Proper Curing Research Articles

Effect of Tyre Waste on Ground Granulated Blast Furnace Slag (GGBFS) Based Concrete Blocks

Objectives: To determine the effect of tyre waste on its addition to Ground granulated blast furnace slag (GGBFS) based Concrete Blocks in respect to compressive strength. Methods: Cube specimens of size 150 x 150 x 150 mm were casted with 45% replacement of cement by GGBS and tyre waste in different proportions 45%, 40%, 35%, 30% and 0%, 5%, 10%, 15% respectively. Cube specimens were kept in ambient conditions, so as to protect it from heat and cold, thus avoiding surface evaporation. After proper curing, compressive strengths were determined at 1, 3, 7, 14 and 28 days respectively. Findings: This research determined the exact quantity of tyre waste and GGBFS which can be used as a cement replacement in Concrete mix. It was found that maximum compressive strength was achieved at 45% GGBFS content and 0% Tyre waste content. Although tyre waste can be introduced up to 15% in the concrete mix and compressive strength is more than only OPC based concrete mix. Novelty: According to the findings of the comprehensive study, use of tyre waste at 15% and GGBFS at 30% in concrete mix reduces the requirement of cement, which finally plays a major role in reduction of construction cost by use of cheap tyre waste and less cement. It encourages us to use tyre waste on a larger scale in construction, along with the protection of environment. Keywords: Ground granulated blast furnace slag; compressive strength; tyre waste; Ordinary Portland Cement; Environment friendly

Effects of nanohybrid flowable resin-based composites on fibroblast viability using different light-curing units.

To investigate the in vitro cytotoxic effects of Bis-GMA-containing and Bis-GMA-free flowable resin-based composites (RBCs) on primary human gingival fibroblast cells (hGFc) using direct and indirect curing methods and three different light-curing units (LCUs). Cells were isolated and cultured in vitro in 24-well plates. The plates were divided into treatment (cells with RBC), control (cells only), and blank (media only) groups. In the treatment groups, two types of nanohybrid flowable RBCs were used: Bis-GMA-free and Bis-GMA groups. Each treatment group was subdivided according to the curing method, i.e., direct curing (RBC was injected into the wells and cured directly on the attached cells) and indirect curing (the samples were pre-cured outside of the well plate and then added to the well plate with cells). To vary the LCU, the subgroups were further divided into three groups: multiple-emission peak light-emitting diode, single-emission peak light-emitting diode, and quartz-tungsten-halogen units. Curing was conducted for 20seconds. The hGFc cytotoxicity was evaluated via 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay after 24, 48, and 72 hours of culturing. The MTT assay results showed that both RBCs were significantly cytotoxic toward hGFc compared to the control group (p < 0.0001). The Bis-GMA group was significantly more cytotoxic to the cells compared to the Bis-GMA-free group. In addition, the curing method and time interval affected cell viability regardless of the LCU used. The Bis-GMA flowable RBC and direct curing method had the highest cytotoxic effects on hGFc regardless of the LCU used. Careful selection of flowable RBCs and proper curing techniques are required to decrease the cytotoxic effects on hGFc and improve the clinical handling of oral tissues.

FEM and experimental investigations of concrete temperature field in the massive stemwall of the bridge abutment

• Prediction of early-age concrete temperature of cast-in-place stemwall of the bridge abutment. • The in-situ measurements using novel temperature monitoring system working on 1-wire digital sensors. • Numerical simulation conducted using the own finite element code for nonlinear thermal problem. • The recorded thermal data highly consistent with FE results. • Recommendations regarding the measurement system and maintenance of massive walls of bridge abutments. The paper deals with the prediction of early-age concrete temperature of cast-in-place stemwall of the bridge abutment. The considered object is an arch bridge located in Gdańsk. In the case of massive structures, it is particularly important to not exceed the temperature difference between the core and the concrete surface. Too high temperature gradient generates an increase in thermal stresses, what could be the reason of exceeding the tensile strength and as a consequence cracking occurrence. Therefore, the numerical simulations of concrete hardening were conducted using own codes of finite difference and finite elements method. Based on numerical results the project of monitoring system was developed. The concrete temperature of stemwall was registered during 12 days by using fifteen 1-wire digital sensors. The recorded thermal data are highly consistent with FE results, which confirms the accuracy of the finite element model. The conducted calculations and in-situ measurements allowed to determine guidelines for proper curing of massive abutment’s wall.

