This study aimed to investigate the effects of different curing temperatures on the hydration and mechanical properties of high-volume fly ash (HVFA) concrete. The key variables were curing temperature (13 °C, 23 °C, 43 °C) and fly ash (FA) content (0%, 35%, 55%). The hydration characteristics of HVFA cement were examined by evaluating the setting time and …
AbstractSawcut timing of contraction joints in concrete pavements is affected by interactions between the time-dependent concrete properties, notch depth, base friction, climate, and type of saw. E...
Reducing the carbon footprint of the cement industry has become one of the main concerns of researchers in the field. This study explores different strategies to reduce the setting retardation effect of high-SO 3 fly ash (HSFA) on cement paste.The SO 3 phase was found to correspond to hannebachite (CaSO 3 ·0.5H 2 O). Chemical (calcium chloride), physical (fine …
The color and shape of the fly ash class F demonastrated in Figure 1(a). Another Fly ash type was used in the concrete mortar which is named Class C dry fly ash [18] obtained froma commercially availablelocal company. Specific gravity is 2.74 and fineness is 316 m2/kg. The chemical compositions of two types of fly ash are
Heat-cured fly ash based geopolymer concrete achieved good properties in terms of strength and durability because of its high alumina and silica content which form the ... (50% GGBS + 50% fly ash) decrease initial setting time by 85 min and 25 min and decrease final setting time by 19.5 hrs and 40 min compared to that of FA and FASS mixes ...
This paper investigates the incorporation of ordinary portland cement (OPC) to adjust/improve the workability, setting time, and compressive strength of Class F fly ash (FA)-based geopolymer binder.
On the other hand, the final setting time for cement is from the moment where it is mixed with water until it starts to gain structural strength and lose its plasticity ... . A study showed that the calcium content affects the setting time of fly ash-based geopolymers . Low-calcium fly ash is known to have long setting times, ...
This study focusses on upgrading the fresh and hardened properties of fly ash-based geopolymer mix samples such as initial and final setting time, flow table test and compressive strength with the substitution of ground granulated blast furnace slag at varied percentage levels and with different alkali binder ratios. Substitution of slag in geopolymer mix …
There are 4 combinations of setting time test in this research focusing on setting time of ultra fine fly ash as binder and the use of lime water as mixing water. The combinations are: a. Portland …
fly ash or ground-granulated blast-furnace slag, the setting times are generally increased compared with Type I cement concrete, because hydration of the cement replacement …
Standard test method for time of setting of hydraulic cement by vicat needle. West Conshohocken, PA: ASTM. Google Scholar ... Tribikram Kundu, Alkali Activated Fly Ash-Based Concrete: Evaluation of Curing Process Using Non-Linear Ultrasonic Approach, Journal of Nondestructive Evaluation, Diagnostics and Prognostics of Engineering Systems, 10. ...
identified the two primary causes preventing increased use of fly ash in ready-mixed concrete: 1) performance issues including setting time and strength gain, and 2) specifications that restrict …
Ordinary Portland cement (OPC) is known for its significant contribution to carbon dioxide emissions. Geopolymer has a lower footprint in terms of CO2 emissions and has been considered as an alternative for OPC. …
Using Test Method for Time of Setting of Concrete Mixtures Paste by Penetration Resistance (ASTM C 403), Proctor penetration resistance was determined under isothermal curing temperatures ranging from 6 to 80°C for concretes containing up to 50% of fly ash or ground-granulated blast-furnace slag.
The results indicated that fresh geopolymer concrete had short setting time of 28-58 min due to the presence of high calcium content of fly ash. In general, strengths and modulus of elasticity increased with the increase in NaOH concentration. For compressive strength, the optimum Na²O content was around 12% of fly ash.
The mortar mixtures were produced at a constant water/binder ratio of 0,50 and at a binder/sand ratio of 2,5. In order to evaluate the effect of fly ash on cement hydration, fly ash was used at a cement replacement level of 10%, 20% and 30% (by total mass of binder).
This document is a chemistry investigatory project report on the setting of cement. It includes an introduction on cement and its uses. The aim is to study how the strength of cement mixtures with sand, fly ash, and lime varies over time. The methodology involves preparing mixtures and testing their strength after 3, 7, and 10 days.
