At present, due to the lack of professional knowledge and weak quality consciousness of many site managers of commercial concrete stations, they have insufficient knowledge of the production organization of commercial concrete and commercial concrete products, improper choice of mixing equipment, inaccurate measuring instruments, and construction equipment put into production without any inspection, leading to serious production waste, which eventually leads to various kinds of engineering quality accidents and huge losses. Therefore, it is of great practical significance to strengthen the cost management and cost control of commercial concrete mixing plant. This paper firstly analyzes the composition of the cost of commercial concrete plant, and then discusses in detail the measures of cost control of commercial concrete mixing plant from five aspects.
1. The composition of the cost of commercial concrete plant
Cost of raw materials
The cost of raw materials is the heaviest part of the overall cost of commercial concrete, reflecting the procurement level, technical level and management level. The influence of procurement price is relatively small, because the raw materials purchased are basically purchased locally, and there is a government budget guideline price comparison, so the price is transparent. High technical level can bring relatively low cost of raw materials, but if the management level does not reach the right level, especially in the procurement and quality control of the link of mistakes, will make the high technical level to bear greater quality risks.
Human resource cost
The human resource cost mainly refers to the compensation of the personnel directly involved in the production of each party of commercial concrete, mainly including the fixed part and the performance part, the fixed part reflects whether the staffing is reasonable, and the performance part considers whether the management system is reasonable.
Depreciation of Fixed Assets
It mainly reflects whether the fixed assets are reasonably invested.
Fuel and power consumption
It refers to the fuel consumption and electricity (coal) consumption per cubic meter of commercial concrete, which is the reflection of transportation quality and production control quality.
Refers to the cost of equipment maintenance and repair, is the reflection of the quality of equipment operation.
Including non-production personnel costs, hospitality, non-production water, electricity, oil and other costs, as well as office expenses.
It is closely related to the equity structure of each commercial concrete mixing plant, the purchase status of equipment and the local market situation, and is a reflection of the investment level.
Measures for Cost Control of Commercial Concrete Mixing Plant
Innovative cost management model
The company implements three management modes for the mixing plant: First, the management mode of self-built mixing plant and self-organized concrete processing and production, i.e., the project department invests all the funds to purchase all the mixing plant equipment and temporary facilities and organizes concrete processing and production by itself; second, the management mode of self-built mixing plant and commissioned concrete processing and production, i.e., the project department invests all the funds to purchase all the commercial concrete mixing plant equipment and temporary facilities and commissions external collaborators to process and produce concrete. The third is the management mode of joint construction of mixing plant and entrusted concrete processing and production, i.e., the project department is responsible for building temporary facilities, and the external collaborators are responsible for providing production equipment and transportation equipment, as well as concrete processing and production and transportation. The cost control points of these three management modes are explained below.
Control of labor costs
During the accounting period (quarterly), the labor costs incurred by the project department’s own production workers or the labor costs of external laborers paid directly by the project department under the "employment contract" shall be collected by the project department’s finance department and included directly in the current production costs according to the actual number of costs incurred in the current period. Labor cost" is included directly in the line item "labor cost" in the current concrete production cost. Specifically, labor costs are controlled from the following aspects:
Calculate the fixed amount of labor according to labor quotas, and assign a certain percentage of safety, civilized construction and piecemeal labor to the foreman or team for contract control.
It is necessary to improve the technical level of production workers and the organization and management level of the team, organize labor reasonably, streamline personnel, reduce and avoid ineffective labor, and improve labor efficiency.
For unit projects with low technical content, they can be subcontracted to subcontractors and controlled by lump sums to reduce labor costs. Sub-contracting teams are generally determined through bidding, and can be done in the form of fixed work Et unit price or square meter lump sum for management. In the construction process, strict control of expenditure, once a month pre-settlement, such as the discovery of overspending phenomenon, must be timely analysis of the reasons.
Accurate control of material costs
During the accounting period (quarterly), the material department of the project department will follow the principle of "how much to use and how much to pay" for materials that are easy to measure.
