General cement (6 types): silicate cement, ordinary, slag, pozzolite, fly ash and composite silicate cement.

Special cement: oil well cement, road cement, etc. (in terms of use)

Special cement: fast hard cement, low-heat cement, expanded cement, etc. (in terms of nature)

Fineness: a. The fineness of silicate cement is detected by a breathable specific surface area meter, and its specific surface area is required to be greater than 300m2/kg; b. Other five general cements are tested by screening analysis method, and the 80μm standard screening margin must not exceed 10% (that is, the screening volume shall not exceed 10%).

Condensation time: a. The initial solidification should not be too short (to prevent the upper layer from being poured and the lower layer has condensed), and the final solidification should not be too long; b. The initial setting time of six major categories of silicate cement shall not be shorter than 45 minutes; c. The final set time of silicate cement shall not be longer than 6.5h, and the rest shall not be longer than 10h.

Volume stability: a. Poor volume stability of cement: cracking, bending, brittle and collapse; b. Reason: Free lime, magnesium oxide or sulfur trioxide contained in cement; c. Unqualified volume stability is a waste product.

strength: a. According to the strength measured after standard test and standard maintenance, it is divided into three types: compressive, flexural and tensile strength. b. Grade 42.5 cement means that the compressive strength of 28d should not be less than 42.5MPa.

Hydrating heat: beneficial for winter construction

Concrete consists of cement, aggregate, water and admixtures (not necessary).

Concrete strength: a. Including the compressive strength of concrete cubes, axial compressive strength, split strength and bonding strength to steel bars; the concrete strength grade refers to the compressive strength value of the cubes; b. Factors affecting strength: material composition, construction method, curing conditions, experimental conditions, etc. c. Measures to improve intensity: Start with influencing factors. d. Maintenance measures to ensure strength: Moisturizing and maintenance can be done by sprinkling water, covering, spraying and other methods; e. Curing time: Concrete prepared by silicate, ordinary silicate and slag silicate cement should not be less than 7 days; concrete in other situations should not be less than 14 days.

Methods to improve concrete performance: reduce the water-adhesive ratio, reduce the amount of cement, add admixtures, correct construction and maintenance methods, etc.

Disadvantages of building steel: poor corrosion resistance, heat resistance but not fire resistance, poor thermal insulation effect, easy to cause distortion, and unique cold bridge problems.

Main mechanical properties of building steel: a. Tensile properties are the most basic technical indicators that reflect the quality of steel, including strength (divided into yield strength and ultimate strength.), elastic modulus, elongation, etc., which are generally obtained through tensile tests. Elastic deformation-yield strength-plastic deformation-extreme strength b. Impact toughness: refers to the ability of steel to resist impact loads c. Fatigue strength: Generally speaking, the higher the tensile strength of a steel, the higher the fatigue limit. d. Hardness: There are four methods to measure the hardness of steel - Brinell hardness method, Rockwell hardness method, Vickers hardness method and Nitrogen hardness method (four types of Blowway nitrate)

Special mining steels: mainly mine I-shaped steel, special mining steel (U-shaped steel), light rail, etc.

Common steel processing methods: a. Cold processing strengthening: refers to cold drawing, cold drawing and cold rolling of building steel at room temperature to improve its yield strength and correspondingly reduce plasticity and toughness. b. Aging strengthening: refers to the phenomenon that after the steel is cold-worked, the yield strength and ultimate strength gradually increase with the extension of time, and the plasticity and toughness gradually decrease.

The commonly used metal materials in mining engineering are mainly steel cables and wire ropes.

According to the mechanical characteristics of steel wire ropes, the special grade, the I and the II grade wire ropes are available. The toughness of the special-grade wire rope is finally pressed to enhance personnel.

The flat wire rope is not twisted and knotted, and serves as a tail rope for lifting the friction wheel.

Ordinary silicate cement should be used for grouting, with a strength grade of no less than 42.5, and the concentration of general cement slurry should be 1~0.6.

Ultrafine cement: used to reinforce formations, fill cracks and seal water sources

Clay: thinner than cement, better insufficiency than cement

Cement-water glass double slurry

Chemical grouting materials: small amount and fast effect. In relatively urgent situations, they are often used as working surface grouting. Commonly used: Malisan, polyurethane and epoxy resin.

Water flow velocity is less than 200m/d: cement slurry or clay cement slurry Water flow velocity is greater than 200m/d: cement-water glass double slurry or clay cement slurry When encountering a cave, first fill in inert materials such as rock powder, sand and gravel Poor injectability: ultrafine cement or chemical slurry