Vol. 07, No. 1, February 2022: 24-28 Effect Of Borax On Setting Time Of Geopolymer Concrete Based On Fly Ash Type C [26] − FigureBG5B = Geopolymer concrete with
AbstractIn this paper, setting time, strength and bond of high-calcium fly ash geopolymer concrete were investigated. The high-calcium fly ash was from Mae Moh power plant in northern Thailand. Both sodium silicate solution and sodium hydroxide solution were used as alkali activators in every mix. Sodium hydroxide solution with 10 M, 15 M, and 20 M concentrations, sodium …
To provide a comprehensive understanding, this research examines the compressive strength, mineral phase, chemical bonds, and microscopic evolution of fly ash geopolymer mortar incorporating...
In this study, ordinary Portland cement (ASTM Type I) and de-air water were used. Fly ash blended cement pastes with water to binder (cement + fly ash) ratio 0.4 by mass were prepared in an environmental chamber with temperature (20 ± 5 °C) and humidity (90 ± 5%).These pastes were noted as F0, F10, F20, F30, F40, F50, F60 and F70 in which the …
Research showed that fly ash used as an additive to Portland cement has a number of positive effects on the resulting concrete. A decrease in water demand, decreasing the water:cement …
The pH value measured in fly ash, according previous research, can influence the setting time of geopolymer and fly ash with high pH values can cause flash-setting in the concrete.
Geopolymer binders are attracting the attention of researchers as substitution to cement binder in conventional concrete. In manufacturing 1 ton of cement, 1 ton of CO2 is released into the atmosphere. Thus, replacement of cement by geopolymer material in construction industry reduces pollution by two ways: reduction in carbon dioxide emission into …
Principally, it is a flowable material which is frequently prepared by using coal fly ash (≥ 70 wt% solids, depending on both specific gravity and mineralogy) [19, 20] and then mixing with single or composite cement (3–30%, ordinary Portland cement OPC or a mix of OPC and other mineral additives such as slag, pulverized fly ash and silica ...
This study aims to study the feasibility of using additives to prolong the setting times of high-calcium fly ash-based geopolymer. Moreover, the effect of sodium silicate and sodium hydroxide ratios (S/N) on the compressive strength was observed by varying ratio at 1.0–2.5 by weight (wt%).
Some fly ashes may delay the time of set and may reduce the need for a retarder. Water reducers. Fly ash concrete normally requires less water, but it can be further improved with the use of a water-reducing admixture. ... First-time users of fly ash in concrete should evaluate the performance of proposed mixes prior to construction. All ...
In this paper, setting time, strength and bond of high-calcium fly ash geopolymer concrete were investigated. The high-calcium fly ash was from Mae Moh power plant in northern Thailand.
A model for predicting the initial setting time of concrete with and without fly ash is presented. Based on a theoretical initial spacing between the particles of unhydrated cementitious material ...
The results show that as the temperature increases, the initial and final setting times decrease for all types of concrete, with fly-ash concrete having the longest setting times. At …
The important point to identify fly ash character in geopolymer is its setting time and strength in paste form. Setting time is the most important thing to identify because if the paste set rapidly, …
Geopolymer concrete with low calcium oxide fly ash occurs long enough hardening time. This study aims to influence the use of CaO in gypsum, lime and carbide waste in the testing of setting the time on geopolymer and conventional paste. ... the longer the setting time of the concrete paste. Geopolymer paste 8M and 12M with the addition of a ...
Fly ash prolongs the setting time either class C or class F ie high calcium or low calcium fly ash because of its low heat of hydration, which prolong the setting time and it...
Setting time tests were conducted under two conditions, 17 °C and 28 °C, as the room temperature greatly affects the setting time and workability of the alkali-activated fly ash/slag concrete. Compressive strength tests were conducted using a universal testing machine according to ASTM C 39 at 3, 7, 14, 28 and 56 days.
Fly Ash Geopolymer Concrete Pattanapong Topark-Ngarm1; Prinya Chindaprasirt2; and Vanchai Sata3 ... The results indicated that fresh geopolymer concrete had short setting time of 28–58 min due to the presence of high calcium content of fly ash. In general, strengths and modulus of elasticity increased with the increase in NaOH concentration. ...
The input data required for the model are water-cementitious material ratio, fineness, specific gravity, temperature, and the blended oxide ratio: CaO/(SiO2 + Al2O3 + Fe2O3). Final setting …
The proper slag content in an alkali-activated fly ash/slag mixture was determined to be 15-20% of total binder by weight considering the setting time and compressive strength of the alkali ...
Recently, alkali-activated high calcium fly ash (FA) has been investigated for use as a repair material due to its advantage of reasonable setting time and hardening [8].It has also been shown that alkali-activated high calcium FA could be used as an alternative commercial repair material with relatively high 28-day compressive and shear bond strengths comparable …