Cement Weight Ratio Research Articles

Study on preparation and activation enhancement effect of cold bonded multi-solid waste wrap-shell lightweight aggregates (SWSLAs) with low cement content

Cement production consumes large amounts of depleted resources and energy, and causes environmental pollution. In order to reduce cement consumption and realize the closed-loop recycling of solid waste, cold bonded solid waste wrap-shell lightweight aggregates (SWSLAs) with a sextuplet blended system composed of dredged sediments, mineral powder, steel slag, phosphogypsum, fly ash, and a minimal amount of cement were prepared. Through the single-factor experiment, the influences of the types and dosages of solid wastes in the nuclear phase of SWSLAs (SWSLAs-NP) and shell phase of SWSLAs (SWSLAs-SP) on the strength and water resistance were explored, and the optimum ratio was obtained. On this basis, the influence of the types and amounts of activators incorporated in SWSLAs on the physical properties of aggregates was studied, and the primary microstructure of the aggregate was characterized. Our results showed that the optimal ratio of solid waste in the SWSLAs-NP was: 40 wt% of dredged sediments, 24 wt% of mineral powder, 18 wt% of steel slag, and 18 wt% of phosphogypsum. The optimal weight ratio of cement and solid waste in the SWSLAs-SP was 5:95. The resulting aggregate had a bearing capacity of single grain of 73.83 N and a water-resistance coefficient of 0.67. After the above aggregates were treated with Na2SO4 (activator) at 2%, the bearing capacity and water-resistance coefficient of the aggregates increased by 47.00% and 11.94%, respectively. The performances were even better than that of the aggregate composed of100w cement in the shell phase. Microstructural observations demonstrated that the structure of the raw material was reconstructed under the action of Na2SO4, and the raw materials reacted with each other, and thus the densification of the aggregate and its core-shell interface structure was enhanced, which improved the comprehensive performance of the aggregate. This study represents a step toward efficient utilization of industrial solid wastes.

Utilization of Sandblasting Waste as an Alternative Material for Paving Blocks

Sandblasting is an activity of cleaning industrial equipment made of metal using quartz sand. Every day the amount of waste produced is getting bigger so it needs to be processed to reduce its surface area. One way that can be used to process sandblasting waste is solidification into building material products. This study uses sandblasting waste as a substitute for fine aggregate in the manufacture of paving blocks. Paving block production was carried out using three research variables, namely the weight ratio of cement and waste, cement water factor (FAS), and maximum grain size. Comparison of the weight of cement and waste using composition of 1:3, 1:4, and 1:5. The cement water factor used was 0.35, 0.425, and 0.5. While the grain sizes that were filtered were 1.2 mm, 2.4 mm, and 4.75 mm. The results showed that of the 27 variations of the mixture produced, the samples with sample code V5 (composition 1:3, FAS 0.425, and grain size 2.4 mm) produced the highest compressive strength, namely 25 MPa with quality B. ANOVA analysis was performed to determine the effect of the three variables on compressive strength and it was found that the weight ratio composition of cement and waste was the most influential. The TCLP test was carried out to determine the potential for leaching of heavy metals Cr6+, Cu, Pb, and Zn, which then resulted in the content of the four substances being below the quality standard of Government Regulation Number 22 of 2021

Sustainable cement and clay support in Ni–Cu/Al2O3 catalysts for enhancing hydrogen production from methanol steam reforming

Sustainable cement-clay composite is used as the support of bimetallic Ni–Cu/Al2O3 catalysts for hydrogen production from methanol steam reforming (MSR) reaction. The results indicate that higher methanol conversion and hydrogen yield can be obtained using composite supported catalysts. The cement-clay composite possesses CO2 absorption capability, which can enhance MSR performance. In the cases of a large proportion of cement, the CO2 concentration in the product is decreased by 1–2% where methanol conversion and hydrogen yield are not reduced. By varying the catalyst compositions such as Ni content, Ni–Cu/Al2O3 loading, and the weight ratio of cement and clay, 100% methanol conversion can be achieved as Ni content and Ni–Cu/Al2O3 loading increase. However, the CO concentration also increases due to the enhanced reverse water gas shift reaction. The results of the prepared 12 cement-clay-supported cases show the best performance with methanol conversion of 100%, hydrogen yield of 2.85 mol·(mol CH3OH)−1, and CO concentration of 5.90%. The scanning electron microscope images indicate no sintering of the spent catalyst, and the thermogravimetric analysis shows low coke formation on the catalyst surface. Overall, cement-clay replacing metal components in catalysts can efficiently reduce costs and intensify hydrogen production.

