Effect Of Different Curing Conditions Research Articles

Compositional Design of New Environmentally Friendly Geopolymer Mortar Based on Kaolin and Granite Residues.

The use of industrial residues in civil construction is an exciting alternative to mitigate environmental impacts and promote the circular economy. This work developed new compositions of geopolymer mortars activated by NaOH from fine kaolin residue (RCF), coarse kaolin residue (RCG) and granite (RG). All residues were benefited and characterized by chemical analysis (X-ray fluorescence), mineralogical phases (X-ray diffraction) and granulometry (laser granulometry). Additionally, the RCF was calcined at 650 °C for 2 h (RCFC) to produce metakaolin, which is the starting point for the geopolymer reaction. A mixture of experimental designs was accomplished to evaluate the water/binder factor (Wexp (%)) necessary for new geopolymer mortar compositions to reach the consistency index (260 mm, ASTM C1437-15) and the effect of different curing conditions on the simple compressive strength (SCS). The geopolymeric compositions with RCFCs, pre-cured at room temperature, exhibited the highest Wexp% values (>40%) and significant SCS, with curing conditions A and B reaching 6 MPa and 7 MPa, respectively. Such behavior can be explained by the fact that the pre-curing step at room temperature keeps the system humidity relatively high, favoring the dissolution of Si4+ and Al3+ ions and, therefore, increasing the Si/Al ratio, which positively influences the geopolymerization kinetics reaction.

The effects of different curing conditions on the polypropylene fibre reinforcement concrete

The effects of different curing conditions on the polypropylene fibre reinforcement concrete

Effect of different curing conditions on the electro-optical properties of directional polymerisation monomer based polymer\\liquid crystal composites

ABSTRACT Polymer\\liquid crystal composites have garnered significant attention as a material due to their facile preparation and pronounced light modulation effect. With the increasing range of applications, effectively modulating the relevant electro-optical parameters has emerged as a major challenge. In this study, two specific monomers were chosen to investigate the impact of curing conditions on the electro-optical parameters. Compared to previous research, the findings presented here offer a much simpler approach for regulating the parameters. This work not only provides insights for future advancements in polymer\\liquid crystal composites with novel functionalities and morphologies but also serves a valuable reference for related industrial production.

Investigation of the effect of different curing conditions on the mechanical performance of calcium aluminate cement concrete at elevated temperatures

Research on improving the performance of concrete at elevated temperatures has been increasing in recent years. In this context, Calcium Aluminate Cement (CAC) can be used in concrete mixes to increase the performance of concrete at elevated temperatures. However, the use of CAC has not yet become widespread in structural applications due to the unstable nature of CAC, which is highly affected by curing temperature and humidity. Therefore, it is of great importance to investigate the curing conditions that directly affect the unstable nature of CAC. In the present study, different curing methods were applied to calcium aluminate cement concretes (CACC) and their performance at elevated temperatures (300 °C, 600 °C, 900 °C) was investigated. In this framework, compressive strength, modulus of elasticity and flexural strength of the samples were determined, load–displacement relations and microstructural changes were evaluated. As a result of the study, it has been determined that CACC samples have better mechanical performance than normal concrete at elevated temperatures and especially the mechanical performance of CACC samples cured at high temperature (CACCH) is better than CACC samples cured under normal conditions (CACCN).

Improving the Characteristics of Less Active Geopolymer Binders Utilizing Ground Granulated Blast-Furnace Slag under Different Curing Conditions

In the current study, the influence of substitution of ground granulated blast-furnace slag (GGBFS) on the characteristics of less active geopolymer binders, including pumice and the waste material produced during the washing process of sand in aggregate industries (waste soil), is investigated. The aforementioned materials were examined individually and in hybrid form. In the hybrid mixes, less-active materials (pumice and the waste soil) were replaced with GGBFS at levels of 25%, 50%, and 75%. The evaluated properties consisted of compressive strength, modulus of rupture, sorptivity, rapid chloride ion migration coefficient, and the content of water absorption. Moreover, the effects of different curing conditions on the properties were investigated. The results indicate that partial replacement of the waste soil and pumice with GGBFS leads to enhanced durability and mechanical characteristics owing to the higher reactivity of GGBFS. The mixture denoted as P25S75 (with 75% GGBFS and 25% pumice) exhibited the best durability properties, surpassing even the S100 mixture (with 100% GGBFS). Substituting the waste soil with GGBFS had a greater enhancing effect compared to the mixtures containing the pumice mixes.

