Most of the steel mills in Bangladesh use induction furnace which produces large quantities of slags that have very little use except land filling. Therefore, feasibility of using this slag is examined in concrete with recycled aggregate, which is another waste product that is generated due to removal of old structures. Concrete with three target strengths, 17.23, 20.68, and 24.13 MPa, was prepared using recycled concrete acquired from a recently demolished building in Dhaka, Bangladesh. Recycled coarse aggregate was replaced with induction furnace slag by 0%, 25%, 50%, 75%, and 100% for each target strength. Samples prepared from these concretes were tested for workability, compressive strength, splitting tensile strength, modulus of elasticity, and durability properties e.g., porosity, absorption, and rapid chloride penetration. Review of test results suggests that workability of concrete was not adversely affected by incorporation of induction furnace slag. For up to 50% of induction furnace slag replacement, both compressive strength and splitting tensile strength increased in recycled aggregate concrete. Further, for all ratios of induction furnace slag replacement, modulus of elasticity increased compared to 100% recycled aggregate concrete. Porosity and absorption also decreased in concrete where up to 50% of recycled aggregate was replaced by induction furnace slag. Considering these, it is concluded that 50% of recycled aggregate can be replaced by induction furnace slag that will result in superior mechanical and durability properties in recycled aggregate concrete.

Water permeability characteristic of concrete made from crushed clay bricks as coarse aggregate is investigated and compared with concrete made from natural stone aggregate. For this, six different brick and five different natural stone samples were selected. Crushing strength of brick samples and water absorption of aggregate produced from them were also measured. Concrete samples of three different compressive strengths were prepared as per ACI mix design method from each of these aggregate samples. Compressive strength of concrete that could be achieved with brick aggregate varied between 19 and 28 MPa, whereas, for stone aggregate, compressive strength varied between 24 and 46 MPa. These samples were then tested for water permeability using the AT 315 machine as per EN 12390-8: “Depth of Penetration of Water under Pressure.” Experimental results and subsequent analysis indicate that water permeability of brick aggregate concrete is 225% to 550% higher than that of concrete made from natural stone aggregate of identical compressive strength. Water permeability was found to be directly related to compressive strength, water absorption, and porosity of hardened concrete. It was also observed that water permeability of concrete is influenced by water absorption of brick aggregate and crushing strength of brick.

To study the effect of crushed clay bricks as coarse aggregate on creep behavior of concrete, a comprehensive testing program was conducted. Concrete cylinder specimens having characteristic or specified compressive strength of 17.2, 24.0, and 27.5 MPa were prepared from both natural stone and crushed clay brick aggregate. Mix design ratios were evaluated in a way so that volumetric content of coarse aggregate, both brick and stone, remained same for all concrete samples. Specimens were subjected to creep testing at the 7th and 28th day after casting and creep strain data were recorded up to 300 days. Results show that although strength and other environmental parameters remain the same, concrete made from crushed clay brick as coarse aggregate have a higher creep strain than that of concrete made from natural stone aggregate. This increase in creep strain ranges from 30% to as high as 45% for the 300-day loading history considered. Additionally, to select an appropriate model to predict creep in brick ag...

In this paper, structural adequacy and life-cycle economic feasibility of bamboo as primary construction material for a rooftop low-height telecommunication tower is examined. For this, a relatively strong locally cultivated bamboo species in Bangladesh named Bambusa tulda has been selected for the project. A joint system with transverse steel bolts, with steel plates attached to these bolts, has been proposed as a mechanism to transfer a load between different bamboo members of the tower. Bamboo samples have been tested using this joint system to ascertain the characteristic compressive (40.5 MPa), tensile (53.4 MPa), and bending strength (73.1 MPa) and also the corresponding modulus of elasticity. A 5-m high bamboo lattice tower has been modeled in the three-dimensional finite-element software SAP2000. The analysis results have showed that maximum axial and bending stresses developed in bamboo members of a 5-m high tower is much less than the allowable stresses of bamboo. The top deflection of the bamboo tower has been checked and is found to be within the acceptable limit. An analysis considering a 15-year life-cycle has showed that the bamboo tower is 18% less expensive than a galvanized iron (GI) pipe tower of an equivalent height, which it intends to replace. This proves that a low-height rooftop telecommunication tower may be economically constructed using bamboo.

This study investigates the utilization of waste iron slag (WIS) as a sustainable alternative in concrete production to reduce environmental impact and preserve natural resources. The experimental investigation of WIS-incorporated concrete focused on compressive and tensile strength with machine learning (ML) models for prediction. Among the tested ML algorithms, Decision Tree (DT) and XGBoost showed the highest accuracy (R² = 0.95135) in predicting concrete strength properties, while models like SVM and Symbolic Regression underperformed. Experimental results indicate that up to 20 % WIS replacement maintains adequate strength, whereas higher proportions reduce structural integrity. A ranking score index and cost analysis confirmed the technical and economic feasibility of using WIS in concrete. Cost analysis demonstrated substantial cost savings with 25 % WIS incorporation, confirming its economic feasibility. Integrating experimental data with ML predictions highlights WIS's potential for sustainable concrete applications, enabling optimized mix designs and reduced reliance on physical testing. Future work should address limitations, including dataset expansion and the exploration of additional durability and mechanical properties to validate WIS's practicality in construction further.