Effect of organic additives on reactive powder concrete

Effect of organic additives on reactive powder concrete

Abstrakt

Reactive powder concrete (RPC) is an ultra-high performance cementitious composite that was first presented by Richard and Cheyrezy in the 1990s. This ma- terial normally consists of cement, microsilica, fine aggregate, superplasticizer and fibers. Unlike ordinary concrete, no coarse aggregate is used here, and the particle size of the individual components is designed in such a way to minimize the poro- sity of the material. Furthermore, compared to ordinary concrete, a significantly lo- wer amount of mixing water is used during preparation. It is obvious that for such a dense material with an extremely low water content, it will be crucial to maintain suitable workability of the mixture. Therefore, the possibility of increasing the wor- kability of RPC with the use of organic additives was investigated in this work. Studied additives were added to the RPC mixture in dissolved form in the RPC preparation process in one step together with water and superplasticizer. The effect of the additives on the flow of RPC was monitored. Furthermore, its influence on the course of RPC hydration was monitored using isothermal calorimetry. The effect on the compressive strength, flexural strength and specific weight of RPC was also monitored. It was observed that compounds of simple carboxylic acids and alkali metals in combination with calcium formate, make it possible to increase the workability of RPC. The resulting specific weight values show that the observed increase in workability was not related to these additives causing foaming of the RPC mixtures.

Reactive powder concrete (RPC) is an ultra-high performance cementitious composite that was first presented by Richard and Cheyrezy in the 1990s. This ma- terial normally consists of cement, microsilica, fine aggregate, superplasticizer and fibers. Unlike ordinary concrete, no coarse aggregate is used here, and the particle size of the individual components is designed in such a way to minimize the poro- sity of the material. Furthermore, compared to ordinary concrete, a significantly lo- wer amount of mixing water is used during preparation. It is obvious that for such a dense material with an extremely low water content, it will be crucial to maintain suitable workability of the mixture. Therefore, the possibility of increasing the wor- kability of RPC with the use of organic additives was investigated in this work. Studied additives were added to the RPC mixture in dissolved form in the RPC preparation process in one step together with water and superplasticizer. The effect of the additives on the flow of RPC was monitored. Furthermore, its influence on the course of RPC hydration was monitored using isothermal calorimetry. The effect on the compressive strength, flexural strength and specific weight of RPC was also monitored. It was observed that compounds of simple carboxylic acids and alkali metals in combination with calcium formate, make it possible to increase the workability of RPC. The resulting specific weight values show that the observed increase in workability was not related to these additives causing foaming of the RPC mixtures.

Reactive powder concrete, organic additives

Reactive powder concrete, organic additives

ŠULEKOVÁ, N.; NOVOTNÝ, R.; ŠOUKAL, F.

28.11.2024

Vysoké učení technické v Brně, Fakulta chemická, Purkyňova 464/118, 612 00 Brno

Brno

978-80-214-6298-4

Studentská odborná konference - Chemie je život 2024 - Sborník abstraktů

66

66

1

https://www.fch.vut.cz/vav/konference/sok/vystupy/sbornik-abstraktu-2024-p276490