Study on the interfacial bonding performance of basalt ultra-high performance concrete repair and reinforcement materials under severe service environment

The aim of this study was to investigate the effects of different curing conditions, interface types and new concrete types on the bond properties of new-old concrete bond specimens. The splitting tensile test, sulfate resistance dry/wet cycle test and salt freeze/thaw cycle test were carried out on four different types of new-old bonding specimens. The prediction model of splitting tensile strength of bonded specimens and the damage degree model of interface bonding strength based on damage mechanics under erosion environment were established. The results show that: (1) Curing conditions and interface types have a significant impact on the interfacial bond strength of new-old concrete bonded specimens. (2) Basalt fiber can significantly improve the bonding property. Nano-SiO2 was found to reduce the negative effects of low-temperature curing environment on the interfacial bond strength. (3) The degradation law of bond strength of specimens under corrosive environment shows that basalt fiber can improve the interfacial bonded durability of new-old concrete (4) Through the reconstruction and analysis of characteristic parameters of pore space network by CT scanning technology, it is found that basalt fiber was beneficial to retard the interface deterioration of bonded specimens under erosive environment.

Post-Cure Development of the Degree of Conversion and Mechanical Properties of Dual-Curing Resin Cements.

This study investigated the effect of different curing conditions on the degree of conversion and mechanical properties of contemporary dual-curing resin cements. The material specimens were either light-cured directly, light-cured through a 1-mm lithium disilicate glass-ceramic layer, or self-cured. The degree of conversion was measured in 0.1-mm films using Fourier-transform infrared spectroscopy 1 day, 7 days, and 28 days post-cure. Specimens used to study the flexural strength and modulus were prepared according to the ISO 4049 protocol, stored for 28 days post-cure, and subjected to accelerated aging by absolute ethanol immersion. The degree of conversion values ranged between 44.3–77.8%. Flexural strength varied between 11.4–111.1 MPa, while flexural modulus amounted to 0.7–5.5 GPa. The degree of conversion was significantly affected by material type, curing conditions, and post-cure time; however, variations in curing conditions were the least influential factor. A statistically significant effect of curing conditions on the degree of conversion was identified for only one of the five materials tested, whereas the flexural strength and modulus of all tested materials were significantly reduced in the experimental groups that were light-cured through a ceramic layer or self-cured. The effect size analysis showed that mechanical properties were most affected by the material type, while the differences in curing conditions were less influential. A comparison of the degree of conversion and mechanical properties indicated that different curing conditions may lead to significantly different flexural strength and modulus, which are not necessarily accompanied by identifiable variations in the degree of conversion.

Effect of early curing and substrate preparation conditions on the physical and mechanical properties of TRM-masonry composites

• The effect of different curing conditions on TRM composites performance is investigated. • The influence of moisture content bricks on TRM-to-substrate bond behavior is investigated. • The development of the fiber-to-mortar bond behavior is influenced by the curing conditions. • The substrate initial water content affects the TRM-to-substrate bond behavior. Textile reinforced mortars (TRMs) are innovative sustainable composite materials that recently received extensive attention for strengthening of masonry structures. Understanding the mechanical performance of these composites has therefore been the subject of many recent studies. However, most of these investigations have focused on the mechanical properties of these composites under controlled laboratory conditions, and their performance under field conditions is still unknown. The critical role of substrate preparation and curing conditions on the performance of these repair systems have never been addressed before. To address this gap, this paper presents an experimental investigation on the role of these factors on the performance of two different TRM systems (a steel-based TRM and a glass-based TRM) commonly used for strengthening masonry structures. The results show the importance of these factors and the need for the identification of standard procedures for the application of these systems aiming the optimization of their performance in the field.

