# The Effect of Cementitious Macrocapsule Addition on the Hardened Properties of Concrete with Different Packing Structures

## TL;DR

This study examines how adding cementitious capsules affects concrete properties, finding that capsule size, dosage, and aggregate packing influence strength and voids.

## Contribution

The novel contribution is evaluating the impact of capsules in concrete with different packing structures and identifying an optimal fine fraction for strength.

## Key findings

- Capsule addition reduces compressive strength, with variation based on fine fraction, capsule dosage, and size.
- An optimal fine fraction of 0.4 maximizes strength and minimizes voids in aggregate mixtures.
- Capsules show good bonding with concrete matrix and break during compression tests.

## Abstract

This paper aims to assess the influence of cementitious capsules on the hardened properties of concrete, considering several parameters such as the fine fraction (n) of aggregates, capsule size, and capsule dosage. The presence of capsules has been formerly found to disturb packing, which eventually escalates the voids ratio of the inert skeleton. In order to understand the behavior of capsules in various packing structures, two mix design programs were developed, resulting in twenty-three concrete mixtures. The fine fraction of the aggregates was determined to be from 0.2 to 0.8. Both long and short cementitious capsules were used, with dosages of 1 to 7 vol.%. The results show that the incorporation of capsules reduced the compressive strength of concrete, and this reduction varied depending on the fine fraction, capsule dosage, and capsule size. Nevertheless, the optimum fine fraction was found to be 0.4, corresponding to the highest strength and the lowest voids ratio of the aggregate mixtures. In addition, a good bond between the capsule shell and the concrete matrix was showcased, and the embedded capsules broke during compression.