The use of silica-breccia as a supplementary cementing material in mortar and concrete

• Silica-breccia as a newly discovered supplementary cementing material is introduced.
• The durability of Silica-breccia mortar samples is investigated.
• The fresh and mechanical properties of Silica-breccia concrete samples are investigated.
• Silica-breccia with a particle size <20 μm can be qualified as a supplementary cementing material.
• The addition of 10% Silica-breccia slightly enhanced the mechanical properties of concrete.

Silica-breccia (SB), also known as Aplite, is a newly discovered supplementary cementing material (SCM) that has shown to have some pozzolanic effect when mixed with cement. Like any other SCM, pulverized SB reacts with the calcium hydroxide formed during Portland cement hydration, creating additional cementitious products that modify the mixture structure and enhance its overall strength and durability. The objective of this study was to investigate the effectiveness of using SB as a supplementary cementing material in mortar and concrete. The first part of the investigation included testing the pozzolanic activity index, sodium sulfate attack, and alkali-silica reactivity on mortar samples containing SB. The second part was designed to test the fresh properties and mechanical performance of concrete samples containing SB. The investigation also involved testing other SCM’s including fly ash, metakaolin, silica fume, and slag for comparison. The results showed that pulverized SB with a particle size less than 20 μm can be qualified as an alternative SCM. Replacement of cement by 10% SB slightly enhanced the mechanical and durability performance of mortar and concrete samples. The results also showed that the addition of SB improved the mixture workability and proved to enhance the fresh properties of self-consolidating concrete mixture.