The masonry mortar configuration adopts general portland cement or masonry cement.

Special purpose mortar is formulated with special cement

For masonry mortar of grade M15 and below, it is advisable to use grade 32.5 general-purpose Portland cement or masonry cement.

For masonry mortar of grade M15 or above → general Portland cement grade 42.5 should be used.

In cement mortar: cement dosage ≥200 kg/m3;

In cement mixed mortar: the total amount of cement and admixtures is ≥350 kg/m3.

Coarse sand, maximum particle size not larger than 5.0mm

Medium sand, the maximum particle size is not larger than 2.5mm

Fine sand, maximum particle size not larger than 1.2mm

Measured with a mortar consistency meter, expressed in sinking degree (mm)

Porous water-absorbing masonry materials and hot and dry weather require greater fluidity of the mortar. For dense non-water-absorbent materials and humid and cold weather, less fluidity may be required.

The factors that affect the fluidity of masonry mortar are mainly the amount of cement, the thickness, gradation and particle shape of the sand, and the amount of water used.

The greater the mortar sinking degree, the better the fluidity.

Measured with a delamination meter, expressed in delamination (mm)

Within the specified range, the smaller the delamination value, the better the water retention, but it should not be too small.

Mortar with a large degree of layering is prone to segregation and is inconvenient for construction; Mortar with a degree of delamination close to zero has too strong water retention and is prone to shrinkage cracks during the hardening process of the mortar.

5. To improve the water retention of mortar, you can use

Lime paste, clay paste, fly ash

Prevent bricks from taking away a lot of moisture from the mortar

The mortar strength is the ultimate compressive strength measured using a 70.7mm×70.7mm×70.7mm cube test block cured to 28 days of age under standard conditions.

Mortar strength grades are divided according to the average compressive strength.

Strength of mortar on non-absorbent base (dense stone masonry) , similar to concrete, mainly depends on cement strength and water-cement ratio.

When using water-absorbent substrates (such as bricks or other porous materials), The strength of mortar mainly depends on the cement strength grade and cement dosage.

·Masonry relies on mortar to bond block materials into a solid whole, so the mortar is required to have a certain bonding force.

·Influencing factors of mortar adhesion:

In ancient my country, glutinous rice juice and yellow rice juice were added to lime mortar to improve the adhesion of the mortar.

Masonry mortar for ordinary fired clay brick masonry, Its bonding strength is closely related to () and other factors.

Masonry mortar for dense stone masonry, Its bonding strength is closely related to () and other factors.

Deformation performance (mortar is required to have smaller deformability):

Impact: Deformation of masonry mortar → will reduce the quality of the masonry and cause settlement or cracking. Deformation of the plastering mortar → will cause cracks or peeling of the plastering layer.

Improvement: In actual projects, the deformation performance of the mortar can be improved by adding anti-cracking materials to improve the plasticity and toughness of the mortar.

·Durability: Hardened mortar must withstand the physical and chemical effects of the surrounding medium together with the masonry blocks, so the mortar is required to have durability that is compatible with the use environment.

The addition of fiber materials such as hemp into building mortar has a good toughening effect, which can inhibit the volume shrinkage of the mortar and improve the crack resistance of the mortar.

1. Calculate the mortar trial strength fm,o

2 Determine water consumption Qw

3. Calculate cement dosage Qc

4. Calculate the dosage QD of admixtures

5. Determine the amount of sand Qs in each square of mortar

6. Trial matching, adjustment and determination of mix ratio