Muhammad Aamer Rafique Bhutta

Mix design and compressive strength of geopolymer concrete containing blended ash from agro-industrial wastes

Geopolymer concrete is a type of amorphous alumino-silicate cementitious material. Geopolymer can be polymerized by polycondensation reaction of geopolymeric precursor and alkali polysilicates. Compared to conventional cement concrete, the production of geopolymer concrete has a relative higher strength, excellent volume stability and better durability. This paper presents the mix design and compressive strength of geopolymer concrete manufactured from the blend of palm oil fuel ash (POFA) and pulverized fuel ash (PFA) as full replacement of cement with a combination of sodium silicate and sodium hydroxide solution used as alkaline liquid. The density and strength of the geopolymer concrete with various PFA: POFA ratios of 0:100, 30:70, 50:50 and 70:30 together with sodium silicate to sodium hydroxide solution by mass at 2.5 and 1.0, are investigated. The concentrations of alkaline solution used are 14 Molar and 8 Molar. Tests were carried out on 100x100x100 mm cube geopolymer concrete specimens. Specimens were cured at room temperature and heat curing at 60°C and 90°C for 24 hours, respectively. The effects of mass ratios of PFA: POFA, the alkaline solution to PFA: POFA, ratio and concentration of alkaline solution on fresh and hardened properties of concrete are examined. The results revealed that as PFA: POFA mass ratio increased the workability and compressive strength of geopolymer concrete are increased, the ratio and concentration of alkaline solution increased, the compressive strength of geopolymer concrete increases with regards to curing condition.

Sulphate Resistance of Geopolymer Concrete Prepared from Blended Waste Fuel Ash

AbstractThe aim of this study is to investigate the performance of geopolymer concrete prepared using blended ash of pulverized fuel ash and palm oil fuel ash from agroindustrial waste along with alkaline activators when exposed to a 5% sodium sulphate solution for up to 18 months. Ordinary portland cement (OPC) concrete was also prepared as the control concrete. The main parameters studied were the evaluation of mass change, compressive strength, products of degradation, and microstructural changes. The deterioration was examined using X-ray diffraction (XRD), a Fourier transform infrared spectroscopy (FTIR), a thermogravimetry analyzer (TGA), and a field emission scanning electron microscope (FESEM). The results of geopolymer and OPC concretes were compared and discussed. The compressive strength of geopolymer concrete, when exposed to a 5% sodium sulphate solution for more than 1 year, was superior to that of OPC concrete. These materials could be used for making sulphate-resistant concretes, attributa...

Effects of polymer―cement ratio and accelerated curing on flexural behavior of hardener-free epoxy-modified mortar panels

This experimental study reports the applicability of hardener-free epoxy-modified mortar panels to permanent forms as precast concrete products. Hardener-free epoxy-modified mortars are mixed using a Bisphenoal A-type epoxy resin without any hardener with various polymer–cement ratios and steel fiber reinforcement, and subjected to different curings. Hardener-free epoxy-modified mortar panels are prepared with same polymer–cement ratios and steel fiber reinforcement on trial, and tested for flexural behavior under four-point (third-point) loading. The effects of polymer–cement ratios and curings on strength properties of hardener-free epoxy-modified mortars, and on the flexural strength, flexural stress-extreme tension fiber strain relation, flexural load–deflection relation of hardener-free epoxy-modified mortar panels were examined. The adhesion in tension (to placed concrete) of the hardener-free epoxy-modified mortar panels was also tested. As a result, the hardener-free epoxy-modified mortar panels develop a high flexural strength, large extensibility and good adhesion to the placed concrete. The epoxy-modified mortar panels are more ductile and have high load-bearing capacity than unmodified mortar panels and can be used as precast concrete permanent forms in practical applications.

Binary Effect of Fly Ash and Palm Oil Fuel Ash on Heat of Hydration Aerated Concrete

The binary effect of pulverized fuel ash (PFA) and palm oil fuel ash (POFA) on heat of hydration of aerated concrete was studied. Three aerated concrete mixes were prepared, namely, concrete containing 100% ordinary Portland cement (control sample or Type I), binary concrete made from 50% POFA (Type II), and ternary concrete containing 30% POFA and 20% PFA (Type III). It is found that the temperature increases due to heat of hydration through all the concrete specimens especially in the control sample. However, the total temperature rises caused by the heat of hydration through both of the new binary and ternary concrete were significantly lower than the control sample. The obtained results reveal that the replacement of Portland cement with binary and ternary materials is beneficial, particularly for mass concrete where thermal cracking due to extreme heat rise is of great concern.

Strength and Durability Characteristics of Polymer Modified Concrete Incorporating Vinyl Acetate Effluent

Waste generation from surface coating industries brings about worsening of the environmental scenery and human health in the world. The production of these wastes is detrimental to surrounding areas in landfill or dumping spaces, therefore necessary action is required to minimize the unpleasant situation. This research is aimed at using waste generated from the manufacture of paint known as vinyl acetate effluent as an admixture in concrete. The material is rinse water taken from the cleaning process reactor. Concrete of 0% vinyl acetate effluent cured in water with those of 2.5%, 5%, 10% and 20% by weight of cement were produced and cured using Japanese standard. The specimens were tested for compressive strength, splitting tensile strength and durability at 3, 7 and 28 days. Findings show that incorporating of 2.5% of Vinyl acetate effluent improves strength properties of concrete. Higher resistance of water absorption and sulfate conditions were observed in polymer modified concrete. The study has shown that incorporating vinyl acetate effluent in producing polymer modified concrete could bring lights of using the waste material for sustainable and environmental preservations.

UNDERWATER ADHESION OF POLYMETHYL METHACRYLATE CONCRETES TO REINFORCING STEEL (REINFORCING BARS)

In this research work, polymethyl methacrylate (PMMA) concretes are prepared and tested for bond strength through the pullout of vertically embedded reinforcing bars in PMMA concretes. The specimens are placed underwater at 20 deg C and in air at 20 deg C and 50% relative humidity for 1, 3, 7, and 28 days. To improve the bond strength of PMMA concretes to the reinforcing bars embedded underwater, a silane coupling agent is added to PMMA binders. To prevent the formation of rust on the reinforcing bars and effectively improve the bond strength between PMMA concretes and reinforcing bars with the silane coupling agent in underwater construction work, the use of the reinforcing bars coated by three types of processes is examined. As a result, a significant improvement in the bond strength between PMMA concretes and reinforcing bars with silane coupling agent embedded underwater is achieved, and the coating of the reinforcing bars with a PMMA binder before PMMA concrete placement is recommended to prevent the formation of rust on reinforcing bars.