 days, the compressive strength of saltwater (half concentration) mixing and curing mortar incorporating BFS is the highest (78 MPa). The freshwater mixing and curing control mortar has the lowest compressive strength (36.2 MPa). At 28 days, the compressive strength of saltwater (twice concentration) mixing and saltwater (half concentration) curing mortar incorporating BFS is the highest (90.2MPa). The strength of the control mortar is 53.0MPa under the same curing water, which is still relatively low. It can be seen from this that the mixing and curing of saltwater are beneficial to improving the compressive strength of cement mortar. The freshwater mixing and saltwater (twice concentration) curing cement mortar incorporating 30% BFS can have a higher strength at 28 days.

Abstract: Due to the challenges of providing constant observation and control of the curing environment, the effectiveness of the conventional concrete process on site is poor. This causes a significant difference in the curing regimes encountered by various concrete pours. Yet, the potential of Internet of things (IoT) technologies has not yet been exploited in this context. To improve concrete practice, technologies have been harnessed that reduce human participation and enable more rigorous management of the ambient variables impacting curing. The interior temperature of concrete may be directly measured in real time and continuously monitored by a management system for in-place concrete using an all-in-one wireless sensor network (WSN) during the initial phases of curing. Without considering the wiring at the building site, the algorithm may also provide a well-informed choice about the removal of the formworks. To monitor and regulate the moisture content of hardening concrete to the levels necessary for high-quality hardened concrete, this research study looked at an IoT-based concrete curing control system based on sensor technologies. The effectiveness of this IoT-based technique was compared to the effectiveness of conventional curing procedures based on on-site trials. According to the findings, the system developed beats the conventional method in terms of both the effectiveness of concrete curing and the amount of time required for supervision.

Abstract: The goal of this study was to investigate the effect of varied proportions of silica/M-BNT/BNT on the curing properties of natural rubber (NR) composites. Thirteen ternary-filled NR composites and a control sample were prepared in this study based on a third degree – simplex lattice mixture design of experiment. It was observed that high loading of silica has a retarding effect on vulcanization rate due to the presence of silanol groups on its surface. Replacement of silica with BNT led to a big reduction in scorch time and increase in vulcanization rate due to the presence of metallic oxides acting as co-activators. The addition of the organoclay M-BNT to silica and BNT resulted to shorter scorch time, an increase in vulcanization rate, and a decrease in minimum and maximum torques improving the processability of the rubber composite. The kinetic model was able to demonstrate the vulcanization behavior of the rubber composites as supported by the very high coefficient of determination (R²) values for all samples. The generated contour plots for maximum torque (M_H), minimum torque (M_L), scorch time (t_S1), cure rate index (CRI), induction time (t_i) and rate constant (k₁) were able to display the trends observed in the experimental values.

Abstract: In general, steam curing is applied to improve the productivity of precast concrete products. After steam curing, products are stored outdoors for secondary curing before shipment. However, drying shrinkage and microcrack expansion that occurs during steam curing may impede strength enhancement. On the other hand, water curing is also clearly effective as a secondary curing process. However, installing a water curing pool in a precast concrete plant is not easy due to limited space. Therefore, this study focused on water sprinkling curing, which is relatively easy to perform without such restrictions. In this study, the effects of water sprinkling curing on the physical properties of mortar at the initial age of steam curing were investigated from the aspects of materials, mix proportions, curing conditions, and test piece dimensions. The results showed that water sprinkling curing increased the compressive strength by about 10% compared to curing under air. The effect of water sprinkling curing increased as the specific surface area of the test piece increased.

Abstract: Steam curing is generally applied to improve productivity of precast concrete products. After steam curing, the products are stored outdoors as a secondary curing process until shipment. However, drying shrinkage and expansion of microcracks that occur during steam curing may inhibit strength improvement. On the other hand, water curing is also clearly effective as a secondary curing process. However, installing a water curing pool in a precast concrete plant is not easy due to limited space. Therefore, we focused on water sprinkling curing, which is relatively easy to perform without such restrictions. In this study, the effects of water sprinkling curing on the physical properties of mortar at the early age of steam curing were studied from the aspects of materials, mix proportions, curing conditions, and temperature of water used for sprinkling curing. As a result, it was confirmed that water sprinkling curing at an early age after demolding resulted in a rapid decrease in the temperature of the mortar surface layer. However, it was confirmed that the same conditions were effective in increasing compressive strength.

