Types Of Superabsorbent Polymers Research Articles

Effect of self-healing behavior and self-healing technologies on the structural characteristics of cracked RC/ECC composite beams

The improving potential of self-healing behavior and self-healing technology to degradation of structural characteristics of cracked reinforced concrete structures was explored at the member level. Reinforced concrete/engineered cementitious composite (RC/ECC) composite beams were prepared by three self-healing technologies, including crystalline additives (CA), two types of superabsorbent polymers (SAP), and beam without self-healing technology was used as reference specimens. The self-healing properties of structural characteristics of beams were studied by four-point bending tests, including bear capacity, stiffness, ductility index, energy absorption capacity (EAC), and failure mode. The self-healing behavior of damage was evaluated by ultrasonic wave test and damage identification test based on natural frequency. Self-healing behavior of four types of RC/ECC composite beams improved the structural characteristics after cracking to varying degrees. The stiffness of CB-0, CB-S, CB-C, and CB-SH after self-healing increased by 10.80%, 22.88%, 36.71%, and 28.80% compared to that without self-healing, respectively. Recovery ability of structural characteristics of RC/ECC composite beam is enhanced by self-healing technologies. Moreover, CA exhibits a superior improvement in the recovery ability of the structural characteristics compared with two types of SAP. Moreover, the natural frequency and ultrasonic velocity of pre-cracked beams after self-healing were higher than those without self-healing, especially when self-healing technologies were applied. There is a positive correlation between the recovery ability of ultrasonic velocity and self-healing behavior of the structural characteristics of RC/ECC composite beams. This also explains why the structural characteristics of pre-cracked beams have been improved to varying degrees due to different self-healing techniques.

Effects of several superabsorbent polymers on soil exchangeable cations and crop growth

Owing to their excellent water absorption and water retention properties, superabsorbent polymers have become an important technology for realizing agricultural water savings. To explore the exchange pathways of exchangeable cations in soil caused by different superabsorbent polymers and their effects on crop nutrient uptake and growth, three types of superabsorbent polymers, sodium acrylate, potassium acrylate and acrylamide–sodium acrylate, were used in this project to study the effects of different dosages on crop growth, root morphology and the distributions of Na+, K+, Ca2＋ and Mg2+ in the root tips. The results were as follows: among all the treatments, the inhibition effect of the sodium acrylate superabsorbent polymer was the most obvious. Compared with CK, the biomass decreased by 70.3% (AN2), the root length and root surface area decreased by 62.7% and 61.1% respectively, plant K+ and Na+ increased by 18.5% and 2423% respectively, and Ca2+ and Mg2+ decreased by 27.6% and 18.7% respectively. Adsorption experiments with Ca2＋ and Mg2+ further proved that the superabsorbent polymers adsorbed more than 95% of the Ca2＋ and Mg2+ in the soil while releasing Na+ and K+ into the soil after swelling.

Characterization and under Water Action Behaviour of a New Plaster-Based Lightened Composites for Precast.

Plaster is a construction material widely used for the production of prefabricated parts in building construction due to its high capacity for hygrothermal regulation, its good mechanical performance, and its fireproof nature, among other factors. Its historical use has been linked to ornamental elements, although more recent research is oriented towards the industrialisation of plaster composites and the design of prefabricated parts for false ceilings and interior partitions. In this work, the behaviour against water of four new plaster-based composite materials is studied, using additions of two types of super absorbent polymers (sodium polyacrylate and potassium polyacrylate) and a lightening material (vermiculite) in their manufacturing process. In addition, the transmission of water vapour through the samples was studied together with the water absorption capacity of the samples in order to check the suitability of the use of plaster-based materials exposed to these environments. The results of this study show that composites with the addition of super absorbent polymers as well as vermiculite significantly improve their water performance compared to traditional materials up to 7.3% water absorption with a minimal (13%) reduction in mechanical strength compared to current materials with similar additions. In this sense, a plaster material is obtained with wide possibilities of application in the construction sector that favours the development of sustainable and quality buildings, in line with Goal 9 for Sustainable Development included in the 2030 Agenda.

Biodegradation of a Nanocellulose Superabsorbent and Its Effect on the Growth of Spinach (Spinacea oleracea)

In this study, spinach (Spinacea oleracea) plants were grown in two soils, a clay loam (CL) and a sandy (SD) soil, amended with two types of superabsorbent polymers (SAPs), nanocellulose and commercial, at different levels of soil moisture: 70, 40, and 20%. The effect of the superabsorbent on the soil properties, water management, and plant biomass was measured and compared to that in soils treated with a commercial anionic polyacrylamide-based SAP. Plant biomass is the highest in SD soil amended with a commercial superabsorbent. However, it decreases in the CL soil when a superabsorbent is applied, independent of the SAP type. This effect is magnified when a nanocellulose SAP is used; this is likely attributed to waterlogging stress and the fast biodegradation of this superabsorbent, where approximately 50% of the initial mass remains after 5 days of exposure. The use of a nanocellulose SAP as a water retention agent offers the potential for a much-needed sustainable solution for global agriculture. Future studies are needed to modify the structure of the nanocellulose SAP to inhibit its biodegradation and increase its benefits for agricultural use.

