Retracing the history of the Lincoln Memorial Reflecting Pool
The Lincoln Memorial is an American national monument built to honor the 16th President of the United States, Abraham Lincoln. It is located on the National Mall in Washington D.C. across from the Washington Monument. The architect was Henry Bacon and the sculptor of the primary statue – Abraham Lincoln, 1920 – was Daniel Chester French. Dedicated in 1922, it is one of several monuments to a US president.
The building is in the form of a Greek Doric temple and contains a large seated sculpture of Abraham Lincoln and inscriptions of well-known speeches by Lincoln. The Lincoln Memorial Reflecting Pool, Washington’s largest, is situated right next to the monument. The reflecting pool is long and can be seen in countless photographs of the Washington Monument. With paths and trees on both sides, it is a popular place for exercisers. Reflections of both the Washington Monument and the Lincoln Memorial can be seen in the water.
Famous events at Lincoln Memorial
Located right in front of the Lincoln Memorial, the reflecting pool has witnessed many famous events. In 1939, singer Marian Anderson was not allowed to perform in the Constitution Hall in Washington on grounds of her race. Instead, she sang on the steps of the Lincoln Memorial on Easter Sunday. Over 75,000 people went to the reflecting pool area to hear her. President Franklin D. Roosevelt and his wife Eleanor helped make her concert at the Lincoln Memorial possible.
In 1963, the March on Washington for Jobs and Freedom held a large Civil Rights rally around the reflecting pool. This was where Martin Luther King gave his "I Have a Dream" speech to a quarter million people standing around and in the reflecting pool.
113.6 billion litres of the city’s potable water each year
The reflecting pool is exactly on the west side of the National Mall. It is about 618 m long and 51 m wide, around 46 cm deep on the sides and 76 cm deep in the middle.
Completed in 1924 and demolished in 2009, it held 25.5 billion litres of water, much of which evaporated or continually leaked from the pool. More than 113.6 billion litres of the city’s potable water were needed each year to replenish the old pool, which became cracked and fragile over the years.
Unstable subgrade gets after 90 years
It was built with an asphalt and tile bottom on poorly supported soil, consisting primarily of marshes. The unstable subgrade had deflected 30.5 cm over the past 90 years under the pressure exerted by the reflecting pool above. In 1980, a new concrete slab was poured over the existing one, but the added weight simply worsened the soil settlement, causing subsequent leakage.
Durability, shrinkage and water tightness - pool structure stabilization
It was imperative to stabilize the subgrade and to minimize the settlement potential to the new reflecting pool structure. A watertight concrete mix design by Sika US was required to meet all the project specifications for durability, shrinkage and water tightness. To ensure the water tightness of the entire project, a cost effective and efficient joint sealing system was also needed.
To stabilize the pool, 2,133 timber piles were driven into the bedrock to provide more stable support. The concrete specifications called for a highly durable, watertight concrete, with minimal shrinkage. And so the reflecting pool is poised to add to an already rich history of unforgettable events, as locals and guests alike meanwhile enjoy their morning sports and evening work-outs in the surrounding park.