Micro and macro level properties of natural zeolite contained concretes

•Effect of natural zeolite, as a supplementary cementitious material (SCM), on properties of concretes having different w/cm.•SEM/XRD study on pastes containing natural zeolite.•Influence of natural zeolite, as an SCM, on quality of paste and transition zone.

This study assesses effects of natural zeolite, as a supplementary cementitious material, on micro and macro properties of pastes and concretes having different water-to-cementitious materials ratios. The experimental program included evaluation of strength, transport properties, and microscopic images. Strengths of natural zeolite contained concretes were almost similar to or slightly lower than that of reference concretes. Transport properties improved considerably through replacing a portion of Portland cement with natural zeolite, whereas contrary was found for carbonation depth. The microstructure analysis showed modifications in transition zone and quality of pastes by use of natural zeolite through production of secondary C–S–H.