AbstractThe present study envisaged the development of a novel admixture based on the composites of amino trimethylene phosphonic acid and boric acid (AB) that exhibited an intense inhibition of the hydration effects for Portland cement. The study was aimed to lay a solid foundation for the utilization of AB in large volume concrete by reducing the temperature control measures. The setting time at different temperatures, and the compressive strength of the cement pastes containing AB were examined. The hydration characteristics of the Portland cement containing AB were investigated using isothermal calorimetry measurements, X-ray diffraction, thermogravimetric analysis, Zeta potential, and scanning electron microscope. The results showed that the fitting curves for the setting time of amino trimethylene phosphonic-based material (ATMP) exhibited a linear relation in the concentration range of 0.02% to 0.40%. However, the fitting curves for the setting time of AB presented an exponential relation in the concentration range of 0.02% to 0.20%, and exhibited a linear relation at the addition dosages from 0.20% to 0.40%. It was observed that, at 0.40% concentration, the initial and final setting times of the AB sample was longer by 1,954 min and 3,767 min, respectively, than those of the ATMP sample. ATMP and AB exhibited intensive retarding effects at higher temperatures, and the temperature adaptability of both ATMP and AB was excellent. The reduction in the cumulative hydration heat and heat evolution rate effect in the Portland cement was significantly higher in AB than ATMP. AB substantially inhibited the formation of Ca(OH)2 (CH) and ettringite (AFt) than ATMP. Thus, the inhibition of cement hydration by AB was clearly superior to that of ATMP, which could be attributed to the inhibition of C3S and C3A hydration by AB.

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