"When used, when out of the account" principle of material out of the account, in a timely manner in accordance with the actual number of materials consumed to fill out the material "with the material order", the material out of the account procedures
At the end of the period (the end of the quarter), for large piles of materials such as sand and gravel materials that are not easy to measure, the actual quantity consumed is calculated according to the "inventory method" of the remaining materials (i.e., the material department and the commercial concrete mixing plant are jointly responsible for taking inventory of the remaining quantity of large piles of materials such as sand and gravel materials, and filling in the "inventory material inventory sheet" by material name and specification). Material inventory list".
According to the "inventory list", the material department will calculate the actual quantity of raw materials for the period according to the formula of "actual consumption for the period = quantity in stock at the beginning of the period + quantity received at the end of the period – quantity remaining in stock at the end of the period" and fill out the "material use order". (5) The finance department will fill in the "material use order" according to the formula of "material".
The finance department will charge the cost of concrete production according to the material "bill of materials".
Cost control of other production costs
On the basis of accurate raw material billing and actual labor cost, all departments and related personnel of the project department, in accordance with the division of labor, shall timely, accurately and completely collect all other costs incurred in the process of concrete production (including: depreciation and maintenance of concrete mixing plant equipment, amortization of temporary facilities, rental of equipment, utilities, concrete quality inspection and testing fees, etc.) and submit the settlement invoices to the finance department in a timely manner. The invoices and other documents will be submitted to the finance department in time to be included in the current concrete production cost.
At the end of the period, for costs that cannot be settled or are not settled enough for the period, the relevant departments and personnel are responsible for providing timely information on the withholding of costs in accordance with the contract price and the actual quantity used (water and electricity degrees or machinery units), and handing them over to the finance department for inclusion in the current concrete production cost, so as to ensure complete collection of production costs and accurate cost accounting.
2. Reasonable control of the ratio of commercial concrete
The role of the ratio of commercial concrete
The ratio of commercial concrete is an important basis for calculating the cost of commercial concrete station, which directly determines the amount of each raw material of commercial concrete, and is the most important of the cost control of commercial concrete station. A reasonable mix ratio design is a reflection of the technical level of a project or even the whole company. Operators should implement the idea of "serving the next process", consider the difficulty of the construction site in the ratio design, study the ratio design carefully, and find out the rules through tests to make the ratio more scientific and reasonable.
Determination of the ratio of commercial concrete
Generally according to the cement strength grade, coarse and fine aggregate grade and admixture type, initially set a number of appropriate intervals of water-cement ratio. And after a series of ratio tests, according to the production control level of the formulation strength, selected different commercial concrete strength corresponding to the water-cement ratio. Then adjust the ratio and test mix, after the test mix of commercial concrete mixes to meet the requirements of the compatibility can be used as the selected ratio. In the mix design, the performance of commercial concrete mix should be fully considered to ensure that the factory does not segregate, not water, not sticky, not to catch the bottom, and maintain good fluidity. For special requirements or special commercial concrete, it is also necessary to specially design, mix ratio and conduct relevant tests.
Control of commercial concrete ratio
In order to control the ratio of commercial concrete, you can take one commercial concrete mix for each commercial concrete ratio in each work shift and conduct a commercial concrete mix analysis test. At the same time, do not stick to the rules, to dare to scientific and technological research, in the case of meeting the actual needs of the site to use new mixes, and actively use new materials, new technologies, to find alternatives to high-priced, scarce materials, to achieve the purpose of cost savings.
3. Strictly control the procurement of materials
The production of commercial concrete should be based on the large rotary kiln cement with stable quality and good reputation, and the temperature of bulk cement into the tank should be strictly controlled when it is purchased (to not be hot). Otherwise, the cement will be lumped after entering the tank, which is not conducive to the mixing of commercial concrete and causes waste.
Coarse and fine aggregates
Using high-quality sand and gravel materials to mix commercial concrete, although the unit price of sand and gravel materials has increased, but the strength and strength guarantee rate of commercial concrete is greatly improved. Therefore, in the case of the same strength and strength guarantee rate, the amount of cement and admixtures can be properly reduced, the cost of mixed materials for commercial concrete is often lower than the cost of using poor quality sand and gravel materials. At present, natural sand resources are becoming increasingly tight, it is recommended that the mechanism sand. When using mechanism sand, the stone powder content should be controlled within 10%, while strictly controlling its single-stage maximum crushing value (not more than 25%). At present, in the project construction, the supervisory unit generally requires sand sieving and stone washing, which will cause great waste if the incoming sand and stone have high mud content or the particle size does not match the design. Therefore, before the materials come in, we also need to make field visits to the origin of the materials and choose high-quality materials.
