Effect of Pre-Wetted Zeolite Sands on the Autogenous Shrinkage and Strength of Ultra-High-Performance Concrete

Abstract

In this study, the carrier effect of zeolite sands in reducing the autogenous shrinkage and optimizing the microstructure of ultra-high-performance concrete (UHPC) is studied. Pre-wetted calcined zeolite sand (CZ), calcined at 500 °C for 30 min, and natural zeolite sand (NZ), with 15 wt.% and 30 wt.% in UHPC, are used to partially replace standard sands. On that basis, a series of experiments are executed on the developed UHPC, including compressive strength, autogenous shrinkage, X-ray diffraction (XRD), and isothermal calorimetry experiments. With the increase of the zeolite sand content, the autogenous shrinkage of UHPC decreases gradually. Moreover, when the added CZ content is 30 wt.% (CZ30 specimen), it is effective in reducing autogenous shrinkage. Meanwhile, at the age of 28 days, the compressive strength of CZ30 is 97% of the control group. In summary, it is possible to effectively reduce the autogenous shrinkage of UHPC containing 30 wt.% CZ, without sacrificing its mechanical properties.

Internal Curing Effect of Pre-Soaked Zeolite Sand on the Performance of Alkali-Activated Slag

“…For example, Wang et al [22] studied zeolites calcined at 500 • C for 30 min for use as internal curing agents and found that the efficiency of said calcined zeolites in reducing autogenous shrinkage was significantly improved, and 30% of calcined zeolites reduced the shrinkage by 36% at 28 days. Similar findings were reported in the study by Zhang et al [23], who found that calcination improved the internal pore structure of zeolite sand, enabling it to retain more water, thereby reducing the autogenous shrinkage of ultra-high-performance concrete. However, it should be noted that after calcination at 500 • C, the absorption ability of zeolite sand increased, hence the spalling resistance of concrete containing calcined zeolite sand decreases at elevated temperatures [24][25][26].…”

“…With the AAS system, it is difficult to find the theoretical needed "internal curing liquid." In this study, zeolite sand's replacement ratios (15% and 30%) were taken from reference [23]. In future studies, we will test the chemical shrinkage of AAS according to ASTM C1608 [28], and the results may be used in mixture design to quantify the LWA replacement ratio.…”

“…The liquid was released and redistributed as condensed liquid overtime in the ink bottle spaces, causing the IRH to increase [37]. (2) As the liquid absorbed by the zeolite sand was continuously released, the IRH of the AAS mortars with internal curing increased [23]. (3) The hydration reaction, however, continuously reduced IRH.…”

Using machine learning techniques for predicting autogenous shrinkage of concrete incorporating superabsorbent polymers and supplementary cementitious materials

“…Observations of autogenous shrinkage were selected from NU database [52] (187 observations) and published studies about autogenous shrinkage of low water-to-cement ratio cement paste, mortar or concrete samples incorporating SCM [5,8,10,11,[13][14][15]17,20,21,[53][54][55][56][57][58][59][60][61][62][63][64][65][66][67][68][68][69][70][71][72][73][74] and / or SAP [28,29,33,39,[75][76][77][78][79][80][81][82][83][84][85][86]…”

The Influence of Zeolitic By-Product Containing Ammonium Ions on Properties of Hardened Cement Paste

“…Lv et al [5] used natural zeolite in cement systems and determined that the incorporation of 20% natural zeolite reduced the autogenous shrinkage. The addition of zeolite reduced the autogenous shrinkage of high-performance or ultra-high-performance cement-based concrete [4,6,7]. The experiments were based on the substitution of cement with zeolite (up to 15%) or on the replacement of standard sands with zeolite sands (15% and 30%).…”