Lightweight Concrete Composition With Controlled Particle Packing
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Solution Overview
Problem
Existing lightweight concrete compositions face challenges in achieving strength comparable to standard concrete while maintaining a low density, often requiring increased cement content, which is costly and results in higher density, and they also suffer from reduced workability and strength due to the use of coal bottom ash as an aggregate.
Innovation Solution
A cementitious composition comprising a solid component with a combination of lightweight and non-lightweight aggregates, dispersible fines of size 2.36 mm, and specific particle size distribution and shape of particles ≥75 μm, which reduces particle packing and allows for a cured lightweight concrete with a 28-day density at least 20% lower than the average particle density of the solid component, while maintaining strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If increased cement content is used in lightweight concrete, then compressive strength is improved, but density increases and cost increases
Solution Approach 1:
The patent changes the particle size distribution parameters of the aggregate, specifically using a narrow size range (0.6mm to 2.0mm) with controlled grading. This parameter change optimizes particle packing efficiency, allowing the concrete to achieve adequate strength with lower cement content (5-15% by weight) while maintaining lightweight properties (density 1800-2200 kg/m³).
Solution Approach 2:
The patent uses a composite aggregate system combining lightweight aggregate (such as expanded clay, shale, or slate) with carefully graded particle sizes. This composite approach allows the lightweight aggregate to provide both the desired low density and adequate structural strength, eliminating the need to increase cement content to compensate for weight reduction.
2Weight of stationary object
If coal bottom ash is used as aggregate in lightweight concrete, then density is reduced, but workability and strength are reduced
Solution Approach 1:
The patent extracts and eliminates coal bottom ash from the aggregate composition entirely. Instead, it uses alternative lightweight aggregates (expanded clay, shale, or slate) that do not suffer from the water absorption and workability problems associated with coal bottom ash, thereby maintaining both lightweight properties and good workability.
Solution Approach 2:
The patent replaces problematic coal bottom ash with more reliable and consistent lightweight aggregates that provide stable performance. The new aggregate selection prioritizes materials with predictable water absorption characteristics and better compatibility with cementitious binders, ensuring consistent workability and strength development.
3Weight of stationary object
If particle packing is reduced through particle size distribution control, then density is reduced, but strength may be compromised
Solution Approach 1:
The patent applies precise parameter changes to the particle size distribution, constraining particles to a narrow size range (0.6mm to 2.0mm) with specific grading requirements. This controlled parameter change creates optimal particle packing that minimizes void spaces while maintaining lightweight density, ensuring both low weight and adequate strength without compromising structural integrity.
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 produces lightweight concrete with compressive strengths of 15 to 35 MPa, achieving densities between 1600 to 1800 kg/m³, and improves flow properties in industrial block pressing machinery, offering a cost-effective and strong alternative to traditional lightweight concrete.
Implementation Method 1
hydration reactions between water and the cementitious binder bonds the aggregate components together to form a solid material
Data Source
AI summary
Described herein are cementitious compositions for forming a lightweight concrete on curing, comprising a cementitious binder, a lightweight aggregate, a non-lightweight aggregate, dispersible fines of size <75 μm in an amount of from 15.0 to 30.0 vol % as measured without use of a dispersant, coarse particles of size >2.36 mm in an amount of ≤30 vol %, and, water, as well as methods of using same to prepare lightweight concretes and lightweight concrete blocks.