Abstract: Generally, only a few especially acrylic monomers have photoabsorption characteristics to allow for effective stereolithography (STL) to take place. Biomaterial product from palm oil, Acrylated Palm Olein (APO), is seen as an ideal alternative to petroleum-based polymers due the diminishing petrochemical supply and abundant of the natural polymer in the market. In this study, APO as a biopolymer is introduced to synthetic polymers Polyethylene Glycol Dimethylacrylate (PEGDMA) and Polyethylene Glycol Diacrylate (PEGDA), separately. All three polymers offer photoabsorption characteristics that enable them to be the resins for ultraviolet (UV) 3D printing. The crosslinking of both copolymers is optimized by comparing two different UV radiation techniques; UV cured machine and UV STL 3D printer. The degree of crosslinking for both APO-co-PEGDMA and APO-co-PEGDA through gel fraction analysis are studied and compared with their prepolymer resins. As predicted, the maximum degree of crosslinking of APO-co-PEGDMA and APO-co-PEGDA samples are achieved from the fabrication of samples by 3D printing and recorded at 67.50% and 59.50% respectively, comparing to the samples cured by UV cure machine, which recorded maximum crosslinking percentage at only 21.31%. Further analysis is done using swelling test to study water absorption capacities of copolymers and results shows that APO-co-PEGDMA able to retain water at maximum of 42.47% and APO-co-PEGDA at 52.02% from the 3D printed samples, and recorded lowest readings at 22.82% and 25.56% respectively. UV cured samples are recorded to have lowest readings at 3.89% for APO-co-PEGDMA, and 4.23% for APO-co-PEGDA. Fourier Transform Infrared (FTIR) Spectroscopy confirmed the successful crosslinked of the copolymers. Analysis of FTIR shows that there are presence of new peaks and shifting of peaks, indicating that APO is crosslinked with PEGDMA backbone as well as PEGDA backbone. These also suggest that both polymers are suitable to be incorporated with APO as new photopolymer resins, fabricated using UV radiation crosslinking, with PEGDMA shown a slightly better result. All results are agreeable with FTIR results.

Abstract: A curing system has been developed for obtaining high-strength compositions matrix, which is used in the production of composites based on reinforced carbon fiber using prepreg technology with a curing temperature of . A technology has been developed for combining an epoxy oligomer with a curing agent and modifier. The pot life of the prepared prepregs is at least 15 days.

Abstract: In recent years, automotive hose and belt specifications have changed, requiring longer product life in terms of swelling, wear and heat ageing. Diene-based rubbers, such as natural rubber (NR) and styrene-butadiene rubber (SBR), have been widely used in diverse industries. However, some apparent defects such as limited ageing resistance and large compression set, have been demonstrated in some rubbers cured by sulfur or peroxides. In the making of general and industrial rubber goods, short production and sufficient scorch time is crucial especially by using an injection moulding. In this work, blend of Epoxidised Natural Rubber (ENR 25) and Butadiene was developed with two types of curing systems namely Conventional and Efficient Vulcanisation system. The aim of the study is to produce a satisfactory heat resistance rubber compounds and adequate process safety for rubber manufacturing. Results showed that curing system applied significantly affected thermal stability property of the compounds. Modulus and hardness of the blends appeared to decrease progressively with ageing. However, greater thermal stability especially ageing at 100°C for 200h was observed with compound containing efficient curing system compared to conventional curing system which corresponded to the cross link density attributed by the torque value and dynamic mechanical analysis. The results on stiffness however was effected by the curing system applied. The influence of cure temperature on the chemical crosslink density on both cure systems are being investigated. The network results will be correlated with the technical properties.