Eco-, economic- and mechanical- efficiencies of using precast rejects as coarse aggregates in self-compacting concrete

This paper investigates the eco-, economic- and mechanical- properties of self-compacting concrete (SCC) containing recycled coarse aggregates generated from prefabricated concrete rejects (PRA) or construction and demolition wastes (CRA). A total of 720 specimens from 36 unique SCC mixes are prepared and tested. The effects of the key parameters including, water-to-binder ratio (w/b), fly ash replacing ordinary Portland cement weight ratio, recycled coarse aggregate replacing natural coarse aggregate volume ratio, heat curing temperature, mixing method or the addition of steel fibers, on the fresh and hardened properties of SCC are experimentally explored. In addition to the experimental study, cradle-to-gate life cycle cost (LCC) analysis and life cycle assessment (LCA) of the SCC are carried out, where these are done through considering different levels of functional units. Based on the results of the experimental work, LCA and LCC, it is found that the PRA based concrete shows ecological-, environmental- and economic- benefits over conventional SCC with slightly compromised rheological and mechanical properties. When considering only the volumetric equivalence, it is observed that a higher w/b, the inclusion of higher amount of recycled coarse aggregate (RCA), or fly ash, or using a lower curing temperature can efficiently reduce the cost and environmental impacts of SCC with PRA. PRA concrete products are more eco-friendly and less cost intensive than those associated with the CRA ones due mainly to the shorter distance to transport PRA compared to CRA. Beyond the volumetric functional unit, the results of LCC and LCA show that, as indicated by carbon dioxide equivalent-, embodied energy- or cost- intensity, a higher w/b, the incorporation of higher content of RCA or fly ash, and using a lower curing temperature no longer benefit the eco-, environmental and mechanical performance of recycled coarse aggregate SCC (RCASCC) and the effect of curing temperature becomes ambiguous.

Sustainability enhancement of calcined clay and limestone powder hybrid ultra-high-performance concrete using belite-rich Portland cement

• BRC is used to produce sustainable LC3-UHPC. • BRC can control the hydration of LC3-UHPC. • BRC concrete has lower shrinkage, hydration heat, and CO 2 emissions. • BRC can improve late age strength. • 33% BRC is the optimal substitution amount for LC3-UHPC. In this study, limestone calcined clay cement (LC3) was used to prepare ultra-high-performance concrete (UHPC), and the effects of different cement types (ordinary Portland cement (OPC) and belite-rich Portland cement (BRC)) on the performance of LC3-UHPC were investigated. The main objective was to develop UHPC with low autogenous shrinkage, low heat of hydration, low CO 2 emissions, and high compressive strength. The water–cement ratio of the specimens was 0.2, the weight ratio of cement: calcined clay: limestone was 7:2:1, and the replacement rates of BRC for OPC were 0, 33, 66, and 100%. A series of macroscopic and microscopic tests were conducted for all specimens to assess their properties and performance. The experimental results show that BRC can effectively control cement hydration, reduce the internal temperature increase, slow the decrease in internal relative humidity, and effectively reduce autogenous shrinkage. After 28 d of curing, the compressive strength and ultrasonic pulse velocity of the BRC-doped specimens significantly increased, and the Ca(OH) 2 content and resistivity decreased compared to those of the OPC specimens. In addition, the CO 2 emission calculations revealed that the incorporation of BRC reduced the total and normalized CO 2 emissions. The specimens doped with 33% BRC exhibited the lowest normalized CO 2 emissions. In general, LC3-UHPC showed a good comprehensive performance, particularly after replacing OPC with BRC. It exhibited low autogenous shrinkage, low heat of hydration, low CO 2 emissions, and high compressive strength, which promote sustainability and engineering applications of UHPC.

