#Sap ecc crack cracked#
applied the commercially available SAP polymers in cracked concrete and examined the sealing efficiency with the flow-through-crack test, which is conducted under permanent hydraulic gradient of 4 m/m.
#Sap ecc crack crack#
Besides that, SAP has also been utilized to seal the crack in the concrete and prohibit the entrance of moisture content and ions. It is also reported that the internal curing can help to reduce the residual stress in concrete structure. Specifically, it is considered that the enhanced internal humidity with SAP can reduce the autogenous shrinkage by lowering both Laplace pressure and the osmotic pressure in capillary pores and achieve similar curing effect compared to the traditional curing methods. SAP can provide internal curing for cementitious materials, prevent the loss of internal humidity and thus mitigate the autogenous shrinkage. Compared to normal concrete, more significant loss of internal relative humidity can be observed in high performance concrete, ultra-high performance concrete and high-strength concrete due to the lower water-cement ratio. This study aims to investigate the crack sealing effect of the SAP and its related regulation effect on concrete pore solution.Ĭurrently, the SAP has been widely applied to mitigate the autogenous shrinkage in cementitious materials, ,, ], including the application in concrete with the supplementary cementitious materials (SCMs), high strength concrete, ultra-high strength concrete, high-performance concrete and ultra-high performance concrete, ,, ], and alkali-activated slag material. The mentioned concrete pore solution represents the remained pore solution in the hardened concrete, which own high alkalinity (pH value in the range of ). Also, the interaction between the alkaline concrete pore solution and SAP has not been fully understood. However, the related study on preparing self-sealing cementitious materials with synthesized SAP is still relatively limited. It is also possible the swelled SAP can help to seal the internal cracks of the cementitious materials. Recently, it was found adding the SAP into concrete can reduce its shrinkage through internal curing, especially the autogenous shrinkage due to self-desiccation of concrete. Durability has become a major factor affecting the mixture design of cementitious materials. However, concern on the durability performance of Portland cement concrete has been widely raised, including its brittle nature for internal cracking susceptibility (Enhanced permeability, penetration of chloride ion and corrosion ) and high alkaline pore solution (Alkali-silica reaction ). Portland cement concrete is currently the most consumed man-made materials (around 5.4 billion tons in 2018 ) due to its relative cost-effectiveness ($100–120/ton in the United States) and appropriate mechanical performance. And further experimental studies are needed to optimize the wax-size and shell thickness for enhanced self-sealing efficiency. Furthermore, durability tests supported the wax-shell could be broken by the crack propagation in concrete. It was found that the strength reduction for samples with wax-coated SAP was insignificant compared to that of the control samples. A wax-coating protocol for the SAP was designed by using the hot-water method to prevent its swelling during mixing process. After that, the performance tests were conducted for the evaluation of concrete with SAP.
Besides that, it was also found the solution/gel ratio and the Ca(OH) 2 content could affect the swelling potential of the SAP. Further examination indicated the alkalinity of the buffer solution was reduced during the adsorption test, which can be caused by the hydrolysis of the amide groups and the crosslinker. The examination on the pH sensitivity indicated that the swelling capacity of the prepared SAP would first increase and then decrease with solution alkalinity, and the peak swelling potential was achieved around pH value of 12 for all the three type SAP with solution/gel mass ratio of 500. The SAP was synthesized with acrylic acid (AA)-methyl acrylate (MA) precursors, and three type samples with different crosslinking levels were prepared. This study aims to enhance the durability performance of cementitious material with the pH-responsive Superabsorbent Polymer (SAP).
The crack development is considered to be one of the most severe threats to the durability of concrete infrastructure.
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