Development and Promotion of Concrete Strength at Initial 24 Hours

Abstract

Knowing and promoting the strength development of concrete at an earlier age is essential for accelerating formwork circulation of the on-site construction and precast product manufacture. The strength development rate at earlier ages of less than the initial 24 h was investigated. The effect of measures of adding silica fume, calcium sulfoaluminate cement, and early strength agent on the strength development of earlier concrete at ambient temperatures of 10, 15, 20, 25, and 30 °C was studied. The microstructure and long-term properties were further tested. It is shown that the strength increases exponentially first and then logarithmically, different from what is commonly recognized. Increasing cement content exhibited a certain effect only above 25 °C. When the cement content increased from 420 to 460 kg/m3, the strength only increased from 6.2 to 6.7 MPa after 12 h at 25 °C. The early strength agent could increase the strength significantly, the strength could be increased from 6.4 to 10.8 MPa after 20 h at 10 °C and from 7.2 to 20.6 MPa after 14 h at 20 °C. All measures for promoting earlier strength did not have an evident negative effect. The results could be potentially referred for the formwork removal at a suitable moment.

Evaluation of Early-Age Compressive Strength in Winter Prefabrication: A Comparative Study

“…However, this expedited process encounters notable challenges, especially under wintry conditions, where the concrete's hydration process, crucial for strength development, is impeded by low temperatures. This poses a significant risk to attaining the minimum compressive strength of 10 MPa required for the safe handling of prefabricated panels [13][14][15][16][17].…”

“…Despite extensive research into the prefabrication of concrete elements, there remains a significant gap in our understanding of how different environmental conditions, particularly winter conditions, affect the early strength development of precast concrete [13,18,19]. However, the specific challenges associated with cold weather accelerated curing processes are less explored, particularly with regard to the overall structural integrity and safety of precast concrete elements.…”

Early Strength of Concrete by using Ground Granulated Blast Furnace Slag and Local Ordinary Portland Cement Materials

“…An alternative technique entails mixing pozzolans and chemical accelerators, like calcium nitrate and triethanolamine, with regular concrete [8]. It has also been discovered that adding 15% Metakaolin and accelerators to regular Portland cement can improve its early strength and durability performance [9]. Furthermore, early strength agents, calcium sulfoaluminate cement, and silica fume can help concrete develop its strength earlier [10].…”