Research Project Details

Influence of locally available burnt clay brick aggregates on bond strength of concrete-to-steel interface.

Project ID: WUB/2022/P1/028

Project Duration: 2022 - 2023

Project Leader: Md Hasibul Hasan (Department of Civil Engineering)

Project Members: Sagor Kumar Podder, Taimur Rahman.

As a developing country, Bangladesh is undergoing massive change with regards to people’s housing in urban areas as well as rural areas. To accommodate overpopulated urban areas, high-rise buildings are being constructed to utilize vertical space. As the average living standard is rising in rural area, people are building better houses. Thus, amount of construction of reinforced concrete buildings are rising day by day. Crashed burnt clay bricks are the major source of coarse aggregate in production of concrete in Bangladesh. By understanding the bond behavior of concrete which use brick chips (khoa) as coarse aggregate with steel bars, development length can be computed appropriately instead of guess work. This research work aimed to verify the value of the parameter λ which is a modification factor reflecting the reduced mechanical properties of lightweight concrete, all relative to normal weight concrete of the same compressive strength. This parameter is being used in the equation proposed by Bangladesh National Building Code (BNBC) 2020 to calculate development length of reinforcing bars. Reduced value for the λ has been included in BNBC for lightweight concrete. Lightweight concrete defined in BNBC as concrete containing lightweight aggregate and an equilibrium density as determined by ASTM C567, between 1450 - 1850 kg/m3 . Density of brick chips is less than density of stone chips. Concrete made from brick chips may be categorized as lightweight concrete. The range of λ value provided in BNBC for lightweight concrete varied from 0.75 to 1. Choosing lower limit of the λ value will result 33% increase in development length which is not economical. More accurate value of the λ can be chosen based on density of the lightweight concrete. Problem lies in the determination of density of concrete made out of clay brick chips as properties of bricks manufactured in different brickfield defer significantly. The question is "what is the most suitable value for the λ to be used in Bangladesh?".