Performance and microstructure development of lime – calcined fluvial sediment binders under different curing conditions

Fluvial sediments need to be periodically dredged from waterways. At the same time, the building sector has to find high-volume alternatives to the extraction of non-renewable mineral resources. In this context, recent research has shown the benefit of reusing calcined sediments as supplementary cementitious materials. On a different note, this study examines the hydration and performance of blends of calcined fluvial sediment with low amounts (10 to 30 wt%) of hydrated lime with the aim of keeping the carbon footprint of the binder the lowest as possible. The effect of different curing conditions (moist curing at 20 °C or 50 °C and dry curing at 65%RH) is studied on compressive strength, reaction kinetics (fixed lime by TGA and heat of hydration), reaction products (XRD), microstructure (SEM) and porosity (MIP). The outcomes of the study revealed that heat curing for 3 days and 10 wt% of lime results in satisfactory strength development for the design of bio-based concretes (compressive strength of 9 MPa). Furthermore, the highest compressive strength of 17.5 MPa was achieved at 110 days at 20 °C for the mix with 20 wt% of lime. The amount of unreacted lime was found to be the highest for the mix including 30 wt% of lime for which the degree of reaction of lime at 90 days was around 0.7 for both curing temperatures. Under dry curing, a large part of the initially available lime was carbonated and some reaction products underwent carbonation leading to very low strength by 110 days.

Effects of temperature and humidity on properties of ethylene/vinyl acetate‐modified ternary complex mortar

AbstractThe ternary complex system of Portland cement, aluminate cement, gypsum is suitable for the repair and strengthening of concrete structures due to its excellent characteristics, such as fast hardening, early strength, micro‐expansion, and so on. However, the application of this ternary complex was limited by the problems of low toughness and strength degradation in the late curing period. Therefore, it is meaningful to study the effects of different curing conditions on repairing materials in concrete engineering. In this paper, the actual repair environment was simulated, and the effects of different curing temperature and humidity on performances of ethylene/vinyl acetate (EVA) modified ternary complex were researched. The initial and final setting time of ternary complex increases with the increase of EVA content. And under different curing temperature and humidity, the addition of EVA improved the toughness of the ternary complex and reduced the water absorption, EVA can effectively prevent the late strength decrease of ternary complex caused by high curing temperature. Under the curing conditions of 40 and 60°C, the addition of EVA greatly improved the flexural strength and toughness of the ternary complex, low temperature environment is not suitable for EVA‐modified ternary complex.

Effects of different curing conditions on the long-term properties of alkali activated GBP + GBFS mortars exposed to high temperatures

This study investigates the effects of Na concentration, steam curing and oven curing conditions on the long-term mechanical and microstructural properties of alkali activated ground basaltic pumice (GBP) and ground blast furnace slag (GBFS) mortars subjected to ambient and high temperatures. The alkali activated mortars are produced with 50% GBP + 50% GBFS as binding material. To bind these materials, liquid Na2SiO3 and solid Na(OH) as activator are used at different Na concentrations. The alkali activated GBP + GBFS mortars subjected to ambient and high temperatures are tested for unit weight, ultrasonic pulse velocity, flexural strength and compressive strength. Additionally, XRD, SEM and EDAX analyses are performed on the alkali activated GBP + GBFS mortars subjected to ambient and high temperatures. The results have shown that the higher strength values can be obtained from alkali activated GBP + GBFS mortars compared to the control mortars. Moreover, the results have shown that the strength values gradually decrease as the temperature exposed to the control mortars increases, but the strength values of alkali activated GBP + GBFS mortars up to 450 °C temperature gradually increase, and decrease gradually at later high temperatures.