Microstructure and Strength Properties of Sustainable Concrete Using Effective Microorganisms as a Self-Curing Agent

In practical applications, problems related to proper curing arise for inclined structural elements, especially in skyscrapers, wherein concrete is very thick. To overcome this problem, the implementation of self-curing technology using varieties of smart materials has become significant. Based on these factors, this study determined the impact of effective microorganisms (EMs) as a new self-curing agent on the microstructures and strength properties of sustainable concrete. Five concrete mixtures were prepared with various EM content (5, 10, 15, 20, and 25%) as water replacement under air-curing condition. The workability of the concretes was found to increase with the increase in EM contents from 0 to 25%. In addition, concrete designed with 10% of EM achieved the highest compressive strength (42 MPa) after 28 days of aging as opposed to the control specimen (35 MPa). The microstructures of the concrete made with 10% of EM revealed very a compact network, fewer voids, and formulation of dense C-S-H gel. Based on the results, the proposed EM may be implemented as a self-curing agent to achieve high-performance sustainable concretes beneficial for the construction sectors.

Evaluation of glycolaldehyde as a formaldehyde substitute in urea-based wood adhesives

Glycolaldehyde, produced from cracking of glucose, was tested as a substitute for formaldehyde in urea-based wood adhesives. Initially, different parameters (water content, aldehyde/urea-ratio, curing temperature, and time) were screened to identify the optimal curing conditions providing the highest bond strength. Afterwards, the system was reformulated as a 2-component system and compared to a urea-formaldehyde 2-component system, which showed a comparatively low strength of the resulting resin. Different hardeners were tested, and AlCl3 showed an 80% increase in bond strength for the resin compared to NH4Cl. Infrared and nuclear magnetic resonance analyses were performed to ensure formation of the desired aminal bond network, which showed that the hardener was essential for proper curing of the resin. Finally, a urea-glycolaldehyde-formaldehyde resin was tested that further indicated major differences between the reactivity of formaldehyde and glycolaldehyde.

Improvement of Mechanical Properties and Microstructure of Cementitious Materials in a Hot-Dry Environment

The hot-dry environment in high geothermal tunnels negatively affects the development of properties of cementitious materials. In order to improve the mechanical properties of cementitious materials in such environments, a proper curing system was developed, the material compositions were taken into account, and the related mechanism was analyzed by microscopic tests. The results showed that the mechanical properties and microstructure of cementitious materials can be improved effectively by adopting film curing and an adequate dosage of fly ash in a hot-dry environment. Compared with standard curing, a hot-dry environment accelerates the evaporation of water in fresh cementitious materials and the early hydration rate of cementitious materials, resulting in lots of unhydrated cement particles and an uneven distribution of hydration products, seriously decreasing the properties of the cementitious materials. Film curing keeps the water from evaporating and ensures enough water is available for hydration at an early age. The addition of FA reduces the amount of cement clinker and decreases hydration reaction rate in high temperature environments at an early stage, avoiding the unevenness of hydration products. High temperatures stimulate the pozzolanic activity of fly ash and promote the degree of secondary hydration reaction, producing more hydration products, as well as contributing to the improvement of the mechanical properties and microstructure of cementitious materials. In this study, in a hot-dry environment, the mechanical properties of mortar with 25% fly ash and 2–3 d film curing are better than those of other experimental groups, including those of standard curing.

Strength Evaluation and Durability on Addition of Nanosilica in M30 Grade Concrete

