Iano's backfill

Self-Consolidating Masonry Grout

PCA Masonry Today (Winter 2004/2005) devotes its two main articles to a relatively new material self-consolidating grout (SCG). Like its close relative self-consolidating concrete, SCG is a cementitious grout material formulated with special additives to achieve very high-flow, low-slump properties without the addition of excess water to the mix. The most significant benefit of using SCG in grouted masonry construction is its ability to flow easily through complex, extended void spaces and around densely spaced reinforcing within the masonry assembly. This simplifies the masonry construction, speeds the grouting process, and greatly reduces the chance of voids or partially filled cores in the completely construction.

According to Characteristics of Self-Consolidating Grouts, an SCG mix has a lower water-cement ratio and includes superplasticizing admixtures (polycarboxylates) to increase its workability or flow in comparison to conventionally formulated grout. When the standard test for slump is applied to SCG, the test is more accurately termed a “flow test”. When the test cone is lifted, the SCG typically spreads out in a shallow pool or “pat” roughly 22 to 30 inches in diameter. In addition to verifying adequate flow, the pat is also checked for absence of segregation, bleed water, or aggregate clumps--all signs of deficiencies in the mix that could lead to poor quality in the finished construction.

Other common tests that are used to ensure the quality of both conventional grout and SCG construction include compressive strength testing of cured samples, and the post-placement inspection of strategically located openings in the masonry assembly to confirm the full flow of grout throughout the intended spaces within the masonry.

Grout Goes Straight on Prison Project discusses additional benefits of SCG in grouted masonry construction. While SCG itself may cost 8% to 11% more than conventional grout, it can be placed in roughly half the time. This reduces off-loading time for the ready mix trucks that deliver the grout to the construction site and speeds construction. Additional labor savings accrue from the absence of any need to vibrate SCG to ensure proper consolidation, and potential savings in the simplification of the masonry construction due to the high-flow capabilities of SCG.

More information
Grouting of reinforced brick masonry construction is discussed on page 294, and grouting of concrete masonry unit construction on pages 324 - 328 of the textbook. Additional information is also contained in Chapter 10, Masonry Loadbearing Construction.
The concrete slump test, the compressive strength testing of test cylinders, and the use of self-consolidating concrete are discussed on pages 477 - 478.

Pop Quiz!

The accompanying photo shows a reinforced concrete masonry wall under construction. When the author observed this wall during a recent site visit, he immediately instructed the contractor to take corrective action.

Can you identify the problem and what corrective action was required? Use the comment link below to submit your answer.

Hints: No work is currently taking place on the wall. The problem is nonstructural, and does not relate to temporary bracing.

10 - Masonry Loadbearing Wall Construction Links

This article contains external links to resources on the Web relevant to Chapter 10 Masonry Loadbearing Wall Construction.

Extreme Masonry: Earthquakes

Portland Cement Association's web page dedicated to links and information resources related to seismic design considerations in masonry construction.

MasonrySystems.org

The industry association-sponsered web site provides a useful variety of information regarding wall system selection guidelines, wall system examples, and more.