Compressed Desert Sand Concrete for Full Sand Replacement
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Solution Overview
Problem
Desert sand, due to its poor gradation, round and smooth particles, and high fineness, results in poor durability and mechanical properties when directly substituted for natural river sand in concrete, limiting its replacement rate.
Innovation Solution
A method involving mixing cement, coarse and fine aggregates, including desert sand, with controlled compression casting and curing to produce high-performance compressed desert sand concrete, utilizing chemical treatments like acid leaching and heat treatment for desert sand, and specific ratios and conditions for mixing and curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If desert sand is directly substituted for natural river sand in concrete, then the replacement rate of desert sand increases, but the mechanical properties and durability of concrete deteriorate
Solution Approach 1:
The desert sand undergoes preliminary chemical treatment (acid leaching, alkali leaching, or heat treatment) before being used in concrete. This preliminary action modifies the surface properties of desert sand particles, improving their adhesion with cement matrix and reducing the negative effects of their smooth, rounded morphology, thereby enabling higher replacement rates while maintaining mechanical properties
Solution Approach 2:
The patent applies compression casting with specific pressure parameters (0.5-2.0 MPa for 2-24 hours) to change the physical state and arrangement of concrete components. This parameter change compacts the concrete mixture, reducing voids and improving the interfacial bond between desert sand particles and cement matrix, thus enhancing mechanical strength despite high desert sand content
2Quantity of substance
If desert sand is directly substituted for natural river sand in concrete, then the replacement rate of desert sand increases, but the durability of concrete deteriorates
Solution Approach 1:
Chemical treatments (acid leaching with HCl or H2SO4, alkali leaching with NaOH, or heat treatment at 600-900°C) are applied to desert sand before concrete mixing. These preliminary actions remove harmful impurities, modify surface chemistry, and create micro-roughness on particle surfaces, improving long-term durability by reducing permeability and enhancing interfacial durability
Solution Approach 2:
Compression casting applies sustained pressure (0.5-2.0 MPa for 2-24 hours) to change the density and pore structure of concrete. This parameter change reduces total porosity and connects remaining pores into less harmful configurations, significantly improving durability metrics such as water absorption resistance, carbonation resistance, and chloride ion penetration resistance
3Strength
If compression casting is applied to desert sand concrete, then mechanical properties improve, but the processing complexity increases
Solution Approach 1:
The patent uses relatively low compression pressures (0.5-2.0 MPa) applied over extended periods (2-24 hours), which can be achieved with simple hydraulic pressing devices. This parameter selection balances mechanical property improvement with processing simplicity, avoiding the need for complex high-pressure equipment while still achieving significant strength enhancement
Solution Approach 2:
The compression casting process maintains continuous pressure application throughout the curing period (2-24 hours), ensuring sustained compaction and bond strengthening. This continuous action simplifies the process control compared to intermittent high-pressure methods, as it requires only maintaining constant pressure rather than managing complex pressure cycling
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 enables 100% replacement of natural river sand with desert sand, enhancing mechanical properties and durability, with significant improvements in compressive strength, elastic modulus, splitting tensile strength, water absorption, carbonation resistance, and chloride ion penetration resistance.
Implementation Method 1
the compression casting is conducted at a pressure of not less than 2 MPa for not less than 2 min
Implementation Method 2
the chemical treatment includes one or more selected from the group consisting of acid leaching, alkali leaching, and heat treatment
Implementation Method 3
the chemical treatment includes one or more selected from the group consisting of acid leaching, alkali leaching, and heat treatment
Data Source
AI summary
A method for preparing a high-performance compressed desert sand concrete is provided. The method includes: mixing a cement, a coarse aggregate, a fine aggregate, and water, and subjecting a mixture to compression casting, and curing in sequence to obtain the high-performance compressed desert sand concrete; where the compression casting is conducted at a pressure of not less than 2 MPa for not less than 2 min.