1. The utilization rate of concrete production capacity continued to decline
. According to incomplete statistics, in the first half of 2023, there were very few new projects in the province, and the old projects in supply were gradually coming to an end. Many mixing stations in the province had closed down due to low output. In the first half of the year, the utilization rate of concrete production capacity in the province was about 9.5%. The year-on-year decline is about 20%, but the fluctuation range of capacity utilization rate is also large. By the end of June, the volume of concrete completed in the whole province decreased by about 20% + compared with the same period last year. The industry trend continues to decline and the situation is grim. The ex-factory price of
cement is the lowest in 16 years, 215 yuan/ton. Even though the industry organization has coordinated the price increase for many times, the market has never seen the sound of palm (rising). The lowest ex-factory price of mineral powder is 140 yuan/ton, and the lowest ex-factory price of fly ash is 10 yuan/ton.
3. Land transactions in the infrastructure market were not successful
From January to June 2023, Changsha supplied 29 commercial land parcels with an area of about 1.47 million square meters in six districts and one county, and sold 28 (commercial and residential) land parcels with an area of about 1.36 million square meters, with a total transaction amount of about 18.544 billion yuan.
Regionally, the main supply force in the first half of the year was Yuelu District, with 10 land transactions, 6 in Changsha County, 5 in Wangcheng District, 2 in Yuhua District, Tianxin District and Furong District, and 1 in Kaifu District.
In terms of the nature of land transactions, there were 15 residential land transactions, 2 commercial and residential land transactions and 11 commercial land transactions in Changsha land market in the first half of the year. In addition to the land transaction, a commercial and residential land transfer was suspended in the first half of the year, which was the No.025 plot in Changsha City, Yuhua District [2023]. It is noteworthy that there was no residential land transaction in Wangcheng District in the first half of the year. Conversion of
land transaction area into concrete volume:
1.47 million square meters of 29 commercial land, concrete consumption is calculated as 0.2m ³/㎡, concrete consumption = 290,000 m ³; 28 commercial and residential land covers an area of 1.36 million square meters, and the concrete consumption is calculated as 0.45m ³/㎡ of the top grid, and the concrete consumption is 610,000 m ³. Total demand for concrete = 900,000 m ³. Although this is not the total demand for concrete in Changsha, real estate has always been a big user of concrete. Moreover, the demand for land sold in the first half of the year cannot be fully released in the second half of the year, which cannot be compared with the demand of about 50 million m ³/year in the first few years of 2020.
4、 Pyrite aggregate panic
has attracted great attention in the concrete industry since July 14, when the Provincial Housing and Construction Department issued a document prohibiting the use and thorough investigation of the production and use of sulfide pyrite aggregate. It can be said that iron discoloration has been discussed, but due to the serious lack of detection methods and identification means, there have been many Oolong incidents. Some mixing stations refuse to accept sand and gravel only according to the Fe content of several points detected in the aggregate or the adsorption of sand and gravel particles by magnets, which makes the products of many sand and gravel enterprises unsalable and miserable.
In fact, not all iron ores are harmful to concrete, only pyrite containing iron sulfide is harmful to concrete, and the key detection index is whether the sulfur content exceeds the standard.
5. Illegal mining
of river sand In the first half of the year, the satellite of the superior department found that there were problems such as cross-border mining, excessive mining and overtime mining in Hunan river sand mining. In early August, the Minister of the Ministry of Environment personally went to Hunan to inspect and ordered several mining areas to stop mining and rectify, resulting in a shortage of some river sand and pebbles.
6. Cracking
of houses At the beginning of August, the walls of underground garages, shops and households in Huarun Wucaicheng Community in Changsha County cracked, the walls fell ash, peeling, and the doors and windows could not be opened and closed normally. The widest part of the cracks on the negative second floor could reach into two fingers, which was suspected to be caused by the underground construction of the surrounding construction sites. Network hot degree, nearly Tuoyu incident, 429 collapse incident, the relevant departments have been involved in the investigation and handling.
7. The influence of weathered rock sand making and flocculant on the quality of machine-made sand is prominent.
On the weekend, I was invited to a mixing station for technical guidance. The mixing station reported that the machine-made sand contained too much flocculant, which seriously affected the fluidity of concrete. The amount of admixture had been increased to 16-18kg/m3 (normal 6-7), and the fluidity was lost after 10-20 minutes out of the machine, which could not meet the requirements of transportation and construction. & nbsp; & nbsp; & nbsp; It is understood that due to the recent ban on the mining of natural sand around yuanjiang Dongting Lake, the machine-made sand shipped from Yichang has become the first choice in the local area. After being washed and dried in the sun, this kind of sand does not look like sand from a distance, but looks like mud from a distance. According to the qualitative analysis, the flocculant content in the machine-made sand is relatively high (no quantitative analysis method is available). After washing and screening, the content of mud powder is 7.5%. It is suspected that the sand is made of weathered particles. According to the conditions of raw materials, the long flow agent is prepared on site. On the basis of the original actual production mix proportion, 1% of the long flow agent is added, the initial slump is 210 mm, the 1-hour slump is 180, and the 1-hour slump loss is only 30 mm, which fully meets the requirements of transportation and construction. But the cost has increased.
This kind of sand has many unqualified items and has hidden quality hazards. Even if the sand is cheap, it will increase the comprehensive cost of concrete. It is recommended to replace the sand or try not to use more than 30% of the sand.
(This article does not represent the views of the DataBM. Com of digital building materials, but is only for exchange and learning) & nbsp;
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