Functional Properties of SAP-Based Humidity Control Plasters

The application of materials with high moisture storage capacity close to the interior surface presents a prospective passive method for improving indoor relative humidity conditions. In this paper, lime-cement plasters containing three different types of superabsorbent polymers (SAPs) in varying dosages are introduced and their mechanical, hygric, and thermal characteristics are analyzed in a relation to microstructure. The experimental results show a significant effect of both SAP amount and chemical composition on all functional properties of studied plasters. The incorporation of 1.5% of SAP may induce up to 2.5 better moisture buffering, thus significantly improving the passive humidity control capability. Considering overall functional parameters of SAP-modified plasters, the dosage of 1 wt.% can thus be viewed as a rational compromise between the moisture storage capability and mechanical properties. The obtained wide sets of parameters can be utilized directly as input data of computational models suitable for the assessment of the interior microclimate of residential and administrative buildings.

Applications of Absorbent Polymers for Sustainable Plant Protection and Crop Yield

Natural strategies for protecting the environment as well as plant, animal and human health is considered one of the main goals of developed countries. Recently, the use of absorbent polymers and hydrogel in agriculture has demonstrated several benefits for soil amendments, saving water content, reducing the consumption of soil nutrients, minimizing the negative impacts of dehydration and moisture stress in crops and controlling several phytopathogens. The seed-coating technology for establishing the crops is a recent common practice used for improving seed protection and enhancing plant growth. Coating materials include absorbent polymers and hydrogels based on growth regulators, pesticides, fertilizers and antagonist microorganisms. The current review has highlighted the importance of different types of superabsorbent polymers and hydrogels in an integrated strategy to protect seeds, plants and soil in a balanced manner to preserve the ecosystem.

The effect of air-entraining admixture and superabsorbent polymer on bond behaviour of steel rebar in pre-cracked and self-healed concrete

This paper intends to study the effect of air-entraining admixture (AE) on self-healing method at rebar-concrete interface using superabsorbent polymer (SAP). AE with a constant dosage of 0.83 kg/m3, and 0.25% and 1.0% SAP dosages are considered. Two types of superabsorbent polymer with different chemical compositions and particle sizes are considered for the experimental tests. Pull-out test results of mixtures containing AE admixture are compared with those in non-AE concrete. Scanning electron microscopy/energy dispersive X‐ray spectrometry (SEM/EDS) along with microscopic analysis is performed to study the healing products at crack surface and SAP macro voids around the rebar. Overall, results indicate that AE admixture has a considerable impact on the performance of the self-healing method at the rebar-concrete interface especially for higher dosage of SAP (1.0%). This can be attributed to the internal voids networks around the rebar generated by AE admixture, which can ease the water transfer between SAP macro voids to participate in healing cracks after wet-dry cycles. SEM analysis shows that stalactites, healing products at the external surface of crack, are composed of a large amount of calcium and oxygen.

Investigation of superabsorbent polymer absorbency at reduced chemical potential of water

Different types of superabsorbent polymers (SAP) exhibiting varied absorbency properties were investigated for their performances at varying concentrations of an electrolyte. Water chemical potential, which is a function of concentration and pressure, was interpreted as a major parameter for absorbency and swelling properties of SAP. Superabsorbent polymers that were investigated gave different values of permeability which was carried out in a layer of swelled superabsorbent polymer. This result revealed differences on the structure of the superabsorbent polymers particularly on the crosslinking density. SAP’s absorbency properties were further tested and a correlation between the quantity of absorption and the chemical potential of water in terms of sodium chloride concentration was developed using experimental data on free swelling capacity and absorption under pressure. Results showed decreasing quantity of absorption by the superabsorbent polymers with decreasing chemical potential of water with higher reduction in the absorbency at higher pressure applied on the swelled SAP.

Evaluation of two types of superabsorbent polymer on soil water and some soil microbial properties

In this study, two types of superabsorbent polymers, Luquasorb (Luqua) and Stockosorb (Stock), at 180 kg ha−1 were applied by scattering and mass treatments in an experimental farm to assess their influences on spring wheat growth (Dez variety) and on the physical characteristics and microbial plenty of soil. The following treatments were used in this study: the control (C, without SAPs), Luqua with mass application (Luqua-M), Stock with mass application (Stock-M), Luqua with scattered application (Luqua-S), and Stock with scattered application (Stock-S). Approximately 0.3 m3 of irrigation water was supplied for every subplot. The results indicated that adding superabsorbent polymers could improve the soil water-holding capacity and enable the soil to retain more water. Besides, superabsorbent polymers significantly enhanced the soil water content in the three growth stages compared with the control. The use of superabsorbent polymers did not have obvious opposite influences on the soil microbial colony and might even increase soil microbial movement.

The Effect of Super-Absorbent Polymer as a Self-Curing Admixture on the Performance of Mortars

Super-absorbent polymer (SAP) was used as a self-curing admixture for cement-based materials. Two types of super-absorbent polymer and effect of super-absorbent polymer on fluidity and mechanical properties of mortars were investigated. The performance of the mortars cured for different ages was tested. The results showed that SAP could play a role of reserving water and reserving water of SAP particles A with an average diameter of 180 mm was more effective than that of SAP particles B with an average diameter of 80 mm, the optimal performance of reserving water was obtained at 0.07 wt.% of SAP particles A; Mechanical properties of hardened mortars with SAP particles A were better than those with SAP particles B, the favorably experiment ratio was 0.05 wt.% of SAP particles A.