Surprising and new explanations about superior older recipes for concrete

For a few years I have been collecting data about fibers in cement, various admixtures  and how the Romans created such long lasting concrete.   Here is some info about how the Hoover dam was constructed and for old Amish  builders etc.    Check this out and  try to incorporate with all the other new info.

the summary from Youtube:

The Portland Cement Association quietly phased out pozzolan additives after the American Society for Testing and Materials standardized modern cement in 1940 with a built-in fifty-year lifespan.
USDA Farmers' Bulletin 1772, published in 1937 by agricultural engineer Howard P. Mathewson, documented the exact burn-and-mix method using kaolin clay.

This video shows the exact eight-percent ratio the Amish use: six pounds of kaolin clay per eighty-pound bag of Portland cement, mixed dry before adding sand and water, plus the slurry wash method that seals existing cracked concrete from the inside using a one-to-one-to-four ratio of lime to clay to water brushed in with a stiff broom.