Abstract: Nano technology plays a very vital role in all the areas of research. The incorporation of nano materials in concrete offers many advantages and improves the workability, the strength and durability properties of concrete. In this study an attempt has been made to carry out an experimental investigation on concrete in which cement was replaced with nano sized cement. Nano-silica has a unique advantage in the potential pozzolanic-reaction with cement hydration products over other nanoparticles. Addition of Nano-silica is known to redefine pore size and distribution which would alter the durability of the concrete. Ordinary Portland cement of 53 grade was ground in a ball grinding mill to produce nano cement. . Nano technology is an emerging field of interest for civil engineering utility. A few of the nano substances presently used in concrete, nano-silica very own greater pozzolanic nature. It has the functionality to react with the unfastened lime inside the route of the cement hydration and bureaucracy extra C-S-H gel giving strength, impermeability and durability to concrete. Present paper investigates the effects of addition of nano silica in normal strength of concrete. The present research deals with Partial alternative cement through nano silica powder as partial replacements in concrete at associate with various materials like OPC53 grade cement, fine aggregate, coarse aggregate to check their suitability for making concrete. The mix proportions of concrete were modified as micro silica (5%, 7.5%, 10%, 15%) and nano silica (1%, 1.5%, 2%, 2.5%) as partial replacement of cement. The cubes were cast by replacing Specimens were cast as per mix design and the tests are conducted after proper curing, the tests are compressive strength of cubes (150mm x 150mm x 150mm) and split tensile strength of cylinders (150mm x 300mm). The results had been compared with the outcomes of concrete specimens with 0% of nano silica. Keywords: M30 grade, nano silica, Nano technology,pozzolanic-reaction

Ohmic heating as an effective path to rapidly cure and strengthen alkali activated material

Alkali activated material has been considered as a high potential construction material for replacing or reducing cement usage. However, proper curing at specific temperatures is necessary for optimizing the alkali activated material’s strength and durability performance. In this work, a novel technique for curing alkali activated material is proposed based on the ohmic heating principle by passing electrical current through the just casted alkali activated paste. With this method, the alkali activated paste was rapidly cured right from the start. As a result, it set very quickly (∼15 min) compared to hours for setting for the controlled sample without ohmic heating. Moreover, the compressive strength (22.9 MPa) and flexural strength (0.42 MPa) of the 80 °C ohmic cured samples for 90 min were significantly improved compared to the non-heated sample (compressive strength of 0.68 MPa and unmeasurable for flexural strength). The prolonged mechanical properties (7-day age) were also increased, with the compressive strength (47.0 MPa) nearly double and the flexural strength (1.32 MPa) almost quadruple, compared to the controlled sample. The reasons for the quick setting and enhanced mechanical strengths cannot be related to microstructures from the SEM image analysis. However, the FTIR analysis showed that ohmic heating accelerated early geopolymerization. The Al-O-Si bonding (the absorption band at ∼ 948 cm−1), the backbone of the geopolymeric structure, was found to increase almost linearly with the ohmic heating time (R2 of 0.93). Rapid formation of the geopolymeric structure was thus responsible for the quick setting and the early and prolonged strength enhancement. Furthermore, this ohmic curing technique does not require the addition of conductive fillers, such as carbon fiber, since ionic conduction from the presence of alkali and hydroxide ions is sufficient to induce ohmic heating. Nevertheless, the carbon fiber addition to alkali activated pastes led to strength enhancement. In addition, this technique is not limited to a lab-scale sample but can be extended to cure alkali activated material in large-scale construction.

Manufacturing and characterization of graphene oxide reinforced composites

The present work focuses on the mechanical characterization of polymer matrix composites reinforced with graphene oxide (GO) nanostructures. Firstly, the selection of the polymer matrix, the parameters for performing a proper curing and the fabrication of the composite material are carried out. The proposed procedure results in an adequate dispersion of the GO, without the need for solvents, which positively influences the mechanical properties of the resulting material. The epoxy resin selected as matrix is ​​reinforced with different percentages of GO in order to study the influence of the reinforcement on the apparent mechanical properties. The composites obtained using such nanostructures are characterized by compression and three-point bending testing. Through the use of the Digital Image Correlation (DIC) technique is possible to evaluate the strain state of the material during the tests. This behaviour is combined with the analytical estimations developed to take into account in the results of the bending testing the difference of the tensile and compressive elastic properties of the material. In addition, numerical simulations are developed by applying both the Finite Element Method (FEM) and the eXtended Finite Element Method (XFEM) whose results are used to validate the experimental data and the analytical model.

