The Effect of Variation of Molarity of Alkali Activator and Fine Aggregate Content on the Compressive Strength of the Fly Ash: Palm Oil Fuel Ash Based Geopolymer Mortar

Abstract

The effect of molarity of alkali activator, manufactured sand (M-sand), and quarry dust (QD) on the compressive strength of palm oil fuel ash (POFA) and fly ash (FA) based geopolymer mortar was investigated and reported. The variable investigated includes the quantities of replacement levels of M-sand, QD, and conventional mining sand (N-sand) in two concentrated alkaline solutions; the contents of alkaline solution, water, POFA/FA ratio, and curing condition remained constant. The results show that an average of 76% of the 28-day compressive strength was found at the age of 3 days. The rate of strength development from 3 to 7 days was found between 12 and 16% and it was found much less beyond this period. The addition of 100% M-sand and QD shows insignificant strength reduction compared to mixtures with 100% N-sand. The particle angularity and texture of fine aggregates played a significant role in the strength development due to the filling and packing ability. The rough texture and surface of QD enables stronger bond between the paste and the fine aggregate. The concentration of alkaline solution increased the reaction rate and thus enhanced the development of early age strength. The use of M-sand and QD in the development of geopolymer concrete is recommended as the strength variation between these waste materials and conventional sand is not high.

The Effects of Various Concentrations of NaOH on the Inter-Particle Gelation of a Fly Ash Geopolymer Aggregate

“…It is because of the high concentration of NaOH solution that produces a greater dissolution process from the leaching of silica and alumina. This great dissolution process will contribute to the increase in geopolymerization reaction [ 24 ]. The percentage of increasing density regarding the increasing concentration of sodium hydroxide is related to the aggregate impact value of the fly ash geopolymer aggregate, which shows that a denser aggregate will also contribute to a better mechanical strength.…”

Influence of Molarity and Chemical Composition on the Development of Compressive Strength in POFA Based Geopolymer Mortar

“…The utilization of waste materials or industrial by-products, such as fly ash (FA), metakaolin (MK), silica fume (SF), ground granulated blast furnace slag (GGBS), rich husk ash (RHA), and palm oil fuel ash (POFA), as binders in the development of geopolymer concrete is gaining momentum [1][2][3] due to the overuse of virgin materials in the production of ordinary Portland cement (OPC). The use of OPC has resulted in a high volume of carbon dioxide (CO 2 ) emissions, as the construction industries cannot replace the use of OPC entirely with the other cementitious materials due to the huge demand for concrete.…”

Performance of hybrid fibre reinforced geopolymer concrete beams

“…where d = defective depth of beam in mm, x n = depth of neutral axis in mm, I cr = cracked moment of inertia of the transformed section in mm 4 Then stress in steel (f s ) is calculated using Eq. 3At yielding, f s = f y (yield stress in N/mm 2 ) and M = M y (yield moment in N-mm) and substituting this in Eq.…”

“…Attempts were made in the past to reduce the usage of cement in concrete by replacing it with other suitable materials so as to reduce the cost and make concrete more eco-friendly. One of the alternatives to produce more eco-friendly concrete is to replace cement in concrete with suitable eco-friendly material, such as fly ash, palm oil fuel ash rice husk ash (RHA), silica fume (SF), ground granulated blast furnace slag (GGBFS) and metakaolin [3][4][5][6]. An important investigation in this regard is the development of high volume fly ash concrete that contains about 60% fly ash [3].…”