Development of Strength for Calcium Aluminate Cement Mortars Blended with GGBS

Abstract

In the present study, the development of strength in different calcium aluminate cement (CAC) mixture mortars with granulated ground blast-furnace slag (GGBS) was investigated. The substitution of GGBS levels was 0, 20, 40, and 60% weight of binder, of which the CAC used in this study naturally contained C2AS clinker as a secondary phase. To activate a hydraulic nature of the phase, in addition to the mineral additive, all specimens were cured at 35 ± 2°C for the first 24 hours and then stored in a 95% humidity chamber at 25 ± 2°C. The penetration resistance of fresh mortar was measured immediately after pouring, and the mortar compressive strength was monitored for 365 days. Simultaneously, to evaluate the hydration kinetics at early ages, in terms of heat evolution, the calorimetric analysis was performed at the isothermal condition (35°C) for 24 hours. The hydration behavior in the long term was characterized by X-ray diffraction, which was supported by microscopic observation using scanning electron microscopy with energy dispersive spectroscopy. Furthermore, an examination of the pore structure was accompanied to quantify the porosity. As a result, it was found that an increase in the GGBS content in the mixture resulted in an increased setting time, as well as total heat evolved for 24 hours in normalized calorimetry curves. In addition, the strength development of mortar showed a continuous increased value up to 365 days, accounting 43.8–57.5 MPa for the mixtures, due to a formation of stratlingite, which was identified at the pastes cured for 365 days using chemical and microscopic analysis. However, GGBS replacement did not affect on the pore size distribution in the cement matrix, except for total intrusion volume.

Assessment of Altawseea Ordinary Portland Cement Northern Iraq: Mineralogy, Microstructure, and Hydration

“…The C3A phase is the product of the interaction of three molecules of calcium oxide with one package of aluminum oxide at a temperature ranging from (1200 -1280)C ̊ inside the rotary kiln. Its reaction with water or hydration process is very fast, so the temperature emitted from this reaction is high, and this phase is characterized by high early hardness, and the late hardness is weak (Yang et al, 2019). This phase is called Tri Calcium Aluminate and is found in clinker as a secondary phase (Yang et al, 2019).…”

The Effect of Fine-Ground Glass on the Hydration Process and Properties of Alumina-Cement-Based Composites

“…In many articles, researchers have considered the possibility of reducing the conversion of cement hydration products by using mineral additives such as blast furnace slag, fly ash, silica fume, metakaolin and zeolite [ 11 , 12 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ]. Replacing part of alumina cement with these mineral additives reduces the heat of hydration and causes a reduction in strength.…”

Calorimetry in the studies of by-pass cement kiln dust as an additive to the calcium aluminate cement

“…Mickiewicza 30, 30−059 Kraków, Poland volume changes and strength reduction. The reactive silica released from these additives enters the hydration process, and the so-called strätlingite phase C 2 ASH 8 is produced [9][10][11][12][13][14][15].…”

“…Recently, the use of both high-calcium aluminate material and the by-products of different origins are discussed from the "environmental footprint" point of view [13,14,18,19]. It has been found that usage of CAC as a component of different dry mixtures demonstrates significant environmental benefits in terms of environmental impact (low CO 2 emission, low energy demand vs. early compressive strength, etc.)…”