Absorbent Polymer Research Articles

Comparative review on mechanical properties of concrete with replacing curing water by self-curing compounds

The curing of concrete requires large amount of water. Self-curing concrete is one kind of concrete, which fix itself by holding water (dampness content) in it. A body of literature on the different self-curing compounds is uses for curing purpose without externally curing the concrete is currently available, but a systematic review is lacking. Therefore, this paper reviews the published literature on the use of different self-curing compounds in concrete and past work analysis on self-curing concrete. Various chemicals were uses to attain this curing. It was found out that various chemical admixtures like Poly ethylene glycol, Sodium lignosulphonate, Polyvinyl alcohol, Super absorbent polymer and normally accessible and regularly utilizes materials like Light weight aggregates, Wood powder and Light expanded clay aggregate were uses to fabricate self-curing concrete. This paper summarizes the collected literatures on replacement of curing water with self-curing compounds and how these affects the fresh properties and hardened (solidified) properties of concrete, furthermore, we expected that this work may advise further examination regarding the utilization of curing compounds to upgrade the properties of cement and concrete items.

Multimodal Reduction of Elastic Vibrations in Plate Structure using Super Absorbent Polymer Beads

This paper deals with multimodal reduction of structural elastic vibrations. Super absorbent polymer beads (SAP beads) have been introduced as a simple damping device inspired by the multimodal vibration reduction effect by passengers on railway vehicles. A series of vibration measurement tests using a 1:10 scale model of railway vehicle floor structure (model underframe) was carried out. The SAP beads which are sold commonly as water retention agent were stacked in a container and applied to the model underframe. From the experiments, multimodal vibration reduction effects have been demonstrated. A drastic difference has been observed when water was added together with SAP beads. To investigate the basic mechanism of the damping effect obtained by the experiments, an analytical model, which consists of multiple masses that are supported at an angle to each other, and its simplified model was proposed and numerical studies were conducted. Some specific combinations of the mass, spring, and damping elements in the model could express the experimental results well, and it has been estimated from the numerical results that each SAP layer act as an un-uniform subsystem.

Microwave-Assisted Hydrothermal Decomposition of Super Absorbent Polymers

Absorbent hygiene products contain a super absorbent polymer (SAP) as one of the main constituents that is not easily biodegraded or recycled. Currently, the vast majority of the material is landfi...

Influence of super absorbent polymers on early-age behavior and tensile creep of internal curing high strength concrete

High strength concrete (HSC) possessing high strength and excellent durability has been widely put into use in the reinforced concrete structures. However, a low water-to-cement (w/c) ratio is usually utilized for HSC, which may increase the autogenous shrinkage due to self-desiccation, and then decrease the cracking resistance of HSC. Internal curing (IC) with super absorbent polymers (SAPs) is utilized to mitigate the autogenous shrinkage and improve the cracking resistance of HSC. Although cracking resistance and tensile creep of IC concrete utilizing SAPs under axial or circumferential restrained conditions have been investigated, research on tensile creep of IC HSC (ICHSC) utilizing SAPs under a constant initial stress to strength (s/s) ratio at early age remains insufficient. Accordingly, the early-age behavior and tensile creep of ICHSC utilizing different SAPs contents (0%, 0.57%, 0.86%, and 1.14% of the cement by weight) under a constant initial s/s ratio were experimentally investigated by the Temperature Stress Test Machine in this research. Test results and related analysis showed that: (1) the mechanical properties of ICHSC with the same basic w/c ratio decreased as SAPs content increased; (2) the autogenous shrinkage of ICHSC decreased as SAPs content increased; (3) the basic tensile creep, basic tensile creep coefficient, and specific tensile creep of ICHSC increased nonlinearly as SAPs content increased, which was due to the increase of total w/c ratio.

