Development and Experimental Performance Evaluation of Sustainable Concrete Incorporating Industrial Waste and Recycled Construction Materials for Low-Carbon Infrastructure

2026-10-08T07:02:02+00:00

Concrete production is a major source of anthropogenic carbon emissions, and the reuse of construction and demolition waste together with industrial by-products offers a practical route to reduce this burden. This study reports an experimental programme on seven concrete mixtures designed at a fixed water-to-binder ratio of 0.45 and a fixed total binder content of 380 kg/m³. Natural coarse aggregate was replaced by mass with 0%, 25%, and 50% recycled concrete aggregate (RCA), 30% of the Portland cement was replaced by a binary blend of 20% ground granulated blast-furnace slag (GGBS) and 10% fly ash, and in one mixture a further 5% of the binder mass, taken from the Portland cement, was replaced by silica fume, which gave a total cement replacement of 35%. Slump, compressive strength at 7, 28, and 90 days, splitting tensile and flexural strength, ultrasonic pulse velocity (UPV), water absorption, and rapid chloride penetration test (RCPT) charge passed were measured, and an itemised raw-material embodied carbon inventory was prepared for every mixture. Among the investigated mixtures, R50S30SF5 (50% RCA and 35% cement replacement) showed the best combination of properties, although no formal optimization procedure was applied. Its compressive strength was 43.8 MPa at 28 days and 47.9 MPa at 90 days, which is 6.4% and 2.0% below the control, its RCPT charge passed was 37% lower than that of the control (1980 C compared with 3150 C), and its calculated embodied carbon was 247.3 kg CO₂-eq/m³ compared with 356.9 kg CO₂-eq/m³ for the control, a reduction of 30.7%. At 28 days, the binary binder alone did not offset the strength loss caused by 50% RCA, and its benefit appeared mainly at 90 days and in combination with silica fume. The results show that these waste streams can be combined into concrete with mean strengths of about 44 to 48 MPa and a lower embodied carbon, but characteristic strength, chloride transport coefficients, and a wider life cycle boundary must be established before structural use.

The Production of Geopolymer Concrete in Iraq Using Raw Local Materials

2026-09-07T07:07:16+00:00

Geopolymer concrete is an emerging construction technology in Iraq, and further research is needed to assess its technical performance, economic feasibility, environmental benefits, and long-term durability. Such investigations are essential to determine its suitability as a sustainable alternative to conventional Portland cement concrete and to support its potential adoption in Iraq’s construction sector. This study investigates the feasibility of producing geopolymer concrete using locally sourced Iraqi fly ash and imported fly ash as aluminosilicate precursors. Locally available attapulgite clay was also investigated as a geopolymer precursor and pozzolanic material following thermal treatment. The experimental program examined the compressive strength and workability of the geopolymer concrete mixtures, as well as the influence of different curing methods. Three curing conditions were investigated: water immersion, oven curing at 60°C, and outdoor ambient curing. The results demonstrated that geopolymer concrete could be produced using locally sourced Iraqi fly ash, despite the imported fly ash exhibiting a higher content of certain chemical constituents. The mixture incorporating high-reactive attapulgite achieved the highest compressive strength among the mixtures investigated. Curing conditions had a significant influence on strength development, with oven curing at 60°C producing the highest compressive strength, while water-immersion curing resulted in the lowest strength. In terms of workability, the imported fly ash mixture exhibited the highest slump compared with the local fly ash and attapulgite mixtures. Overall, the findings demonstrate the potential of locally available Iraqi materials for geopolymer concrete production and provide a basis for further research into their application as a sustainable alternative to conventional concrete materials in Iraq.

Journal of Construction and Building Materials Engineering

Development and Experimental Performance Evaluation of Sustainable Concrete Incorporating Industrial Waste and Recycled Construction Materials for Low-Carbon Infrastructure

The Production of Geopolymer Concrete in Iraq Using Raw Local Materials