Alkali Activated Fly Ash-Based Concrete: Evaluation of Curing Process Using Non-Linear Ultrasonic Approach

Abstract This paper investigates the applicability of the nondestructive testing and evaluation (NDT&amp;E) method using ultrasonic signals to monitor the curing of alkali-activated fly ash-based concrete (AAFC). The evaluation was carried out on AAFC specimens with two different water/binder (W/B) ratios of 0.3 and 0.5 and after curing at 60 °C for 7, 14, and 28 days, respectively. The signals are recorded and analyzed using linear and non-linear ultrasonic techniques. The results show that the non-linear ultrasonic technique has a clear advantage over the linear ultrasonic technique when monitoring the curing of AAFC specimens with a lower W/B ratio. However, the specimens with the higher W/B ratio do not undergo proper curing and therefore do not show clear distinctions between the curing times measured from the two ultrasonic techniques. The unconfined compressive strength (UCS) of the AAFC specimens at different W/B ratios and curing times is also measured. The UCS results showed a good correlation with the ultrasonic results.

A new intelligence fuzzy-based hybrid metaheuristic algorithm for analyzing the application of tea waste in concrete as natural fiber

Concrete is an ecologically friendly substance in which green concrete is a revolutionary subject in concrete industry records. The emphasis of this study was on the impact of Tea Waste (CA) as natural fiber onhardened concrete characteristics as a substitution for cement. Taking account of CO2 generation in cement manufacture, green concrete decreases emissions of CO2 into environmental production to an environmentally-friendly technique of pollution prevention. C1, C2, C3, C4 were then made of concrete of a class of 1, 2, 3, 4 kg reinforced in 1 m3 mix, then prepared and molded 4 distinct concrete types. After 28 days, the flexural and compressive strength tests have been carried out in a proper curing environment on the concrete. The findings were evaluated using the adaptive inference system neuro-fuzzy (ANFIS) to accurately predictthe concrete flexural and compressive strengthwith low error rates. Finally, the reinforced concrete with tea wastes raised the water requirement, but reduced the compressive and flexural strength compared to control mix, however, it was raised while using up to 5.4 kg waste in 1 m3 concrete. The result showed that up to 5 kg of tea wastes in 1 m3 of concrete could also be utilized as natural fibers. Also, ANFIS could show its outperformance in analyzing test results in predicting the compressive and flexural strength.

Carbonized Biomass as a bonding agent for Non-Load Bearing CHB Production

One‌ ‌of‌ ‌the‌ ‌most‌ ‌prominent‌ ‌construction‌ ‌materials‌ ‌for‌ ‌walls‌ ‌in‌ ‌the‌ ‌Philippines‌ ‌is‌ ‌the‌ ‌concrete‌ ‌hollow‌ ‌blocks‌ ‌or‌ ‌CHB‌ ‌due‌ ‌to‌‌ their lower cost‌ ‌than‌ ‌other‌ ‌available‌ ‌materials‌ ‌and‌ ‌the‌ ‌ease‌ ‌of‌ ‌production‌ ‌and‌ ‌installation.‌ To manage our energy and resources, including waste, carbonized‌ ‌biomass‌ ‌as‌ ‌a‌ ‌bonding‌ ‌agent‌ ‌for‌ ‌CHB‌ ‌production was studied to ‌aid‌ ‌in‌ ‌the‌ ‌country's growing‌ ‌need‌ ‌for‌‌construction materials‌ ‌. On-site fabricated CHB with several percent of carbonized biomass (CB) as substitutes for sand (0%, 20%, and 50% CB), including commercial CHB, are subjected to volume, weight, density determination, and ultimate compressive strength test. The gathered data undergo analysis through one-way ANOVA to determine the difference among the gathered compressive strength of CHB produced with different percentages of carbonized biomass. Cost analysis was also done to determine the costs and profitability of the CHB. As a result, the CHB with carbonized biomass as bonding agent produced CHB with low density, ultimate compressive strength better than commercially available CHB (with proper curing applied), and can be more profitable with increasing the carbonized biomass content.

Development of sustainable concrete incorporating seawater: A critical review on cement hydration, microstructure and mechanical strength

Many countries are experiencing freshwater crises due to the increasing growth of the population together with the infrastructure construction that is aligned with the needs of freshwater for concrete production. There are also deficiencies in freshwater in many coastal areas where seawater is more accessible. To reduce unnecessary resource-wasting and meanwhile drive sustainable development in the construction industry, great efforts have been made to utilize seawater as the alternative mixing water for concrete casting, which presents potential economical and environmental benefits in the coastal and island regions. This paper comprehensively reviews the current studies on the predominant performance differences between seawater-mixed and conventional concretes with freshwater. Particular attention is paid to the chloride-induced hydration mechanism due to the chloride ions in seawater. The main findings of this review reveal that although harmful ingredients in seawater may weaken some of the concrete performances, applying proper curing conditions and adding moderate additives and admixtures could significantly and effectively mitigate these defects in properties. However, the unstable chloride binding ability in cement hydrates cannot eliminate the risk of rebar corrosion caused by chlorides in seawater, resulting in a limited scope of practical application. Finally, some trade-offs are recommended in using seawater in concrete, suggesting prospects of applications in the future construction industry. This study guides for the safer use of seawater in sustainable concrete through reviewing the advanced research progress.

