Core tip: In the second quarter of 2016, the Shandong Provincial Quality Supervision Bureau organized six types of construction projects: construction sealants, autoclaved aerated concrete blocks, cement, construction waterproofing membranes, insulating glass, and hot-rolled ribbed steel bars. Provincial supervision and random inspections of materials and products conducted random inspections on 520 batches of products produced by 520 companies, and 33 batches were found to be unqualified. Among them, there are many quality problems with construction sealants and autoclaved aerated concrete blocks, and product quality needs to be improved urgently.
Results of quality spot checks on building materials products
In the second quarter of 2016, the Shandong Provincial Quality Supervision Bureau organized and carried out construction sealants, autoclavedaerated concrete blocks, cement, construction waterproofing membranes,Insulated glass and hot-rolled ribbed steel bars were inspected at the provincial level for six types of building material products. A total of 520 batches of products produced by 520 companies were randomly inspected, and 33 batches were found to be unqualified. Among them, there are many quality problems with construction sealants and autoclaved aerated concrete blocks, and product quality needs to be improved urgently.
The products of 4 companies “continue to be unqualified”
Construction sealant is mainly used for sealing or bonding various joints and holes in buildings, and plays a variety of functions such as thermal insulation, sound insulation, and waterproofing. Structural adhesive is one of the important materials for building curtain walls. Shandong Province is the main production area of sealants in my country. Currently, there are more than 100 companies producing one or more sealant products of different types, mainly concentrated in Longkou City and Linqu County.
In order to fully understand the production status of construction sealant companies, investigate product quality and safety risks, and urge companies to effectively improve product quality, the Shandong Provincial Quality Supervision Bureau has organized provincial supervision and spot inspections of construction sealant products for two consecutive years. This time, 10 batches of construction sealants were found to be unqualified. The unqualified items were elongation at break, elastic recovery rate, tensile modulus, tensile adhesion (tensile bond strength), and penetration. Experts analyzed the reasons for the unqualified products and believe that the following points are: First, the threshold of the sealant industry is low. Some companies blindly cater to the market demand for ultra-low unit price products, produce sealants with rudimentary equipment, and reduce the active ingredients in the formula. , seizing the market with low quality and low price; secondly, the degree of automation of enterprise production equipment is not high, ingredients are mostly measured manually, and the dosage is difficult to be accurate; thirdly, some enterprises do not have product inspection rooms, and product quality cannot be effectively controlled. Although some companies have established inspection rooms, they do not strictly follow the standard requirements for inspection. This spot inspection also tracked the 9 unqualified companies in the spot inspection in the third quarter of 2015, and found that the products of 4 companies were still unqualified, which shows that some companies have never paid enough attention to product quality.
Technically “poor control” is a flaw
Autoclaved aerated concrete block is a new lightweight wall material. It has the advantages of light weight, high strength, goodthermal insulation performance, good earthquake resistance, and high temperature resistance. In recent years, it has been widely used in wall masonry of industrial or civil buildings. According to incomplete statistics, there are currently more than 300 autoclaved aerated concrete block manufacturers in Shandong Province, with a total output of approximately 30 million cubic meters. Almost every county-level city has such enterprises, and the enterprises are relatively concentrated in areas that implemented the regulations to eliminate clay bricks earlier, such as Jinan, Qingdao, Yantai, Weifang, Zibo, etc.
This time, 58 batches of autoclaved aerated concrete blocks were randomly inspected, and 8 batches were found to be unqualified. The unqualified items include strength level, dry density and frost resistance, of which 7 batches were unqualified for strength level. According to experts, the main reason for unqualified strength levels is the unreasonable silicon-to-calcium ratio in the raw material ratio. Compressive strength, thermal conductivity, and dry density are closely related. Only by reasonable product ratio, uniform gas generation, and long enough curing time can the dry density, compressive strength, and thermal conductivity of the product reach standards at the same time. Therefore, how to control the three? The balance requires testing and analysis in formula, process control, post-maintenance and other aspects to find the best combination point to ensure product quality and achieve good energy-saving effects.
Unqualified enterprises have become the focus of supervision for two consecutive years
The person in charge of the First Supervision Division of the Shandong Provincial Quality Supervision Bureau pointed out that in order to improve the quality of building materials products, companies should strengthen their awareness of quality responsibility, establish a complete quality assurance system, strengthen process quality control, and strictly inspect raw materials, production processes, and products before leaving the factory. , improve the factory product quality certificate and product identification to make them more traceable. Regulatory departments in various localities should intensify supervision, especially for enterprises that have failed to meet the standards for two consecutive years in supervisory spot inspections. They should be regarded as key supervision objects and urge enterprises to implement their main responsibilities in accordance with the law.