Abrasion and Strength of high percentage Graphene Oxide (GO) Incorporated Concrete

Incorporating Graphene Oxide (GO) in concrete composite has been a good alternative to Pristine Graphene due to its hydrophilic nature and its ability to readily disperse in water the consequent cementitious mix. The addition of GO to the cementitious mix has been found to enhance mechanical properties. This paper aims to assess the abrasion resistance of GO incorporated concrete for its application in road pavement design. Experiments for strength in terms of compression, workability in terms of slump and abrasion resistance in accordance with ASTM-C418-20 using a sand-blasting rig are presented in the paper. It is shown that the addition of GO at percentages between 0% to 0.08% (to cement weight ratio), the compressive strength improves by 39% and 26% at 7 days and 28 days, respectively. The addition of GO consequently affected the workability where it was found that the addition of polycarboxylate ether (PCE) (superplasticisers) can drastically improve the workability, which is essential in practical applications. The abrasion was measured for specimens prepared with a high GO percentage between 0.1% to 0.3% and measured at 7 days and displayed a reduction of 70% of abraded volume at 0.3% GO. Finally, the study presents the benefits of using GO where the reduced amount of cement usage will consequently lead to sustainable concrete construction.

Study on the Contact Angle, Adhesion Strength, and Antibacterial Activity of Polymer/Cement Composites for Waterproof Coating

In the present work, polymeric composites were prepared for coating floors and swimming pools in dark colors. This was achieved through the use of a polymer coating solution added to fine cement with weight percentage (wt%) values of 5, 10, 15, 20, and 25 to obtain dark-colored (gray) composites. Mortar samples were prepared using the adhesion test. The contact angle and adhesion strength were studied for the prepared samples concerning the effect of changing the weight ratio of additive cement on water absorption. Also, the antibacterial activity was tested for the prepared coatings. The results showed that the contact angle increases with increasing the weight ratios of additive cement, which indicates that the prepared coating is not hydrophilic and water-impermeable. Besides, the adhesion was shown to increase with increasing the weight ratio of cement. According to the antibacterial activity analysis, it was found that the highest efficacy for killing Staphylococcus areus was observed at cement ratios of 5 and 15 wt%, whereas no activity was observed against Escherichia coli.

Retraction Note to: Prediction compressive strength of Portland cement-based geopolymers by artificial neural networks

In the present study, compressive strength results of geopolymers produced by ordinary Portland cement (OPC) as aluminosilicate source have been modeled by artificial neural networks. Six main factors including NaOH concentration, water glass to NaOH weight ratio, alkali activator to cement weight ratio, oven curing temperature, oven curing time and water curing regime each at 4 levels were considered for designing. A total of 32 experiments were conducted according to the L32 array proposed by the method. The neural network models were constructed by 10 input parameters including NaOH concentration, water glass to NaOH weight ratio, alkali activator to cement weight ratio, oven curing temperature, oven curing time, water curing regime, water glass content, NaOH content, Portland cement content and test trial number. The value for the output layer was the compressive strength. According to the input parameters in feed-forward back-propagation algorithm, the constructed networks were trained, validated and tested. The results indicate that artificial neural networks model is a powerful tool for predicting the compressive strength of the geopolymers in the considered range.

Laboratory investigation on the behavior of ballast stabilized with bitumen-cement mortar

In order to obviate the ballast degradation during railway operation and maintenance, many polymeric and bituminous additives have been proposed for bonding the ballast particles. Amongst the proposed methods, utilizing the bitumen-cement mixtures have been less payed attention by researchers. So, in the present study, the bitumen-cement mortar is considered as a possible solution to control the ballast degradation. In this matter, an extensive laboratory test has been carried out on ballast stabilized with bitumen-cement mortar. In the first step to achieve the most suitable mortar mixture design the water to cement weight ratio (w/c) and bitumen to cement weight ratio (b/c) have been varied in the range of 0.55–0.75 and 0.2–0.6 respectively and the mortar performance has been evaluated in two ages of 7 and 28 days on the basis of uniaxial compression tests and flexural strength tests results. Secondly, after exploring the most desirable mortar mixture design, it has been added to the ballast in three different forms: fully saturated ballast with bitumen-cement mortar (MSB-F), ballast stabilized with 15% bitumen-cement mortar (MSB-H), and 10 cm bottom ballast stabilization with bitumen-cement mortar (MSB-U). All three mentioned forms with three different bitumen-cement percentages of 0.2,0.4 and 0,6 have been examined by ballast box test apparatus and their load-settlement behavior have been evaluated under 200,000 cycles of vertical loading. Comparison of the settlement, stiffness, and damping of the samples have shown the best performance of MSP-U in comparison to the others and the bitumen-cement ratio of 0.42 has been introduced as an optimum percentage which can minimize the ballast settlement by 334% and in parallel increase the ballast layer stiffness and damping ratio by 217% and 187%, respectively.

Prediction of Concrete Strength Based on Design Parameters, Hammer Test and Test UPV by Using Artificial Neural Network (ANN).

