Archive for July, 2013

Hot Weather Masonry Construction

Tuesday, July 2nd, 2013

Ten Tips for Placing Masonry in Hot Weather

Hot weather poses a few challenges for masonry construction.  As ambient temperatures rise, and materials and equipment heat up, moisture evaporates more rapidly, leaving less water available for cement hydration. This article outlines ten recognized techniques to overcome the negative effects of hot weather on masonry construction. For masonry construction, hot weather is defined as “ambient temperature exceeding 100 deg. F (37.8 deg. C), or 90 deg. F (32.2 deg. C) when the wind velocity is greater than 8 mph (12.9 km/h).” Compounding factors include low relative humidity and direct sunshine. As the temperature of mortar increases:

● Work ability is reduced

● More water is required to maintain a given work ability

● A given amount of air-entraining agent yields less entrained air

● Initial and final set occur earlier, and evaporation rates are generally faster

● Units absorb more moisture from the mortar As a result, the mason will find it more difficult to place mortar and units.

In addition to effects on work ability, rapid drying can result in a lack of sufficient normal strength development of mortar, leading to a reduction in strength. Exposed mortar surfaces are particularly vulnerable. Evaporation removes moisture more rapidly from the outer surface of a mortar joint.

Selecting a Mortar Mix for Hot Weather

In hot-weather construction, mortar properties such as water retentivity and work ability should be given careful consideration when selecting ingredients and mortar type. For example, provided Type N and Type S mortars are both structurally adequate for a given masonry application, the increased water retentivity and work ability generally associated with a Type N mortar make it a better choice for construction during hot weather.

Ten techniques that can be used for construction for masonry in hot weather include:

1. Select workable, water-retentive mortar mixes.

2. Schedule construction to avoid hot, midday periods.

3. Minimize exposure of materials and equipment to direct sunlight.

4. Use cool water to mix mortar.

5. Maintain sand piles in damp, loose condition.

6. Flush metal equipment and wooden mortar boards with cool water before contact with fresh mortar.

7. Pre-wet clay masonry units if they have high absorption (high IRA).

8. Don’t spread mortar too far ahead or work.

9. Place upper units on mortar bed as quickly as possible.

10. Under extreme drying conditions, use windbreaks, fog sprays, or wall coverings to assure adequate moisture for curing of mortar.

Collins Web Site

Tuesday, July 2nd, 2013

Charles J. Collins Jr./Architect 

In addtition to this Architecture Blog prepared by and supported by     Charles J. Collins, Jr./Architect, we also have a company web site located at  and cordially invite any one interested in architecture or architectural services to visit the site.