Modelling and Experimental Characterization of Unsaturated Flow in Absorbent and Swelling Porous Media: Material Characterization

A comprehensive experimental protocol is presented for the characterization of physico-chemical and morphological properties of absorbent hygiene products (AHPs), composite materials, mainly made of super absorbent polymer (SAP) granules blended with cellulose fibres (fluff). The protocol is based on a combination of experimental methods for the characterization of the material properties varying SAP/fluff ratio (SFR): absorption rate, porosity, hydraulic conductivity, retention model and swelling. Major findings were that: (1) liquid absorption rate by the SAP particles was nonlinear; (2) the hydraulic conductivity could be expressed as a function of the porosity of the composite medium for any sample and liquid uptake; and (3) the retention model showed moderate variability with SFR, in the range investigated. Experimental results have been used to determine the constitutive equations for the multiphase flow model developed in the literature (Diersch et al. in Theory Transp Porous Media 83:437–464, 2010. https://doi.org/10.1007/s11242-009-9454-6 ) for the prediction of the performance of AHPs during cycles of imbibition and drainage (Chem Eng Sci 224:115765, 2020. https://doi.org/10.1016/j.ces.2020.115765 ).

A Physical-chemical Synergetic Inhibitor for Coal Spontaneous Combustion and Its Fire Prevention Performance

ABSTRACT A single physical or chemical inhibitor can hardly meet the uttermost requirements for coal spontaneous combustion prevention. Therefore, it has become essential to develop an efficient inhibitor with multiple inhibitory properties. In light of studies on the properties of the super absorbent polymer (SAP), the main antioxidant pentaerythritol tetrakys 3-(3,5-ditert-butyl-4-hydroxyphenyl) propionate and auxiliary antioxidant tris (2,4-di-tert-butyl-pheny) phosphite, a synergistic antioxidant with both physical and chemical inhibitory properties was prepared. According to the determination of volatile matter and calorific value of coal, the optimum molar ratio of the compound antioxidant (main antioxidant: auxiliary antioxidant = 2:1) was selected. Furthermore, the optimum formulation ratio (SAP: antioxidant = 1:3) and the optimum mass ratio (12%) were determined, taking the low-temperature oxygen consumption and cross-point temperature (CPT) of coal as indexes. Three grades of metamorphic coal were selected to obtain the gaseous product, oxygen consumption at 70°C, CPTs and inhibition rate. The addition inhibitor reduced the release of CO and C2H4 gas and oxygen consumption, while it raised CPTs and inhibition rate of coal oxidation. The inhibiting capacity of MgCl2 is mainly at low-temperature stage, while the synergistic inhibitor has excellent congenerous physical and chemical effect in the whole coal oxidation process.

Emerging Photovoltaic (PV) Materials for a Low Carbon Economy

Emerging photovoltaic (PV) technologies have a potential to address the shortcomings of today’s energy market which heavily depends on the use of fossil fuels for electricity generation. We created inventories that offer insights into the environmental impacts and cost of all the materials used in emerging PV technologies, including perovskites, polymers, Cu2ZnSnS4 (CZTS), carbon nanotubes (CNT), and quantum dots. The results show that the CO2 emissions associated with the absorber layers are much less than the CO2 emissions associated with the contact and charge selective layers. The CdS (charge selective layer) and ITO (contact layer) have the highest environmental impacts compared to Al2O3, CuI, CuSCN, MoO3, NiO, poly (3-hexylthiophene-2,5-diyl (P3HT)), phenyl-C61-butyric acid methyl ester (PCBM), poly polystyrene sulfonate (PEDOT:PSS), SnO2, spiro-OMeTAD, and TiO2 (charge selective layers) and Al, Ag, Cu, FTO, Mo, ZnO:In, and ZnO/ZnO:Al (contact layers). The cost assessments show that the organic materials, such as polymer absorbers, CNT, P3HT and spiro-OMeTAD, are the most expensive materials. Inorganic materials would be more preferable to lower the cost of solar cells. All the remaining materials have a potential to be used in the commercial PV market. Finally, we analyzed the cost of PV materials based on their material intensity and CO2 emissions, and concluded that the perovskite absorber will be the most eco-efficient material that has the lowest cost and CO2 emissions.