Investigation of the Effect of Different Curing Conditions on the Mechanical Performance of Calcium Aluminate Cement Concrete at Elevated Temperatures

Investigation of the Effect of Different Curing Conditions on the Mechanical Performance of Calcium Aluminate Cement Concrete at Elevated Temperatures

Flexural behaviour and evaluation of ultra-high-performance fibre reinforced concrete beams cured at room temperature

Heat treatment is often required for ultra-high-performance concrete (UHPC) to achieve high strength. To broad its use in construction, the effect of different curing conditions on the properties of UHPC has been developed for many years. The experimental investigation of large scale ultra-high-performance fibre reinforced concrete (UHPFRC) beams is limited. In the present study, UHPFRC specimens and concrete cured at 20 °C were prepared to investigate the properties and flexural behaviour. The standard cubic compressive strength of UHPFRC specimens cannot be achieved at curing temperature of 20 °C. The bearing capacity under flexure was enhanced with the increase of reinforcement ratio. The failure modes of beams changed from ductile to brittle as the reinforcement ratio increased from 1.26 to 9.50%. The flexural behaviour of UHPFRC beams cured at room temperature was in accordance with the UHPFRC beams cured at high temperature in previous studies. In addition, the calculation model of CECS38-2004 underestimated the bending moment capacity of the under-reinforced UHPFRC beams (with reinforcement ratio from 0 to 7.85%) and overestimated the bending moment capacity of the UHPFRC beams with high reinforcement ration of 9.50%.

Monitoring the effect of age and drying on the fracture behavior of earth concrete

This work aims to assess at days 14, 28 and 90 the effect of different curing conditions on earth concrete mixtures on the compressive strength and fracture energy. Moreover, the compression tests were monitored in parallel with AE technique and image processing. The results show the domination of suction effect at the age of 14 and 28 days in all mixtures. Nevertheless, its dominance reduces at later ages in the RS mixtures. Moreover, the fracture energy decreases with time indicating a more brittle behavior. The acoustic emission (AE) technique was able to reflect this brittleness by displaying fewer phases of AE activity during the fracture process, delay in crack formation and decrease in AE hits. In addition, the cameras’ photos revealed the occurrence of higher damage at 90 days.

CIGS Mini‐Modules with Dispensed Metallization on Transparent Conductive Oxide Layer

This article presents the application of a parallel dispensing device for low‐temperature silver paste metallization on transparent conductive oxide (TCO) layers of Cu(In1 − xGax)Se2 (CIGS) substrates as an alternative metallization technology to screen printing and inkjet printing. A curing variation experiment is performed to analyze the effect of different curing conditions on the resulting contact resistivity of the metal grid. Contact resistivity values below 5 mΩcm2 are achieved. Furthermore, CIGS mini‐modules are metallized with three different low‐temperature paste formulations obtaining a record core finger geometry of 25 μm and an average optical aspect ratio of 0.46 using 25 μm nozzle openings. The dispensed metal grid on the TCO layers achieves the comparable current density values of jsc = 32.2 mA cm−2 and the open‐circuit voltages values per cell of Voc = 672 mV as the screen printed metal grid on CIGS mini‐modules and, hence, a nominal power of 2.05 W. The metal grid enables the use of broader cell widths compared with grid‐free CIGS samples and results in a reduced dead area.

Effect of curing conditions during the first 24 hours after casting on the properties of mortar mixtures

As it is well known, the curing method directly affects many properties of cementitious composites. In previous studies, the effect of different curing conditions on the properties of the cementitious systems has been generally investigated in the period after first 24 hours after casting. However, there are not many studies in the literature related to the effects of curing conditions on the specimens kept in mold during 24 hours after casting. In this study, strength development, ultrasonic pulse velocity (UPV) and water absorption capacity of mortar specimens subjected to steam-curing at different temperatures during keeping in mold for the first 24 hours after production were compared. In this regard, all mortar specimens were exposed to curing in a steam-curing cabin at 95% constant relative humidity (RH) under 5 different temperatures such as 20, 35, 50, 65 and 80˚C for the first 24 hours after the specimens were placed into the molds. Afterwards, the specimens were removed from the molds and cured in water conformed to the standard until the testing day. In this context, the water-cement ratio, sand-binder and slump-flow value of all mortar mixtures were kept constant as 0.485, 2.75, 25±2 cm, respectively. As a result, the application of steam-curing at high temperature for the first 24 hours positively affected the 1-day compressive strength and UPV values of the mixtures, while the 3,7 and 28-day compressive strength, UPV values and the 28-day water absorption capacity of mixtures were adversely affected.

