Effect Of Superabsorbent Polymer Research Articles

The effect of superabsorbent polymers on the mitigation of plastic shrinkage cracking of conventional concrete, results of an inter-laboratory test by RILEM TC 260-RSC

This article presents the results of an inter-laboratory study performed by six international research groups in the framework of RILEM Technical Committee 260 RSC “Recommendations for use of superabsorbent polymers in concrete construction”. Two commercially available superabsorbent polymer (SAP) samples with different chemical compositions were tested in terms of their ability to mitigate plastic shrinkage cracking of concrete. The SAP mixtures showed a clear reduction of plastic shrinkage cracking in conventional concrete. On the contrary, if only additional water is added and no SAP, the area of plastic shrinkage cracks increases. This suggest the ability of SAP to mitigate plastic shrinkage cracking. Upon addition of the predetermined amount of SAP and additional water, the compressive strength decreased on average by 3% for the mixtures with 0.15% SAP (by mass of cement) and by 10% for the mixtures with 0.30% SAP.

Effect of superabsorbent polymer on mechanical properties of cement stabilized base and its mechanism

Abstract Superabsorbent polymers (SAPs) are cross-linked polymers that can absorb and retain large amounts of water. In recent years, a growing interest was seen in applying SAPs in concrete to improve its performance due to its efficiency in mitigating shrinkage. This paper presents findings in a study on effect of SAPs on performance of cement-treated base (CTB), using the experience of internal curing of concrete. CTB specimens with and without SAPs were prepared and tested in the laboratory. Tests conducted include mechanical property testing, dry shrinkage testing, differential thermal analysis, mercury intrusion porosimetry and scanning electron microscope testing. It was found that 7-day and 28-day unconfined compressive strength of CTB specimens with SAPs was higher than regular CTB specimens. 28d compressive strength of CTB specimens with SAPs made by Static pressure method was 5.87 MPa, which is 27% higher than that of regular CTB specimens. Drying shrinkage of CTB specimens with SAPs was decreased by 52.5% comparing with regular CTB specimens. Through the microstructure analysis it was found that CTB specimens with SAPs could produce more hydration products, which is also the reason for the strength improvement.

Effect of Superabsorbent Polymer on Seedling Emergence and Growth of Cotton under Water Stress Conditions

Water availability is one of the major limiting factors of cotton productivity. The soil application of superabsorbent polymers (SAPs) may increase water use efficiency, improve soil physical properties, enhance seed germination and emergence, crop growth and yield and reduce the irrigation requirements of plants. The objective of this study was to investigate the effect of Zeba®, a polymer based on corn starch, on seedling emergence and growth of cotton under water stress. A set of pot experiments was conducted under completely randomized design with four replications of 25 seeds. Treatments included application rates of 5, 10, 15, 20 kg/ha and an untreated control, all under three levels of irrigation (adequate, moderate and deficit). The emergence performance was evaluated by final emergence percentage and mean emergence time. Root and shoot growth were measured for length and weight. The application of Zeba® promoted seedling emergence (higher emergence percentage from 17.9 to 22.6% and lower mean emergence time from 36 to 46% compared to control). Higher values for root and shoot traits were observed under Z10 and Z15 rates regardless of irrigation treatments. The adoption of the proposed SAP could represent a promising solution and thus increase moisture conservation in cotton.

Autogenous Healing of Early-Age Cracks in Cementitious Materials by Superabsorbent Polymers.

The effect of superabsorbent polymers (SAPs) on autogenous crack healing in cementitious materials with early-age cracking was investigated. SAP-containing samples exposed to wet/dry cycles showed better autogenous healing than those only exposed to wet conditions, as determined by water flow and compressive strength recovery tests. The water flow rates through cracks (380 ± 40 µm) in cement paste and cement mortar containing 1.0% SAP decreased by around 97.1–100% and 79.7–90.7%, respectively, after 14 cycles of healing compared to 1 cycle. Although the initial compressive strength decreased with SAP addition, it recovered somewhat after a 28-d healing period. Microscopy and spectroscopy results identified CaCO3 and/or calcium silicate hydrate (CSH) as the main healing products.

