Water Curing Research Articles

Assessing the Effect of Using Porcelanite on Compressive Strength of Roller Compacted Concrete

Roller-Compacted Concrete (RCC) is a zero-slump concrete, with no forms, no reinforcing steel, no finishing and is wet enough to support compaction by vibratory rollers. Because the effectiveness of curing on properties and durability, the primary scope of this research is to study the effect of various curing methods (air curing, emulsified asphalt(flan coat) curing, 7 days water curing and permanent water curing) and different porcelanite (local material used as an Internal Curing agent) replacement percentages (volumetric replacement) of fine aggregate on some properties of RCC and to explore the possibility of introducing more practical RCC for road pavement with minimum requirement of curing. Cubes specimens were sawed from the slabs of (38*38*10) cm for determination of compressive strength. The results show that using (5) % porcelanite improved the compressive strength of RCC (with air curing) as compared with reference RCC (with permanent curing) by percentage ranging from(-2.9 to 6)%.

Mechanical properties and microstructural characterization of ferrock as CO2–negative material in self-compacting concrete

The construction industry is one of the major sources of pollution and global warming, with the utilization of cement being a significant contributor. This study aimed to minimize cement usage in construction while maintaining overall strength through the development of sustainable and eco-friendly concrete. A self-compacting concrete (SCC) was created by replacing cement with eco-friendly ferrock, aggregates and superplasticizers at levels of 5%, 10%, 15%, 20% and 25%. The optimal blend was determined based on fresh and mechanical behaviour parameters. Rheological analysis of the fresh concrete was conducted using L-box, Slump cone, V-funnel equipment and visual stability index. The SCC was then cured through water immersion, CO2 exposure and a combination of both. The performance of the ferrock SCC was evaluated under different curing conditions to determine its hardened and microstructural properties. The addition of ferrock altered the properties of the concrete, and changing the curing method also influenced the behaviour of the hardened concrete. CO2 curing achieved about 40% of the concrete strength within four hours, while combined water and CO2 curing produced higher-quality concrete, as shown by UPV, SEM, and XRD results. The incorporation of ferrock almost doubled the strength of the concrete in combined curing. At an optimum replacement level of 10%, the compressive strength values of water, CO2, and combined curing increased by 21.9%, 25.9% and 32.6%, respectively, after 28 days. The bond strength also increased by 20% at this level of ferrock addition for combined curing. Comparison with normal SCC indicated that the ferrock-based SCC was physically stronger at an optimum replacement level of 10%, with a higher degree of compaction and dense matrix. These findings suggest the superiority of ferrock SCC, which offers potential for use in future construction.

Development and investigation of thermal composite insulation from environmentally hazardous waste fly ash

Researchers all over the world are working on developing fly ash (FL-A) utilization technologies and turning the environmentally hazardous waste into a useful product. In the present study, an attempt to develop FL-A thermal insulation was made. Three thermal composite insulation were prepared with combination of FL-A (40, 60 and 70%), Sand (40, 20 and 10%), Cement (10, 5 and 15%) and Perlite (10, 15 and 5%) with water curing. The sequence of preparation of mixture was modified to improve the samples strength, and investigated for thermal conductivity. The samples with 60% FLA showed the lowest thermal conductivity of 0.1388, 0.136, and 0.1601 W/mK for thicknesses of 30 mm, 50 mm, and 70 mm, respectively, compared to other samples. The optimal composition was obtained in the sample with a ratio of FL-A: S: C: P = 60:20:5:15. The minimum density (750 kg/m3) was obtained. An optimized composite specimen shows the best thermal resistance with the thermal conductivity (k = 0.1388 W/mK) measured by the thermal conductivity measurement apparatus. The properties of the composites will help in estimating their suitability and potential for various commercialized applications in thermal insulation, thus also utilizing waste and reducing environmental concerns.

