Abstract
This paper presents the experimental results of an on-going research project on geopolymer lightweight concrete using two locally available waste materials—low calcium fly ash (FA) and oil palm shell (OPS)—as the binder and lightweight coarse aggregate, respectively. OPS was pretreated with three different alkaline solutions of sodium hydroxide (NaOH), potassium hydroxide, and sodium silicate as well as polyvinyl alcohol (PVA) for 30 days; afterwards, oil palm shell geopolymer lightweight concrete (OPSGPC) was cast by using both pretreated and untreated OPSs. The effect of these solutions on the water absorption of OPS, and the development of compressive strength in different curing conditions of OPSGPC produced by pretreated OPS were investigated; subsequently the influence of NaOH concentration, alkaline solution to FA ratio (A/FA), and different curing regimes on the compressive strength and density of OPSGPC produced by untreated OPS was inspected. The 24-hour water absorption value for OPS pretreated with 20% and 50% PVA solution was about 4% compared to 23% for untreated OPS. OPSGPC produced from OPS treated with 50% PVA solution produced the highest compressive strength of about 30 MPa in ambient cured condition. The pretreatment with alkaline solution did not have a significant positive effect on the water absorption of OPS aggregate and the compressive strength of OPSGPC. The result revealed that a maximum compressive strength of 32 MPa could be obtained at a temperature of 65°C and curing period of 4 days. This investigation also found that an A/FA ratio of 0.45 has the optimum amount of alkaline liquid and it resulted in the highest level of compressive strength.
Highlights
The worldwide consumption of cement has risen to around 2.6 billion and the use of virgin materials in the production of cement has had negative impact on the environment [1]
Alkaline-activated binders are produced by the activation of different natural materials and industrial by-products such as fly ash (FA), metakaolin, ground granulated blast furnace slag (GGBS), kaolinitic clays, rice husk ash (RHA), and red mud are being used in the development of cementless concrete [2]
The results show that the compressive strength of oil palm shell geopolymer lightweight concrete (OPSGPC) made from a 14 M concentration of NaOH in alkali activator increased as the alkaline solution to FA ratio (A/FA) ratio increased from 0.2 to 0.45 and reach a peak of about 30 MPa at A/FA ratio of 0.45
Summary
The worldwide consumption of cement has risen to around 2.6 billion and the use of virgin materials in the production of cement has had negative impact on the environment [1]. Research works on minimizing the use of cement through waste materials such as fly ash (FA) and ground granulated blast furnace slag (GGBS) produced positive outcome. Alkaline-activated binders are produced by the activation of different natural materials and industrial by-products such as FA, metakaolin, GGBS, kaolinitic clays, rice husk ash (RHA), and red mud are being used in the development of cementless concrete [2]. Many researchers focussed their attention on the use of FA as an environmental friendly material to replace cement in concrete. Fly ash with lower levels of calcium is preferred for geopolymers because high amount of calcium can impact the process of polymerization and change the microstructure of the final geopolymer [7]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