This study aims to predict the compressive strength of existing concrete without using destructive tests which can damage the surface of the concrete. Destructive testing has the disadvantage of damaging the surface of the concrete, requires a long time and need expensive cost, while the Non Destructive Test (NDT) has the advantage of not damaging the surface of the concrete and faster when combined with the Artificial Neural Network (ANN) method . In this research, the Non Destructive Test (NDT) result such as hammer test and UPV were combined with concrete mix design properties and used to predict the compressive strength of concrete at three and 28 days. The Artificial Neural Network (ANN) method is used to make correlation of mix design properties data and NDT. In this study experimental tests were performed using variation of design parameters such as water per cement ratio and weight ratio of fly ash. The water per cement ratio used in this research was in range 0.45 until 0.55. Furthermore, the weight ratio of fly ash was in range 0% until 25%. Based on the modeling result using ANN method, it found that that the neural network method successfully predicts the compressive strength of concrete at three and 28 days with the mean square error (MSE) value and regression of concrete at three days are5.83 and 0.89 respectively. While at 28 days the MSE and regression value are 4.7 and 0.87 respectively.

Alkaline Sustained-Release Material Based on In Situ Manganese Removal Technique of Groundwater

To improve the pH of groundwater for in situ manganese removal, we prepared high-performance and long-life alkali sustained-release materials (ASRMs) from calcium oxide (CaO) and cement (CEM) by a physical mixing method. The ASRMs were tested by alkali-releasing experiments under dynamic conditions and filtration experiments. Surface microstructures were characterized using scanning electron microscopy and energy-dispersive spectrometry. ASRMs exhibited high alkali-releasing performance and effective pH controllability. The optimal matching conditions were flow rate of 5.0 ml/min, solid–liquid ratio of 13.5 g/l, and CaO:CEM weight ratio of 1:20. Under the influence of flow velocity, initial dosage and raw material ratio, the Elovich equation well fitted alkali release with correlation coefficients above 0.982476. The release kinetic equation of ASRMs was determined on MATLAB. In these conditions, the ASRMs could release well and maintain the aqueous pH over 9.5, with a long releasing life of 10 days. This study can be referred to for practical application of this technology into groundwater restoration.

Investigation of the deformability properties of fiber reinforced cemented sand

In this study, 72 consolidated drained triaxial tests have been carried out to evaluate the effect of relative density, weight ratio of fibers, weight ratio of cement and confining pressure on the deformability properties of specimens made from Babolsar sand, Portland cement type II and polyvinyl alcohol (PVA) fibers. The results of this study show that the stiffness corresponding to 50% of the shear strength increases with the addition of cement. The presence of fibers within the cement specimen reduces stiffness. On the other hand, for uncemented specimen, adding fibers can reduce the stiffness of the specimens by 80% density, while adding fibers increases stiffness for specimens with 50% density. Adding cement to sand increases the secant stiffness at lower strains, but at high strains, cement content does not affect the secant stiffness. For specimens with relative density of 80%, in low strains, adding fibers reduces the secant stiffness. In high strains, the presence of fibers increases the secant stiffness. The distance between the yielding point and failure point increases with increasing confining pressure and fiber content, but adding cement reduces this distance. The yielding point of cemented sample depends on cement content and confining pressure. The inclusion of PVA fibers to the cemented soil increases the energy absorption. The addition of cement increases the energy absorption, but the amount of energy absorption increase is not significant. Moreover, the increase of confining pressure increases the difference in the absorbed energy of the specimens with different relative densities.

Synergistic Benefits of Using Expansive and Shrinkage Reducing Admixture on High-Performance Concrete.

High-performance concrete (HPC) is widely used in construction according to great mechanical properties, but it has a high risk of shrinkage cracking due to autogenous shrinkage stress. Therefore, the aim of this research was to investigate the effect of a combination of expansive admixture (EA) and shrinkage reducing admixture (SA) on the autogenous shrinkage of high-performance concrete without heat treatment. Two different EA to cement weight ratios of 0.0, 5.0%, and two different SA to cement weight ratios of 0.0, and 1.0% were combined and considered. To investigate the differences in the time-zero conditions effect on the autogenous shrinkage behaviors, four different initial points were compared. The test results indicate that the EA and/or SA content was conductive to a little bite increase compressive strength (22.6–37.9%) and tensile strength (<4.8%). According to the synergistic effect of the EA and SA on the HPC, the autogenous shrinkage significantly decreased (<50%), as compared to those specimens with only one type of admixture (EA or SA). Furthermore, all the specimens incurred restrained autogenous shrinkage cracks at an early age, except the specimen using the combined EA and SA. Therefore, it can be concluded that the combination of EA and SA is effective for improving the properties of HPC.

