1. Introduction

2. Product Line

3. Thermal Properties

4. Fire Resistance

5. Acoustic Absorption

6. Moisture Absorption

7. Environmental

8. Structural Design

9. Standard Construction Detials

10. Installation Procedures

11. Tools and Fasteners

12. Wall Finishes

13. News

Structural Design/Engineering Services

Navajo FlexCrete Building Systems Inc. offers engineering services that include the following:

* Sealed set of wall calculations, shop drawings showing all FRAC block, product details, connections, specifications, schedules and other related information.

* Design coordination with architectural / structural drawings.

* Engineering and design assistance to the Engineer and (or) Architect of record.

* Consultation services for design-build projects.

* Structural Inspections - Special inspection services

* Forensic Analysis for structures built using FRAC products.

Photo above was built with Aerated Concrete (AC)

8.1

Design Introduction In accordance to ASTM C 1692, FlexCrete FRAC blocks exhibit the same structural characteristics as conventional Autoclaved Aerated Concrete (AAC) blocks, therefore in accordance to ICC ES Report ESR-2866, the structural design procedures used are the same as prescribed in ACI 530/TMS 402 for ACC blocks.

AAC has been widely used successfully as a structural and non-structural building product around the world since 1923, and in the United States since 1990. AAC has great durability and resistance to wind and earthquake forces, and has shown it can survive the test of time. After twenty years of research, testing, engineering and product history in the United States AAC was incorporated in to the masonry code (ACI 530/TMS 402) in 2005. in 2006 AC was introduced in to the International Building Codes (IBC), and International Residential Codes (IRC).

FRAC masonry blocks are designed in accordance to the IBC, IRC and ACI 530 codes. The masonry codes (ACI 530/TMS 402) has design provisions for the use of AAC in all seismic design categories A, B, C, D and E; however, the IBC has limited the use of AAC masonry blocks to seismic design category C for AAC walls used as the main seismic load resisting system. For residential projects, the IRC does not place restrictions on the use of AAC in seismic areas and may be designed in accordance to ACI 530/TMS 402 codes per the “General Masonry Construction” IRC section R606. Please check with your local building code officials for additional requirements and/or restrictions.

FRAC wall systems can be designed as reinforced or un-reinforced, load or non-load bearing walls. FRAC products are pre-drilled with one 4-inch diameter hole at a distance of t/2 (t = block thickness) to allow for vertical wall reinforcing as required by the designer and codes. Where vertical reinforcing is required it should be spaced in 24 inch increments (24” O.C., 72” O.C., etc.,) FRAC can be drilled on site for special reinforcing requirements as needed.

Minimum vertical wall reinforcing requirements are (1) #4 rebar at wall corners, within 24 inches of each side of wall openings, wall ends and control joints. Horizontal reinforcing requirements are (2) #4 rebar’s in solid grouted FRAC masonry “U-blocks” at floor and roof bearing and (1) #4 rebar at the top of parapet walls. Horizontal reinforcing at FRAC masonry lintels should extend 24 inches past wall openings. Additional reinforcing may be required depending on the structural demands of the building and as required by the engineer of record.

8.2

Notable Differences Some of the notable differences between FRAC systems, masonry and concrete walls are:

FRAC weighs approximately 30 lb/ft3 (AC Class 3) compared to 150 lb/ft3 and 50 lb/ft3 for concrete and masonry, respectively.

FRAC is constructed using a thin-set mortar that has a greater compressive and tensile strength than the FRAC material itself. The bond strength of the thin set-mortar results in a monolithic wall assembly and prevents failure at the joints. FRAC wall systems behave like a beam with a neutral stress axis at the wall’s center, thus reducing or eliminating the minimum reinforcing requirements that are currently required for regular un-reinforced masonry. Concrete and masonry have a minimum reinforcement requirement because they both need to be designed as a cracked section; this is not the case with FRAC wall systems.

