rag bolt
C2Technical (engineering, construction)
Definition
Meaning
A metal bolt with a shank that is deliberately deformed, roughened, or jagged to provide extra grip when set in concrete or masonry.
A fastener designed for permanent anchorage by mechanical interlock, typically used in foundational construction, heavy machinery installation, and structural engineering where high tensile or shear strength is required.
Linguistics
Semantic Notes
A highly specific term; the 'rag' refers to the torn, ragged appearance of the deformed shank, not to cloth or cleaning.
Dialectal Variation
British vs American Usage
Differences
Terminology is identical; 'Lewis bolt' is a less common alternative in both regions.
Connotations
Purely technical with no regional connotative differences.
Frequency
Equally rare in general language but standard within construction and civil engineering jargon in both the UK and US.
Vocabulary
Collocations
Grammar
Valency Patterns
[verb] + rag bolt + [prepositional phrase]: 'The engineers installed rag bolts into the wet concrete.'[rag bolt] + [verb] + [object]: 'The rag bolt anchors the generator to the slab.'Vocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Phrases
Idioms & Phrases
- “[none - technical term]”
Usage
Context Usage
Business
Rare, except in procurement for construction projects: 'The quote includes fifty rag bolts for the machine foundations.'
Academic
Used in engineering and construction textbooks and papers on structural connections.
Everyday
Virtually never used.
Technical
Standard term in construction, civil engineering, and mechanical installation manuals.
Examples
By Part of Speech
verb
British English
- The steel column was rag-bolted to the reinforced plinth.
- We need to rag bolt these before the pour.
American English
- The equipment will be rag-bolted to the foundation.
- The specs call for rag bolting the supports.
adverb
British English
- [Not applicable]
American English
- [Not applicable]
adjective
British English
- The rag-bolt fixings must meet the shear load specification.
- Use a rag-bolt anchorage system here.
American English
- The rag-bolt installation is scheduled for Tuesday.
- Check the rag-bolt torque after 24 hours.
Examples
By CEFR Level
- [Too technical for A2]
- [Too technical for B1]
- The construction crew used strong rag bolts to secure the machine to the floor.
- Rag bolts provide a very firm hold in concrete.
- Prior to pouring the concrete foundation, the rag bolts were positioned precisely in the formwork according to the engineer's template.
- The structural integrity of the assembly relies on the shear strength of the rag bolts cast into the substrate.
Learning
Memory Aids
Mnemonic
Imagine a bolt wearing ragged, torn jeans ('rags') to get a better grip in rough concrete.
Conceptual Metaphor
ROOT/ANCHOR: The bolt is conceptualised as a root system or anchor that grips and holds fast.
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Avoid direct translation as 'тряпичный болт' (cloth/rag bolt). Correct terms are 'анкерный болт' or specifically 'болт с заусенцами'.
Common Mistakes
- Confusing it with a bolt used for attaching fabric or rags.
- Using 'rag bolt' as a general term for any anchor bolt (some are smooth or hooked).
Practice
Quiz
What is the primary purpose of the 'rag' on a rag bolt?
FAQ
Frequently Asked Questions
No, rag bolts are designed for permanent anchorage. Removing one typically requires destroying the surrounding concrete or cutting the bolt.
They serve a similar purpose but work differently. A rag bolt grips via its deformed shank cast into concrete, while a wedge anchor expands inside a pre-drilled hole.
Civil engineering, construction (especially industrial and foundation work), and heavy machinery installation.
They are usually made from high-strength steel, often with a corrosion-resistant coating like hot-dip galvanising.