Effect of super absorbent polymer on microstructural and mechanical properties of concrete blends using granite pulver

AbstractIndustrialization and urbanization has caused a serious impact on the environment due to the vast consumption of energy and eco‐unsustainable production. Therefore, scientists and engineers are placing more effort to design environmentally sustainable systems. To achieve sustainability, one potential solution is to use renewable resources to produce construction materials. The effect on various amounts of admixed super absorbent polymer (SAP) on microstructural, fresh and hardened properties of autogenous cured concrete incorporating Granite Pulver (GP) have been investigated. For this purpose, a small quantity of Portland cement was replaced by GP as 5, 10, 15, and 20%. The SAP was used at volume fractions of 0.1 to 1% to the GP‐concrete blends to counteract self‐desiccation during the hydration of concrete. Along with the GP, fly ash (FA) was also added as filler to improve the workability of GP‐concrete blends. The chemical and microstructural properties of unprocessed GP, fly ash, and cement samples along with the mechanical properties of GP‐concrete blends were investigated through different tests. A total of 627 specimens were prepared for mechanical testing of GP‐concrete blends. The GP along with the SAP increases the compressive strength and flexural strength in comparison with the control mixture by around 1.6 and 6.8% respectively, when a replacement of cement by GP up to 15% was made with an addition of 0.4% of SAP in the mixture.

Effect of superabsorbent polymers on the drying and autogenous shrinkage properties of self-leveling mortar

This paper aims at putting forward the shrinkage control measures for evaluating the effect and mechanism of shrinkage compensation of self-leveling mortar by analyzing the shrinkage characteristics of cementitious self-leveling mortar (SLM). The drying shrinkage, autogenous shrinkage and mechanical properties of the self-leveling mortar are analyzed by comparing it with the ordinary mortar. The difference between the two kinds of matrix was explained by the result of hydration and pore structure. The internal curing of self-leveling mortar was carried out by superabsorbent polymer. The variation of drying shrinkage and autogenous shrinkage of self-leveling mortar were tested with the content at 0%wt, 0.2%wt, 0.4%wt and 0.6%wt. The pore structure and pore size distribution were also investigated. The experimental results show that the self-leveling mortar has larger the drying shrinkage and smaller the autogenous shrinkage than those of ordinary mortar. The main reasons for this are the hydration delay and the change of pore structure of self-leveling mortar caused by the addition of organic admixture. The internal curing by using superabsorbent polymer has excellent effect on drying shrinkage and autogenous shrinkage compensation which decrease by 10% and 10.2%, respectively, when the content is 0.4%wt.

The effect of superabsorbent polymer on various scale of pore structure in ultra-high performance concrete

The addition of superabsorbent polymer (SAP) mainly has two opposite effects on the pore structure of ultra-high performance concrete (UHPC): the densification of microstructure due to internal curing (IC) and the increase of large voids by swollen SAP particles. To further elucidate these effects on various properties of UHPC, the pore structure of internally cured UHPC is studied in a wide range of 3 nm–10 mm (in diameter), by two methods of micro X-ray computed tomography (μ-CT) and mercury intrusion porosimetry (MIP). Owing to the different measurable pore scale, each method provides different total porosity and pore size distribution. The SAP voids significantly increase the porosity in the size range of 267 µm–2.7 mm, whereas IC makes the pore structure finer within 3–100 nm. In particular, the microstructural change due to the IC has a more decisive influence on the compressive strength than larger SAP voids. In addition, it is discovered that the positive effect of heat-treatment (HT) for UHPC is diminished due to the applied IC. The IC and HT have to share limited amounts of raw materials and space necessary to promote the hydration reaction. However, the IC consumes parts of them before the HT does, thereby limits conventional positive effect of the HT.

Effect of superabsorbent polymer on the shrinkage and crack resistance of concrete at early age

The superabsorbent polymer (SAP) with different volumes and modes of entrained water is incorporated into concrete to study the effect of SAP on the compressive strength, flexural strength, shrinkage, plastic cracking and electrical resistivity of concrete at early age. The result indicated that the influence of SAP with different modes of entrained water on the early strength of concrete is relatively obvious. It is beneficial for the early strength of concrete to add pre-absorbed SAP whose internal curing (IC) is detracted from mixing water and unabsorbed SAP. But the early strength of concrete is decreased by adding pre-absorbed SAP. The effect of pre-absorbed SAP is limited on shrinkage of concrete when IC water is detracted from mixing water. The unabsorbed SAP gradually decreases the concrete shrinkage with its volume increase. The moderate volume of pre-absorbed SAP can decrease the early concrete shrinkage. In addition, SAP can effectively alleviate the early appearance and development of concrete cracks. Furthermore, the pre-absorbed SAP can efficiently enhance the crack resistance of concrete. When the unabsorbed SAP is added, the cracking of concrete is reduced with the increase of volume. The longer the curing age, the more obvious would be the influence of SAP on the internal humidity of concrete, which effectively delays the increase of concrete resistivity.

Effect of Superabsorbent Polymer on the Properties of Concrete.

