1. Chapter 5 Construction Mortar

2. There are two methods to design mix of mortar  Consult table–based on experience  Calculation–consult with JGJ98-2000 Calculating steps  Calculating trial strength  Calculating cement quantity Qc  Fix admixtures quantity  Fix sand quantity  Fix the water quantity §5. 4 Mix design of mortar

3. Mix ratio design of masonry mortar Trial Strength f m,0 =f m,k +1.645σ= f 2 +0.645σ f m,0 － Trial strength f m,k —Standard design strength f 2 － Average compressive strength, MPa σ － site strength standard deviation, with accuracy of 0.01MPa Calculating trial strength

4. Cement Quantity Qc=1000(f m,o -β)/αf ce Qc — Cement quantity of mortar per cubic metre, with accuracy of 1kg. f ce — Survey strength of cement, with accuracy of 0.1MPa α 、 β － α ＝ 3.03 ， β ＝ -15.09 Calculating Cement Quantity Qc Mix ratio design of masonry mortar

5. Workability of mortar is good when cement quantity >350 while the water retentivity is poor when the cement quantity is low; thus admixtures are needed Admixtures quantity Q D Q D = Q A -Qc Q D － admixture quantity of mortar per cubic metre, with accuracy of 1kg. Qc － cement quantity of mortar per cubic metre, with accuracy of 1kg. Q A － cement quantity of mortar and admixture quantity of mortar per cubic metre, better between 300 ～ 5000 Fix admixture quantity Mix ratio design of Masonry Mortar

6. Water percentage of sand The quantity of sand per cubic meter mortar Volume （ m ³ ） Weight （ Vs · ρ os ） 1 ～ 3 0 ＞ 3 1 0.92 1.1 ～ 1.2 V · ρ os ρ os · 0.92 ρ os · （ 1.1 ～ 1.2 ） Fix sand quantity Quantity of sand can be fixed according to Tab5.4.1 Tab5.4.1 Fix quantity of sand ρ os —Apparent density of Sand Mix ratio design of Masonry Mortar

7.  The water quantity is fixed by experiments according to the sinking degree  Note  The above calculated mix ratio is fixed by adaptation of workability and strength. Fix the water quantity Mix ratio design of masonry mortar

8. Chapter 5