Investigation on the resistivity of concrete with high density polyethylene (DHPE) as partial replacement for fine aggregates against sulfate attack

• Main Authors: Borbon, Grant Yves Martin V., Go, Kenrick F., Jardiniano, Rockwell Moricz G.
• Format: text
• Language: English
• Published: Animo Repository 2018
• Subjects: Concrete; High-density polyethylene
• Online Access: https://animorepository.dlsu.edu.ph/etd_bachelors/7083
• Institution: De La Salle University

Sulfate attack poses as one of the threats in construction through the deterioration of the concrete material. Due to the limited studies that have been conducted regarding the matter, the problem is often deemed to be negligible. However, previous studies from other countries consider sulfate attack to be a serious complication in terms of construction. The formation of ettringite crystals lead to the deterioration of the mechanical properties of concrete, as well as the expansion of the cement paste. To address the issue, partial substitution of high-density polyethylene (HDPE) as fine aggregates was investigated under the effects of sulfate attack for HDPE is considered resistant against certain chemicals, especially sodium sulfate. The mechanical properties of the first set of concrete specimens were tested. The second set was then exposed in a sodium sulfate solution with a concentration of 50 grams per liter for twenty-eight (28) days before testing its mechanical properties. The mortar bars were submerged in the same solution before assessing the length change and formation of ettringite crystals through scanning electron microscope (SEM). Results show that the change in compressive strength is insignificant for increasing percentage substitution but a significant decrease of the splitting tensile and flexural strength for the concrete specimens. The mortar bars show increasing sulfate resistivity as the percentage of HDPE replacement increases. Also, the SEM testing procedure exhibits less ettringite formation with the increase HDPE present in the mortar bars by considering its interfacial transition zone (ITZ). Thus, the partial substitution of HDPE as fine aggregates is beneficial in resisting sulfate attack. Moreover, 10% of the volume of fine aggregates replaced with HDPE is considered as the ideal percentage substitution in terms of volume.