Combined Effect of Polypropylene Fiber and Nano Calcium Carbonate to Improve Compressed Earth Blocks Produced from Clayey Soil, Kirkuk City, Iraq

This research studies the effect of adding polypropylene fibers and nano-calcium carbonate to compressed earth blocks. The soil used is taken from the Laylan area, north of Kirkuk City, Iraq. Chemical and physical tests are performed to determine soil properties. Different percentages of fibers (0%, 0.1%, 0.2%, 0.3%, and 0.4 %) and nano calcium carbonate (0.05%, 0.15%, and 0.25%) are added to dry weight of soil in different water percentages. Two sets of blocks are produced in both small-scale and large-scale; the blocks are compressed using a manual pressing machine with a pressure of 15 MPa. Compressive, flexural, and durability tests are performed for the block specimens to determine the effect of the added materials on the compressed earth block. The results show the best improvement by fiber and nano calcium carbonate observed at 28 days of curing period for blocks with 0.2% fiber-0.25% nano calcium carbonate treatment, and the highest compressive reaches 17.9 MPa for the small-scale blocks and 7.7 MPa for the large-scale blocks; and the highest flexural strength is 1.67 MPa. Furthermore, the results show that the durability index increases with increasing percentages of fibers and nano-calcium carbonate, which indicates mass loss percentages decrease with increasing percentages of additive improvers for the compressed earth blocks.