Sodium Silicate-Activated Slag Grout for Rapid Early Strength
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Solution Overview
Problem
Current cementitious compositions with high slag content exhibit low reactivity and limited early compressive strength, making them unsuitable for applications requiring rapid hardening and high mechanical properties, especially in aggressive environments or for backfilled grouts and self-leveling applications.
Innovation Solution
A multi-component cementitious composition comprising ground granulated blast furnace slag and a sodium silicate solution with at least 42 wt.-% sodium silicate, combined with a binder and hardener component, achieving a high early compressive strength of over 0.5 MPa within 2 hours and a gel time of 10 to 100 seconds, with a water-to-solids ratio of 0.5 to 0.95, and optional additives like superplasticizers and fly ash.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high slag content is used in cementitious composition, then durability and low heat development are improved, but reactivity and early compressive strength deteriorate
Solution Approach 1:
The invention changes the chemical parameters by introducing sodium silicate solution (containing Na2O and SiO2) as an activator. This modifies the compositional parameters of the slag system, enabling high reactivity and early strength development while maintaining high slag content (60-95 wt%). The sodium silicate provides alkali activation that overcomes the inherent low reactivity of slag.
Solution Approach 2:
The invention creates a composite cementitious material combining ground granulated blast furnace slag with sodium silicate solution. This composite system leverages the durability advantages of slag while the sodium silicate component provides the necessary activation energy and chemical environment for rapid strength development, achieving both high durability and early strength.
2Object-generated harmful factors
If high slag content is used in cementitious composition, then CO2 emissions are reduced, but reactivity and setting speed deteriorate
Solution Approach 1:
The invention introduces sodium silicate solution as a chemical activator that changes the reaction parameters of the slag system. This enables rapid setting and hardening (gel time 10-100 seconds, early compressive strength >0.5 MPa within 2 hours) while maintaining high slag content (60-95 wt%), thus preserving the low CO2 emission advantage of slag-based cements.
Solution Approach 2:
The sodium silicate solution acts as an intermediary substance that facilitates the activation of slag. It provides the necessary chemical environment (alkaline conditions and silica source) to trigger rapid geopolymerization reactions in the slag, enabling fast setting without compromising the environmental benefits of high slag content.
3Strength
If traditional Portland cement systems are used, then early compressive strength is achieved, but stability and workability in aggressive environments deteriorate
Solution Approach 1:
The invention creates a composite material system combining ground granulated blast furnace slag with sodium silicate solution. This composite provides both rapid strength development (>0.5 MPa within 2 hours) and superior chemical resistance due to the geopolymer matrix formed, which is inherently more resistant to aggressive environments than traditional Portland cement systems.
Solution Approach 2:
The invention changes the fundamental chemical composition and microstructure of the cementitious material by using sodium silicate-activated slag instead of Portland cement. This results in a geopolymer system with different hydration products and microstructural characteristics that provide both early strength and enhanced durability in aggressive environments.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composition provides a compressive strength up to 20 times higher than traditional Portland cement systems, with improved stability and workability, enabling its use in structural applications and backfilled grouts with enhanced performance.
Implementation Method 1
Geopolymer hardening is based on the formation of three dimensional aluminumsilicate networks. Usually geopolymers are fabricated from mixtures of silicate precursors such as sodiumsilicate and an aluminium source such as calcined bauxite.
Implementation Method 2
The use of granulated blast furnace slag is permitted as a cement component by European standard EN 197-1, type II (Portland slag cement) and III (blast furnace cement) up to a theoretical slag content of 95%. This high value is related to the potential hydraulicity of slag and its activability in cementitious mixtures
Implementation Method 3
the ratio of total water to the combined solids in the binder and hardener component is in the range of 0.5 to 0.95
Implementation Method 4
When this by-product is quickly cooled, a vitreous granulate with latent hydraulic properties is obtained
Data Source
AI summary
The present application is directed at a multi-component cementitious composition with at least a binder and a hardener component, wherein the binder component comprises ground granulated blast furnace slag and water and wherein the hardener component comprises a sodium silicate solution containing at least 42 wt.-%, preferably at least 45 wt.-% or sodium silicate (Na2SiO3). Such multi-component cementitious compositions have been found to provide excellent early strength in excess of 0.5 m Pa after hardening for just 2 h with a gel time in the range of 10 to 20 s. In addition the binder components are stable or at least remixable for up to 4d in the absence of the hardener, which makes them particularly suitable for back filled grouts.