RELIABILITY OF ALKALI-ACTIVATED AND PORTLAND CEMENT MORTAR UNDER COMPRESSIVE TEST BY ACOUSTIC EMISSION

Abstract

Alkali-activated materials or geopolymer technology is one of the material innovations that can provide several benefits by reducing the use of Portland cement. The source of precursor materials come from industrial by-products. This study investigated the reliability failure of seven-variation of alkali-activated fly ash/slag/micro-silica mortar (AAM) and one-type of Portland Cement (PC) mortar. Compressive strength test accompanied by acoustic emission is used to characterize cylindrical mortar specimens. Examination of fracture distribution according to stress level until final failure was then performed. The compressive strength of four-type of alkali-activated mortar AAM (AAM-IV, V, VI, and VII) at 14 and 28 days shows a slight strength increase, 61.9 to 63.6 MPa, 62.3 to 65.6 MPa, 64.8 to 68.3 MPa and 63.1 to 63.6 MPa, respectively. The slight increase of AAM compressive strength is caused by high early strength achieved due to the replacement of more than 40 % of fly ash with GGBFS.  The presence of more CaO in the AAM mixture accelerates the reaction in early age. By contrast, PC mortar shows significantly strength increases from 55.2 MPa to 69.5 MPa during the same period. Amplitude filters greater than (50dB, 60dB, 70dB and 80 dB) is utilized to investigate the reliability of compressive strength of the mortar by acoustic emission. It was found that filter greater than 60dB is the most suitable filter. Alkali-activated mortars which contain raw material of 42.5% fly ash, 42.5% GGBFS, and 15% micro-silica has the lowest reliability of failure than those of other mortars whereas Portland cement mortar shows the highest reliability of failure than other alkali-activated mortars.