Effect of A200 super absorbent polymers on corn growth and yield under Partial Root-Zone Drying Irrigation

Water crisis: One of the most important and effective solutions to cope with water crisis is optimum use of consuming water in agriculture section. In other word, increasing “agricultural water productivity” is unavoidable in future planning and decision making as an effective factor. Therefore, deficit irrigation is stated as a proper solution in water limitation aiming to maximally use water volume unit. In addition to applying irrigation management methods, using developed techniques to save soil moisture is of the effective measures to increase irrigation efficiency and achieving sustainable agriculture. One of the strategies for optimal use of water resources and its preservation is using super absorbent polymers. This study was conducted during two growth seasons and within 2014-2015 in the farm and in Sari University of agricultural sciences and natural resources on single cross 704silage maize. The treatments included three irrigation regimes (as the main plot) and three levels of super absorbent (as subplots) with three replications. Irrigation treatments included complete and partial root irrigation in two levels of 55 and 65% (PRD65, PRD55) and three levels of water super absorbent polymer of A200 type, including 20, 40 and 60kg/hectare. Based on the obtained results, the plants, were regularly irrigated during their growth period and cultivated in the conditions of 60kg/hectare of super absorbent, had the most rate of yield components but they weren’t significantly different from those plants, irrigated with 55 and 65% volume. In other word, the function of super absorbent in these treatments increased the efficiency of water use and partial irrigation in 55 and 65% volume has been able to generate an equal yield with the conditions of complete irrigation.

Compressive Strength and Shrinkage Behavior of Concrete Produced from Portland Limestone Cement with Water Absorption Polymer Balls

From the sustainability point of view a combination of using water absorption polymer balls in concrete mix produce from Portland limestone cement (IL) is worth to be perceived. Compressive strength and drying shrinkage behavior for the mixes of concrete prepared by Ordinary Portland Cement (O.P.C) and Portland limestone cement (IL) were investigated in this research. Water absorbent polymer balls (WAPB) are innovative module in producing building materials due to the internal curing which eliminates autogenous shrinkage, enhances the strength at early age, improve the durability, give higher compressive strength at early age, and reduce the effect of insufficient external curing. Polymer balls (WAPB) had been used in the mixes of this research to provide good progress in compressive strength with time. Water absorption polymer balls have the ability to absorb water and after usage in concrete it will spill it out and shrink leaving voids of their own diameter before shrinking that lead to provide internal curing. The required quantity of water for the mixes were reduced due to the addition of water from the absorption polymers. Mixes produced from Portland limestone cement in this research show drying shrinkage results and compressive strength results lower than mixes made from ordinary Portland cement.

Influence of Barchip fiber on early-age autogenous shrinkage of high-strength concrete internally cured with super absorbent polymers

High-strength concrete (HSC) usually suffers the high early-age autogenous shrinkage owing to the low water-binder (w/b) ratio. Barchip fiber and super absorbent polymers (SAPs) have been utilized to reduce the autogenous shrinkage of HSC at early age. The relationship between autogenous shrinkage and ultrasonic velocity of internally cured high-strength concrete (ICC) reinforced with Barchip fiber was studied utilizing the non-contact shrinkage test. Experimental study and corresponding analysis demonstrated that: (1) the autogenous shrinkage and ultrasonic velocity of concrete decreased with the volume percentage of Barchip fiber increasing, and decreased with the addition of SAPs; (2) models for predicting early-age autogenous shrinkage strain and ultrasonic velocity of ICC reinforced with Barchip fiber considering the fiber volume percentage and age were proposed; (3) the model of early-age autogenous shrinkage strain based on the results of ultrasonic velocity at different ages and at 28 d with no addition of Barchip fiber was proposed; (4) the prediction model of early-age autogenous shrinkage strain of ICC reinforced with Barchip fiber based on the age-dependent parameter on ultrasonic velocity was proposed.

Space Environmental Chamber for Planetary Studies.

