Hydration and strength development in blended cement with ultrafine granulated copper slag

Abstract

This study aims at evaluating the effect of ultrafine granulated copper slag (UGCS) on hydration development of blended cement and mechanical properties of mortars. The UGCS with the median particle size of 4.78 μm and BET surface area of 1.31 m 2 /g was used as a cement replacement to prepare blended cements. Hydration heat emission of blended cement and mechanical performance of mortars were investigated by using isothermal calorimetry and strength tests, respectively. X-ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) were applied to the analysis of pozzolanic reaction and hydration products. The results illustrate that UGCS has influence on the hydration heat evolution of blended cement due to its filler effect and pozzolanic reaction. The cumulative hydration heat of blended cement is reduced by partial cement replacement with UGCS. The test mortar prepared by using blended cements with 30 wt. % UGCS shows a retardation of strength development with a low value at early ages (7 days) and a rapid growth at later ages (28 days). The 90-day compressive strength of test mortar is 45.0 MPa close to that of the control mortar (49.5 MPa). The obtained results from XRD and TGA analysis exhibit an increase in calcium hydroxide (CH) consumption and calcium silicate hydrates (C–S–H) formation in blended cement pastes with curing time. The cement replacement with UGCS induces changes in microstructure of blended cement paste and chemical composition of hydration products.

Experimental Investigation on Short-term Properties of High-flowing Fine-grained Concrete Applying for Marine Structures

“…Figure 4. Generally, the compressive strength of concrete, particularly HFFC specimens increases with normal curing time due to the cement hydration and the pozzolanic reaction of binder materials [28]. This tendency was also observed in this study.…”

Mechanical Strength and Hydration Characteristics of Cement Mixture with Highly Concentrated Hydrogen Nanobubble Water

“…In all cases, major hydration products such as portlandite (Ca(OH) 2 , CH), ettringite, unhydrated clinker minerals, and calcite (CaCO 3 ) were observed; the peak corresponding to CH was particularly strong. CH and ettringite were produced via an active hydration reaction at the initial stages of curing [ 43 ]. During underwater curing, CH collectively dissolved in water, and calcium ions (Ca 2+ ) were formed.…”

“…It was determined that a small amount of carbon dioxide (CO 2 ) was released into the atmosphere and reacted with calcium ions to generate calcite [ 44 ]. In the case of calcium silicate hydrate (C-S-H), which plays a crucial role in enhancing the strength of the cement mixture, the crystal phase was not observed in the XRD pattern, because it was amorphous and irregular [ 43 , 45 ].…”

The effect of added high-iron slag on the frost resistance of cement compositions

“…Together with portlandite, calcium hydro silicate C-S-H, goethite FeOOH is formed, which corresponds to the endothermic effect -300 qC. [13][14][15][16] The considered iron-containing acidic slag contains divalent iron cations Fe 2+ in the glass phase and olivine (curve 1 in Fig. 1).…”