Related Experiment Video
Updated: Feb 13, 2026
09:39
Production and Testing of Moisture Behavior and Thermal Properties of Rapeseed Straw and Ganoderma resinaceum Mycelium Bio-Composites
Published on: September 5, 2025
741
Influence of Substrate Moisture State and Roughness on Interface Microstructure and Bond Strength: Slant Shear vs.
Dale P Bentz1, Igor De la Varga2, Jose F Muñoz2
1Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899.
Cement & Concrete Composites
|March 6, 2018
Summary
The optimal substrate moisture for repair material application depends on the testing method. Dry substrates excel in shear tests, while saturated-surface-dry (SSD) substrates perform better in pull-off tests due to microstructural differences.
Area of Science:
- Construction Materials Science
- Civil Engineering
- Materials Science
Background:
- Conflicting literature exists on the ideal substrate moisture state (saturated-surface-dry or dry) for repair material application.
- Testing methodologies, specifically pull-off (direct tension) versus shear, may influence observed bond performance.
- Understanding interfacial microstructure is crucial for optimizing repair material bonding.
Purpose of the Study:
- To investigate the interfacial microstructure developed when repair material is applied to dry versus saturated-surface-dry (SSD) substrates.
- To observe dynamic microstructural rearrangements during the initial curing phase.
- To formulate a hypothesis explaining the influence of substrate moisture on bond test results.
Main Methods:
- Application of various microstructural characterization tools.
- Simultaneous neutron and X-ray radiography to observe dynamic microstructural changes.
- Analysis of water movement and particle densification at the interface during the first 4 hours of curing.
Main Results:
- Differences in water movement and particle densification were observed between dry and SSD substrate specimens.
- Dry substrates showed increased frictional resistance in shear loading due to particle compaction.
- SSD substrates exhibited higher bond strengths in pull-off tests.
Conclusions:
- The optimal substrate moisture state is dependent on the bond testing configuration (shear vs. pull-off) and substrate roughness.
- Particle compaction at dry substrate surfaces enhances shear resistance but offers minimal benefit in pull-off tests.
- Maximizing repair material bond performance requires consideration of material fluidity, substrate roughness, and moisture state.
Related Concept Videos
01:12Bonding and Strength of Aggregate
519
The bond between aggregate particles and the cement matrix is significantly influenced by the shape and surface texture of the aggregates. High-strength concretes benefit from a rougher texture, which leads to stronger bonding due to greater adhesion. Angular aggregates with larger surface areas also enhance this bond. The bonding quality, however, is complex to assess as no universally accepted test exists. Good bonding is indicated when a crushed concrete specimen shows some aggregate...
519
02:49Bond Energies and Bond Lengths
31.6K
Stable molecules exist because covalent bonds hold the atoms together. The strength of a covalent bond is measured by the energy required to break it, that is, the energy necessary to separate the bonded atoms. Separating any pair of bonded atoms requires energy — the stronger a bond, the greater the energy required to break it.
31.6K
01:12Non-destructive Tests for Concrete Strength
589
The rebound hammer test, also known as the Schmidt hammer test, is a non-destructive technique for evaluating the hardness of concrete and, indirectly, the strength of concrete. It operates on the principle that the rebound of a spring-driven mass from a concrete surface correlates to the surface's hardness. The device comprises a mass within a tubular housing, a spring mechanism, and a plunger that strikes the concrete. Upon release, the energy imparted to the mass by the spring causes it...
589
00:42Ionic Bonds
132.2K
Overview
When atoms gain or lose electrons to achieve a more stable electron configuration they form ions. Ionic bonds are electrostatic attractions between ions with opposite charges. Ionic compounds are rigid and brittle when solid and may dissociate into their constituent ions in water. Covalent compounds, by contrast, remain intact unless a chemical reaction breaks them.
Opposing Charges Hold Ions Together in Ionic Compounds
Ionic bonds are reversible electrostatic interactions between ions...
When atoms gain or lose electrons to achieve a more stable electron configuration they form ions. Ionic bonds are electrostatic attractions between ions with opposite charges. Ionic compounds are rigid and brittle when solid and may dissociate into their constituent ions in water. Covalent compounds, by contrast, remain intact unless a chemical reaction breaks them.
Opposing Charges Hold Ions Together in Ionic Compounds
Ionic bonds are reversible electrostatic interactions between ions...
132.2K
01:27Slant Asymptotes
156
A function's behavior is often guided by asymptotic constraints, where one term dominates another, defining a limiting trend. In the given scenario, the mathematical pattern follows a rational function: a cubic term in the numerator is divided by a squared term in the denominator. This results in a function with distinct characteristics, including an oblique asymptote, critical points, and undefined regions.The function's validity is determined by the denominator, which must be nonzero. This...
156
03:05Acid Strength and Molecular Structure
33.2K
Binary Acids and Bases
In the absence of any leveling effect, the acid strength of binary compounds of hydrogen with nonmetals (A) increases as the H-A bond strength decreases down a group in the periodic table. For group 17, the order of increasing acidity is HF < HCl < HBr < HI. Likewise, for group 16, the order of increasing acid strength is H2O < H2S < H2Se < H2Te. Across a row in the periodic table, the acid strength of binary hydrogen compounds increases with increasing...
In the absence of any leveling effect, the acid strength of binary compounds of hydrogen with nonmetals (A) increases as the H-A bond strength decreases down a group in the periodic table. For group 17, the order of increasing acidity is HF < HCl < HBr < HI. Likewise, for group 16, the order of increasing acid strength is H2O < H2S < H2Se < H2Te. Across a row in the periodic table, the acid strength of binary hydrogen compounds increases with increasing...
33.2K