Conventional masonry block wall systems require horizontal joint reinforcement and since FRAC uses a thin-set mortar, that acts more like an epoxy to bond the blocks together, and thus does not require joint reinforcement.

When designing for FRAC materials, the engineer should take caution as to not over reinforce the wall. The compression capacity of FRAC is lower than conventional masonry and concrete, the codes have placed a limit on wall reinforcement, depending on the density of FRAC used. FRAC walls are required to be designed as a ductile system. This is accomplished by ensuring the failure mode to the steel in lieu of the compression of the block.

Like conventional masonry and concrete, FRAC is also produced with a variety of compression and density grades per ASTM C 1693.

FRAC is a solid block system with grouted cells only where required for vertical and horizontal wall reinforcing. The lower compression strength of FRAC block, compared to conventional masonry block, is compensated by the increased bearing surface area of the solid block.

8.3

Structural Design Considerations FRAC products are available in a variety of grades with corresponding density and compressive strength. The most common grade produced by FRAC is FRAC-3. Refer to later sections of this manual for availability of other density grades.

∗ If vertical reinforcing is required it should be spaced in 2’ increments (2’, 4’, 6’, etc.).

FRAC can easily be drilled or notched on site for additional reinforcing requirements. Caution should be taken to make sure that there is at least 1/3 of the wall thickness

(2 inch minimum) of FRAC remaining, when notching or drilling the block, to prevent possible blowout when grouting.

∗ Vertical reinforcing at each end of wall openings should be within 2’ of the opening

which will allow the installer flexibility in maintaining a 2’ module to minimize on site drilling.

∗ For long walls, expansion control joints should be placed at 20’ O.C. to prevent temperature and shrinkage cracking.

∗ FRAC lintels can be designed in two different ways as illustrated in the FRAC

masonry lintel design examples. FRAC “U” blocks may split when grouting if stirrups are spaced less than 12” O.C.. To prevent possible blowouts of the FRAC “U-blocks” when grouting, the sides should be braced, and it is best to limit the lintel

height to 32” high. If deeper lintels are required consider steel beams.

∗ Steel lintels can be used similar to conventional masonry. Power Steel Lintels

(specific brand) are available to use with FRAC masonry. Load tables are provided at

the end of this chapter.

∗ If needed, concentrated loads can be spread out by using a bond beam in the same

manner as conventional masonry.

∗ Anchor bolts are to be designed in accordance to ACI 530 and the FRAC “U-block”

should be notched 6” around the anchor bolt and grouted solid. See ledger detail in

the construction detail section.

∗ Special inspection is required for all FRAC wall assemblies. Inspections are to be

performed using the same requirements as conventional masonry.

8.4

GENERAL INFORMATION All construction shall conform to the International Building Code (IBC) or International Residential Code (IRC).

Navajo FlexCrete (FRAC) walls designed per ICC ESR - 2866 and/or ACI 530 with the following classes per ASTM C 1694:

Class Compressive

Strength (PSI)

Nominal Density (LB/FT3)

FRAC-2 290 22 to 34

FRAC-3 435 28 to 34

The contractor shall be responsible for and provide all measures necessary to protect the structure during construction. These measures shall include, but not be limited to: bracing and shoring for loads due to wind. The contractor shall be responsible for the design implementation of all scaffolding, bracing and shoring.

Contractor shall verify all dimensions and coor-dinate the site conditions with the drawings prior to construction. Any discrepancies and omissions shall be resolved with the architect. Do not use scaled dimensions. Where any discrepancies occur between plans, the greater requirement shall govern, where no specific detail is shown, construction shall conform to similar work on the project. All details shown shall be incorporated into the project at all appropriate locations, whether specifically indicated or not.

In general, like all other construction products, FRAC is susceptible to minor breakage during transit. Less handling means lower potential for damage. In some instances, spalling may occur from shipping. Damaged AC can be trimmed away and then installed, to reduce job waste.

