Durability and mechanical properties of seashell partially-replaced cement

Abstract

This research investigates the possibility of grinding and burning bivalve clam seashells to produce seashell ash powder. This ash is used to partially replace cement by 5, 10, 15 and 20% by weight. These mixes are tested and compared with a SC0 that has 0% seashell ash powder (SC0). The fresh and hardened properties of all mixes are studied through a variety of tests, including: slump, unit weight, compressive strength and splitting tensile strength. The durability of seashell concrete cubic specimens is studied by immersion in 5% NaOH(aq) and MgSO4(aq) solutions. The addition of thermally treated seashells increased the calcium hydroxide content. The results also show that the compressive strength of the 5% replacement is slightly higher than the SC0 at 28 and 90 days of age, while the tensile strength is higher than the standard for the 5% and 10% of replacement at 7 and 28 days. Furthermore, the slump test value generally increases with increasing the percentage of replacement. The highest durability against sulfate and alkaline attacks is obtained with 5% replacement of cement with seashells which reported the lowest decrease in weight and the highest compressive strength after immersion in 5% NaOH(aq) and MgSO4(aq) solutions. The 5% replacement mix is the optimum percentage of replacement. Therefore, this study recommends replacing cement with 5% seashell cement.