Automated concrete curing and assessment of strength and durability using IoT system

Manual water curing is a widespread practice, yet achieving proper curing to prevent plastic cracking and ensure long-term strength and durability poses a difficulty. Aside from being labor-intensive, manual water curing is also uneconomical and has negative effects on aesthetics. As an alternative, certain researchers suggest an automated curing method that estimates water loss and replenishes it using a theory-based calculation and taking into account the weather conditions. However, their effectiveness is restricted as the estimated water loss may not be completely accurate due to several factors that impact it. To address these challenges, we propose a conceptual automated water curing system that utilizes real-time monitoring with the Internet of Things (IoT) technology. The system involves wireless sensors for temperature and relative humidity, a smart water valve, water sprinklers, and an IoT gateway. As per ASTM F2170, the sensors can be positioned, and data will be collected, examined, and handled in real-time using an IoT gateway. The IoT gateway transmits data to the smart water valve, which then sprays water when the moisture level drops below the preset threshold. This process continues until the concrete reaches a certain strength level estimated using internal concrete temperature data and the Maturity method. Moreover, the data can be transmitted continuously to cloud storage to keep track of the concrete's durability. The proposed automated water curing system offers numerous advantages, such as eliminating the risk of concrete failure caused by inadequate curing, being efficient in terms of time and resources, monitoring real-time strength development, not being impacted by other factors, and having practical benefits for both stakeholders and society.

Fresh and mechanical properties of concrete containing recycled fine aggregate as partial sand replacement

Concrete is one of the world's oldest established construction materials, having been employed in the creation of various structures throughout history. Due to increased demand, the materials used in concrete buildings, particularly granite aggregates and natural sand, are rapidly decreasing. Continuous use of these natural resources has a detrimental effect on the ecosystem. Simultaneously, concrete waste from construction and demolition waste (CDW) created landfills and environmental damage. Therefore, recycled fine aggregate (RFA) was utilized in this research to replace natural sand. This experiment used a total of five mixtures. Mixes with RFA replacement amounts of 0%, 10%, 20%, 30%, and 40% were cast and subjected to water curing. The slump test, compressive test, and water absorption test were done for concrete containing various percentages of RFA. Incorporation of RFA up to 20% enhances the concrete strength. Generally, concrete produced using RFA up to 40% exhibits water absorption not exceeding 10% enabling it to be categorized as good quality concrete. The approach of channeling concrete waste to be utilized as recycled fine aggregate would decrease waste dumping at landfill and mining of sand from local rivers.

Ispitivanje primjene otpadnih mineralnih dodataka u betonu ultravisokih svojstava

This study examined the effects of various waste materials on the properties of ultra-high-performance concrete (UHPC), along with their designs and ideal mix ratios. Several UHPC mixtures have been developed using the Taguchi L16 method, which generally forms part of the experimental programs for evaluating the properties of UHPCs. Furthermore, the proportions of the component materials were chosen based on approximate ranges found in literature. The samples were cured under two different regimes: standard immersion water curing (SC) and hot water immersion curing (HC). The properties of both hardened and fresh concretes were assessed. A flow test was conducted on the fresh concrete to determine the workability, and a standard test was conducted to assess the density. To investigate a hardened concrete sample, the compressive and flexural strengths were examined and density, absorption, and void tests were conducted. The results obtained from the Taguchi approach for the compressive strength at 28 days were found to be 20 % for SF, 0 % for FA, and 0 % for GBFS; the flexural strength was 10 % for SF, 0 % for FA, and 0 % for GBFS. The compressive strength was 147.07 MPa with SC and 150.13 MPa with HC and flexural strength was 26.88 MPa with SC and 27.31 MPa with HC (as conducted at 28 days in a mixture of 10 % SF and 10 % GBFS).

The influence of calcium sulphoaluminate on the properties of low-cost magnesium phosphate cement mortars

Magnesium phosphate cement (MPC) exhibited many excellent performances, however, the high cost of raw materials of MPC limited its application in construction areas. Calcined dolomite powders containing CaO could not be applied in MPC production. The dolomite-bauxite-gypsum powders after calcination were used to replace dead burned MgO and the free-CaO in dolomite was transferred into calcium sulphoaluminate (ye'elemite, C4A3S‾). This study intends to investigate the performance of the low-cost MPC mortars prepared with calcined dolomite-bauxite-gypsum powders containing C4A3S‾. The setting times, fluidities, hydration temperature developments, compressive strength developments and volume changes of MPC mortars with C4A3S‾ were investigated. Furthermore, the differences in compressive strength, flexural strength and bond strength development of MPC mortars with C4A3S‾ in air and water curing were compared. Phase developments, microstructures and pore diameter distribution of MPC mortars with ye'elemite were also investigated. MPC mortars prepared with the calcined dolomite powders containing 51% C4A3S‾ and 26% MgO showed a setting time of 27 min, free-fluidity of 150 mm, 3-h compressive strength of 41 MPa, 7-d compressive strength of 58 MPa and 180-d compressive strength of 74 MPa. C4A3S‾ in MPC mortars could form some amorphous hydration products and its hydration may be promoted in water curing. The new amorphous phases may have filling and cementitious effects, leading to denser structures and higher strengths.

