Evaluation of physical characteristics and microscopic structure of mortar containing synthetic resin

• The applicability of synthetic resin as neutron shielding aggregate were evaluated.
• The strengths showed overall reduction regardless of the type of synthetic resin.
• The HDPE and PP appeared that the ITZ was wider than OPC.
• The UPE was the dense than the HDPE and PP.
• The UPE shows even distribution at the whole but the HDPE and PP are not uniform.

This study investigated the applicability of synthetic resin as neutron shielding aggregate provided by its high hydrogen content. The adopted synthetic resin was mixed using quantities of high density polyethylene (HDPE), polypropylene (PP) and ultra-high molecular weight polyethylene (UPE) replacing the fine aggregates by volume ratios of 20%, 40% and 60% converted into weight. Slump flow and tensile and compressive strength tests were conducted to evaluate the physical properties of the mortar, and image analysis, SEM and X-ray CT were performed on the fracture surface to examine the micro-structure inside the specimens. The flow of the mortar containing synthetic resin increased when using HDPE and PP but decreased in the case of UPE. Besides, the tensile and compressive strengths tended to reduce at the whole regardless of the type of resin. The image analysis showed that the strength of mortar containing HDPE and PP was influenced by the fraction of synthetic resin at the fracture surface regardless of the quantities. It seemed that the non-uniform distribution of the materials and faults with the cement matrix inside mortar provoked the loss of strength. On the other hand, larger content in powdered UPE increased the internal porosity. The loss of strength remained insignificant under a definite level but became steep beyond this level and, especially for replacement ratio higher than 60% in the present study.