Lowering cement content in mortar by adding superfine zeolite as cement replacement and optimizing mixture proportions

Abstract

Reducing the cement consumption in concrete construction is an effective method to lower the carbon footprint and alleviate global warming. One strategy is to replace part of cement by a cementitious or non-cementitious filler. Another strategy is to optimize the mixture proportions to minimize the cement content. Although these strategies have been separately adopted, there is little research on their combined adoption. To study the feasibility of combining these two strategies, a number of mortar samples with varying amount of superfine zeolite (SZ) added, binder/aggregate (B/A) ratio and water/binder (W/B) ratio were made for packing density, flowability, cohesiveness and strength tests. The results revealed that adding 5% SZ to replace cement would increase the packing density and flowability and decrease the cement/strength ratio by 17%–28%, depending on the other mixture parameters. There is an optimum B/A ratio for minimum cement/strength ratio, which is generally lower at lower strength level. The use of a suitable B/A ratio of 0.65 or 0.55 instead of a constant and conservative value of 0.75 at strength level lower than 60 MPa could reduce the cement content by about 10%.