Incorporating superabsorbent polymer (SAP), which has the abilities of absorption and desorption in concrete can achieve the effect of internal curing. The influences of the volume, particle size and ways of entrained water of SAP on the workability, compressive strength, shrinkage, carbonation resistance and chloride penetration resistance of concrete were analyzed through the macroscopic and microscopic test. The results show that pre-absorbed SAP can increase the slump of the mixture, but SAP without water absorption and pre-absorbed SAP with the deduction of internal curing water from mixing water can reduce the slump. The improvement effects of SAP on compressive strength of concrete increase gradually with the increase of age. Especially from 28 days, the compressive strength of concrete increases obviously. At later age, the compressive strengths of SAP concrete under natural curing environment exceed the strength of reference concrete under natural curing environment and nearly reach the strengths of reference concrete under standard curing environment. SAP effectively reduces the shrinkage of concrete, improves the concrete’s abilities of carbonation resistance and chloride penetration resistance. The microscopic test results show that SAP can effectively improve the micro structure and make the pore structure refined. When SAP is added into concrete, the gel pores and small capillary pores are increased, the size of big capillary pores and air pores are reduced.

Effect of superabsorbent polymer on soil and plants on steep surfaces

AbstractIn this study, a superabsorbent polymer (SAP; Super‐AB‐A‐200) was used for the amendment of the water‐holding capacity of soil on a steep surface. Three concentrations of SAP [0.20, 0.40 and 0.60% (w w−1)] and a control (0%) were blended with sandy soil. This study aimed to evaluate the evaporation rate, water retention capacity and saturated water content of polymer‐treated soils for determining plant survival and seed germination rate through cylinder and steep surface experiments. The results demonstrated that sandy soil treated with SAP showed significantly enhanced soil water holding compared with the controls. Furthermore, the seed germination rate was significantly higher in polymer‐treated soils than in the controls. The survival times of grass and ligneous plants were lengthened under water stress conditions. Finally, treatment with 0.40% SAP was the optimum selection for sandy soil amendment on steep surfaces.

Effect of superabsorbent polymer on root water uptake and quantification of water uptake from soil profile in dry land

AbstractFew reports focus on the source of water used in crop uptake from the soil profile following superabsorbent polymer (SAP) application, particularly the quantification of crop water uptake from SAP‐treated soil and non‐SAP‐treated soil. Using column experiments, we investigated the effect of SAP on root water uptake of maize over two years and researched in depth the utilization of water from different soil layers under SAP application by employing stable isotope D/18O. The results suggest that SAP can increase root water uptake by 16.3–27.8% in SAP‐treated soil layers. The water used by the crop mainly originated in the 0‐ to 20‐cm soil layer at the jointing stage, 20‐ to 40‐cm at heading stage and 0‐ to 20‐ cm during grain filling.

Rapid self-sealing of cracks in cementitious materials incorporating superabsorbent polymers

The effect of superabsorbent polymers (SAPs) on rapid self-sealing of cracks in cementitious materials was investigated experimentally. Rapid swelling of SAPs effectively sealed cracks in materials within five minutes, resulting in the reduction ratio of water runoff per unit time in ranges of 34–52% and 52–72% for SAP dosages of 0.5% and 1.0%, respectively. X-ray computed tomography (CT) analysis showed that the swelling ratio of SAPs in the specimens was less than that in the filtered cement pore and synthetic solutions. Analyses of images obtained using X-ray CT, cryofracture scanning electron microscopy, and optical microscopy indicated that when a crack occurred, most SAPs, which were split because of the crack while remaining bonded to the surrounding cement matrix, swelled only as much as the volume of voids formed by swelling of SAPs, not including the crack. However, a part of the SAPs that remained intact swelled across voids, including the crack.

Effect of Super-Absorbent Polymer on the Undrained Shear Behavior of Cemented Dredged Clay with High Water Content

AbstractA series of isotropically consolidated undrained triaxial tests were performed on cemented clay with super-absorbent polymer (SAP) at high water content to investigate the effect of SAP con...

