1.
The concrete mix proportion and slump do not meet the requirements;.
Precast News From China
Most concrete enterprises are private enterprises that adopt family style management and lack professional production management personnel, resulting in many loopholes in production management.
Here, the author shares five common cases that occur in concrete enterprises with colleagues and proposes corresponding preventive measures, hoping to draw attention and prevent similar incidents from happening again.
.
With the development of our city’s national economy, the demand for concrete is also increasing, and concrete mixing plant projects are being launched one after another.
However, the construction administrative management department did not strictly control the situation, and some mixing plants had unreasonable staffing and incomplete hardware facilities.
However, they passed the acceptance inspection in an abnormal way and obtained the qualification of a construction enterprise.
This phenomenon has caused overcapacity in the region.
In order to survive, various mixing plants compete in price wars and undertake business through entertaining guests, giving gifts, and giving kickbacks to relevant personnel.
In order to reduce costs, the amount of cement used in concrete is reduced and the amount of admixtures is increased.
But the concrete specifications have requirements for the minimum amount of cement, and in order to meet the requirements of the specifications, the yin-yang mix ratio has emerged.
.
With the increasing scarcity of natural sand resources and the continuous improvement of environmental protection requirements in construction, machine-made sand has gradually become an important raw material for concrete production.
However, in the production process of mechanism sand, there are common problems such as excessive particle edges, rough surface, and discontinuous gradation, which lead to high water demand and poor workability of concrete, as well as significant strength fluctuations.
At the same time, cement, as the main cementitious material in concrete, generates a large amount of carbon dioxide emissions during its production process, causing serious environmental burden.
.
In coastal mudflat, saline land areas or around northern salt lakes, concrete structures not only bear loads, but also face multiple attacks of chemical corrosion and freeze-thaw cycles.
The combination of these three factors, known as’ multiple failure factors (MDF) ‘, poses a serious challenge to the durability of concrete.
.
Recently, the Ministry of Housing and Urban Rural Development publicly solicited opinions on the national standard “Test Method for Ultra High Performance Concrete (Draft for Comments)”.
.
The Municipal Engineering Center of Zhangzhou Housing and Urban Rural Development Bureau uses C40 black concrete with steel fibers, which has the advantages of high temperature anti rutting and low temperature anti cracking.
It is planned to slightly improve the asphalt road junctions and turns.
Compared with ordinary concrete, steel fiber C40 black concrete not only increases the tensile strength, but also shows good toughness, is easy to operate and control, improves maintenance efficiency, saves maintenance costs, and is a good measure for the sustainable development of road maintenance.
.
Shandong Expressway Changtong Road Bridge Engineering Co.
, Ltd.
Weifang 261500, Shandong.
As the most widely used building material today, concrete has the advantages of high compressive strength, good durability, and low cost.
However, its inherent brittleness leads to the formation of microcracks during use, which not only reduce the mechanical properties of the material but also provide channels for harmful substances to invade, accelerating structural aging and steel corrosion.
The traditional repair method relies on manual detection and external intervention, which is inefficient and difficult to deal with internal micro damage.
The emergence of self-healing concrete provides a new approach to solving this problem.
.
Winter construction is an inevitable engineering reality in cold regions, and as the most important building material, the performance control of concrete in low-temperature environments becomes the key to engineering quality.
Elaborate on the basic principles, freezing mechanisms, and curing processes of winter concrete construction, providing theoretical support for scientific research and engineering practice.
.