We describe a versatile simulation chamber that operates under representative space conditions (pressures from < 10−5 mbar to ambient and temperatures from 163 to 423 K), the SpaceQ chamber. This chamber allows to test instrumentation, procedures, and materials and evaluate their performance when exposed to outgassing, thermal vacuum, low temperatures, baking, dry heat microbial reduction (DHMR) sterilization protocols, and water. The SpaceQ is a cubical stainless-steel chamber of 27,000 cm3 with a door of aluminum. The chamber has a table which can be cooled using liquid nitrogen. The chamber walls can be heated (for outgassing, thermal vacuum, or dry heat applications) using an outer jacket. The chamber walls include two viewports and 12 utility ports (KF, CF, and Swagelok connectors). It has sensors for temperature, relative humidity, and pressure, a UV–VIS–NIR spectrometer, a UV irradiation lamp that operates within the chamber as well as a stainless-steel syringe for water vapor injection, and USB, DB-25 ports to read the data from the instruments while being tested inside. This facility has been specifically designed for investigating the effect of water on the Martian surface. The core novelties of this chamber are: (1) its ability to simulate the Martian near-surface water cycle by injecting water multiple times into the chamber through a syringe which allows to control and monitor precisely the initial relative humidity inside with a sensor that can operate from vacuum to Martian pressures and (2) the availability of a high-intensity UV lamp, operating from vacuum to Martian pressures, within the chamber, which can be used to test material curation, the role of the production of atmospheric radicals, and the degradation of certain products like polymers and organics. For illustration, here we present some applications of the SpaceQ chamber at simulated Martian conditions with and without atmospheric water to (i) calibrate the ground temperature sensor of the Engineering Qualification Model of HABIT (HabitAbility: Brines, Irradiation and Temperature) instrument, which is a part of ExoMars 2022 mission. These tests demonstrate that the overall accuracy of the temperature retrieval at a temperature between −50 and 10 °C is within 1.3 °C and (ii) investigate the curation of composite materials of Martian soil simulant and binders, with added water, under Martian surface conditions under dry and humid conditions. Our studies have demonstrated that the regolith, when mixed with super absorbent polymer (SAP), water, and binders exposed to Martian conditions, can form a solid block and retain more than 80% of the added water, which may be of interest to screen radiation while maintaining a low weight.

Beneath the surface: Application of transparent super absorbent polymer substrates to track faunal activity within the sediment layer

Abstract Tracking the movement of organisms is a fundamental goal of many ecological studies. Several techniques exist in the study of terrestrial and aquatic fauna; however, to date, the ability to monitor aquatic fauna within the sediment layer efficiently and in multiple dimensions is lacking. Given the importance of subsurface sediments in supporting ecosystem functioning, this inability to observe organism behaviour represents a fundamental gap in our knowledge and limits our capability to holistically characterise the response of freshwater systems to stressors. Here we present an experimental study that employs novel transparent super absorbent polymer substrates (c. 8–12 mm in diameter) in combination with computer vision technology, which enables, for the first time, real‐time observation and tracking of organisms within the sediment layer under lotic flow conditions. Use of these substrates allowed the successful extraction of organism trajectories, which enabled the velocity and body orientation of a freshwater amphipod (Gammarus fossarum) in the sediment layer to be calculated in response to a number of vertical hydrological exchange treatments (upwelling, downwelling, and no vertical exchange). Results indicate that under vertical hydrological exchange, a higher proportion of fast velocities (both horizontal and vertical) were recorded for G. fossarum in the sediment layer compared to no vertical exchange (control) conditions. This increase was most marked for upwelling flow exchange. We also observed a change in the body orientation of individuals in the sediment layer from a vertical alignment under no vertical exchange to a more horizontal one under downwelling and more notably upwelling flow exchange. This shift in body position was exacerbated under stronger vertical exchange rates. We identified that following the flow transition of downwelling to upwelling conditions, there was an immediate shift (0–2 min) in both the orientation angle and activity level of individuals. This increased rate of activity was maintained for the individuals' velocity but not for their changing orientation angle. These trends were not apparent within the flow transition of no vertical exchange to downwelling flow. Our new methodological approach enables vital insights into the behaviour of organisms within the sediment layer. Use of super absorbent polymer substrates allows real‐time multi‐directional tracking of multiple organisms in parallel. We believe the method represents an innovative tool that can be employed to tackle a wide range of ecological questions and thereby improve our mechanistic understanding of ecological responses to biotic and abiotic processes/stressors.

