Document Type : Research Paper


Civil Engineering Dept., University of Technology-Iraq, Alsina’a street, 10066 Baghdad, Iraq.


This study aimed to develop an eco-friendly, lightweight, and synthetic aggregate (SLA) based on clay suitable for use in structural lightweight concrete. The researchers utilized the cold-bonded pelletization process to agglomerate pozzolanic materials, specifically attapulgite extracted from a quarry, and crushed into a fine filler. The appropriate calcination temperature for manufacturing this clay as a pozzolanic material is 750°C. A total of 22 mixes were created using a combination of high reactive attapulgite (HRA) and cement (PC), with the attapulgite replacement rate varying from 100-50% by a 10% decrement. Different types of curing methods, including oven-dry, oven-water, room-water, and room-room, were applied. The aggregate properties were evaluated to determine density, specific gravity, water absorption, aggregate impact value, crushing strength, and compressive strength. The results revealed that it could produce lightweight synthetic aggregate from clay-based materials with a bulk density of 793kg/m3 with suitable physical and mechanical properties. As the percentage of cement in the mixture increased, the specific gravity and density were increased to 18.12% and 36.61%, whereas impact and crushing values of aggregate improved by 81.83%. This, in turn, leads to a significant boost in compressive strength up to 100.94%. Furthermore, there is a noticeable decrease in absorption. Moreover, the aggregate held under oven water positively impacts the strength development of cement-based composites.

Graphical Abstract


  • SLA was fabricated using HRA and PC via a cold-bonded process
  • Different percentage levels of HRA and PC were used
  • SLA with a density of 793 kg/m3 can be produced