Evaluation of Surface Roughness of Composite, Compomer and Carbomer After Curing Through Mylar Strip and Glycerin: A Comparative Study

Aim: To compare the effect of mylar strip and glycerin topical application on the surface roughness of composite, compomer, and carbomer during polymerization. Materials and Method: Each of 45 disc-shaped specimens of Z250, Dyract, Carbomer, were prepared according to manufacturer’s instructions and molded in silicone rubber molds by one operator (5 mm diameter × 2 mm thickness; n = 135). Each restorative group was divided into 3 groups as oxygen group (control), mylar strip, and glycerin group (n = 15). In the control group, specimens were light cured in the open air for 40 s, whereas in the test groups they were covered either with a mylar strip or a drop of glycerin solution and cured for 40 s. Glycerin was rinsed off before polishing. Sof-Lex discs were used for polishing before the surface roughness measurements by a profilometer. The obtained data were statistically analyzed using two-way analysis of variance at a confidence level of 95% ( P < .05). Results: The mean surface roughness values of composite, compomer, and carbomer polymerized in air, through mylar strip and glycerin showed no statistically significant difference ( P > .05). Conclusion: Mylar strip and glycerin application did not affect the surface roughness of the composite, compomer, and carbomer. Polishing may mask the effect of different curing conditions.

Volatile compounds of pastırma under different curing processes

The effects of different curing processes (curing temperature 4°C or 10°C and curing agent 150 mg/kg nitrite or 300 mg/kg nitrate) on the volatile compound profile of the pastırma (Turkish dry-cured meat product) have been investigated. A total of 45 volatile compounds, including alcohols, aldehydes, ketones, aliphatic and aromatic hydrocarbons, terpenes, sulphur compounds, esters, furans and nitrogenous compounds have been identified in pastırma samples. The curing temperature did not have a significant effect on any compound. The curing agent had statistically a significant or very significant influence on 12 compounds. In general, the use of nitrate increased the amount of volatile compound. However, lower mean hexanal value was determined in pastırma samples cured with nitrite than those cured with nitrate. Practical applications Pastırma is a traditional dry-cured meat product. It is produced from whole muscle and/or mucsles of certain parts of beef or water buffalo carcasses. In curing stage, nitrate was used generally. However, nitrite can be used alone or with nitrate in this stage. In this study, the effects of different curing conditions (150 mg/kg nitrite or 300 mg/kg nitrate and 4°C or 10°C) on volatile compounds of pastırma were investigated. According to the results, pastırma produced with nitrate generally showed higher amounts of volatile compounds. On the other hand, curing temperature was not significant factor in terms of volatile compounds.

Effect of different curing conditions on compressive strength and durability of kenaf fibre reinforced blended cementitious composites

This paper investigates the effect of normal curing (NC), air curing (AC), and burlap curing (BC) under different curing periods on the mechanical strength and durability of kenaf fibre reinforced blended cementitious composites (KFRBCC) with thermally activated alum sludge ash (AASA). The aim is to determine the most efficient condition and period for curing KFRBCC and to assess the effect of accelerated ageing on strength and durability of KFRBCC after wet/dry cycles. Meanwhile, the microstructure of these mixes is observed via scanning electron microscopy (SEM). The KFRBCC is designed to achieve strength beyond 50 MPa after 28 days (d) of curing by adding 2% treated kenaf fibre (KF) and by replacing Ordinary Portland Cement (OPC) with AASA. The findings suggest that compressive strength and durability of KFRBCC with 40% AASA cured under BC after age of 28 d are enhanced. The addition of treated KF with AASA have helped in limiting the reduction in the compressive strength and durability of the KFRBCC, particularly under prolonged curing period.

Effects of different curing conditions on the properties of geopolymeric mortar

Effects of different curing conditions on the properties of geopolymeric mortar