Authorization for Use of High-Silica Content Cement
- The use of high-silica content cement in certain public works is authorized upon recommendation by the Director of Public Works and the Secretary of Public Works and Communications.
- The objective is to enhance durability and cost-effectiveness of public works.
Composition Requirements for High-Silica Content Cement
- The cement must be produced by inter-grinding Portland cement clinker with a pozzolanic material containing at least 50% silica.
- The pozzolanic material should be dehydrated and calcined at an appropriate temperature before grinding.
- Gypsum addition is allowed before or during grinding to regulate the cement properties.
Chemical Composition Limits
- The cement must not exceed the following chemical limits:
- Loss on ignition: 5.00%
- Sulphuric anhydride: 2.00%
- Magnesia: 5.00%
Physical Property Requirements
- Fineness: At least 85% of the cement must pass through a standard 325-mesh sieve.
- Tensile Strength: Average tensile strength of mortar briquettes (1 part cement to 3 parts Standard Ottawa sand by weight) tested at specified ages must meet or exceed:
- 300 psi at 7 days (1 day moist air storage, 6 days water storage)
- 400 psi at 28 days (1 day moist air storage, 27 days water storage)
- No strength retrogression is permitted between 7 and 28 days.
Repeal of Previous Executive Orders
- Executive Orders Nos. 75 (1912), 19 (1918), and 367 (1932) are repealed to the extent that they conflict with this order.
Legal Authority and Effectivity
- The amendment is ordered by the President of the Philippines, Manuel L. Quezon, under his lawful powers.
- The order was issued on August 30, 1937, in Manila, during the second year of the Philippine Commonwealth.
- The Secretary of the Interior, Elpidio Quirino, countersigned the order, signifying official enactment.