RESISTIVITY AGAINST SULFATE ATTACK OF CONCRETE WITH HDPE AS PARTIAL SUBSTITUTE FOR FINE AGGREGATES

Abstract

High-Density Polyethylene (HDPE) when used as partial substitute of fine aggregates in concrete is investigated to determine if it addresses sulfate attack in concrete. Since HDPE is known to be resistant against chemical compounds including sodium sulfate, it is hypothesized in this study that sulfate attack problems in concrete will be lessened by incorporating HDPE in concrete mix. Mechanical properties of concrete were determined to ensure that HDPE is limited to an amount where there will be no serious compromise to strength, hence, compressive, and split tensile test are included in the study. To determine the influence of HDPE in addressing sulfate attacks, length change of mortar specimen is investigated using ASTM C1012 (length change of mortar exposed to sulfate solution). Scanning Electron Microscopy (SEM) is also employed to qualitatively assess the microstructure of concrete with HDPE exposed to sulfate attacks. Mechanical test results showed that increasing HDPE did not adversely affect the compressive strength. However, there was a decrease observed in tensile strength. To achieve balance between mechanical properties, HDPE replacement of fine aggregates was set at 10% by weight of fine aggregates. The mortar bar test demonstrated that increasing HDPE resulted to an increased resistivity against sulfate attacks. SEM have also shown reduction in voids and ettringite with increasing HDPE content