Design Loads:

Roof Live Load = ____ psf

Roof Dead Load = ____ psf

Floor Live Load = ____ psf

Floor Dead Load = ____ psf

Wind Speed = ____ mph @ 3 sec. gust, expo-sure - ____

Seismic Design Category “____”

FOR ALL FRAC CONSTRUCTION PRO-JECTS:

Deliver only an amount of material that can readily be installed. Unload pallets using rough terrain forklift or pallet forks. Consult your OSHA safety manual for “rigging” for other safety considerations. It is not advisable to use crane straps and slings.

Storage areas should be accessible to delivery trucks and convenient to material staging areas. If possible, drop-deliver the material directly to the material staging areas.

FRAC pallets should always be stored away from other construction activities on a flat and level area that is not susceptible to standing water, erosion or settling.

Keep the material covered from the elements and banded until ready for installation.

All FRAC material should be clean of any dust or particles - brushing and spraying down with water may be necessary to clean the FRAC blocks in order to achieve proper adhesion.

Recommended Structural Notes

8.5

LEVELING MORTAR BED (FIRST COURSE ONLY):

Mortar shall conform to ASTM C 270, type S or M mortar with water proofing additive to prevent moisture wicking up from the slab. Mortar to have a 28 day compressive strength of 1800 psi.

THIN BED MORTAR

Thin-bed mortar provided by FlexCrete Building Systems Inc. is in accordance to ASTM C 1660.

GROUT

Grout shall conform to ASTM C 476, fine or coarse grout, 28-day compressive strength of 2000 psi, tested per IBC.

See details and notes on drawings for size and spacing of reinforcing bars.

Provide vertical dowels from footings continuous through stem walls in to FRAC walls above. All shall match size and spacing of vertical dowels reinforcing above. Extend all horizontal bond beam reinforcing in FRAC walls continuous around corners and intersections or provide bent corner bars to match and lap horizontal bond beam reinforcing at corners and intersections. All reinforcing in FRAC walls shall be accurately located prior to grouting and the position maintained during grouting.

All cells and courses with reinforcing and additional grout spaces as required by the drawings shall be filled solid with grout. Maximum grout lift height shall be 12’8” where the following conditions are met:

* The blocks have cured for at least 4 hours

* The grout slump is maintained between 10 inch and 11 inch

* No intermediate reinforced bond beams are required between floor and roof lines.

* FRAC U-block is utilized for door and window lintels.

Otherwise, place grout in lifts not exceeding 5’-0”. In all cases, between grout pours, a horizontal construction joint shall be formed by stopping all wythes at the same elevation and with grout stopping a minimum of 1-1/2 inches below the mortar joint; except at the top of the wall where bond beams occur, the grout pour shall be stopped a minimum of 1/2 inch below the top of the masonry.

Depending on regional requirements cleanouts may be necessary in the bottom course of masonry for each grout pour when the grout pour height exceeds 5’-0”. Construct cleanouts with a minimum opening dimension of 3” so that the space to be grouted can be cleaned and rebar inspected. Place grout continuously. Do not interrupt grouting for more than one hour. Gently mechanically vibrate grout in vertical spaces immediately after pouring and again about 5 minutes later. Do not over vibrate. Rodding of grout is not acceptable.

Unless noted otherwise on the drawings, provide vertical FRAC wall control joints such that no straight run of wall exceeds 20”-0”. Coordinate locations with architect. Every effort is made in the design to minimize the possibility of cracks, but they may still appear, in most cases these cracks are non-structural. Coordinate location of control joints with architectural plans. Reinforcement mesh can add shear strength to the final stucco finish.

Recommended Structural Notes

8.6

REINFORCING STEEL:

Reinforcing steel shall conform to ASTM A 615, grade 40 (Fy = 40 KSI) deformed bars for all bars #5 and smaller. Welding of reinforcing shall be in accordance to AWS D1.4. No tack welding of reinforcing bars allowed.

