With reference to Mr. G. P. Wilson's memo dated November 8th, 1976 and subsequent discussion, a series of laboratory trial tests were carried out using different cement factors and dosages of set-accelerator in order to obtain a strength of 1000 psi at 7 to 9 hours. It was also decided to try using a superplasticizer to cut the water requirement of the mix and thus producing a high early strength concrete. The following materials were used in all the evaluation tests: (a) Type-30, High Early Strength Cement from Canada Lafarge Cement Co. (b) A 3/4" inch nominal size crushed dolomitic limestone from Nelson Quarry (Lab. Standard) with bulk specific gravity 2.66 and absorption 1.47 percent. (c) Sand (Lab. Standard) from Consolidated Sand and Gravel Co. Ltd., Guelph, Ontario (Pickering Plant) with bulk specific gravity 2.65 and absorption 0.63 percent and FM-2.66. (d) Sufficient air entraining admixture Darex (Lab. No. 501-76) to product 6 plus or minus 1% air in the concrete. (e) Darex Set Accelerator of various dosages as described in this report. (f) Superplasticizer "Melment L-10" was used in some of the test mixes as described in this report. It would appear that: (a) A set accelerating effect and increase in strength are obtained by increasing the dosage of the admixture "Darex set accelerator". (b) The desired early strength of 1000 psi can be achieved with a cement factor of 700 lbs. and 1.5 lb. of Darex Set Accelerator per 100 lb. of cement at 7-1/2 hour under laboratory conditions. (c) The 6 hour strength of Melment modified 800 lb. cement factor concrete was significantly lower than that with Darex Accelerator. However considerably higher strength was achieved at 12 hours. (d) The temperature rise characteristics of all test mixes were normal and comparable to the control concrete. On the basis of these observations and test results it is recommended that the concrete with 700 lb. cement factor and 2 lb. of Darex Set Accelerator per 100 lb. of cement be used in order to produce the desired strength under field conditions. (Author)

  • Corporate Authors:

    Ontario Ministry of Transportation & Communic, Can

    Engineering Materials Office, 1201 Wilson Avenue
    Downsview, ONo M3M 1J8,   Canada 
  • Authors:
    • Mukherjee, P K
  • Publication Date: 1977-3

Media Info

  • Features: Appendices; Figures; Tables;
  • Pagination: 12 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00335531
  • Record Type: Publication
  • Report/Paper Numbers: EM-3
  • Files: TRIS
  • Created Date: Nov 23 1981 12:00AM