Effect of Superabsorbent Polymer on the Properties of Concrete

Abstract

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.

Influence of Environmental Factors on the Swelling Capacities of Superabsorbent Polymers Used in Concrete

“…Depending on their structure, polymers can influence the rheological properties [ 5 ], increase tensile strength [ 6 ] or help control the curing process [ 7 ]. Superabsorbent polymers (SAP) [ 8 , 9 ] have gained significant interest as additives in concrete due to their unique properties. These are e.g., the mitigation of autogenous [ 10 ] and plastic shrinkage [ 11 ] or increasing the freeze–thaw resistance [ 12 , 13 ].…”

Synthesis and Characterization of Polymer-Silica Composite Hydrogel Particles and Influence of Hydrogel Composition on Cement Paste Microstructure

“…Hydrogel particles can absorb up to 1,500 times their dry weight in water [48] and can be used in place of traditional lightweight aggregate (LWA) for internal curing. Hydrogel particles have several advantages over LWA in that they require no presoaking and can be added in very small amounts to cementitious mixtures (e.g., 0.2 % by weight of cement) while still providing effective internal curing [1,49,50]. Although hydrogel particles are mechanically weaker than LWA, the direct impact that hydrogel particles have on the compressive strength of mortar and concrete is still unclear.…”

Autogenous Healing of Early-Age Cementitious Materials Incorporating Superabsorbent Polymers Exposed to Wet/Dry Cycles

“…The water absorption and initial sorptivity of S-1.5 in Figure 5 and Figure 6 are relatively high compared to the other specimens, as both the SAPs in cracks, and some of the SAPs inside the cement matrix which was connected to the SAP voids in the cracks, could absorb capillary water. However, as the connection between SAP voids in crack surfaces and SAP voids in the cement matrix gradually became blocked, due to the progress of hydration reactions and formation of healing products [37,38], the initial sorptivity of the S-1.5 specimen noticeably decreased, as the number of wet/dry cycles increased, as shown in Figure 5 and Figure 6.…”