The effect of super absorbent polymers on soil and water conservation on the terraces of the loess plateau

The loess plateau of northern China has always been severely affected by drought and rainfall, impacting ecological integrity and sustainable development in particular. Super-absorbent polymers (SAPs) can relieve the pressure of water shortages and change the process of rainfall-runoff. In this study, SAPs were mixed with soil in percentages(weight ratio) of 0, 0.25%, 0.5%, 0.75%, 1% and 2%; then, these mixtures were applied in 5cm depth layers in runoff plots of 5m×4m for every treatment (T1, T2, T3, T4, T5). Artificial rainfall intensity was controlled at 40mm/h, and the rainfall duration was 0.5h when the soil physical and chemical properties were surveyed. With SAPs, the initial runoff time of different treatments increased by 21.5-102.7%; the amount of surface runoff decreased remarkably; the SAPs could reduce the loss of soil and water: the runoff reduction effect was 24.6% (T1), 41.5% (T2), 46.5% (T3), 50.7% (T4), and 60.6% (T5); the sediment reduction effect was very significant at 58.8% (T1), 74.1% (T2), 85.6% (T3), 80.9% (T4), and 75% (T5); and the lowest losses of total nitrogen (TN 0.09kg), total phosphorus (TP 5.02g) and total potassium (TK 0.08kg) were measured in T3,with 14.9%, 14.2% and 13.1% that of the control (CK), respectively. The soil moisture content increased by 19.2%, 32.5%, 33.5% and 31.3% compared to CK in the different soil layers; SAPs could raise the soil temperature by 0.72°C (T5) and lower the soil temperature by 0.53°C (T5) in September and July, respectively. The aboveground biomass and underground biomass of the treatments increased by a maximum value of 84.4% in T3, which was 38% greater than CK, and the vegetation in T3 (44 kinds) was the most abundant and it was 69.2% more than CK (26 kinds). The effect was not always positively correlated with the percentage of SAPs. The application of SAPs in this study showed a comprehensive utility (soil erosion prevention, redistribution of soil water and temperature, maintenance of fertility and the synergy between SAPs and plants), which suggest that the most basic goal, to ensure socio-economic and ecological sustainability in dryland systems, is obtained.

Effect of superabsorbent polymers (SAP) on the freeze–thaw resistance of concrete: results of a RILEM interlaboratory study

This article presents the results of an interlaboratory experimental study performed by 13 international research groups within the framework of the activities of the RILEM Technical Committee 225-SAP “Applications of Superabsorbent Polymers in Concrete Construction”. Two commercially available superabsorbent polymers (SAP) were tested in terms of their influence on the freeze–thaw resistance of ordinary concrete. To test the robustness of the method, all participating laboratories used locally produced materials. Furthermore, following this aim, various accelerated methods were used to estimate the resistance of the concrete to freeze–thaw cycles. The effect of adding SAP was from insignificant to considerably positive in terms of improvement in material performance as determined by reduced mass loss after freeze–thaw cycles; only one participant observed worsening of the material behaviour. At the same time, due to the addition of SAP, a much less pronounced decrease in the dynamic Young’s modulus was observed as a result of freeze–thaw testing without deicing salt.

An Inverse Method to Estimate the Root Water Uptake Source-Sink Term in Soil Water Transport Equation under the Effect of Superabsorbent Polymer.

The widespread use of superabsorbent polymers (SAPs) in arid regions improves the efficiency of local land and water use. However, SAPs’ repeated absorption and release of water has periodic and unstable effects on both soil’s physical and chemical properties and on the growth of plant roots, which complicates modeling of water movement in SAP-treated soils. In this paper, we proposea model of soil water movement for SAP-treated soils. The residence time of SAP in the soil and the duration of the experiment were considered as the same parameter t. This simplifies previously proposed models in which the residence time of SAP in the soil and the experiment’s duration were considered as two independent parameters. Numerical testing was carried out on the inverse method of estimating the source/sink term of root water uptake in the model of soil water movement under the effect of SAP. The test results show that time interval, hydraulic parameters, test error, and instrument precision had a significant influence on the stability of the inverse method, while time step, layering of soil, and boundary conditions had relatively smaller effects. A comprehensive analysis of the method’s stability, calculation, and accuracy suggests that the proposed inverse method applies if the following conditions are satisfied: the time interval is between 5 d and 17 d; the time step is between 1000 and 10000; the test error is ≥ 0.9; the instrument precision is ≤ 0.03; and the rate of soil surface evaporation is ≤ 0.6 mm/d.

Effect of Super Absorbent Polymer and Irrigation Deficit on Water Use Efficiency, Growth and Yield of Cotton

