Pottery Sand as Fine Aggregate for Preparing Alkali‐Activated Slag Mortar

Abstract

Alkali-activated slag (AAS) mortars were prepared using pottery sand as a fine aggregate in a ratio of 1 : 1.75 using a blend of sodium silicate and NaOH as an alkaline activator at room temperature. e effects of sodium oxide content and silicate moduli on the setting time, fluidity, consistency, compressive strength, and drying shrinkage of different AAS mortars were determined. ese results revealed that sodium oxide content and silicate modulus had little effect on the setting time and workability of the mortar; however, they did have a significant effect on their mechanical performance and drying shrinkage levels. All the AAS mortars exhibited faster setting times, better workability, and higher early and late compressive strength compared to traditional mortars. Optimum compressive strength was achieved at 93 and 123 MPa after 1 d and 28 d, respectively, using a silicate modulus of 1.2 and Na 2 O content of 8%. e microstructures of mortars were characterized using scanning electron microscopy with energy dispersive spectrometric (SEM/EDS) and mercury intrusion porosimetry (MIP). ese results reveal that AAS mortars containing pottery sand as a fine aggregate may represent a promising building material with improved properties for use in the construction industry.

Use of Industrial Waste Slag in Alkali-Activated Slag Ceramsite Concrete Hollow Blocks

“…It is worth noting that Wang et al [15] have reported that the slump, slump flow, and setting time of an AASC cannot be tested as its viscosity is too high and it exhibits no plasticity when the liquid-solid ratio is 0.45. Therefore, the setting time and slump of the AASC were not tested; values for the setting time and fluidity of AAS mortars can be found in Reference [12].…”

“…The observed density of the pore structure of AASC provides a great deal of its strength. Previously, the authors of Reference [12] indicated that the pore size distribution of alkali-activated slag mortars included three ranges (<50 nm, 50-10,000 nm, >10,000 nm) within which the pore structure <50 nm played a significant role in the drying shrinkage: the higher the volume of pores <50 nm, the greater was the drying shrinkage resulting from the higher contracting stress influenced by the finer capillary pores [53].…”

“…However, mix M1.2N6 tended to set quickly and thus necessitated rapid placement and consolidation in the molds. According to a previous study [12], the setting time of the mortar corresponding to a silicate modulus of 1.2 and Na 2 O content of 6% is too short, limiting its potential applications. However, the setting time of M1.2N8 was somewhat longer than that of M1.2N6, while the compressive strength of M1.2N8 was 96.8%, 99.2%, 98.8%, and 91.3% that of M1.2N6 after 3, 7, 14, and 28 days, respectively, and never less than 45 MPa.…”

“…Alkali-activated cementitious material is an inorganic binder consisting of a mixture of alkaline activator and silicate cementitious materials, such as fly ash, metakaolin, phosphorous slag, steel slag, or blast furnace slag [6]. Many researchers have indicated that alkali-activated slag concrete (AASC) provides excellent mechanical performance [7,8], good durability [9,10], and fast setting times [11,12]. In general, the key parameters determining the properties of AASC are the composition of materials, type of alkaline activator, and the admixtures used [11,13,14].…”

Experimental study on high-temperature resistance of alkali-activated slag concrete block masonry

“…The mix proportion of the crushed AASCM aggregate and AASCM paste of specimens was the same as that of the block and mortar. The mix proportions of the block and mortar were adjusted according to that of the alkali-activated slag ceramsite concrete and alkali-activated slag mortar with pottery sand, as reported by Zhu et al (2018a, 2018b, 2019). The specimens were constructed by staggering five layers of main blocks and auxiliary blocks.…”