the “exposed aggregate” concrete block

Boyd Brothers Company first began making “exposed aggregate” blocks in 1914.[1] This type of block was made with a mixture of cement and various colours of crushed aggregates. After blocks were removed from the moulds, they were sprayed with “a fine mist of water” to remove the concrete residue and expose the crushed aggregate on the “face” side of the block.[2] The surface colour and texture of the block could be varied by using different types of crushed stone in the concrete mix. Boyd Brothers Co. purchased stone from a variety of sources in order to vary the appearance of its blocks. A white stone was brought from Kingdon lead mines at Galetta, Ontario. The white stone consisted of the tailings from the mine after the lead had been extracted.[3] Mica spar was brought in from Crown Point, New York.[4] Stone was also brought from Asbestos, Quebec;[5] Verona, Ontario; and from Pennsylvania.[6]

The blocks ranged in colour from white to a very dark gray. Many of the aggregates used in block-making were of types that had a naturally reflective quality that contributed greatly to the aesthetic appeal of the blocks. Although the blocks were textured by the sharp granules of aggregate, they had a flat, square surface which resulted in smooth, clean finished masonry. The blocks were very durable and most structures made from them have remained In a very good state of preservation.

Most early “exposed aggregate” buildings used a single colour of aggregate for the main wall masonry sections, but incorporated some form of the “imitation stone” blocks for accent areas such as quoins and window surrounds. Later, the “exposed aggregate” blocks were used for almost ail masonry surfaces, but different colours of aggregate blocks were used for accent areas.

In 1921, Harry Boyd began to develop a variation of the “exposed aggregate” block which would result In a unique type of masonry pattern. The new blocks were made in a variety of square and rectangular shapes ranging in size from 4″ by 4″, up to 12″ by 12″ In multiples of 4 inches in width and height”.[7] These blocks were used to form the “broken ashlar pattern” of masonry work which became very popular after its introduction.[8] It is the style of masonry which has become most recognizable as a product of the Boyd factory. This block pattern was well suited for use on houses that required smooth surfaces, but which would be enhanced by a variation of colour and pattern similar to that of natural fieldstone.

The first “broken ashlar pattern” house in Osgoode is said to be a Tudor Revival house at 5494 Main Street, built in 1937. A detail photograph of the house, shows the use of several different greys on the face sides of the blocks. The more distant photograph, illustrates how the various sizes and colours of blocks contribute to a fieldstone-like appearance suited to this Tudor style house.

In later years, the factory abandoned its wide selection of coloured “exposed aggregate” blocks, partly because it was becoming economically unfeasible to produce the blocks because of the labour involved.[9] Also, in later years, the blocks became less popular for domestic architecture, and commercial buildings did not require blocks with such decorative surfaces. By the 1960s, most of the blocks produced at the factory were of the smooth surfaced type which we generally associate with modern concrete blocks.

Footnotes:

1. Ann Gillespie. “Early Development of the Artistic Concrete Block”,
APT Bulletin, Vol. XI, No. 2 (1979), p. 42.

2. ibid, p. 36.

3. Oscar Kingston, “Boyd Bros: 1907-1973.” (unpublished essay). Boyd File – archives of Osgoode Township Museum). p. 2.

4. PAC File: MG 26. III. 71. Vol. 1.5. — EXPENSES — Entry for 1920.

5. ibid.

6. Kingston, p.2.

7. ibid, p.2.

8. ibid, p.2.

9. ibid, p.4