The effects of different production parameters (NaOH concentration, curing regime and replacement ratio of recycled aggregate) on fresh, hardened and elevated temperature performance of geopolymer mortar samples

This paper presents the findings of objective to examine the effects of construction and demolition wastes (CDW) as fine aggregate on the performance of geopolymer mortar (GPM) specimens. In order to examine the effect of NaOH concentration on the performance of GPM samples, NaOH solutions with 3 different concentrations (8, 10 and 12 M) were prepared. GPM samples, in which the fine aggregate part was formed by replace of natural aggregate (NA) and CDW at three different ratios (0%, 50% and 100%), were cured in water and ambient conditions for 7 and 28 days. The alkali liquid/binder ratio was not determined as a variable and was kept constant at 0.6 for all GPM samples. Subsequently, compressive strength, workability, water absorption, unit weight and high temperature performance on GPM specimens were investigated in detail. All of these experimental parameters were also supported by microstructural analysis (scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR)). The results showed that the compressive strength values of granulated blast furnace slag (GBFS) based GPM samples can be increased up to 105% in case of choosing of water curing instead of curing in ambient conditions. It was determined that the increase in NaOH concentration decreased the compressive strength values of GPM samples. Furthermore, experimental findings revealed that although CDW had a negative impact on the performance of GPM samples, it could still find potential usage area in the geopolymer production. On the other hand, the increases in NaOH concentration and CDW usage ratio led to decreased workability of GPM samples. Finally, it was underlined that the mechanical and physical characteristics of GPM samples decreased sharply with the increasing elevated temperature values (especially at 750 °C).

Experimental and Numerical Study of the Influence of Solar Radiation on the Surface Temperature Field of Low-Heat Concrete in a Pouring Block

With the influence of intense solar radiation heat and the greater temperature difference between day and night, surface concrete with a drastic temperature change can easily experience a great nonlinear temperature difference, which increases the risk of early-age concrete cracking. In this study, a distributed optical fiber temperature sensing (DTS) system is used to monitor the surface temperature gradient of concrete in real time, and a solar radiation heat monitoring test is also carried out based on the Baihetan project. Based on this, a solar radiation loading model and a finite element model of a typical pouring block considering solar radiation are established. Combined with the measured temperature data and different calculation conditions, the surface temperature changes of medium-heat and low-heat concrete experiencing solar radiation are analyzed, and the temperature control effect of surface concrete with different surface insulation measures is further analyzed. The results show that the temperature variation of medium-heat concrete at the same depth is more obvious than that of low-heat concrete. Additionally, the temperature variation of low-heat concrete is noticeable within 20 cm of the top surface. In addition, in an intense solar radiation environment, covering the concrete with a 4- or 5-centimeter-thick polyethylene coil can effectively control the surface temperature gradient and maximum daily amplitude of low-heat concrete, and surface concrete cured by running water has a significant temperature control effect. Therefore, it is suggested that 22–24 °C water temperatures be used for water curing during periods of intense solar radiation during the day and a 4-centimeter-thick polyethylene coil be used for coverage at night. These study results have been employed in the Baihetan project to optimize the temperature control scheme of the pouring blocks.

Curing–dependent structural behavior of ultra-high-performance hybrid fiber-reinforced concrete beams