Mixing commercial concrete is generally used in drinking water, if non-potable water is used, it should be tested in advance or periodically to see if it meets the regulations. If it does not meet the requirements, we should also determine whether it can be used through the commercial concrete test, so as not to affect the quality of commercial concrete and cause waste.
The types of mineral admixtures are finely ground fly ash, finely ground slag, finely ground natural zeolite, silica fume and its complexes. To ensure the effective content of the admixture, should strengthen the liquid admixture concentration test. When replacing the variety of admixture, the original admixture storage tank and measuring apparatus must be cleaned up the residue. The current expansion agent is mostly powdered products, and a larger amount of admixture, for this reason, it is best to set up a special silo, in the same meter with cement, mineral admixture together with the cumulative measurement. All kinds of chemical admixtures should be batch sampling according to the corresponding provisions of its main physical properties of commercial concrete, in addition, but also with different varieties, different batches of cement and mineral admixtures to verify the adaptability. At present, the unit price of commercial concrete admixtures, quality varies, and the general unit price is high, can not underestimate its share in the cost of commercial concrete, so more tests and comparisons to optimize the use of admixtures cost.
4. strict control of the construction process of commercial concrete
Although the site of commercial concrete mixing plant have automatic measuring device, however, we can not ignore the point that all use loader loading, due to the loader bucket is large, while the batching bucket is small, and no baffle between the batching bucket, the loading process of sand and stone mixed, thus causing inaccurate measurement, which affects the pumpable performance of commercial concrete and the strength level of commercial concrete, easy to cause pipe blockage, the solution can only be The solution can only be to increase the amount of cement or increase the sand rate, which makes the cost increase.
The minimum mixing time of commercial concrete is clearly stipulated in the specification, and the mixing time of pumped commercial concrete with "double blending" technology should not be less than 120s, but in practice, it often fails to meet the requirements of the minimum mixing time, resulting in the reduction of commercial concrete compatibility and pumpability, and easy to block the delivery pipe.
Commercial concrete is a non-homogeneous material, should be in the range of 2 ~ 3m horizontal movement of uniform fabric, especially the horizontal area of the larger structure. However, there is a large discrepancy in the actual operation, that is, along a point of concentration of material, with a vibrating rod "infusion" of commercial concrete, resulting in the concentration of stones at the point of material, while other parts are mostly cement mortar or floating slurry, which is in the strength of the component rebound, why some parts reach or exceed the design strength, while some parts are lower than the design One of the main reasons for the strength. Mistakenly think that the ratio design problems, and then by increasing the amount of cement to solve the lack of strength, so that the cost of commercial concrete increased.
Commercial concrete should be timely maintenance after casting, early water loss not only impede the normal growth of strength, but also make the final strength of commercial concrete will be reduced. According to the seasonal changes must take appropriate measures to ensure that the strength of commercial concrete growth must have the temperature and humidity.
5. Control the accident rate
Accident refers to the loss caused by various subjective and objective factors, including the return of ash, pouring ash, the use of reduced grade, site repair, additional testing, compensation, etc., no matter whose cause is caused, will cause losses to the enterprise, but a single-minded pursuit of responsibility for the accident, without analyzing the cause of the accident, will only treat the symptoms but not the root cause, in fact, the accident rate is a comprehensive reflection of the level of technology, quality control level, production management level, should be on the accident We should have an objective and fair attitude towards accidents. The quantitative analysis of management is to reflect the causes of accidents in the form of figures as far as possible, so that decision makers can analyze the causes of accidents more easily.
In summary, commercial concrete, as the most commonly used material in the construction industry, has a high percentage of cost and can be mined to a great depth. Although the production management of commercial concrete is still in many regions in many cases roughly managed, and the existence of many uncertainties makes the quantitative management more difficult, it should be seen that all surface phenomena have their intrinsic causes, and the production cost of commercial concrete must be accumulated from every calculable part, therefore, the quantitative management, through the re-definition of various data of the commercial concrete station Definition and measurement, it is possible to understand the clear composition of the cost of production of commercial concrete, so that the decision makers of the enterprise can find the most effective way to control the cost, so that the enterprise can get the fundamental motivation for sustainable development.