What are the advantages of dry mixed mortar?

What are the advantages of dry mixed mortar? The following Zhong Da consults the bidding teacher to answer your questions for your reference.

1 preface

Dry-mixed mortar is one of the emerging dry-mixed materials in the field of building materials. According to the Guangdong provincial standard "Technical Specification for Application of Dry-mixed Mortar DBJ/T 15-36-2004", it is defined as: Dry-mixed mortar is a mixture produced by professional manufacturers, with cement as the main binder, fine aggregate, mineral admixture, reinforcing material and admixture in a certain proportion, which is dried and screened.

Dry-mixed mortar developed in the European construction market in 1950s. Nowadays, in Germany, Austria, Finland and other countries, dry-mixed mortar is the main mortar material. There are more than 200 factories in Germany alone, with an annual output of 654.38+10,000 tons, with an average of one dry-mixed mortar manufacturer for every 500,000 people. In Asia, dry-mixed mortar in Singapore, Japan, South Korea and Hong Kong has also developed very rapidly. For example, more than 30% of plastering mortar in the construction field in Hong Kong is dry-mixed mortar. Since 1990s, the development of dry-mixed mortar in China is in full swing. Dry-mixed mortar has been popularized in Guangzhou for six years, and the corresponding guiding policies and norms have been gradually implemented. The local standards of Beijing and Shanghai on the technical regulations of dry-mixed mortar application have been implemented for several years, and the local standards of Chongqing are also being formulated.

This paper will mainly analyze the advantages of ordinary dry-mixed mortar compared with traditional mortar, so that readers can deepen their understanding of dry-mixed mortar and realize that it is inevitable that dry-mixed mortar will replace traditional mortar with the development of society.

2 social benefits and technical advantages of dry-mixed mortar

With the continuous improvement of engineering quality, environmental protection requirements and civilized construction requirements, the shortcomings and limitations of mixing mortar in construction site are becoming more and more prominent. Dry-mixed mortar is favored by more and more people because of its advantages in technical performance and social benefits.

2. 1 shortcomings and limitations of traditional mortar

2. 1. 1 It is difficult to meet the requirements of civilized construction and environmental protection.

The first is the storage site of various raw materials (including cement, sand, lime paste, etc.). ), will have an impact on the surrounding environment. Secondly, more dust will be formed during mortar mixing. For example, according to relevant data, construction dust in Guangzhou accounts for about 22% of urban dust emission, while cement use and related dust emission account for about 35% of urban construction dust emission. Therefore, the dust emission during the use of cement is the main pollution source of construction dust. Moreover, the noise of the mixing equipment for mixing mortar on site often exceeds the standard, and noise disturbing people has become a major environmental problem in the city. With the progress of society and the improvement of people's quality of life, environmental problems have become the focus of attention from all walks of life. The above-mentioned site environmental problems not only hinder the image of the city, but also affect people's daily work and life, which is extremely inconsistent with the progress of the times.

2. 1.2 The construction quality is difficult to guarantee.

First of all, the quality of mortar fluctuates abnormally due to inaccurate measurement, and there is often no strict measurement for mortar mixed on site, which is completely estimated by workers on site, so the mixture ratio cannot be strictly implemented; It is impossible to accurately add a small amount of additives; The water addition amount cannot be accurately controlled; The uniformity of mixing is difficult to control and the quality of raw materials fluctuates greatly. For example, the silt content and gradation of river sand from different sources are very different. Under this condition, it is inevitable that the quality of mixed mortar will fluctuate abnormally. Secondly, the construction performance of on-site mixing mortar is poor, because the admixture can not be added or rarely added, the workability is poor, it is difficult to carry out mechanized construction, the operation is time-consuming and laborious, and there are many quality accidents, such as cracking and peeling of plastering mortar and leakage of waterproof mortar. Moreover, the variety of ready-mixed mortar is single, which can not meet the different requirements of various new building materials, such as new wall materials encouraged by the state, such as concrete hollow block, aerated concrete block, lime-sand brick, ceramsite concrete hollow block, fly ash brick and so on. However, ready-mixed mortar has long been a limited mixture ratio of cement mortar and cement lime mortar, which is far from meeting the requirements of new wall materials.

2.2 advantages of dry-mixed mortar

2.2. 1 The production quality is guaranteed.

