Workability and Compressive Strength of Multi-binder Concrete with Calcined Clay
摘要
The use of calcined clay as an alternative cement replacing material (CRM) in Thailand has been recently developed with the goal of reducing CO2 emissions. However, there has been a lack of comprehensive studies on the properties of concrete incorporating calcined clay in Thailand. Therefore, this study is focused on assessing the viability of incorporating calcined kaolinite clay into concrete as a CRM. Two calcined clays produced from clay with different kaolinite contents, limestone powder, Mae Moh fly ash, and BLCP fly ash are utilized with a Portland composite cement, which includes 10% limestone powder. Different binder systems, including control, binary, ternary, and quaternary, are employed with a 0.6 water-to-binder ratio under controlled initial slump facilitated by superplasticizers. The study involves analyzing the basic properties of all binders, monitoring initial slump and slump loss, and compressive strength at 7 and 28 days. It was noted that the use of calcined clay reduces the workability of concrete. However, the inclusion of limestone powder and fly ash as partial replacements for calcined clay improved the workability of the calcined clay mixes while using less amount of superplasticizers. The calcined clay produced from clay with 35% kaolinite content had a better compressive strength than calcined clay produced from clay with 25% kaolinite content. Moreover, increasing the limestone powder proportion in the calcined clay mix adversely affected the compressive strength, while the addition of Mae Moh fly ash showed similar compressive strength values as the calcined clay-cement mix.