Microstructural investigation and strength properties of structural lightweight concrete produced with Zeolitic tuff aggregate

Abstract

In this study, physical, mechanical, and microscopic investigations were carried out on structural lightweight concretes (LWC) produced with zeolitic aggregate. Zeolitic tuff aggregate, 300 kg/m 3 , and 400 kg/m 3 dosages OPC and 0.70 and 0.45 water/cement ratios were used in LWC productions. An optical microscope method was used to determine the aggregate-cement interface zone (ITZ) on the hardened LWC. SEM analyses were performed on the specimens to determine microstructural properties as well. Moreover, water absorption, capillary suction , and compressive strength tests were carried out. The experimental results showed that ITZ thickness and compressive strength are significantly depend on the cement dosage and w/c ratio in structural LWC. ITZ thicknesses were measured 20–33% less in LWC produced with a 0.45 w/c ratio and the 400 kg/m 3 cement dosage. On the SEM analyses, dense CH and ettringite formations were observed at the early age of all LWC in high w/c ratios. However, on the 28 th day, well-formed CSH structures were observed in large areas with lower w/c ratios. • Waste zeolitic tuff can be used as lightweight aggregate in structural lightweight concrete. • 30% lighter buildings can be constructed by using LWC produced with zeolitic tuff as aggregate in structural elements. • Buildings constructed by LC20 and LC30 classes LWC produced with zeolitic tuff can be more cost-effective. • Zeolitic tuff enhanced the microstructural properties of LWC in terms of ITZ.