Dry-mixed mortar is produced by professional manufacturers with fixed place, complete sets of equipment, accurate measurement and perfect quality control system. Such as perfect computer control system, to ensure the accuracy and stability of the whole production process. River sand drying controls the water content of sand (generally ≤0.5%), dust removal controls the silt content of sand (generally ≤0.5%), and screening controls grading (generally, the grain size of sand required for production is less than 2.5mm, which is stored separately in several intervals, and then graded reasonably according to product requirements during production). Accurate computer-controlled measurement ensures the accuracy of raw material weighing. Forced mechanical mixing ensures uniform mixing of all materials. Strict quality inspection balances the quality of products. So many measures have fully guaranteed the product quality.

2.2.2 Excellent construction performance and quality.

According to the product types and performance requirements, the dry-mixed mortar is specially designed and modified by adding various additives, such as cellulose ether, redispersible latex powder, thixotropic lubricant, defoamer, air entraining agent, coagulant and waterproof agent. Modified mortar has excellent construction performance and quality, good workability, convenient masonry, plastering and pumping, and improves construction efficiency, such as manual plastering 65438+ 100m2/h and mechanized construction 40 m2/h; When laying, the length of slurry laying at one time is greatly increased. Because of its excellent construction performance and quality, it improves the construction quality, reduces the thickness of construction layer and saves materials. With the improvement of construction quality, the chances of maintenance and rework are greatly reduced, and the long-term maintenance cost of buildings can also be reduced.

2.2.3 The product range is complete, which can meet various engineering requirements.

Dry-mixed mortar manufacturers can design formulas according to different matrix materials and functional requirements, such as high water retention masonry and plastering mortar designed for various high water absorption wall materials, such as aerated concrete blocks, lime-sand bricks, ceramsite concrete hollow blocks, fly ash bricks, etc. Self-leveling platform mortar for high ground flatness. It can also meet various functional requirements such as heat preservation, impermeability, grouting, repair and decoration. According to incomplete statistics, there are more than 50 kinds of dry mortar.

2.2.4 High-quality environmental protection materials have obvious social benefits.

Its dry-mixed mortar is a factory-premixed material, which can be used in the construction site only by adding water and stirring evenly, and it has less dust and is more environmentally friendly. Secondly, due to its excellent construction quality, it will greatly increase the confidence of contractors and owners. For example, there is an old saying in Guangzhou that "tigers are afraid of leakage", which shows that the leakage of waterproof layer of traditional ready-mixed mortar is also a prominent problem that puzzles owners, and waterproof materials with various characteristics in dry-mixed mortar will fundamentally solve such problems. On July 25th, 2002, Guangdong Construction News published a newspaper entitled "Dry Mortar Wearing Waterproof Clothes on the Wall". Thirdly, because of its excellent operation performance, fast construction speed, low labor intensity and less dust on site, it is beneficial to workers' health and more in line with the purpose of "people-oriented" in China. Fourthly, it meets the needs of developing bulk cement in China. Take Guangzhou as an example: in the five years from 1999, the divergence growth rate in Guangzhou has been greatly improved every year, and the popularization of dry-mixed mortar will be beneficial to the further improvement of bulk cement.

3 Conclusion

Although dry-mixed mortar has encountered various obstacles in the process of popularization and use, its historical inevitability of replacing on-site mixing mortar is hard to change. In 2004, the Beijing Municipal Government formally proposed to encourage the use of dry-mixed mortar and other commercial mortars, and issued relevant regulations. Commercial mortar has been used in Shanghai since June 65438+ 10/2004. On March 30th, 2005, the Guangzhou Municipal Construction Committee issued the Notice on Issues Related to Promoting the Use of Dry-mixed Mortar and Ready-mixed Mortar in Construction Projects in Guangzhou (Sui Zhu Jian [2005] 126), demanding that dry-mixed mortar and ready-mixed mortar be given priority in financial investment projects; Whether to use dry-mixed mortar and ready-mixed mortar as one of the assessment conditions for newly started projects to declare quality models and civilized construction models at or above the municipal level since the implementation of this notice. On June 6, 2007, the Ministry of Commerce and other six state departments jointly issued the Notice on Prohibiting Mixing Mortar in Some Cities within a Time Limit (Shanggaifa [2007] No.205): It is forbidden to use cement mixing mortar in construction sites (except small construction sites such as home improvement) by stages. This project uses ready-mixed mortar (including dry-mixed mortar and wet-mixed mortar). Beijing and other cities 10 banned the use of cement mixing mortar in the construction site from September 1 day, 2007 (the first batch); From July 1 2008, 33 cities including Chongqing banned the use of cement mixing mortar in construction sites (the second batch); Eighty-four cities, including Changchun, banned the use of cement mixing mortar on construction sites from July 2009 1 (the third batch). Judging from the promotion progress in many areas, dry-mixed mortar, like commercial concrete, will surely usher in a brilliant spring.

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