Top 25 Common Knowledge about Concrete Materials Based on Commercial Concrete Mixing Stations (Part 1)

Introduction

Concrete is a widely used construction material known for its strength and durability. In this article, we will explore the basics of commercial concrete and provide valuable insights into its various components and properties. Whether you're a construction professional or an enthusiast, this compilation of concrete knowledge will help you gain a better understanding of this essential material.

1. What is Commercial Concrete?

Commercial concrete refers to the concrete mixture produced and sold at concrete mixing stations according to specified proportions of cement, water, sand, aggregate, and mineral admixtures. It is prepared at the mixing station and transported to the desired delivery location using concrete mixer trucks within a specified timeframe.

2. What are Standard Products?

Standard products refer to commercial concrete with strength grades not exceeding C60, slump values not exceeding 180mm, and maximum aggregate particle sizes ranging from 20mm to 40mm, without any additional requirements.

3. What are Special Products?

Special products refer to commercial concrete that exceeds the specifications of standard products or has specific requirements. Examples include fine aggregate concrete, pile foundation concrete, impermeable concrete, and freeze-resistant concrete.

4. What is the Delivery Point?

The delivery point is the designated location, usually the construction site, where the concrete is handed over from the supplier to the customer as specified in the contract.

5. What is Factory Inspection?

Factory inspection involves conducting quality inspections on commercial concrete before it leaves the factory. This includes sampling and testing the slump, preparing strength test specimens, visual inspection of slump and workability, among other checks.

6. What is Delivery Inspection?

Delivery inspection is performed at the delivery point by the supplier, customer, and supervisor collectively to inspect the commercial concrete. It includes slump testing, specimen preparation, visual inspection of slump and workability, and other relevant checks.

7. What is Cement? How many types of cement are commonly used?

Cement is a hydraulic binder made from clinker, suitable proportions of mixing materials, and a suitable amount of gypsum, finely ground to form a solid material. Common types of cement include Portland cement, ordinary Portland cement, and composite cement. Portland cement is further classified into types P·I and P·II, with strength grades of 52.5 and 62.5. Ordinary Portland cement is categorized as ordinary type (P·O) and rapid hardening type, with strength grades of 42.5, 42.5R, 52.5, and 52.5R. Composite cement is designated as P·C, with strength grades of 32.5, 32.5R, 42.5, and 42.5R.

8. What are the items for Cement Retesting?

Cement retesting involves testing the setting time, stability, strength, and fineness (specific surface area) of cement. These tests ensure the quality and performance of the cement and determine its suitability for use in commercial concrete.

9. What is Water in Concrete?

Water is an essential component of concrete. It acts as a lubricant, facilitating the mixing, placing, and compacting of concrete. Water also chemically reacts with cement to form hydration products, providing strength and durability to the concrete.

10. What is the Water-Cement Ratio?

The water-cement ratio is the ratio of the weight of water to the weight of cement used in a concrete mixture. It is a critical factor that affects the workability, strength, and durability of concrete. The water-cement ratio should be carefully controlled to ensure the desired properties of the concrete are achieved.