Design of self-compacting high-performance concrete: Study of mortar phase

The design of self-compacting high-performance concrete (SCHPC) materials, to be applied in marine environments, demands for an adequate selection and combination of constituent materials. In the current study, a ternary mixture of white Portland cement + limestone filler + metakaolin was selected to produce a white SCHPC. Design of experiments approach was employed to investigate the effect of design variables, and their coupled effects, on the relevant mortar properties. Statistical models were developed to predict the fresh state properties, maximum temperature rise (under semi-adiabatic conditions), initial and final setting times and shrinkage deformation of mortars. Metakaolin to cement weight ratio was found to exhibit the highest effect (a negative effect) on workability and on initial/final setting time, which is explained by the high reactivity of metakaolin. The fine aggregate content had the highest effect on both the maximum temperature rise and shrinkage of mortars. Finally, the derived statistical models and a numerical optimization technique allowed finding the best combination of constituent materials to reduce the risk of cracking during the first days, which ensures a more impermeable concrete in the final structure.

Mix Design of Self Compacting Concrete Based on Ultra High Compressive Strength Flow Mortar Mix

Mix design of Self Compacting Concrete or SCC is not straight forward because many parameters control its rheological properties. The case becomes more complicated if high compressive strength is also to be achieved. Therefore simpler approach is used, that is by firstly determining the flow mortar mix which is easier to be designed even with the requirement of ultra-high compressive strength. The mix design of SCC is then determined by simply adding the coarse aggregate with a certain amount of that mortar mix. In this research the ultra-high compressive strength flow mortar was made of Type I cement, 15% of cement weight silica fume, weight ratio of cement and curve No IV sand was 1: 0.35. The water-cementious ratio was 0.22 and the amount of plasticizer was 1.3%, 1.4%, 1.5% and 1.6% of the cement weight. For the SCC, the used coefficient was taken to be 1.4, 1.6, and 1.8 of the volume of that aggregate void for mortars, the aggregate value was at the volume of the remaining count of mortar and its size was 4.8 mm - 9.6 mm. Test results show that the mortar flow ability was 170 mm, 180 mm, 220 mm and 250 mm, where the achieved compressive strength was 83.1 MPa, 96.8 MPa, 111.4 MPa, and 135.5 MPa respectively. Mortar mix with 1.6% super plasticizer was then used for making the SCC and the results show that the concrete flow were 460 mm, 580 mm and 660 mm and the compressive strength were 88.2 MPa, 100.0 MPa, and 97.9 MPa. It can be concluded that using this simpler approach the SCC can have 580 mm flow and 100 MPa compressive strength

PHstimuli‐responsive poly(acrylamide‐co‐sodium alginate) hydrogels prepared by γ‐radiation for improved compressive strength of concrete

AbstractCross‐linking of superabsorbent hydrogels based on poly(acrylamide‐co‐sodium alginate) is carried out using60Co γ‐radiation. Hydrogels ofPAM/NaAlg with 1.5:0.5 and 1.0:1.0 w/v concentrations showed good gel contents of 87 and 66 (%) and swelling degrees in water of 3.7 and 5 (g/g) after 40 min, respectively. The chemical structure of the hydrogel is confirmed byFTIR,XRD, andESR. The morphology of the hydrogel is observed using scanning electron microscopy. Intramolecular H‐bonding in the hydrogel network is confirmed byTGAandDSC. ThepH‐responsive swelling behavior of (PAM‐co‐NaAlg) hydrogels is tested in differentpHranges showing higher swelling capacities in basic than in acidic media. This property proposes the use of (PAM‐co‐NaAlg) hydrogel as internal curing agent for concrete. The hydrogel is examined with cement weight ratios of (0.1–0.5) wt%. The study shows that cement with (PAM‐co‐NaAlg) hydrogel improves the compressive strength of cement at 0.1 and 0.2 wt%.