Sustainable use of water resources in agriculture is a necessity for many arid countries. In order to investigate the effect of water deficit, irrigation after 120 (control), 155 (moderate water stress) and 190 mm (sever water stress) pan evaporation and super absorbent polymer rates (SAP) (0, 30, 60 and 90 kg ha-1) on growth, yield and water use efficiency of cotton, an experiment was conducted as split plot based on a randomized complete block design with three replications. Moreover, the effect of water quality (distilled water and solutions of 0.25, 0.5, 0.75, 1 and 1.25% NaCl) was investigated on water holding capacity by SAP. Results revealed that moderate water stress (irrigation intervals of aprox. 15 days) along with 60 kg ha-1 SAP application was the best treatment in terms of growth and yield indices of cotton. The results for plant height, plant dry weight, boll number per plant and fiber yield in this treatment were 16, 28, 42 and 10% higher than control treatment, respectively. Water deficit and SAP application improved the water use efficiency (WUE) of cotton. The amount of WUE in moderate water stress treatment along with consumption of 60 or 90 kg ha-1 SAP was 26% higher than for control treatment. In addition, water holding capacity by SAP in distilled water treatment was 7 times higher than in the case of 1.25% NaCl solution. The overall results showed that irrigation deficit and SAP application are two appropriate strategies for crop production in areas affected by drought stress, especially if low saline water sources are used.

Effect of Super Absorbent Polymer and Irrigation Deficit on Water Use Efficiency, Growth and Yield of Cotton

Sustainable use of water resources in agriculture is a necessity for many arid countries. In order to investigate the effect of water deficit, irrigation after 120 (control), 155 (moderate water stress) and 190 mm (sever water stress) pan evaporation and super absorbent polymer rates (SAP) (0, 30, 60 and 90 kg ha-1) on growth, yield and water use efficiency of cotton, an experiment was conducted as split plot based on a randomized complete block design with three replications. Moreover, the effect of water quality (distilled water and solutions of 0.25, 0.5, 0.75, 1 and 1.25% NaCl) was investigated on water holding capacity by SAP. Results revealed that moderate water stress (irrigation intervals of aprox. 15 days) along with 60 kg ha-1 SAP application was the best treatment in terms of growth and yield indices of cotton. The results for plant height, plant dry weight, boll number per plant and fiber yield in this treatment were 16, 28, 42 and 10% higher than control treatment, respectively. Water deficit and SAP application improved the water use efficiency (WUE) of cotton. The amount of WUE in moderate water stress treatment along with consumption of 60 or 90 kg ha-1 SAP was 26% higher than for control treatment. In addition, water holding capacity by SAP in distilled water treatment was 7 times higher than in the case of 1.25% NaCl solution. The overall results showed that irrigation deficit and SAP application are two appropriate strategies for crop production in areas affected by drought stress, especially if low saline water sources are used.

The effect of superabsorbent polymers on performance of fly ash cementitious mortars exposed to accelerated freezing/thawing conditions

The paper is focused on identifi cation of micro-structural and mechanical alterations in porous matrices of Portland fl y ash cement mortar, during frost deterioration. An attempt is made to assess the effi ciency of superabsorbent polymer (SAP) ‘protection’ based on analysis of three SAP types with different water absorption/desorption capacities. Two different exposure regimes have been adopted in the study; the exposure to freeze/thaw cycles and the exposure to freeze/thaw with de-icing solution. In order to evaluate the effect of SAPs on the micro-structural features of deteriorating mortars comprehensive MIP and SEM analyses were performed. It has been found that SAPs with high water absorption capacities may prevent fl exural strength reduction caused by frost action. The limitation in micro-cracks propagation by SAP additions can be attributed to the higher tensile strength of ‘SAP pores’ walls, resulting from densifi cation of CSH gel. This is consistent with the fi nding of higher ‘breaking pressure’ for ‘SAP pores’. Nevertheless, it was shown that the additional exposure to salt ions reduces the initial resistance to less than one month. Desorption characteristics of SAPs may play a particularly important role in the case of very early exposure to F/T cycles. Too slow release of water does not suffi ciently facilitate densifi cation of structure prior frost action. Neither can it create a suitable network of air pockets for the expansion of ice and freezing water as in air-entrainers. This is particularly relevant to fl y ash cementitious composites due to delayed pozzolanic reaction.

Effect of superabsorbent polymers (SAPs) on rheological properties of fresh cement-based mortars — Development of yield stress and plastic viscosity over time

Superabsorbent polymers (SAPs) are a new, promising, multipurpose chemical admixture for concrete. This article addresses the rheological behaviour of fresh, cement-based mortars modified with SAP. Two types of SAP with differing water absorption and desorption kinetics were used. Additionally, for one the grading was varied. Three reference mortars were investigated. The rheological properties of these fresh mortars were tested for 90min by continuous flow rheometry. It was found that the distinct kinetics of water uptake inherent in the SAP samples, as governed by their particular chemical structures, is the major factor that governs the rheological properties of fresh mortar. Furthermore, the grading of SAP distinctly affects the development of yield stress and plastic viscosity over time. The particular effects of specific SAP addition on the rheological characteristics of a mortar depend on the water-to-binder ratio, the dosage of superplasticizer, and the dosage of silica fume, if present.