Study on the optimization of the performance of preformed particle gel (PPG) on the isolation of high permeable zone

Unwanted water production is a critical problem in fractured reservoirs. Corrosion of facilities and reduction of oil relative permeability are some of the consequences of high water production. Preformed particle gel (PPG) injection is one of the conformance control methods, which initiated in 2007, has been used to control water production and increase sweep efficiency. There are several parameters which affect the performance of PPG such as stability at reservoir condition, salinity of makeup solution and PPG particle size and concentration. Although the study of the application of PPG in fracture plugging attracted a lot of attention in recent years, there are limited studies to investigate the effect of PPG physical properties on its application in water production control. In this study, the application of a super absorbent polymer on fracture plugging has been investigated. The results of swelling tests indicated that this type of PPG had significant high resistance even at high temperatures and wide range of salinities. In addition, the results of rheology tests showed that the PPG solution was stable even at high salinity and high shear rate condition. In order to study the mechanism of improvement of sweep efficiency through PPG injection, visual investigation using glass etched micromodel was performed. The results showed that the main mechanism for PPG treatment is water diversion into the low permeability zone as the consequence of fracture plugging. Also, core flooding tests were performed to check the performance of PPG in a heterogeneous carbonate porous media. According to the results, PPG was able to reduce the permeability, and this permeability reduction is related to swelling ratio which is controlled by makeup solution salinity. The results of this study revealed the potential of super absorbent polymers as preformed particle gel in unwanted water production through fracture plugging.

Design and Characterization of Secondary and Tertiary Layers of a Multilayer Wound Dressing System

Abstract A nonwoven secondary layer was produced from silk fibroin by a compression and spunlacing method. Super absorbent polymer (SAP) was added to the nonwoven mat to increase the exudates and absorption capacity and manage the moisture in the wound site. Three types of tertiary layers, viz., cotton gauze cloth, adhesive tape, and polyurethane film, were experimented on for the properties that are essential for those layers. The structural stability was found to be better in the spunlaced nonwoven compared to the compressed nonwoven. The Phosphate Buffer Saline (PBS) absorption of the nonwoven increased with an increase in the concentration of SAP percentage. The PBS absorption was found to be lower for the spunlaced nonwoven because of the higher fiber entanglement and packing compared to that of the compressed nonwoven. The vapor permeation rate (grams per square meter a day) across the nonwoven mat decreased with an increase in grams per square meter, and there was no effect from the SAP percentage added to the nonwoven mats. Horizontal and vertical wicking of the spunlaced nonwoven was better than that of the compressed nonwoven. The results showed that spunlaced nonwoven would be a better material for the secondary layer. The vapor transmission rate was highest for cotton gauze cloth, followed by adhesive tape and film. The multilayer wound-dressing system consisting of primary, secondary, and tertiary layers was tested for PBS vapor transmission rate and bacterial penetration. The results showed that the wound-dressing system made from film and adhesive tape did not allow the Staphylococcus aureus bacterial culture to penetrate through the wound-dressing system.

Experimental and Numerical Studies of Brittle Rock-Like Samples with Internal Open Fractures and Cavities Under Uniaxial Compression

Previous laboratory tests conducted using rock-like samples with 2D through fractures are mostly high-level simplifications of real engineering conditions. Thus, the results from these 2D analyses cannot usually be successfully applied to 3D conditions and real engineering conditions. To study the mechanical properties and failure processes of samples that could highly represent the 3D conditions in the real world, brittle rock-like samples with designed internal open-type fractured structures are prepared for this study using the volume loss method and super absorbent polymer, and following studies included the uniaxial compression tests and discrete element numerical simulations. The results from real tests and simulations proved that the shape, position, and volume of internal open-type fractured structures had an obvious influence on the physical properties and spatial distributions of shear and tensile failures of specimens. Different from the results obtained by former 2D studies, failure surfaces in this work are not parallel with the preset structures, and the main failure faces develop along the diagonal directions of the internal structure. In addition, the tensile failure distribution is controlled by the shape and position of the internal structure, and the shear failure distribution is influenced by the height of the internal structure and the positions of the tensile failure surface. The findings are helpful for explaining the failure characteristics of specimens containing 3D fractured structures.

