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Aggregate is a granular material that plays a filling and skeleton role in a mixture, including crushed stone, gravel, machine-made sand, stone chips, sand, etc.
Coarse aggregate refers to crushed stones, broken stones, screened stones, and slag with a particle size greater than 2.
36mm in asphalt mixtures; In cement concrete, coarse aggregate refers to crushed stones, gravel, and broken gravel with a particle size greater than 4.
75mm.
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（1） The construction unit has not designated a pre mixed concrete production enterprise or directly purchased pre mixed concrete.
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（2） The establishment of pre mixed concrete production enterprises and sub stations meets the requirements of qualification management regulations.
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According to the requirements of GB 55030-2022 “General Code for Waterproofing of Building and Municipal Engineering”, the crack resistance measures for the roof fine aggregate concrete leveling layer/surface layer can be prevented and controlled from three aspects: material optimization, structural reinforcement, and construction measures.
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The free water in the mixture affects the slump of concrete.
Cement hydration and water evaporation will consume free water, reduce water content, decrease the distance between particles inside the slurry, increase viscosity, and decrease the slump of concrete.
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Abstract: Based on detailed industry observations and literature research, this article systematically analyzes the underlying reasons for the widespread deterioration of the quality of commercial concrete in China.
Research has shown that quality deterioration is not a single technical issue, but the result of the combined effects of material variation, market disorder, lack of technological ethics, and regulatory lag.
Specifically, it manifests as variations in the performance of cement cementitious materials (low proportion of clinker, complex filling materials), degradation of aggregate system quality (replacement of river sand with machine-made sand, high impurity content in stones), and malicious competition among formulations under the market rule of “winning the bid at the lowest price”.
These factors work together to severely overdraw the durability of concrete, laying long-term structural safety hazards.
Finally, this article proposes comprehensive governance measures and suggestions from the dimensions of standard revision, market supervision, technology guidance, and industry self-discipline.
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Concrete is not just ‘poured’, but ‘cultivated’.
The quality of maintenance directly determines the future strength, durability, and safety of concrete structures.
This article will use the most straightforward language to explain the door to concrete curing.
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Abstract: The curing of concrete is a key link in ensuring its mechanical properties, durability, and structural safety.
This article systematically analyzes the effects of curing start time and duration on cement hydration process, strength development, and microstructure based on the standard curing time of different functional concrete.
Based on the principles of materials science, this paper explores the regulatory mechanisms of environmental factors (temperature and humidity) and material factors (cement variety, additives) on the maintenance system.
Research has shown that following a scientific schedule for curing can effectively suppress plastic shrinkage and drying shrinkage cracks, improve the compactness and long-term durability of concrete.
This article aims to provide theoretical basis and optimization suggestions for engineering practice, and looks forward to the development direction of intelligent maintenance technology in the future.
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Abstract: As the most widely used material in modern construction engineering, concrete construction quality directly affects the safety, durability, and appearance of the structure.
This article is based on engineering practice and systematically summarizes twelve common concrete quality defects, including pockmarks, honeycombs, exposed reinforcement, holes, interlayers, missing edges and corners, rotten roots, cracks, misalignment, expansion molds, looseness, and external defects.
The paper deeply analyzes the apparent characteristics, microstructure influence, and generation mechanism of various defects, tracing the causes from multiple dimensions such as material properties, mix design, formwork engineering, construction technology, and maintenance conditions.
A targeted and refined prevention and control system with the laboratory as the core has been proposed, emphasizing the pre prevention and process control of defects through optimizing mix proportions, strengthening raw material and process quality control, improving construction plans, and enhancing maintenance management.
This provides a systematic theoretical basis and practical guidance for improving the quality of concrete solid engineering.
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Those who study engineering, especially civil engineering related majors, as well as those engaged in civil engineering project design, construction, supervision, and budgeting, inevitably have to deal with the word “tong” frequently.
Speaking of the word ‘concrete’, it’s a bit awkward.
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