The application of ultra-high-performance fiber-reinforced concrete (UHP-FRC) is exceptionally versatile. However, a comprehensive understanding of UHP-FRC beam structural performance characteristics is lacking. The majority of research has concentrated on the behavior of structural members following standard water curing. This study investigated the impact of the curing regime on the structural performance of UHPC beams. The four different curing regimes used were standard, simulated hot arid weather, steam curing at various ages, and 5% sodium sulfate curing. Experimentally measured mechanical properties of UHP-FRC have been determined following ASTM guidelines, and the investigated beams have been tested under displacement-controlled four-point loading. Additionally, ACI 318 and FHWA-HIF codified formulas were employed in this study to predict the moment capacity of the tested beams. As a result of the various steam systems of varying ages, the load-carrying capacities of the beams were improved. By accelerating cement hydration, steam curing produces a stronger bond between fibers and the cementitious matrix, improving flexural strength. The control beam (under standard curing) showed a smaller maximum deflection, while all other beams showed similar deflection capacity. By accelerating the drying shrinkage, the beams under the 28-day standard with hot air curing were negatively impacted, with an average deflection value around 5% lower than control beams. The cured beams under simulated hot, arid conditions had the lowest flexural rigidity. A steam-cured beam had the highest moment-curvature performance, while a beam cured under simulated arid conditions had the lowest. Additionally, the ACI 318 design equation significantly underestimated beam maximum moments, while the FHWA approach marginally overestimated beam maximum moments with a predicted-to-tested average of 0.82.

Assessment of Fly Ash-Rice Straw Ash-Laterite Soil Based Geopolymer Mortar Durability

Geopolymer is an inorganic form of alumina-silica that is synthesized through materials containing lots of silica (Si) and alumina (Al) originating from nature or from industrial by-products. The geopolymer binder is a two-component inorganic system consisting of solid components that have sufficient amounts of SiO2 and Al2O3 to form compounds such as fly ash, rice straw ash, pozzolan, laterite soil, slag, etc. This study aims to analyze the compressive strength, chemical compositions, and geopolymerization process of geopolymers produced from fly ash, rice straw ash, and lateritic soil bound with an alkaline activator, sodium hydroxide (NaOH), with a concentration of 12 M. The durability of the geopolymer mortar was determined by soaking for 3, 7, and 28 days using water curing and sulphate curing (Sodium Sulphate, Na2SO4, and Sulfuric Acid, H2SO4). The results showed that sodium hydroxide (NaOH) can release silica and alumina in the amorphous phase and can be used as a binder for geopolymer mortar made from straw ash, fly ash, and laterite soil without using oven heat, according to compressive strength, chemical compositions, and the geopolymerization process. The results of this study can be used to support the use of waste materials (fly ash and laterite soil) and local materials (straw ash) as geopolymer mortar-forming materials. Furthermore, it can aid in the development of eco-friendly (environmentally friendly) national infrastructure by eliminating the need for oven heat to initiate the polymerization reaction. However, this research can also be developed to increase the compressive strength of geopolymer mortar, which resembles that of conventional concrete in general. Doi: 10.28991/CEJ-2023-09-06-012 Full Text: PDF

Early CO2 capturing mortar by incorporating a new potential carbide lime waste under controlled CO2 curing

Early-age cement paste or mortar can be enhanced by curing it in a CO2 chamber. The study was initiated with investigation on the optimum compressive strength by replacing cement to carbide lime with 0, 5, 10, 15 and 20% of Carbide Lime Waste (CLW) content. The desired CLW mortar at 28 normal curing age was selected and the similar mix proportion was again casted and the fresh CLW mortar was cured for 1,3 and 7 days under controlled CO2 curing. The CO2 concentration and temperature were fixed at 20% and 60% respectively. The compressive strength and depth of carbonation of CLW mortar was investigated. In addition, their microstructural properties under TGA test was analysed at the early curing ages by using cement pastes. It was found that the mortar containing 5% of CLW had the desired optimum compressive strength and UPV under water curing condition. Overall, the strength properties of control mortar and CLW mortar significantly enhanced at early strength gained by controlled CO2 curing as compared to the water curing technique. The used of 5% of CLW as the potential to substitute the cement portion has provide better understanding on CO2 sequestration in cement mortar. The microstructural result shows the CaCO3 precipitation in the CLW mortar was higher than the control mortar as CLW has Ca(OH)2 behaviour which effectively react with CO2 and formed stable CaCO3 precipitation in the mortar.