Experimental investigation of the effect of curing compound on self-compacting concrete properties

Lack of proper compaction and curing in cement concrete may lead to the poor strength and durability characteristics. In this paper the effect of curing compound on self-compacting concrete properties has been investigated. The experimental work was performed in two phases. In the 1st phase the optimum superplasticizer (SP) dosage was determined for the maximum compressive strength and in the second phase the effect of curing agent (PEG4000) on the strength at optimum SP dosage was investigated. Additionally workability, split tensile strength and flexural strength were also investigated at different SP and curing agent dosage. The test results showed that the maximum compressive strength of 27.7MPa and 39.48MPa was obtained at 1% SP dosage after one and four weeks of testing. The splitting tensile strength and flexural strength also showed maximum improvement at 1% SP dosage. The maximum mechanical strength of the self-cured concrete in terms of compression, tension and flexure was obtained at 1.6% dosage of PEG4000. The workability got reduced as the dosage of curing compound was increased from 1.2% to 1.8%. Therefore, the self-compacted and self-cured concrete for the maximum strength can be developed at an optimum dosage of 1% PCE based superplasticizer and 1.6% PEG4000 based curing compound.

Study on the effect of sintered flyash aggregate and steel fibre on the properties of high performance concrete

Light weight aggregates are better solutions for making the structure light weight and they are widely used in construction. Other than the light weight behaviour, the porous nature of these aggregates helps in retaining water content and aids in curing the concrete. Sintered flyash aggregate (SINTAG) is a type of light weight aggregate that can be used as coarse aggregate in concrete. Water content retained through presoaking these aggregates helps in extended hydration of cementitious materials and can increase the strength of concrete even in the absence of proper external curing practice. Steel fibre reinforcement can increase the tensile and flexural strength of concrete. Presoaked SINTAG was added by replacing various percentages of coarse aggregate volume in concrete and steel fibre was added at different percentages by volume of concrete. It was obtained that 20% replacement of coarse aggregate by volume with SINTAG increased the strength of normal concrete by 26.7 % and split tensile strength increased by 2.8%. Addition of steel fibres to SINTAG concrete at 1% increased its compressive strength additionally by 6.2% and tensile strength additionally by 35.1%. Durability studies showed that chloride ion penetration of normal and SINTAG incorporated concrete were low. Water permeability tests revealed that normal, SINTAG and fibre reinforced SINTAG concretes can be used for water retaining structures as well as aggressive environments. Flexural strength of normal RCC beam increased 7.7% when SINTAG was incorporated while it again increased 9.6% when steel fibre was added. Fibre reinforced SINTAG concrete beam showed much less deflection compared to normal and SINTAG beams.

Influence of internal curing on the properties of non-fibrous high strength concrete—A critical review

The demand for the construction of high-strength concrete in the civil engineering zone is growing, particularly in the last couple of years, due to the construction of sustainable and economic buildings with an extraordinary slim design. Concrete curing in construction is an operative manner and essential to provide that concrete structures meet future performance and durability. High-strength concrete has a low water-to-binder ratio; proper concrete curing is important to ensure its planned performance and durability. Conventionally, exterior curing applied after placing and casting concrete stays warm and moist to provide continued cement hydration. Lately, theoretically and experimentally comprehends that internal curing is an important tool to provide additional moisture in the concrete to enhance cement's hydration. Internal curing of high-strength concrete is an active technique to lessen or even remove autogenous shrinkage and effects on chemical shrinkage, dry shrinkage, etc. Most studies recently have emphasized that a reduction in high strength concrete mixtures' shrinkage is due to internal curing, and the compressive strength can increase higher in mixtures with LWA or SAP than in mixtures without this agent rising degree of hydration by providing extra water in the hydrated cement paste. However, the use of internal curing leads to improving the durability of high-strength concrete.

