Amalia de Fortabat, 90, Dies Bill Cunningham/The New York Times The Argentine philanthropist Amalia Lacroze de Fortabat in New York City with Oscar de la Renta in June 2004. Amalia Lacroze de Fortabat, who vaulted to fame after her scandalous marriage to a cement tycoon, then expanded his empire after his death and became a major art collector and philanthropist as well as the richest woman in Argentina, died on Saturday at her home in Buenos Aires. She was 90. Her family announced her death. Mrs. Fortabat was married to another man when the cement mogul Alfredo Fortabat, 27 years her senior and also married, asked her to dance. As he recounted the story to biographers, he had followed her to Paris from Argentina to ask that question. She said yes. He told her he loved her. They traveled through France, Italy and the Aegean. He asked her to marry him. She said yes again. The romance was the talk of Buenos Aires. Soon, two divorces ensued, at a time when that was not easily done in heavily Roman Catholic Argentina. They were married in Uruguay in 1947 and reaffirmed their vows in ceremonies four more times. Mr. Fortabat died of a stroke in 1976 at the age of 81, leaving Mrs. Fortabat with a cement conglomerate, more than a million acres of ranchland, 170,000 head of cattle, three airplanes, a helicopter, a yacht and real estate around the world, including a 14-room duplex in the Pierre hotel in Manhattan. After a period of mourning, Mrs. Fortabat went to work managing the company, Loma Negra, Argentina's biggest supplier of cement and concrete. She became known as the "Dama del Cemento" - the cement lady. She won government contracts from the military dictatorship of the 1970s to build dams, roads and stadiums while tripling the company's assets. Before long it had captured three-quarters of the nation's cement business. "I went to work as if I understood everything," she said. And, finally, I understood very well. She amassed a fortune estimated at $1.8 billion, though America Economia, a Latin American business magazine, now lists it as $902 million. Still, it made her the third-richest person in Argentina and the richest woman there at her death. As a businesswoman, she diversified into fields like banks, a newspaper, a radio station and an 1,800-mile railroad. As a volunteer public servant, she was appointed Argentina's roving ambassador-at-large and president of the National Arts Foundation. As a philanthropist, she gave many millions to various causes, including the arts, the veterans of Argentina's war with England over the Falkland Islands and refugees from the war in Kosovo in 1999. As a socialite in Argentina, New York and Europe, she was often photographed with friends like David Rockefeller and Henry Kissinger. As a patron of the arts, Mrs. Fortabat paid $6.4 million in 1980 for J. M. W. Turner's painting "Juliet and Her Nurse," at the time a record price for a painting sold at auction. In 2008, she built Museo Fortabat, a modernist museum in Buenos Aires designed by Rafael Viñoly to house her large and much admired art collection. It includes a portrait Andy Warhol did of her in the style of his Marilyn Monroe prints. Maria Amalia Lacroze de los Reyes Oribe was born in Buenos Aires on Aug. 15, 1921. Her grandfather had established the city's first streetcar line, and an ancestor was the first president of Uruguay. Known as Amalita, she moved to Paris when she was a year old. Her first language was French, and her second was English. When she was 14, she said, a fortuneteller revealed her future: "You'll marry a maharaja." In 1942 she married a lawyer, Hernan Saenz Valiente Lafuente. They had a daughter, Maria Inez de Lafuente, who survives her, along with three grandchildren. Amalita was at the theater with Mr. Lafuente, her fiancé at the time, when she met Mr. Fortabat in 1941. He invited them to sail on his yacht, the Tigre Fortabat, but said he could not bear to go to their wedding. Five years later he followed the couple to Paris to ask Mr. Lafuente's wife to dance. In recent years, Mrs. Fortabat had respiratory problems and repeated hip replacements. In 2002, she sold some paintings, including a Degas for $16.5 million. She sold the cement company to a Brazilian buyer for $1.025 billion in 2005. Last year, she sold the duplex at the Pierre for $19.5 million. For all the uproar that her divorce and marriage caused in the 1940s, Mrs. Fortabat was scandalized herself in 1997 during a literary contest that her Fortabat Foundation was sponsoring. A jury had decided to give the prize to "The Anatomist" (1998), a novel by Federico Andahazi that tells of a scientist who studies clitorises, first by examining corpses, then prostitutes. Mrs. Fortabat did not approve. She bought a newspaper ad saying the subject matter did not "contribute to the exaltation of the highest values of the human spirit." In the end, she agreed to give Mr. Andahazi the $15,000 award that went with the prize but not the prize itself. Mr. Andahazi, who is also from Argentina, said he had chuckled at first but then felt something else, telling The New York Times, "Being pitted against the most powerful woman in Argentina sent a shudder down my spine."