Effect of magnesium sulfate on properties of low calcium fly ash based-geopolymer- treated hemp shiv bio-concrete

Sulfate attack is one of the major threats to concrete structures. In this study, strength degradation, by magnesium sulfate (MgSO4) reaction, of low-calcium fly ash geopolymer-hemp shiv concrete was carefully investigated. The hemp shiv was pretreated with AlCl3-KOH to prevent water absorption. Air and water curing were also performed to elucidate the effects of air and water degradation that might have co-contributed to the degradation of the geopolymer concretes. After the MgSO4 treatment, the strength reductions of the geopolymer-hemp shiv concretes were 1.5–2.5 MPa in flexural mode and 0.2–0.6 MPa in compressive mode while the strength reduction of the geopolymer matrix was around 2 MPa in both strength modes. The results suggested the ability to prevent sulfate attack of the AlCl3-KOH pre-treatment and thus degradation was primarily from the geopolymer matrix. However, the TGA and XRD analyses did not observe relevant phase changes or significant occurrences of the strength detrimental phase such as brucite (Mg(OH)2) in the matrix bulk after the MgSO4 treatment, suggesting that the degradation was not according to these factors. Besides, similar degradation was observed in the water-cured samples. Strength degradation was suggested to be due to the migration of sodium ions from the geopolymer gel structure in the aqueous-curing system causing structural disintegration.

Combined effect of fineness modulus and grading zones of fine aggregate on fresh properties and compressive strength of self compacted concrete

Self-compacted concrete (SCC) considered as a revolution progress in concrete technology due to its ability for flowing through forms, fusion with reinforcement, compact itself by its weight without using vibrators and economic advantages. This research aims to assess the fresh properties of SCC and study their effect on its compressive strength using different grading zones and different fineness modulus (F.M) of fine aggregate. The fineness modulus used in this study was (2.73, 2.82,2.9& 3.12) for different zones of grading (zone I, zone II& marginal zone(between zone I&II)) according to Iraqi standards (I.Q.S No.45/1984).Twelve mixes were prepared, each mix were tested in fresh state with slump, V-Funnel and L-Box tests, then 72 concrete cubes of (100*100*100) mm for different mixes were tested for compressive strength after 7 and 28 days of water curing. Results indicated that the combined effect of finenessmodulus and grading zone were clear on the passing ability and little effect of grading zone on flow ability and viscosity of fresh SCC properties. Compressive strength decreases with increasing F.M and no effect of grading zone for F.M higher than 2.90

Multi-Response Optimization of High-Performance Low-pH Grouting Materials by Using Taguchi-Based Grey Relational Analysis.

The most accepted approach to sealing in high-level radioactive waste repositories (HLRWs) is to develop a low-pH grouting material with a pH of the pore solution of less than 11. Currently, the most widely used binary low-pH grouting material is MCSF64, which comprises 60% microfine cement (MC) and 40% silica fume (SF). In this study, a high-performance MCSF64-based grouting material was developed by incorporating naphthalene superplasticizer (NSP), aluminum sulfate (AS), and united expansion agent (UEA) to enhance the slurry's shear strength, compressive strength, and hydration process. Orthogonal experiments were conducted to measure the flow time, yield stress, plastic viscosity, initial setting time, shear strength, and compressive strength of the MCSF64-based slurry, and the optimal mix proportion was determined using the Taguchi-Grey relational analysis method. The pH variation of the pore solution, shrinkage/expansion, and hydration products of the optimal hardened slurry were evaluated using simplified ex-situ leaching (S-ESL), a length comparometer, and scanning electron microscopy (SEM), respectively. The results demonstrate that the Bingham model effectively predicted the rheological properties of the MCSF64-based slurry. The optimum ratio for the MCSF64-based slurry was water/binder (W/B) ratio of 1.4, and the contents of NSP, AS and UEA by mass of binder were 1.9%, 3.6% and 4.8%, respectively. The optimal mix exhibited a pH value below 11 after curing for 120 days. The addition of AS and UEA facilitated hydration, shortened the initial setting time, improved early shear strength, and enhanced the expansion ability of the optimal mix under water curing conditions.

Cementitious and hardening properties of magnesia (MgO) under ambient curing conditions

This study investigated the cementitious and hardening properties of MgO under different ambient curing conditions. The strength development of MgO paste and mortar specimens cured in air, water, wet-dry cycles and sealed conditions were measured. The phase assemblage of MgO-(CO2)-H2O system was predicted by thermodynamic calculations and then hydrating and hardening mechanism were identified by multiple microstructural analytical techniques. The results showed that hydration of MgO under air condition yielded low strength pastes due to limited formation of hydrate and carbonate phases, while sealed samples hydrated to form noncementitious crystalline Mg(OH)2 alone. Water curing or wet-dry cycles enhanced hydration of MgO and subsequent carbonation at atmospheric CO2 concentration. The amorphous carbonate phase was confirmed by combining phenolphthalein spray test, TGA and FTIR results, which was speculated as the cause of significant strength gain. Moreover, reduction in water-to-cement ratio enabled MgO mortar to set more quickly and show higher strength up to 40 MPa.