Main Subjects

  1. Atmaca, M. Ibrahim, and A. Atmaca, Comparison of Physical and Mechanical Properties of Cold Bonded and Sintered Lightweight Artificial Aggregates, Adıyaman Üniversitesi Mühendislik Bilim. Derg., 8 (2021) 560–570.
  2. Gesoğlu, E. Güneyisi, and H. Ö. Öz, Properties of lightweight aggregates produced with cold-bonding pelletization of fly ash and ground granulated blast furnace slag, Mater. Struct., 45 (2012) 1535–1546.
  3. Cement Manufacturer's Association (India), Ninth International Congress on the Chemistry of Cement, New Delhi, India, 1992.
  4. S. Mousavi, C. Bhojaraju, and C. Ouellet-Plamondon, Clay as a Sustainable Binder for Concrete—A Review, Constr. Mater., 1(2021) 134–168.
  5. Baykal and A. G. Döven, Utilization of fly ash by pelletization process; theory, application areas, and research results, Resour. Conserv. Recycl., 30 (2000) 59–77.
  6. B. Topçu and T. Uygunoǧlu, Properties of autoclaved lightweight aggregate concrete, Build. Environ., 42 (2007) 4108–4116.
  7. Y. Lo, W. C. Tang, and H. Z. Cui, The effects of aggregate properties on lightweight concrete, Build. Environ., 42 (2007) 3025–3029.
  8. Kayali, Fly ash lightweight aggregates in high performance concrete, Constr. Build. Mater., 22 (2008) 2393–2399.
  9. Atmaca, M. L. Abbas, and A. Atmaca, Effects of nano-silica on the gas permeability, durability and mechanical properties of high-strength lightweight concrete, Constr. Build. Mater., 147 (2017) 17–26.
  10. Gesoʇlu, E. Güneyisi, A. N. I. Ismael, and H. Ö. Öz, Internal curing of high-strength concretes using artificial aggregates as water reservoirs, ACI Mater. J., 112 (2015) 809–819.
  11. İpek, O. A. Ayodele, and K. Mermerdaş, nfluence of artificial aggregate on mechanical properties, fracture parameters and bond strength of concretes, Constr. Build. Mater., 238 (2020) 117756.
  12. Manikandan and K. Ramamurthy, Influence of fineness of fly ash on the aggregate pelletization process, Cem. Concr. Compos., 29 (2007) 456–464.
  13. S. Vali and S. Bala Murugan, Effect of different binders on cold-bonded artificial lightweight aggregate properties, Adv. Concr. Constr., 9 (2020) 183–193.
  14. Colangelo, F. Messina, and R. Cioffi, Recycling of MSWI fly ash by means of cementitious double step cold bonding pelletization: Technological assessment for the production of lightweight artificial aggregates, J. Hazard. Mater., 299 (2015) 181–191.
  15. Loginova, K. Schollbach, M. Proskurnin, and H. J. H. Brouwers, Municipal solid waste incineration bottom ash fines: Transformation into a minor additional constituent for cements, Resour. Conserv. Recycl., 166 (2021) 105354.
  16. Mohamad Ibrahim, K. N. Ismail, R. Che Amat, and M. Iqbal Mohamad Ghazali, Properties of cold-bonded lightweight artificial aggregate containing bottom ash with different curing regime, Int. Conf. Civ. Environ. Eng.,  (CENVIRON 2017) E3S Web Conf., 34, 2018.
  17. Geetha and K. Ramamurthy, Environmental friendly technology of cold-bonded bottom ash aggregate manufacture through chemical activation, J. Clean. Prod., 18 (2010) 1563–1569.
  18. Thomas, A. Mohan, and K. K. Dhannya, Copper slag cold-bonded aggregate concrete exposed to elevated temperature, ACI Mater. J., 117 (2020) 215–230. https://doi: 10.14359/51727000
  19. Thomas and B. Harilal, Mechanical properties of cold bonded quarry dust aggregate concrete subjected to elevated temperature, Constr. Build. Mater., 125 (2016) 724–730.
  20. İpek and K. Mermerdaş, Experimental & computational study on fly ash and kaolin based synthetic lightweight aggregate, Comput. Concr., 26 (2020) 327–342.
  21. A. Ibrahim and W. A. Abbas, Fresh Properties of Self-Consolidating Expired Cement-Fly Ash Cold Bonded Lightweight Aggregate Concrete With Different Mineral Admixtures, Eng. Technol. J., 41 (2023) 734–744.
  22. A. Ibrahim and N. Atmaca, Cold Bonded and Low Temperature Sintered Artificial Aggregate Production by Using Waste Materials, Period. Polytech. Civ. Eng., 67 (2023) 112–122.
  23. J. Frieh, W. A. Abbas, and S. H. Malik, Investigate the Iraqi Attapulgite clay as a Mineral Admixture for concrete, Eng. Technol. J., 32 (2014) 2364–2375.
  24. A. G. Zghair, H. H. Hamad, S. A. Mohamad, and R. K. S. Alhamd, Evaluate the compressive strength of cement paste modified with high reactivity attapulgite and affected by curing temperature, Mater. Today Proc., 52 (2022) 361–366.
  25. Jiang et al., Assessment of Early Hydration and Microstructures of Portland Cement Incorporating Calcined Attapulgite, Arab. J. Sci. Eng., 2023.
  26. ASTM, Standard Specification for Coal Fly Ash and Raw or Calcined Natural Pozzolan for Use, Annu. B. ASTM Stand., no. C, pp. 3–6, 2010.
  27. ASTM C330, Standard Specification for Lightweight Aggregates for Structural Concrete, ASTM Int., 5524, 2009.
  28. ACI Committee, ACI 211.2-98 supersedes ACI 211.2-91 and became effective, Am. Concr. Inst., 1–18, 1998.
  29. American Society for Testing and Materials, ASTM C127-15: Standard Test Method for Density, Relative Densit  (Specific Gravity), and Absorption of Coarse Aggregate, ASTM Stand. B., C, 1–6, 2013.
  30. Bureau of Indian Standards (BIS), Specification for Apparatus for Aggregate Impact Value, IS : 9377 - 1979, Bur. Indian Stand., no. April 1980, 1979.
  31. British Standard BS EN 1097-2 2010 Tests for Mechanical and Physical Properties of Aggregates Method of Determination of R, 3–5, 2010.
  32. BS EN 13055-1, Lightweight aggregates - Part 1: Lightweight aggregates for concrete, mortar and grout, Br. Stand. Inst., 1–40, 2002.
  33. Arslan and G. Baykal, Utilization of fly ash as engineering pellet aggregates, Environ. Geol., 50 (2006) 761–770.
  34. R. Wasserman and A. Bentur, Effect of lightweight fly ash aggregate microstructure on the strength of concretes, Cem. Concr. Res., 27 (1997) 525–537.