Geopolymer Binder Curing Layer for Hydraulic Shrinkage Control
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Solution Overview
Problem
Geopolymer binders in construction face significant hydraulic shrinkage issues leading to cracking, which existing anti-shrinkage products fail to effectively address, especially on rigid surfaces like concrete, due to differences in chemistry and water retention compared to Portland cement-based materials.
Innovation Solution
A method involving the successive application of a geopolymer binder layer composed of aluminosilicate and alkaline compounds, followed by a curing layer containing water, clay, silica, or oil, to create a protective layer that mitigates hydraulic shrinkage by maintaining high relative humidity and reducing capillary stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If geopolymer binder is applied to the surface, then the surface is covered with a functional layer, but hydraulic shrinkage causes cracking that compromises durability
Solution Approach 1:
A curing compound is applied to the geopolymer binder layer before it fully sets, creating a protective barrier that prevents water evaporation during the critical curing period. This preliminary action maintains adequate moisture levels in the binder, preventing capillary tension from causing cracks and ensuring the layer cures without compromising durability
Solution Approach 2:
The curing compound acts as an intermediary substance between the geopolymer binder layer and the ambient environment. It forms a protective film that mediates water loss, allowing the binder to cure properly by maintaining moisture while protecting against external conditions that would cause shrinkage and cracking
2Object-affected harmful factors
If existing anti-shrinkage products are used on Portland cement-based materials, then shrinkage is reduced, but these products fail to effectively combat cracking in geopolymer binders
Solution Approach 1:
The invention changes the chemical parameters of the curing compound to match the alkaline chemistry of geopolymer binders. The curing compound has an alkaline pH range (11-14) that matches the geopolymer binder's chemistry, ensuring proper chemical interaction and effectiveness. This parameter adjustment allows the curing compound to work specifically for geopolymer systems rather than being incompatible with existing cement-based products
3Quantity of substance
If the geopolymer binder is allowed to dry during setting, then water evaporates from capillaries, but capillary forces create tensile stresses that exceed tensile strength and cause cracks
Solution Approach 1:
The curing compound is applied beforehand to cushion against water loss by forming a moisture-retaining barrier on the surface of the geopolymer binder layer. This barrier cushions the binder during the critical early curing period, preventing rapid evaporation that would create capillary tension exceeding the binder's tensile strength and causing cracks
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 method effectively prevents cracking in geopolymer binder layers on construction sites by creating a protective curing layer that retains moisture and reduces capillary stress, offering a cost-effective and efficient solution for large-scale implementation.
Implementation Method 1
This hydraulic shrinkage is mainly attributed to the volume left by the free water which is extracted from the capillaries of the materials during its drying (setting/curing). The first reason is linked to the simple evaporation of this water from the material into the ambient air.
Implementation Method 2
The volume left by the free water creates stresses, called capillary forces. Cracks are then created (and open) when the tensile forces created in the fresh binder (that is to say before total setting) by the capillary forces exceed the tensile strength of the latter.
Data Source
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AI summary
The present invention relates to a method for treating a surface comprising the following successive steps: a) applying to said surface at least one composition comprising at least one geopolymer binder comprising one or more aluminosilicate compounds and one or more alkali compounds so that the surface is covered, at least partially, preferably totally, with a layer of geopolymer binder; b) applying to the layer of geopolymer binder at least one composition A selected from: - a composition containing water and at least one compound selected from clay and silica; - a composition containing oil and optionally clay, preferably a composition containing oil and clay; and - a composition comprising at least one polymer, so that the layer of geopolymer binder is covered, at least partially, preferably totally, with a curing layer comprising at least composition A.