In the field of modern civil engineering and environmental construction, in order to cope with the problems of stormwater management, groundwater drainage and special structural needs, two concrete materials with excellent permeability - sandless macroporous concrete and permeable concrete stand out. Although they all have good water permeability, there are significant differences in their design concepts, material composition, mechanical properties and application scenarios. This article will detail the differences between sand-free macroporous concrete and permeable concrete, and analyze their respective advantages and disadvantages and their scope of application.
1. Material composition and structural characteristics.
Sand-free macroporous concrete.
Sand-free macroporous concrete is a special type of concrete, which is characterized by the absence of fine aggregates (such as sand) and is mainly composed of cement, coarse aggregates (such as crushed stone or gravel), admixtures, etc.
Due to the lack of fine sand filling, a large number of connected macroporous structures are formed inside this concrete, and the pore size is generally comparable to that of coarse aggregate particles, allowing moisture to penetrate quickly through these pores.
Permeable concrete.
Although permeable concrete also emphasizes water permeability, the use of fine aggregates is not excluded in the design, but by adjusting the aggregate gradation and adding special additives to form a suitable pore structure.
The porosity of permeable concrete is high and evenly distributed, and the pore size is moderate, which can not only ensure the permeability effect, but also maintain the overall compactness and mechanical strength of the concrete to a certain extent.
2. Physical and mechanical properties and water permeability.
Sand-free macroporous concrete.
Due to the low overall density caused by the absence of fine sand filling, the compressive strength and bearing capacity of sand-free macroporous concrete are significantly lower than those of ordinary concrete, which is more suitable for occasions that bear small loads.
Its excellent water permeability allows it to drain water quickly and reduce soil pressure, making it widely used in underground construction, tunnel lining, farmland irrigation systems, and infrastructure that requires rapid drainage.
Permeable concrete.
After the optimized design of permeable concrete, it can achieve high permeability under the premise of maintaining a certain strength and stability.
Although its permeability rate may not be as fast as that of sand-free macroporous concrete, due to its better comprehensive performance, it is suitable for public areas such as pavement pavement, city squares, parking lot floors that need to bear heavy loads and require water permeability.
3. Application fields and construction precautions.
Sand-free macroporous concrete is commonly used for:
Underground seepage prevention and drainage layer.
Protective dam structure.
Drainage facilities in farmland improvement and landscaping.
Sound-absorbing, heat-insulating and flame-retardant parts in special structures.
Permeable concrete is more widely used:
Paving of city roads, pedestrian streets, bicycle paths.
Parks, walkways, and recreational plazas.
Part of the city's stormwater management system to reduce runoff pollution and alleviate urban waterlogging problems.
During the construction process, special attention needs to be paid to the control of the mixing ratio, the specification of the pouring process and the post-maintenance work to ensure the expected permeability and durability.
Sand-free macroporous concrete and permeable concrete play an important role in different engineering fields due to their unique structural characteristics and excellent permeability performance, respectively. Understanding the essential differences between the two can help engineers and designers select the most suitable permeable materials according to the actual project needs, so as to better serve the needs of urban construction and ecological environmental protection.