Effect of ash-and-slag waste on the properties of sulphoaluminate portland cement

Abstract

Introduction: there is practically no information on the utilization of ash and slag waste (ASW) application in technology of special (noncontracting, expanding, self-stressing) cements, which predetermines the relevance of research in this direction. The study investigates the properties of experimental samples from cement, ash-and-slag and sand mixtures based on sulphoaluminate Portland cement (SAC) with an additive of the ASW.
 
 
 Materials and methods: a fine-particle binder material consisting of the SAC produced by the Podolsk Cement factory with a fine-grained ASW additive was used to obtain a binder mixture. Silica sand functioned as fine aggregate. All the raw materials used were local to the Russian Federation. The setting time, soundness, and strength of the binder mixture were determined according to GOST 30744-2001 standard. The specific surface area of the Portland cement was established through the use of the air permeability method utilizing of PMTs-500 instrument. The microstructure of the hardened binder mixture was studied employing electron microscopic analysis and X-ray phase analysis.
 
 
 Results: the work investigates the effect of 10 %, 15 %, 20 %, and 50 % ASW additive on the water demand, strength, and setting time of the SAC. The article also explores the kinetics of hardening and structure formation of samples from the binder mixture based on the SAC and ASW for hardening under normal conditions.
 
 
 Conclusions: results of the investigation allow recommending the ASW characterized by high dispersion as an additive for production of special cements without significant reduction of their properties. In the presence of the ASW, setting times of the cement mixtures virtually do not change as compared with the pure SAC. With limiting the amount of the ASW in the composition of the Portland cement, the strength characteristics do not practically change through the entire period of hardening.

Influence of Acid-Activated Micro-Dispersed Additive on the Properties of Cement Sulphate-Resistant Compositions

“…Additionally, it is proposed to grind ash together with a superplasticizer. In this case, a nanomodified organomineral additive is formed, which has a high homogeneity and chemical activity [14].…”

“…Ash, when combined with a superplasticizer, is capable of at the same time reducing the water demand of the concrete mixture [14]. According to K.S.…”

“…According to K.S. Stenechkina the use of ash-based modifiers reduces delamination, water separation, and also reduces the formation of fine-grained concrete efflorescence [14].…”

“…When a nano-modifier based on mechanically activated fly ash is introduced into a multicomponent binder, a greater number of crystals are formed. In a concrete system, an increase in strength and density occurs [14,18]. In addition, according to the authors of [1] fly ash has the properties of an independent hydration-hardening binder, which are enhanced by mechano-chemical activation of ash by additional grinding with cement and a setting regulator.…”

“…The introduction of up to 50 % fly ash contributes to the preservation of the strength of finegrained concrete [1,14]. The introduction of up to 40 % of activated fly ash contributes to an increase in strength up to 50 %.…”