What are the main advantages and disadvantages of ordinary concrete?

Ordinary concrete refers to cement as cementing material, sand and gravel as aggregate, mixed with water, poured and solidified into "artificial stone" with certain strength, that is, cement concrete, which is the most widely used concrete variety in engineering at present. The word "concrete" can usually be classified as "concrete".

First, the main advantages of ordinary concrete

1. Rich sources of raw materials. More than 70% of the materials in concrete are sand and gravel, which are local materials, and can be used locally to avoid long-distance transportation, so the price is low.

2. The construction is convenient. Concrete mixture has good fluidity and plasticity, and can be poured into various shapes and sizes of components and structures according to the needs of the site. It can be cast in place or prefabricated.

3. The performance can be designed and adjusted as required. By adjusting the variety and quantity of each component material, especially adding different additives and admixtures, different workability, strength, durability or good matching can be obtained, and reinforced concrete meeting different requirements in engineering can be poured.

4. High compressive strength. The compressive strength of concrete is generally between 7.5 and 60 MPa. When superplasticizer and admixture are added, the strength can reach above 100MPa. Moreover, concrete and steel bars have a good match. After pouring into reinforced concrete, the defect of low tensile strength can be effectively improved, so that concrete can be applied to various structural parts.

5. Good durability. Concrete with correct selection of raw materials, reasonable proportion and good construction and maintenance has excellent impermeability, frost resistance and corrosion resistance, and has a protective effect on steel bars. The long-term service performance of concrete structure can remain stable.

Second, the main shortcomings of ordinary concrete

1. Self-importance. The weight of 1m3 concrete is about 2400kg, and the structural weight is large, which leads to the increase of foundation treatment cost.

2. Low tensile strength and poor crack resistance. The tensile strength of concrete is generally only 1 10- 120 of the compressive strength, so it is easy to crack.

3. Large shrinkage deformation. The autogenous shrinkage and dry shrinkage caused by hydration, coagulation and hardening of cement are more than 500× 10-6 mm, and concrete is prone to shrinkage cracks.