Tanakorn Phoo-ngernkham

Properties of high calcium fly ash geopolymer pastes with Portland cement as an additive

The effect of Portland cement (OPC) addition on the properties of high calcium fly ash geopolymer pastes was investigated in the paper. OPC partially replaced fly ash (FA) at the dosages of 0, 5%, 10%, and 15% by mass of binder. Sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) solutions were used as the liquid portion in the mixture: NaOH 10 mol/L, Na2SiO3/NaOH with a mass ratio of 2.0, and alkaline liquid/binder (L/B) with a mass ratio of 0.6. The curing at 60°C for 24 h was used to accelerate the geopolymerization. The setting time of all fresh pastes, porosity, and compressive strength of the pastes at the stages of 1, 7, 28, and 90 d were tested. The elastic modulus and strain capacity of the pastes at the stage of 7 d were determined. It is revealed that the use of OPC as an additive to replace part of FA results in the decreases in the setting time, porosity, and strain capacity of the paste specimens, while the compressive strength and elastic modulus seem to increase.

Marginal lateritic soil stabilized with calcium carbide residue and fly ash geopolymers as a sustainable pavement base material

AbstractTwo waste by-products, fly ash (FA) and calcium carbide residue (CCR), are used to develop geopolymer binders for stabilizing marginal lateritic soil as a sustainable pavement base. The liquid alkaline activator is a mixture of sodium silicate solution (Na2SiO3) and sodium hydroxide (NaOH) at a concentration of 10 molars. Unconfined compressive strength (UCS) and scanning electron microscopy (SEM) images of lateritic soil–FA geopolymers at different influential factors (curing times, Na2SiO3∶NaOH ratios, and CCR replacement ratios) are measured. The soaked 7-day UCS of lateritic soil–FA geopolymers meets the strength requirement for both light and heavy traffic pavement specified by the local national authorities. The early 7-day UCS and cementitious products increase with increasing CCR replacement ratio, and the cementitious products are clearly observed at CCR = 30% (the highest CCR replacement ratio tested). However, the CCR replacement ratio providing the maximum 90-day strength is found at 2...

Strength prediction of cement-stabilised reclaimed asphalt pavement and lateritic soil blends

Abstract In this research, marginal lateritic soil (LS) was used for improving the gradation properties of reclaimed asphalt pavement (RAP) prior to cement stabilisation for heavy and light-volume roads. The unconfined compressive strength (q u ) of cement-stabilised RAP–marginal LS blends was found to increase with LS replacement due to the improvement of gradation properties and lower asphalt binder content. The soil–water/cement ratio (w/C) was successfully implemented for a particular RAP:LS ratio to integrate the effects of water and cement contents on strength development at the optimum water content and on the wet side of optimum. By incorporating a new parameter termed as the asphalt binder content (AS), a general strength relation equation was proposed for various water contents, cement contents and RAP:LS ratios. The general strength relation of cement-stabilised RAP-marginal LS blends is presented based on three critical material constants, which are A*, B* and k . The A* and B* constants mainly depends on curing time, while the k constant is essentially the same. The general strength relation was furthermore validated with measured strength data. The general strength relation is useful as a mix design tool for determining the optimal input of cement for various RAP:LS ratios to meet strength requirement for base and subbase applications. A mix design method with a minimum trial test is furthermore proposed in this paper.

Strength Development and Durability of Alkali-Activated Fly Ash Mortar with Calcium Carbide Residue as Additive

Abstract The strength development and durability of alkali-activated fly ash (FA) mortar with calcium carbide residue (CCR) as additive cured at ambient temperature were investigated in this paper. CCR was used to partially replace FA as additional calcium in the alkali-activated binder system by a weight percentage of 0%, 10%, 20% and 30%. Sodium hydroxide and sodium silicate solutions were used as liquid alkaline activation in all mixtures. Test results show that the incorporation of CCR has an effect on the strength development of alkali-activated FA mortar with CCR. The setting time of alkali-activated FA mortar with CCR has decreased whereas its strength development has increased. This is further confirmed by XRD, SEM, and FTIR analyses, which show that the reaction products were increased when the alkali-activated FA incorporated with CCR. The highest 28-day compressive strength of alkali-activated FA mortar was found in the mix of 70% FA and 30% CCR, which is about 40.0 MPa. In addition, the resistances of alkali-activated FA mortar incorporated with CCR to tap water, 5% H2SO4 solution, and 5% MgSO4 solution are found to be superior to those of alkali-activated FA mortar without CCR as indicated by the relatively low strength loss. For the samples immersed in 5% H2SO4 solution and 5% MgSO4 solution for 120 days, the alkali-activated FA incorporated with 30% CCR showed a low strength reduction of around 71% and 53%, respectively.

Water Treatment Sludge–Calcium Carbide Residue Geopolymers as Nonbearing Masonry Units

AbstractIn this research, water treatment sludge (WTS) calcium carbide residue (CCR) geopolymers were evaluated as a sustainable masonry nonbearing unit. The WTS was a by-product from a water treat...

A Mix Design Procedure for Alkali-Activated High-Calcium Fly Ash Concrete Cured at Ambient Temperature

This research focuses on developing a mix design methodology for alkali-activated high-calcium fly ash concrete (AAHFAC). High-calcium fly ash (FA) from the Mae Moh power plant in northern Thailand was used as a starting material. Sodium hydroxide and sodium silicate were used as alkaline activator solutions (AAS). Many parameters, namely, NaOH concentration, alkaline activator solution-to-fly ash (AAS/FA) ratio, and coarse aggregate size, were investigated. The 28-day compressive strength was tested to validate the mix design proposed. The mix design methodology of the proposed AAHFAC mixes was given step by step, and it was modified from ACI standards. Test results showed that the 28-day compressive strength of 15–35 MPa was obtained. After modifying mix design of the AAHFAC mixes by updating the AAS/FA ratio from laboratory experiments, it was found that they met the strength requirement.

Adhesion characterisation of Portland cement concrete and alkali-activated binders

In this paper, alkali-activated binders (AAB) are investigated for their potential use as repair materials of Portland cement concrete (PCC). The adhesion characterization of PCC and repair materials using AAB made from fly ash (FA) and Portland cement (PC) activated with sodium hydroxide and sodium silicate solutions, AAB made from FA and calcium hydroxide (CH) activated with sodium hydroxide and sodium silicate solutions, and commercial repair material (RMs) have been investigated. Test results show that the AAB with additives gives high bond strength which is similar to the use of RMs. Bond strength between PCC substrate and AAB with additives are improved, due to increased reaction products especially C-S-H gel. However, the CH replacement at 15% shows a large amount of calcite resulting in reduction in bond strength. The failure patterns and fracture interface images of the tested specimens also demonstrate the quality of the developed bond strength. It was shown that the interface zone of PCC substr...