Investigation of interlayer adhesion of 3D printable cementitious material from the aspect of printing process

The safety of structure printed by extrusion-based 3D concrete printing (3DCP) is significantly influenced by interlayer bonding, which is governed by fresh material properties and processes, including mixing, printing, and post-processing phases. Much literature focused on improving interlayer bond strength via material tailoring/bonding agent addition but gave insufficient attention to other phases' impacts. This study investigates the effects of parameters on interlayer bond strength from different phases in 3DCP, including superplasticizer dosage, printing speed, and curing condition. In the mixing phase, the superplasticizer dosage was increased to reduce Ithix and increase surface moisture content (SMC), consequently improving interface microstructure and interlayer bond strength. In the printing phase, similar results were observed by increasing pumping speed to increase material shear rate. In the post-processing phase, proper curing also improved interlayer bond strength. While SMC has a critical impact on interlayer bond strength, material thixotropic index (Ithix) probably has a stronger influence.

Development and application of a highly efficient CRISPR-Cas9 system for genome engineering in Bacillus megaterium

Bacillus megaterium has become increasingly important for the biotechnological production of valuable compounds of industrial and pharmaceutical importance. Despite recent advances in rational strain design of B. megaterium, these studies have been largely impaired by the lack of molecular tools that are not state-of-the-art for comprehensive genome engineering approaches. In the current work, we describe the adaptation of the CRISPR-Cas9 vector pJOE8999 to enable efficient genome editing in B. megaterium. Crucial modifications comprise the exchange of promoter elements and associated ribosomal binding sites as well as the implementation of a 5-fluorouracil based counterselection system to facilitate proper plasmid curing. In addition, the functionality and performance of the new CRISPR-Cas9 vector pMOE was successfully evaluated by chromosomal disruption studies of the endogenous β-galactosidase gene (BMD_2126) and demonstrated an outstanding efficiency of 100 % based on combinatorial pheno- and genotype analyses. Furthermore, pMOE was applied for the genomic deletion of a steroid esterase gene (BMD_2256) that was identified among several other candidates as the gene encoding the esterase, which prevented accumulation of pharmaceutically important glucocorticoid esters. Recombinant expression of the bacterial chloramphenicol acetyltransferase 1 gene (cat1) in the resulting esterase deficient B. megaterium strain ultimately yielded C21-acetylated as well as novel C21-esterified derivates of cortisone.

Effects of construction time on the performance of cement treated base

Cement treated base (CTB) has been widely used as a stabilized base layer in pavement for highways, roads, airports, parking areas and some storage areas. CTB comprises mainly three components, namely, cement, water and either natural soil or aggregates. The mixture will become strong and durable after proper compaction and curing. CTB can be produced in central plant, haul to the laying area by dump trucks or can be mixed in-placed using proper materials and equipment. One of the key factors which can affect the performance of CTB is the construction time which consists of mixing to transportation, laying and compaction. This paper describes a study that was conducted to analyse the effects of construction time on the performance properties of CTB. Laboratory tests were conducted for various CTB mixtures. The CTB mixtures were compacted at different time frames and then tested for dry density and unconfined compressive strength. The results were then analysed to study the effects of construction time.

Study on early age and ultimate compressive strength of M30 grade self-curing concrete

Curing concrete is one of the important stages in making quality concrete. Research has not given due attention to this area. Due to the scarcity of potable water and subsequent need for conservation of water, the construction industry is facing a challenge in ensuring proper and adequate curing of concrete elements. Concrete is one of thelargest used construction materials across the world, which can easily be accepted as it has changed the face of rural areas. But in the localities where there is a water insufficiency and in locations of higherelevations, water curing is difficult. There is also a need for reduced water usage for curing for the conservation of potable water for environmental sustainability. These problems can be rectified by using Self-Curing or Internal Curing technique. Self-curing admixturesconsiderablyassist in the preservation of water in concrete, by bringing down the evaporationand transpiration during the hydration of concrete. The present paper is focused to study the performance of M30 grade concrete by using different self-curingcompounds like Poly-vinyl alcohol, Liquid paraffin wax, and Poly-ethylene glycol 400 in comparison with conventional immersion curing.