Effects of Super Absorbent Polymers and Gibberellin on Germination and Growth of alfalfa

For proven effects of eco-friendly super absorbent polymer and gibberellin on germination and growth of alfalfa, taking the germination and growth test in the artificial climate box by adding the different amount of super absorbent polymer and gibberellin. Observed the germination potential, germination rate, shoot length, root length, fresh weight and dry weight, under the different experiment conditions. The test showed that the super absorbent polymer had a promoting effect on alfalfa. The property of slowly release water, water supply on super absorbent polymer could keep plants prolonging the survival rate in the case of insufficient water supply. It could improve the germination rate of the seed of alfalfa. Adding super absorbent polymer and gibberellin not only improved the survival rate, but also promoted the growth of root and shoot on alfalfa.

Use of Super Absorbent Polymers with Euonymus Plants (Euonymus japonicus ‘Aureomarginatus’) in Ornamental Plant Cultivation

In this study, the usability of super absorbent polymers (SAP) and its effects on water consumption, irrigation and labor costs and plant growth in ornamental plant cultivation were investigated by using Euonymus japonicus 'Aureomarginatus,' peat, river sand, and Wesoorb branded SAP. For a period of 152 days, the growth of the control groups without SAP and experimental groups with SAP was monitored, and the obtained results were compared. It was determined that SAP balanced the moisture of the medium with a controlled release and decreased the water stress in the plant and differentiated the root structure. The use of SAP in Euonymus japonicus ‘Aureomarginatus’ cultivation reduced water use by 45% on average and labor costs by 48% on average. It was observed that SAP can be used in ornamental plant cultivation and will decrease production costs.

Heavy metal uptake by wastewater irrigated potato plants grown on contaminated soil treated with hydrogel based amendments

Heavy metal uptake by food crops and the potential for groundwater contamination are of major concern in areas where untreated wastewater is used for irrigation. To minimize heavy metal uptake by wastewater irrigated food crops and to minimize its transport to deeper soil layers, the use of polyacrylamide super absorbent polymer (SAP) and SAP-gasified plantain peel biochar mix (SAP+GBC), as soil amendments, is proposed in this study. A sorption test was conducted to determine the ability of the treatments to adsorb heavy metals (Cd, Cr, Cu, Fe, Pb and Zn). Field experiment was conducted by growing synthetic wastewater irrigated potato plants ( Solanum tuberosum L.) in lysimeters packed with sandy soil, contaminated with heavy metals. Prior to conducting the study, heavy metals Cd, Cr, Cu, Fe, Pb and Zn were present in top 0.10 m of lysimeter soil within ranges of 15.6–23.9, 23.3–27.6, 30.3–62.2, 11538.6–10847.7, 64.9–131.3 and 38.7–46.8 mg kg −1 , respectively. Irrigation occurred eight times, at an interval of 10 days, based on the crop water requirement. After every irrigation, soil samples were collected from different depths (surface, 0.10, 0.30 and 0.60 m) for heavy metal analysis. Upon maturity, potato tubers, plant root, stems, leaf, tuber flesh and tuber peel tissues were sampled separately for heavy metal analysis. Soil samples, collected at the end of the experiment, were also subjected to pH and cation exchange capacity (CEC) analysis. Compared to the control, treatment SAP+GBC was able to retain significantly higher amounts of Cd, Cr and Fe in topsoil (0–0.10 m depth; p<0.05), whereas, the SAP treatment retained significantly higher amounts of Cd, Cu, Fe and Zn in topsoil (p<0.05). Both hydrogel based treatments (SAP and SAP+GBC) were able to significantly (p<0.10) reduce Cd uptake in tuber flesh (1.98 and 1.54 mg kg −1 , respectively) and peel tissue (20.75 and 23.89 mg kg −1 , respectively), as compared to the control (2.63 mg kg −1 in flesh and 43.87 mg kg −1 in peel). Concentrations of Zn in tuber flesh tissue for both, SAP (8.30 mg kg −1 ) and SAP+GBC (8.65 mg kg −1 ) treatments were found to be significantly (p<0.05) lower than that of the control (15.28 mg kg −1 ), indicating the effectiveness of the treatments in reducing Zn uptake by potato tubers. Treatment SAP+GBC was also able to significantly (p<0.05) reduce Pb uptake in tuber flesh (0.05 mg kg −1 ) and peel tissue (1.64 mg kg −1 ), as compared to control (0.09 mg kg −1 in flesh and 4.99 mg kg −1 in peel). Overall, it was found that tuber peels had significantly higher levels of heavy metals, as compared to tuber flesh. The present study indicates that the hydrogel based amendments have the potential to reduce the uptake of Cd, Pb and Zn metals, by wastewater irrigated potato tubers grown on sandy soils. • Irrigating potato with wastewater led to accumulation of heavy metals in soil. • Both treatments led to reduced Cd and Zn uptake by potato tubers. • Treatment SAP+GBC led to reduced Pb uptake in potato tubers. • SAP+GBC treated soil retained higher levels of Cd, Cr and Cr in topsoil. • SAP treated soil retained greater amounts of Cd, Cu, Fe and Zn in topsoil.

