Offset Joint Edge Assembly for Concrete Slab Shrinkage Control

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Solution Overview

Problem

Existing joint edge assemblies for concrete floors often result in wider joints due to excessive shrinkage, leading to tire damage, filler leakage, and increased contamination, which are costly and time-consuming to repair.

Innovation Solution

A joint edge assembly with elongated joint rail members, connectors, anchors, and a closure bar positioned in an offset configuration to prevent excessive joint opening, using temporary formwork to ensure the joint remains substantially closed and secure, even as the concrete slabs shrink.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional joint edge assemblies are used, then the joint edges can self-open to allow concrete shrinkage, but the joint opens too wide causing tire damage and filler leakage

Engineering Contradiction:

Improvejoint self-opening capabilityVSAvoidjoint opening width control

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The joint edge assembly is pre-positioned in an offset configuration during formwork installation, before the concrete is poured. This preliminary positioning ensures that when the concrete shrinks and the joint opens, the closure bar and joint edge members are already in the correct relative positions to maintain proper joint width control, preventing both excessive opening and filler leakage

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The closure bar acts as an intermediary element between the two joint edge members, providing a mechanical link that controls the relative movement and maintains the joint opening within acceptable limits. The closure bar transfers and distributes the shrinkage forces, preventing the joint from opening excessively while still allowing necessary movement

Inventive Principle:

Principle #24Intermediary (Mediator)

2Stability of the object's composition

If the joint opens wider to accommodate concrete shrinkage, then the concrete slabs can shrink freely, but tire damage and contamination increase

Engineering Contradiction:

Improveconcrete shrinkage accommodationVSAvoidtire damage and contamination

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The joint edge assembly is installed and positioned in advance during the formwork stage, establishing the precise geometry and offset configuration that will control joint opening. This preliminary setup ensures that when the concrete shrinks, the joint opens to the correct amount - enough to accommodate shrinkage but not so much as to cause tire damage or contamination

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The joint edge assembly uses adjustable components and offset positioning to control the critical parameter of joint opening width. By adjusting the offset distance and closure bar positioning, the system optimizes the joint opening to accommodate concrete shrinkage while minimizing harmful effects from excessive opening

Inventive Principle:

Principle #35Parameter changes

3Reliability

If heavier or more costly joint edge members are used, then joint integrity can be maintained, but manufacturing cost and device complexity increase

Engineering Contradiction:

Improvejoint integrityVSAvoidjoint edge assembly complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The joint edge assembly is divided into separate, modular components including joint edge members, closure bars, and connectors. Each component can be independently manufactured, positioned, and adjusted. This segmentation allows for simpler, less expensive individual parts while maintaining overall joint integrity through proper configuration and assembly

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The assembly is pre-configured during formwork installation with the correct offset positioning and alignment. This preliminary action ensures that when the concrete is poured and the joint opens, the components are already in the correct positions to maintain joint integrity, eliminating the need for heavier or more complex members

Inventive Principle:

Principle #10Preliminary action

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

This configuration effectively prevents filler leakage and reduces tire damage, maintaining joint integrity without requiring heavier or more costly joint edge members, thus minimizing maintenance and operational disruptions.

Implementation Method 1

Freshly poured concrete shrinks considerably as it hardens due to the chemical reaction that occurs between the cement and water (i.e., hydration)

Methodology Applied

Scientific EffectHydration:

Implementation Method 2

Freshly poured concrete shrinks considerably as it hardens due to the chemical reaction that occurs between the cement and water

Methodology Applied

Scientific EffectThermal contraction: Thermal Contraction

Data Source

PatentUS10385567B2Joint edge assembly and method for forming joint in offset position

Publication Date: 2019.08.20 ILLINOIS TOOL WORKS INC

AI summary

Various embodiments of the present disclosure provide a joint edge assembly and method of positioning and installing joint edge assembly for adjacent concrete slabs. The method includes positioning the joint edge assembly in an offset position from the joint. The method of various embodiments also includes using a plurality of height adjusters or plates fixed to the slab engagement surface of the one of the joint edge members to adjust or assist in adjusting the height of the joint edge assembly relative to the formwork and relative to the plane of the top surfaces of the concrete slabs.