Final answer:
Improving bond strength between mortar and masonry units can be achieved by the use of well-graded sand, controlling the water-to-cement ratio, using additives like pozzolans, ensuring masonry cleanliness and proper dampness, compatibility of thermal expansion properties, and proper curing practices.
Step-by-step explanation:
To improve bond strength between mortar and masonry units, one can employ several methods focusing on the properties of the materials used. The fineness and type of sand used in the mortar mix can significantly affect the bond strength. For example, using well-graded, angular sand will increase mechanical interlocking, and adding certain additives or pozzolans such as fly ash or silica fume can enhance the bond and overall strength of the mortar. Controlling the water-to-cement ratio is also critical since too much water can lead to a weaker bond and lower strength, while too little water can cause poor workability and reduced bonding as the mortar does not fully adhere to the masonry units.
Another method is to ensure the cleanliness and proper dampness of the masonry units before application of the mortar. Dirty or overly dry masonry units can absorb the water from the mortar too quickly, leading to a poor bond. Ensuring that both the mortar and masonry units are compatible in terms of their thermal expansion properties can prevent future bond failure due to environmental stress. Lastly, proper curing practices will help to achieve maximum strength and bond between the masonry units and the mortar.