Method of internal care of cement hydration in 3D printing formulations

Introduction. Improvement of 3D printing technology with the use of concrete mixtures based on Portland cement largely depends on the sustainable solution of the problem of ensuring normal hardening of extruded concrete layers. A violation of hardening has known negative consequences and entails significant economic losses. It has been suggested to use polyacrylate solutions, preparation of which before application in concrete mixture allows controlling the process of their polymerization, postponing the sorption function of the additive in time to ensure the required rheology.&#x0D; Materials and methods. Influence of super absorbent polymer (SAP) solution on structural formation processes and properties of cement materials is studied. Assessment of the degree of hydration was carried out by the calorimetric method for total thermal power using the isothermal calorimeter TAM AIR. Identification of main phases of cement stone (CS) by X-ray phase analysis was performed on XRD-6000 diffractometer.&#x0D; Results. It is established that the use of SAP solutions has a positive effect on the mobility of cement mixtures due to the delayed polymerization and the corresponding water absorption by the polymer. The flexural strength range is 6.6–8.7 MPa and the compression strength range is 68.5–71.7 MPa. The porosity is characterized by extreme dependence with minimum at concentration of SAP 1.0 % from weight of Portland cement. Such changes in the properties of the CS are naturally associated with changes in the parameters of its structural formation. It is established that the range of concentrations of SAP less than 1.5 % provides close to the reference composition (without SAP) the total hydration heat power of Portland cement at the age of 86 hours.&#x0D; Conclusions. The dependences of rheological and mechanical properties of cement materials on SAP concentration have been established. It has been proved that the use of SAP solutions is an effective engineering solution to ensure the hardening of concrete in adverse conditions. Further development of the topic may be aimed at studying the effect of SAP solutions on the properties of concrete mixtures of different compositions for 3D printing.&#x0D; Acknowledgements: The paper was supported by a grant of the President of the Russian Federation for state support of young Russian scientists — Candidates of Sciences MK 1394.2020.8.

Study on SAP with different absorption capacities and its effects on Self Curing HPC

Internal moist curing by Super Absorbent Polymer (SAP) plays an vital role in strength development and durability of High Performance Concrete (HPC). The aim of this study is to examine how the strength reduction happens by adding super absorbent polymer and rectification of strength reduction using micro fillers. The amount of SAP added to the concrete was calculated using the absorption capacity that was obtained as a result of tea bag test. The present study also involves the use of super absorbent polymer in gel and dry state to both mortar and concrete. First strength property was tested in mortar for both gel and dry state. It was found that SAP added in dry state to mortar has no adverse effect on compressive strength and tested. In the present work additional micro filler (silica fume) with different ratios: 0.0%, 10%, 15%, 20% of weight of cement is added to improve the mechanical properties of high strength concrete with SAP. The concrete samples are subjected to ambient curing and mechanical properties (compressive strength and modulus of rupture) were evaluated at different ages, up to 28 days. Durability property such as sorptivity, water absorption and carbonation was conducted on HPC. The effect of internally cured concrete was studied and compared with conventionally cured concrete.