Coupling activation and curing to tune the permselectivity of poly(piperazine amide) nanofiltration membranes

To tune both water transport and solute rejection (i.e., permselectivity) of nanofiltration (NF) membranes, polyamide (PA) films were synthesized under the same interfacial polymerization (IP) conditions following distinct posttreatments, and the underlying relationship between the PA structure and membrane performance was systematically investigated. The combination of hexane activation and water curing was the optimal posttreatment process, which significantly increased membrane permeability from 6.7 ± 0.4 to 19.8 ± 0.8 L·m−2·h−1·bar−1 and enhanced the selectivity of NaCl/Na2SO4 from 9.6 ± 1.2 to 45.8 ± 0.8. For this combined posttreatment process, the outstanding permeability was due to the enlarged PA film pore size, the enhanced hydrophilicity and the reduced PA thickness and crosslinking degree, and the high NaCl/Na2SO4 selectivity was attributed to the increased electrostatic repulsion between the hydrolyzed acyl chloride groups (i.e., carboxyl groups) and divalent anions. Furthermore, a continuous filtration of 10 days was implemented, and the permeation flux and salt rejection trends for the fabricated PA membranes were maintained at high levels, which indicated excellent long-term stability for the combined posttreatment process. The results of the current study are of paramount practical significance for the reconciliation of permeability and selectivity in water treatment and resource recovery from wastewater.

Flexural behavior, porosity, and water absorption of CO2-cured amorphous metallic-fiber-reinforced belite-rich cement composites

The present study aims to scrutinize the flexural behavior and engineering properties of beams reinforced with amorphous metallic fiber (AMF) at varying dosages (0%, 0.25%, 0.50%, and 0.75% AMF according to the volume of mortar) and lengths (5 mm, 10 mm, 15 mm, and 20 mm). A total of fourteen mortar mixes, i.e., seven mixes for water curing (immersed in fresh tap water) and seven mixes for carbonation curing (60% relative humidity, 20 °C, and 10% CO2 concentration) were considered. The load–deflection behavior, flexural strength, pore structures, voids, and water absorption of the beams were investigated. The outcomes were justified with the mix containing 0.5% steel fiber (SF) and a length of approximately 20 mm. The results reveal that the load–deflection behavior and flexural strength were dramatically augmented for the beams with AMF as compared to the control beam (fiber-free beam), and the difference was more pronounced with an increase in both the dosage and the length of the AMF. Greater flexural strength with a lower deflection at failure was registered for the beam with AMF compared to that with SF. The voids and water absorption increased with an increase in the dosage and length of the AMF compared to the control specimen. It was also revealed that the carbonation-cured beams exhibited lower load–deflection behavior and lower flexural strength than those cured in water due to the substantially increased number of voids and greater water absorption driven by the better-connected pores. This study demonstrates that 0.50% AMF with a length of 20 mm can be used in cement-based materials due to the outstanding performance among all mixes.

Study Of Concrete Mixture Using Sea Sand With Fresh Water and Sea Water Cure

The purpose of this study was to (1) analyze the characteristics of fresh concrete mixed with sea sand (2) to analyze the compressive strength of sea sand concrete with fresh water and sea water curing. In this study, the specimens used were 21 cylinders with a job mix design plan of f'c 25 MPa with a curing duration of 7 days, 14 days, and 28 days. At the age of 7 and 14 days the compressive strength of fresh water curing was 30.29 MPa and 33.12 MPa higher than seawater curing 29.02 MPa and 32.13 MPa, while at 28 days the compressive strength of seawater curing was 37. 08 MPa compared to fresh water curing of 33.97 MPa. Sea sand concrete has a very good quality compared to normal concrete and sea sand can be used in construction projects by taking into account the specifications in accordance with the Indonesian National Standard (SNI).

Effect of Initial Water Sprinkling Curing on Strength Development of Precast Concrete

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.