PROPERTI MEKANIK BETON RINGAN DENGAN MENGGUNAKAN AGREGAT BATU APUNG SERTA ABU TERBANG SEBAGAI PENGGANTI SEBAGIAN SEMEN PORTLAND DAN SUPERPLASTICIZER

Abstract Researches about lightweight concrete that be held nowadays, have some weakness particularly in compressive strength. Usually researches about lightweight concrete with pumice that uses Portland giving result about 13,5-16,8 MPa of compressive strength. For reducing the cement using, it is needed to find an alternative of Portland cement exchanged that improve the compressive strength at once. In addition, for compressive strength increasing it is needed to use water low water stirring. But, with a low water stirring, so mixing will be difficult for doing so it is needed superplastizer for mixing easier. Fly ash varieties as an exchanged of a part of Portland cement start from 0%, 10%, 20%, 30%, 40%. The weight ratio of cement : sand : pumice is 1,00 : 3,07 : 1,14 with factor adhesive water 0,32 refers SNI 03-3449-2002 with compressive strength of the plan is 18 MPa. This study uses superplasticizer 0,4% and 0,8% of cement weight is added during the mixing concrete. Distribution of sand and pumice designed by SNI 03-2834-2000, zone 1 for sand and graduation maximum diameter of 12,5 for pumice. Increase compressive strength and modulus of elasticity occurred with age concrete hydration of 28 days to 56 days. Compressive strength increase with fly ash varieties as an exchanged of a part of Portland cement with fly ash until 20% and then decreasing. However, the replacement of Portland cement 40% with fly ash was produced higher compressive strength than without fly ash. A relatively same indicator be shown on modulus of elasticity that be carried out from changing of 20% Portland cement by fly ash and 40% superplasticizer consecutively as 14,34 MPa and 10766,71 MPa in 28 days and 18,12 MPa and 11006,56 MPa in 56 days.

Use of different barium salts to inhibit the thaumasite form of sulfate attack in cement-based materials

We investigated the effects of different barium compounds on the thaumasite form of sulphate attack (TSA) resistance of cement-based materials when they were used as admixtures in mortars. Moreover, we analyzed the inhibition mechanisms within different types of barium salts, namely BaCO3 and Ba(OH)2, on the thaumasite formation. The control cement mortar and mortars with barium salts to cement and limestone weight ratios of 0.5%, 1.0%, and 1.5% were immersed in 5% (by weight) MgSO4 solution at 5 °C to mimic TSA. Appearance, mass, and compressive strength of the mortar samples were monitored and measured to assess the general degradation extent of these samples. The products of sulphate attack were further analyzed by XRD, FTIR, and SEM, respectively. Experimental results show that different degradation extent is evident in all mortars cured in MgSO4 solution. However, barium salts can greatly inhibit such degradation. Barium in hydroxide form has better effectiveness in protection against TSA than carbonate form, which may be due to their solubility difference in alkaline cement pore solution, and the presence of these barium compounds can reduce the degree of TSA by comparison with the almost completely decomposed control samples.

내부식성 콘크리트 개발을 위한 기초연구로서 개질유황 혼합 콘크리트의 물성 평가

Due to the increased construction of offshore concrete structures and the use of de-icing salts for the purpose of snow removal, the needs for the development of anti-corrosive concrete are increasing. To solve these problems, an evaluation of the mechanical and durability properties for concrete were conducted by mixing modified-sulfur as 0 %, 5 %, 10 %, 15 % cement weight ratio. Both strengths and the properties affecting durability such as water absorption coefficient, chloride ion permeability, accelerated carbonation resistance, rapid freezing and thawing, and chemical resistance were evaluated. All evaluations performed were according to the test specifications associated KS. The results indicate that mixing of modified-sulfur lowed chloride ion permeability and improved chemical resistance.

Effectiveness of shrinkage-reducing admixture in reducing autogenous shrinkage stress of ultra-high-performance fiber-reinforced concrete

This study describes the effect of shrinkage-reducing admixture (SRA) on free and restrained autogenous shrinkage behaviors of ultra-high-performance fiber-reinforced concrete (UHPFRC). To investigate the cracking potential, tensile strength development was experimentally obtained and predicted on the basis of the degree of hydration model. Three different SRA to cement weight ratios of 0, 1, and 2% and three different reinforcement ratios of 1.3, 2.9, and 8.0% were considered. A higher SRA content contributed to a slightly higher tensile strength and a lower autogenous shrinkage. In addition, a higher SRA content and a lower reinforcement ratio resulted in better restrained autogenous shrinkage behaviors, such as lower autogenous shrinkage stress and cracking potential. Therefore, it can be concluded that the use of SRA or a lower reinforcement ratio is favorable for improving the restrained shrinkage behaviors of UHPFRC.