Extend all horizontal reinforcing continuous around corners and intersections or provide bent corner bars to match and lap with horizontal bars at corners and intersections of walls.

Provide vertical wall reinforcing at all corners, wall ends, wall intersections, each side of control joints and within 24” of door and window openings, see plans for size and additional requirements; typical unless noted otherwise.

Provide two horizontal reinforcing bars in solid grouted FRAC “U-blocks” at roof and floor supports and one horizontal reinforcing at top of parapet, see plans for additional requirements.

Lap splices of reinforcing in FRAC walls unless noted otherwise, shall be per tables below.

Vertical Bar Lap Splice Length (in) - (Strength Design per ACI 530)

Bar Size fy = 40 ksi fy = 60 ksi

3 12 N/A

4 17 25

5 27 40

6 N/A 54

Horizontal Bar (Bond Beam) Lap Splice Length (in) - (Strength Design per ACI 530) Bar Size fy = 40 ksi fy = 60 ksi

3 17 N/A 4 30 44 5 46 69

Special Inspections: (REQUIRED FOR ALL FRAC BLOCK WALLS)

Special inspections for FRAC walls shall be performed by a qualified inspector, approved by the architect under the direct supervision of a state registered structural engineer who is familiar with the structural design of this project. The special inspection certificate shall be sealed by the supervising structural engineer. The contractor shall be responsible for providing a minimum of 24 hours notice to the special inspector prior to beginning any work for which special or testing is required.

Special inspections for FRAC walls shall be per-formed in accordance with the special inspection re-quirements for masonry as outlined in IBC table 1704.5.1.

Prism test is not required for FRAC masonry systems.

Structural FRAC walls: During placement of rein-forcing, inspect grout space immediately prior to closing of cleanouts and during placement of all grout. Special inspection for placing of units may be performed on a periodic basis.

Duties and responsibilities of the special inspector:

The special inspector shall inspect the work assigned for conformance with the approved design drawings and specifications.

The special inspector shall furnish inspection reports to the building official and to the engineer or architect of record. All discrepancies shall be brought to the immediate attention of the contractor for correction, then, if uncorrected, to the engineer or architect of record and the building official.

Upon completion of the assigned work, the special inspector shall complete and sign a final report veri-fying that to the best of the inspector’s knowledge, the work is in conformance with the approved plans and specifications, and the applicable workmanship provisions of the code.

Suggested FRAC Masonry Structural Notes

8.7

Physical Properties of FRAC Block

FlexCrete Building Systems Inc. offers the highest quality FRAC building products for structural and non-structural applications. The table below indicates the physical properties of the materials per ASTM C 1693

FRAC/AAC Block Physical Properties (ASTM C 1693)

Density Minimum Compressive

Strength Average Drying

Shrinkage

lbs/ft3 kgs/m3

psi mpa %

AAC-2 25-31 400-500 290 2 <0.02

AAC-3 31 500 435 3 <0.02

AAC-4 31-50 500-800 580 4 <0.02

AAC-6 37-50 600-800 870 6 <0.02

*Currently approved by ICC ESR-1371 - ASTM standard will be updated to incorporate AAC-3 designation, properties are included in the ASTM standard between class 2 and 4

8.8

FRAC Single Course Lintel Design Example – Design per ACI 530/TMS402-2005

8.9

FRAC Single Course Lintel Design Example – Design per ACI 530/TMS402-2005

8.10

FRAC Single Course Lintel Design Example – Design per ACI 530/TMS402-2005

8.11

FRAC Multiple Course Lintel Design Example – Design per ACI 530/TMS402-2005

8.12

FRAC Multiple Course Lintel Design Example – Design per ACI 530/TMS402-2005

8.13

FRAC Multiple Course Lintel Design Example – Design per ACI 530/TMS402-2005

8.14