There is a common misconception within industry that solid blocks will accept and provide a stronger and more rigid fixing than will cellular blocks (blocks containing voids).

As one of the UK's foremost manufacturers of cellular blocks we have always suspected that there is little physical foundation or evidence to support this theory.

Recent comparative tests have been conducted for both Tensile and Shear on 440mm x 215mm x 140mm Besblock Medium Density paint grade blocks in both solid and cellular formats.

Tensile tests conducted in accordance with the requirements of BS 5080: Part 1: 1993

Shear tests conducted in accordance with the requirements of BS 5080: Part 2: 1986

The tests were conducted by CERAM Research Ltd. CERAM is a UKAS accredited laboratory. The face size of the blocks tested was 440mm x 215mm.

Summary of test results TENSILE STRENGTHS (mean of 5 tests)

Block Type	Max Load (Kn)	Max Load (kg)
140mm Solid	4.21	429
140mm Cellular '15'	8.50	863

Summary of test results SHEAR TESTS (mean of 5 tests)

Block Type	Max Load (Kn)	Max Load (kg)
140mm Solid	6.04	615.7
140mm Cellular '15'	6.87	699

As can be seen, 140mm cellular '15' block provides a superior performance in these fields to that its solid counterpart. The reasons for this are as follows.

The strength of the concrete and its ability to retain fixings will depend on the concrete mix and its cement content.

Very importantly however, the efficiency of the block machine and how it vibrates and binds the concrete mix together will determine the final strength performance of the concrete product. (At Besblock we employ American Columbia block machines .These are world renowned for their unicontrolled vibration systems)

Where cellular blocks are being manufactured, case hardened core bars will be present in the steel mould box.

When the vibration is applied, the concrete mix therein will be forced against the outer constraints of the mould box, but also against the core bars within the mould thereby receiving compaction from 4 sides.

As a result, the concrete contained in the cellular block will have greater density than its equivalent in solid format thereby providing greater strength.